From c85b624d28564a6f785b25000e2b7825592a919d Mon Sep 17 00:00:00 2001
From: Joel Klinghed <the_jk@yahoo.com>
Date: Tue, 26 Sep 2017 20:09:31 +0200
Subject: Initial commit

---
 .gitignore          |   1 +
 meson.build         |  48 +++
 meson_options.txt   |   1 +
 src/args.cc         | 323 +++++++++++++++++++
 src/args.hh         |  64 ++++
 src/clock.cc        |  24 ++
 src/clock.hh        |  13 +
 src/common.hh       |  10 +
 src/fake_monitor.cc | 191 ++++++++++++
 src/fake_monitor.hh |  11 +
 src/io.cc           | 167 ++++++++++
 src/io.hh           |  87 ++++++
 src/looper.cc       |  10 +
 src/looper.hh       |  31 ++
 src/main.cc         | 872 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/monitor.cc      | 410 ++++++++++++++++++++++++
 src/monitor.hh      |  62 ++++
 src/poll_looper.cc  | 249 +++++++++++++++
 src/poll_looper.hh  |  15 +
 src/x.cc            | 312 +++++++++++++++++++
 src/x.hh            | 255 +++++++++++++++
 21 files changed, 3156 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 meson.build
 create mode 100644 meson_options.txt
 create mode 100644 src/args.cc
 create mode 100644 src/args.hh
 create mode 100644 src/clock.cc
 create mode 100644 src/clock.hh
 create mode 100644 src/common.hh
 create mode 100644 src/fake_monitor.cc
 create mode 100644 src/fake_monitor.hh
 create mode 100644 src/io.cc
 create mode 100644 src/io.hh
 create mode 100644 src/looper.cc
 create mode 100644 src/looper.hh
 create mode 100644 src/main.cc
 create mode 100644 src/monitor.cc
 create mode 100644 src/monitor.hh
 create mode 100644 src/poll_looper.cc
 create mode 100644 src/poll_looper.hh
 create mode 100644 src/x.cc
 create mode 100644 src/x.hh

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..42afabf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/build
\ No newline at end of file
diff --git a/meson.build b/meson.build
new file mode 100644
index 0000000..c61b6f7
--- /dev/null
+++ b/meson.build
@@ -0,0 +1,48 @@
+project('monmon', 'cpp',
+        version: '0.1',
+        default_options: ['cpp_std=c++11'])
+
+cpp_optional_flags = ['-fno-rtti', '-fno-exceptions',
+                      '-fvisibility=hidden',
+                      '-Wall', '-Wextra',
+                      '-Wno-missing-field-initializers',
+                      '-Wno-maybe-uninitialized']
+cpp_flags = ['-DHAVE_CONFIG_H']
+if get_option('buildtype') == 'release'
+  # If asserts are disabled parameters and variables used for only that
+  # end up causing warnings
+  cpp_optional_flags += ['-Wno-unused-parameter', '-Wno-unused-variable']
+  cpp_flags += '-DNDEBUG'
+endif
+cpp = meson.get_compiler('cpp')
+foreach flag : cpp_optional_flags
+  if cpp.has_argument(flag)
+    cpp_flags += flag
+  endif
+endforeach
+add_global_arguments(cpp_flags, language: 'cpp')
+
+conf = configuration_data()
+conf.set('VERSION', '"' + meson.project_version() + '"')
+conf.set10('FAKE_MONITOR', get_option('fake_monitor'))
+
+xcb_deps = [dependency('xcb', version : '>= 1.10'),
+            dependency('xcb-image', version : '>= 0.3.8'),
+            dependency('xcb-event', version : '>= 0.3.8'),
+            dependency('xcb-ewmh', version : '>= 0.3.8'),
+            dependency('xcb-keysyms', version : '>= 0.3.8'),
+            dependency('xcb-icccm', version : '>= 0.3.8')]
+dep_cairo = dependency('cairo-xcb', version : '>= 1.12.0')
+dep_pango = dependency('pangocairo', version : '>= 1.40.0')
+dep_icecc = dependency('icecc', version : '>= 1.1')
+dep_thread = dependency('threads')
+
+configure_file(output: 'config.h',
+               configuration: conf)
+
+executable('monmon',
+           sources: ['src/main.cc', 'src/x.cc', 'src/args.cc',
+                     'src/poll_looper.cc', 'src/looper.cc', 'src/clock.cc',
+                     'src/io.cc', 'src/monitor.cc', 'src/fake_monitor.cc'],
+           dependencies: [dep_thread, dep_pango, dep_cairo, dep_icecc,
+                          xcb_deps])
diff --git a/meson_options.txt b/meson_options.txt
new file mode 100644
index 0000000..2331695
--- /dev/null
+++ b/meson_options.txt
@@ -0,0 +1 @@
+option('fake_monitor', type: 'boolean', value: false, description: 'Connect to a fake monitor to keeps generating job events')
diff --git a/src/args.cc b/src/args.cc
new file mode 100644
index 0000000..9b3e409
--- /dev/null
+++ b/src/args.cc
@@ -0,0 +1,323 @@
+#include "common.hh"
+
+#include <string.h>
+#include <string>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <unordered_map>
+#include <vector>
+
+#include "args.hh"
+
+namespace {
+
+bool is_space(std::string const& str, size_t offset) {
+  return str[offset] == ' ' || str[offset] == '\t' || str[offset] == '\n';
+}
+
+bool is_separator(std::string const& str, size_t offset) {
+  return !((str[offset] >= '0' && str[offset] <= '9')
+           || (str[offset] >= 'a' && str[offset] <= 'z')
+           || (str[offset] >= 'A' && str[offset] <='Z'));
+}
+
+class ArgsImpl : public Args {
+public:
+  ArgsImpl()
+    : good_(true) {
+  }
+  void add(char short_opt, std::string const& long_opt,
+           std::string const& argument, std::string const& help) override {
+    assert(short_opt == '\0' || short_opts_.count(short_opt) == 0);
+    assert(long_opt.empty() || long_opts_.count(long_opt) == 0);
+    assert(long_opt.find('=') == std::string::npos);
+    auto const index = opts_.size();
+    opts_.push_back(Option(short_opt, long_opt, argument, help));
+    if (short_opt != '\0') {
+      short_opts_.insert(std::make_pair(short_opt, index));
+    }
+    if (!long_opt.empty()) {
+      long_opts_.insert(std::make_pair(long_opt, index));
+    }
+  }
+
+  bool run(int argc, char** argv, std::ostream& out) override {
+    if (argc == 0) {
+      assert(false);
+      good_ = false;
+      return false;
+    }
+    auto start = strrchr(argv[0], '/');
+    if (!start) {
+      start = argv[0];
+    } else {
+      start++;
+    }
+    return run(start, argc, argv, out);
+  }
+
+  bool run(std::string const& prg, int argc, char** argv, std::ostream& out)
+      override {
+    reset();
+
+    std::string opt;
+    for (int a = 1; a < argc; ++a) {
+      if (argv[a][0] == '-') {
+        if (argv[a][1] == '-') {
+          if (argv[a][2] == '\0') {
+            for (++a; a < argc; ++a) {
+              args_.push_back(argv[a]);
+            }
+            return good_;
+          }
+          size_t len = 2;
+          while (argv[a][len] && argv[a][len] != '=') ++len;
+          opt.assign(argv[a] + 2, len - 2);
+          auto i = long_opts_.find(opt);
+          if (i == long_opts_.end()) {
+            out << prg << ": unrecognized option '--" << opt << "'\n";
+            good_ = false;
+            continue;
+          }
+          if (argv[a][len] == '=') {
+            if (opts_[i->second].argument.empty()) {
+              out << prg << ": option '--" << opt << "'"
+                  << " doesn't allow an argument\n";
+              good_ = false;
+              continue;
+            } else {
+              opts_[i->second].values.push_back(argv[a] + len + 1);
+            }
+          } else {
+            if (opts_[i->second].argument.empty()) {
+              opts_[i->second].values.push_back("");
+            } else if (a + 1 == argc) {
+              out << prg << ": option '--" << opt << "'"
+                  << " requires an argument\n";
+              good_ = false;
+              continue;
+            } else {
+              opts_[i->second].values.push_back(argv[++a]);
+            }
+          }
+        } else {
+          for (auto opt = argv[a] + 1; *opt; ++opt) {
+            auto i = short_opts_.find(*opt);
+            if (i == short_opts_.end()) {
+              out << prg << ": invalid option -- '" << *opt << "'\n";
+              good_ = false;
+              continue;
+            }
+            if (opts_[i->second].argument.empty()) {
+              opts_[i->second].values.push_back("");
+            } else if (a + 1 == argc) {
+              out << prg << ": option requires an argument "
+                  << " -- '" << *opt << "'\n";
+              good_ = false;
+              continue;
+            } else {
+              opts_[i->second].values.push_back(argv[++a]);
+            }
+          }
+        }
+      } else {
+        args_.push_back(argv[a]);
+      }
+    }
+
+    return good_;
+  }
+  bool good() const override {
+    return good_;
+  }
+
+  bool is_set(char short_opt) const override {
+    return count(short_opt) > 0;
+  }
+  size_t count(char short_opt) const override {
+    auto i = short_opts_.find(short_opt);
+    if (i == short_opts_.end()) return 0;
+    return opts_[i->second].values.size();
+  }
+
+  bool is_set(std::string const& long_opt) const override {
+    return count(long_opt) > 0;
+  }
+  size_t count(std::string const& long_opt) const override {
+    auto i = long_opts_.find(long_opt);
+    if (i == long_opts_.end()) return 0;
+    return opts_[i->second].values.size();
+  }
+
+  char const* arg(char short_opt, char const* fallback) const override {
+    auto i = short_opts_.find(short_opt);
+    if (i == short_opts_.end()) return fallback;
+    if (opts_[i->second].values.empty()) return fallback;
+    if (opts_[i->second].argument.empty()) return fallback;
+    return opts_[i->second].values.back().c_str();
+  }
+
+  char const* arg(std::string const& long_opt,
+                  char const* fallback) const override {
+    auto i = long_opts_.find(long_opt);
+    if (i == long_opts_.end()) return fallback;
+    if (opts_[i->second].values.empty()) return fallback;
+    if (opts_[i->second].argument.empty()) return fallback;
+    return opts_[i->second].values.back().c_str();
+  }
+
+  bool args(char short_opt, std::vector<std::string>* out) const override {
+    auto i = short_opts_.find(short_opt);
+    if (i == short_opts_.end()) return false;
+    if (opts_[i->second].values.empty()) return false;
+    if (opts_[i->second].argument.empty()) return false;
+    if (out) {
+      *out = opts_[i->second].values;
+    }
+    return true;
+  }
+
+  bool args(std::string const& long_opt,
+            std::vector<std::string>* out) const override {
+    auto i = long_opts_.find(long_opt);
+    if (i == long_opts_.end()) return false;
+    if (opts_[i->second].values.empty()) return false;
+    if (opts_[i->second].argument.empty()) return false;
+    if (out) {
+      *out = opts_[i->second].values;
+    }
+    return true;
+  }
+
+  std::vector<std::string> const& arguments() const override {
+    return args_;
+  }
+
+  void print_help(std::ostream& out) const override {
+    struct winsize size;
+    memset(&size, 0, sizeof(size));
+    ioctl(STDOUT_FILENO, TIOCGWINSZ, &size);
+    if (size.ws_col == 0) {
+      print_help(out, 80);
+    } else {
+      print_help(out, size.ws_col);
+    }
+  }
+
+  void print_help(std::ostream& out, size_t width) const override {
+    size_t left = 0;
+    for (auto const& opt : opts_) {
+      size_t l = 0;
+      if (!opt.long_opt.empty()) {
+        l += 6 + opt.long_opt.size();
+      } else if (opt.short_opt != '\0') {
+        l += 2;
+      } else {
+        continue;
+      }
+      if (!opt.argument.empty()) {
+        l += 1 + opt.argument.size();
+      }
+      if (l > left) left = l;
+    }
+
+    size_t const need = 2 + 2 + left;
+    if (need + 10 > width) {
+      width = need + 10;
+    }
+    size_t const right = width - need;
+
+    for (auto const& opt : opts_) {
+      size_t i = 0;
+      if (!opt.long_opt.empty()) {
+        if (opt.short_opt != '\0') {
+          out << "  -" << opt.short_opt << ", ";
+        } else {
+          out << "      ";
+        }
+        out << "--" << opt.long_opt;
+        i += 8 + opt.long_opt.size();
+      } else if (opt.short_opt != '\0') {
+        out << "  -" << opt.short_opt;
+        i += 4;
+      } else {
+        continue;
+      }
+      if (!opt.argument.empty()) {
+        out << '=' << opt.argument;
+        i += 1 + opt.argument.size();
+      }
+      pad(out, need - i);
+      if (opt.help.size() < right) {
+        out << opt.help << '\n';
+      } else {
+        i = right;
+        while (i > 0 && !is_separator(opt.help, i)) --i;
+        if (i == 0) i = right;
+        out << opt.help.substr(0, i) << '\n';
+        while (true) {
+          while (i < opt.help.size() && is_space(opt.help, i)) ++i;
+          if (i == opt.help.size()) break;
+          size_t j = right - 2;
+          pad(out, width - j);
+          if (i + j >= opt.help.size()) {
+            out << opt.help.substr(i) << '\n';
+            break;
+          }
+          while (j > 0 && !is_separator(opt.help, i + j)) --j;
+          if (j == 0) j = right - 2;
+          out << opt.help.substr(i, j) << '\n';
+          i += j;
+        }
+      }
+    }
+  }
+
+private:
+  struct Option {
+    char const short_opt;
+    std::string const long_opt;
+    std::string const argument;
+    std::string const help;
+
+    std::vector<std::string> values;
+
+    Option(char short_opt, std::string const& long_opt,
+           std::string const& argument, std::string const& help)
+      : short_opt(short_opt), long_opt(long_opt), argument(argument),
+        help(help) {
+    }
+  };
+  bool good_;
+  std::unordered_map<char, size_t> short_opts_;
+  std::unordered_map<std::string, size_t> long_opts_;
+  std::vector<Option> opts_;
+  std::vector<std::string> args_;
+
+  void reset() {
+    good_ = true;
+    args_.clear();
+    for (auto& opt : opts_) {
+      opt.values.clear();
+    }
+  }
+
+  static void pad(std::ostream& out, size_t count) {
+    while (count > 4) {
+      out << "    ";
+      count -= 4;
+    }
+    while (count) {
+      out << ' ';
+      --count;
+    }
+  }
+};
+
+}  // namespace
+
+// static
+Args* Args::create() {
+    return new ArgsImpl();
+}
+
diff --git a/src/args.hh b/src/args.hh
new file mode 100644
index 0000000..7f6d94b
--- /dev/null
+++ b/src/args.hh
@@ -0,0 +1,64 @@
+#ifndef ARGS_HH
+#define ARGS_HH
+
+#include <iostream>
+#include <string>
+#include <vector>
+
+class Args {
+public:
+  virtual ~Args() {}
+
+  static Args* create();
+
+  virtual void add(char short_opt, std::string const& long_opt,
+                   std::string const& argument, std::string const& help) = 0;
+  void add(char short_opt, std::string const& long_opt,
+           std::string const& help) {
+    add(short_opt, long_opt, "", help);
+  }
+  void add(std::string const& long_opt, std::string const& help) {
+    add('\0', long_opt, "", help);
+  }
+  void add(std::string const& long_opt, std::string const& argument,
+           std::string const& help) {
+    add('\0', long_opt, argument, help);
+  }
+
+  bool run(int argc, char** argv) {
+    return run(argc, argv, std::cerr);
+  }
+  virtual bool run(int argc, char** argv, std::ostream& out) = 0;
+  bool run(std::string const& prg, int argc, char** argv) {
+    return run(prg, argc, argv, std::cerr);
+  }
+  virtual bool run(
+      std::string const& prg, int argc, char** argv, std::ostream& out) = 0;
+  virtual bool good() const = 0;
+
+  virtual bool is_set(char short_opt) const = 0;
+  virtual bool is_set(std::string const& long_opt) const = 0;
+  virtual char const* arg(char short_opt, char const* fallback) const = 0;
+  virtual char const* arg(std::string const& long_opt,
+                          char const* fallback) const = 0;
+  virtual size_t count(char short_opt) const = 0;
+  virtual size_t count(std::string const& long_opt) const = 0;
+  virtual bool args(char short_opt, std::vector<std::string>* out) const = 0;
+  virtual bool args(std::string const& long_opt,
+                    std::vector<std::string>* out) const = 0;
+
+  virtual std::vector<std::string> const& arguments() const = 0;
+
+  void print_help() const {
+    print_help(std::cout);
+  }
+  virtual void print_help(std::ostream& out) const = 0;
+  virtual void print_help(std::ostream& out, size_t width) const = 0;
+
+protected:
+  Args() {}
+  Args(Args const&) = delete;
+  Args& operator=(Args const&) = delete;
+};
+
+#endif  // ARGS_HH
diff --git a/src/clock.cc b/src/clock.cc
new file mode 100644
index 0000000..c6b5cc8
--- /dev/null
+++ b/src/clock.cc
@@ -0,0 +1,24 @@
+#include "common.hh"
+
+#include <chrono>
+#include <thread>
+
+#include "clock.hh"
+
+namespace clk {
+
+double system() {
+  return std::chrono::duration_cast<std::chrono::duration<double>>(
+      std::chrono::system_clock::now().time_since_epoch()).count();
+}
+
+double steady() {
+  return std::chrono::duration_cast<std::chrono::duration<double>>(
+      std::chrono::steady_clock::now().time_since_epoch()).count();
+}
+
+void sleep(double dur) {
+  std::this_thread::sleep_for(std::chrono::duration<double>(dur));
+}
+
+}  // namespace clock
diff --git a/src/clock.hh b/src/clock.hh
new file mode 100644
index 0000000..48f20bd
--- /dev/null
+++ b/src/clock.hh
@@ -0,0 +1,13 @@
+#ifndef CLOCK_HH
+#define CLOCK_HH
+
+namespace clk {
+
+double system();
+double steady();
+
+void sleep(double dur);
+
+}  // namespace clk
+
+#endif  // CLOCK_HH
diff --git a/src/common.hh b/src/common.hh
new file mode 100644
index 0000000..14d9a2a
--- /dev/null
+++ b/src/common.hh
@@ -0,0 +1,10 @@
+#ifndef COMMON_HH
+#define COMMON_HH
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <assert.h>
+
+#endif  // COMMON_HH
diff --git a/src/fake_monitor.cc b/src/fake_monitor.cc
new file mode 100644
index 0000000..ebdc79b
--- /dev/null
+++ b/src/fake_monitor.cc
@@ -0,0 +1,191 @@
+#include "common.hh"
+
+#include <vector>
+#include <unordered_map>
+
+#include "fake_monitor.hh"
+#include "looper.hh"
+
+namespace {
+
+class FakeMonitorImpl : public Monitor {
+public:
+  explicit FakeMonitorImpl(std::shared_ptr<Looper> const& looper)
+    : looper_(looper), timer_(0), host_id_(0), job_id_(0), max_jobs_(0) {
+  }
+
+  ~FakeMonitorImpl() override {
+    disconnect();
+  }
+
+  void connect(std::string const&, std::string const&,
+               uint16_t) override {
+    disconnect();
+
+    timer_ = looper_->schedule(
+        (rand() % 500) / 1000.0,
+        std::bind(&FakeMonitorImpl::fake_connect, this,
+                  std::placeholders::_1,
+                  std::placeholders::_2));
+  }
+
+  void disconnect() override {
+    if (timer_) {
+      looper_->cancel(timer_);
+      timer_ = 0;
+    }
+    machines_.clear();
+    for (auto* observer : observers_) {
+      observer->state(this, SEARCHING);
+    }
+  }
+
+  size_t machines() const override {
+    return machines_.size();
+  }
+
+  uint32_t id(size_t index) const override {
+    auto it = machines_.begin();
+    while (index--) ++it;
+    if (it == machines_.end()) {
+      assert(false);
+      return static_cast<uint32_t>(-1);
+    }
+    return it->first;
+  }
+
+  Machine machine_at(size_t index) const override {
+    auto it = machines_.begin();
+    while (index--) ++it;
+    if (it == machines_.end()) {
+      assert(false);
+      return Machine();
+    }
+    return it->second.data;
+  }
+
+  Machine machine(uint32_t id) const override {
+    auto it = machines_.find(id);
+    if (it == machines_.end()) {
+      assert(false);
+      return Machine();
+    }
+    return it->second.data;
+  }
+
+  void add_observer(Observer* observer) override {
+    assert(observer);
+    observers_.push_back(observer);
+  }
+
+private:
+  struct Job {
+    uint32_t const host;
+    uint32_t const worker;
+
+    Job(uint32_t host, uint32_t worker)
+      : host(host), worker(worker) {
+    }
+  };
+  struct Entry {
+    Machine data;
+    unsigned active;
+  };
+
+  void fake_connect(Looper*, uint32_t) {
+    timer_ = 0;
+
+    for (auto* observer : observers_) {
+      observer->state(this, CONNECTED);
+    }
+
+    add_machine("alice", 4);
+    add_machine("bob", 10);
+    add_machine("DeuX", 22);
+
+    schedule_jobs();
+  }
+
+  void add_machine(std::string const& name, unsigned max_jobs) {
+    auto id = ++host_id_;
+    auto& entry = machines_[id];
+    entry.data.name = name;
+    entry.data.max_jobs = max_jobs;
+    entry.active = 0;
+    max_jobs_ += max_jobs;
+
+    for (auto* observer : observers_) {
+      observer->added_machine(this, id);
+    }
+  }
+
+  void schedule_jobs() {
+    assert(timer_ == 0);
+    timer_ = looper_->schedule(
+        (rand() % 2000) / 1000.0,
+        std::bind(&FakeMonitorImpl::fiddle_jobs, this,
+                  std::placeholders::_1,
+                  std::placeholders::_2));
+  }
+
+  void fiddle_jobs(Looper*, uint32_t) {
+    timer_ = 0;
+
+    auto remove = !jobs_.empty() ? rand() % jobs_.size() : 0;
+    while (remove--) {
+      auto it = jobs_.begin();
+      auto job = it->second;
+      jobs_.erase(it);
+      machines_[job.worker].active--;
+      for (auto* observer : observers_) {
+        observer->removed_job(this, job.host, job.worker);
+      }
+    }
+
+    auto avail = (max_jobs_ * 7) / 8 - jobs_.size();
+    auto add = avail ? rand() % avail : 0;
+    while (add--) {
+      auto id = ++job_id_;
+      while (jobs_.count(id)) {
+        id = ++job_id_;
+      }
+      auto host = rand() % machines_.size();
+      auto target = rand() % machines_.size();
+      do {
+        auto tgtid = this->id(target);
+        auto& entry = machines_[tgtid];
+        if (entry.active < entry.data.max_jobs) {
+          entry.active++;
+          add_job(id, host != target ? this->id(host) : tgtid, tgtid);
+          break;
+        }
+        target = rand() % machines_.size();
+      } while (true);
+    }
+
+    schedule_jobs();
+  }
+
+  void add_job(uint32_t job_id, uint32_t host, uint32_t worker) {
+    jobs_.insert(std::make_pair(job_id, Job(host, worker)));
+    for (auto* observer : observers_) {
+      observer->added_job(this, host, worker);
+    }
+  }
+
+  std::shared_ptr<Looper> looper_;
+  uint32_t timer_;
+  uint32_t host_id_;
+  uint32_t job_id_;
+  size_t max_jobs_;
+  std::unordered_map<uint32_t, Entry> machines_;
+  std::vector<Observer*> observers_;
+  std::unordered_map<uint32_t, Job> jobs_;
+};
+
+}  // namespace
+
+// static
+Monitor* FakeMonitor::create(std::shared_ptr<Looper> const& looper) {
+  return new FakeMonitorImpl(looper);
+}
diff --git a/src/fake_monitor.hh b/src/fake_monitor.hh
new file mode 100644
index 0000000..836e082
--- /dev/null
+++ b/src/fake_monitor.hh
@@ -0,0 +1,11 @@
+#ifndef FAKE_MONITOR_HH
+#define FAKE_MONITOR_HH
+
+#include "monitor.hh"
+
+class FakeMonitor : public Monitor {
+public:
+  static Monitor* create(std::shared_ptr<Looper> const& looper);
+};
+
+#endif  // FAKE_MONITOR_HH
diff --git a/src/io.cc b/src/io.cc
new file mode 100644
index 0000000..bc70eee
--- /dev/null
+++ b/src/io.cc
@@ -0,0 +1,167 @@
+#include "common.hh"
+
+#include <errno.h>
+#include <unistd.h>
+
+#include "io.hh"
+
+namespace {
+
+bool do_read(int fd, void* dst, size_t max, size_t* got) {
+  auto d = reinterpret_cast<char*>(dst);
+  size_t pos = 0;
+  while (true) {
+    auto ret = ::read(fd, d + pos, max - pos);
+    if (ret < 0) {
+      if (errno == EINTR) continue;
+      if (got && (errno == EAGAIN || errno == EWOULDBLOCK)) {
+        *got = pos;
+        return true;
+      }
+      return false;
+    }
+    if (ret == 0) {
+      if (got) {
+        *got = pos;
+        return true;
+      }
+      return false;
+    }
+    pos += ret;
+    if (got) {
+      *got = pos;
+      return true;
+    }
+    if (pos == max) {
+      return true;
+    }
+  }
+}
+
+bool do_write(int fd, void const* src, size_t size, size_t* wrote) {
+  auto s = reinterpret_cast<char const*>(src);
+  size_t pos = 0;
+  while (true) {
+    auto ret = ::write(fd, s + pos, size - pos);
+    if (ret < 0) {
+      if (errno == EINTR) continue;
+      if (wrote && (errno == EAGAIN || errno == EWOULDBLOCK)) {
+        *wrote = pos;
+        return true;
+      }
+      return false;
+    }
+    if (ret == 0) {
+      if (wrote) {
+        *wrote = pos;
+        return true;
+      }
+      return false;
+    }
+    pos += ret;
+    if (pos == size) {
+      if (wrote) *wrote = pos;
+      return true;
+    }
+  }
+}
+
+}  // namespace
+
+namespace io {
+
+pipe::pipe() {
+  fd_[0] = fd_[1] = -1;
+}
+
+pipe::pipe(pipe&& pipe) {
+  fd_[0] = pipe.fd_[0];
+  fd_[1] = pipe.fd_[1];
+  pipe.fd_[0] = -1;
+  pipe.fd_[1] = -1;
+}
+
+pipe::~pipe() {
+  reset();
+}
+
+bool pipe::open() {
+  reset();
+  if (::pipe(fd_) == 0) return true;
+  fd_[0] = fd_[1] = -1;
+  return false;
+}
+
+void pipe::reset() {
+  if (fd_[0] == -1) return;
+  ::close(fd_[0]);
+  ::close(fd_[1]);
+  fd_[0] = fd_[1] = -1;
+}
+
+void pipe::swap(pipe& pipe) {
+  auto x = pipe.fd_[0];
+  pipe.fd_[0] = fd_[0];
+  fd_[0] = x;
+  x = pipe.fd_[1];
+  pipe.fd_[1] = fd_[1];
+  fd_[1] = x;
+}
+
+unique_fd::unique_fd()
+  : fd_(-1) {
+}
+
+unique_fd::unique_fd(int fd)
+  : fd_(fd) {
+}
+
+unique_fd::unique_fd(unique_fd&& fd)
+  : fd_(fd.release()) {
+}
+
+unique_fd::~unique_fd() {
+  reset();
+}
+
+void unique_fd::reset() {
+  if (fd_ == -1) return;
+  ::close(fd_);
+  fd_ = -1;
+}
+
+void unique_fd::reset(int fd) {
+  if (fd_ == fd) return;
+  reset();
+  fd_ = fd;
+}
+
+void unique_fd::swap(unique_fd& fd) {
+  auto x = fd.fd_;
+  fd.fd_ = fd_;
+  fd_ = x;
+}
+
+int unique_fd::release() {
+  auto ret = fd_;
+  fd_ = -1;
+  return ret;
+}
+
+bool read(pipe const& pipe, void* dst, size_t max, size_t* got) {
+  return do_read(pipe.read(), dst, max, got);
+}
+
+bool write(pipe const& pipe, void const* src, size_t size, size_t* wrote) {
+  return do_write(pipe.write(), src, size, wrote);
+}
+
+bool read(unique_fd const& fd, void* dst, size_t max, size_t* got) {
+  return do_read(fd.get(), dst, max, got);
+}
+
+bool write(unique_fd const& fd, void const* src, size_t size, size_t* wrote) {
+  return do_write(fd.get(), src, size, wrote);
+}
+
+}  // namespace io
diff --git a/src/io.hh b/src/io.hh
new file mode 100644
index 0000000..abd91fa
--- /dev/null
+++ b/src/io.hh
@@ -0,0 +1,87 @@
+#ifndef IO_HH
+#define IO_HH
+
+#include <stddef.h>
+
+namespace io {
+
+class pipe {
+public:
+  pipe();
+  pipe(pipe&& pipe);
+  ~pipe();
+
+  pipe& operator=(pipe&& pipe) {
+    reset();
+    swap(pipe);
+    return *this;
+  }
+
+  bool open();
+  explicit operator bool() const {
+    return read() != -1;
+  }
+
+  void reset();
+
+  void swap(pipe& pipe);
+
+  int read() const {
+    return fd_[0];
+  }
+  int write() const {
+    return fd_[1];
+  }
+
+private:
+  pipe(pipe const&) = delete;
+  pipe& operator=(pipe const&) = delete;
+
+  int fd_[2];
+};
+
+class unique_fd {
+public:
+  unique_fd();
+  explicit unique_fd(int fd);
+  unique_fd(unique_fd&& fd);
+  ~unique_fd();
+
+  unique_fd& operator=(unique_fd&& fd) {
+    reset();
+    swap(fd);
+    return *this;
+  }
+
+  int get() const {
+    return fd_;
+  }
+
+  explicit operator bool() const {
+    return get() != -1;
+  }
+
+  void reset();
+  void reset(int fd);
+
+  void swap(unique_fd& fd);
+
+  int release();
+
+private:
+  unique_fd(unique_fd const& fd) = delete;
+  unique_fd& operator=(unique_fd const& fd) = delete;
+
+  int fd_;
+};
+
+bool read(pipe const& pipe, void* dst, size_t max, size_t* got = nullptr);
+bool write(pipe const& pipe, void const* src, size_t size,
+           size_t* wrote = nullptr);
+bool read(unique_fd const& fd, void* dst, size_t max, size_t* got = nullptr);
+bool write(unique_fd const& fd, void const* src, size_t size,
+           size_t* wrote = nullptr);
+
+}  // namespace
+
+#endif  // IO_HH
diff --git a/src/looper.cc b/src/looper.cc
new file mode 100644
index 0000000..0166c12
--- /dev/null
+++ b/src/looper.cc
@@ -0,0 +1,10 @@
+#include "common.hh"
+
+#include "looper.hh"
+
+// static
+uint8_t const Looper::EV_READ = 1 << 0;
+// static
+uint8_t const Looper::EV_WRITE = 1 << 2;
+// static
+uint8_t const Looper::EV_ERR = 1 << 3;
diff --git a/src/looper.hh b/src/looper.hh
new file mode 100644
index 0000000..4dfe56f
--- /dev/null
+++ b/src/looper.hh
@@ -0,0 +1,31 @@
+#ifndef LOOPER_HH
+#define LOOPER_HH
+
+#include <functional>
+
+class Looper {
+public:
+  virtual ~Looper() {}
+
+  static uint8_t const EV_READ;
+  static uint8_t const EV_WRITE;
+  static uint8_t const EV_ERR;
+
+  virtual void add(int fd, uint8_t events,
+                   std::function<void(Looper*, int, uint8_t)>
+                   const& callback) = 0;
+  virtual void modify(int fd, uint8_t events) = 0;
+  virtual void remove(int fd) = 0;
+
+  // Returned id is never 0
+  virtual uint32_t schedule(
+      double delay, std::function<void(Looper*, uint32_t)> const& callback) = 0;
+  virtual void cancel(uint32_t id) = 0;
+
+protected:
+  Looper() {}
+  Looper(Looper const&) = delete;
+  Looper& operator=(Looper const&) = delete;
+};
+
+#endif  // LOOPER_HH
diff --git a/src/main.cc b/src/main.cc
new file mode 100644
index 0000000..3cdb618
--- /dev/null
+++ b/src/main.cc
@@ -0,0 +1,872 @@
+#include "common.hh"
+
+#include <algorithm>
+#include <cairo-xcb.h>
+#include <iostream>
+#include <math.h>
+#include <mutex>
+#include <pango/pangocairo.h>
+#include <string.h>
+#include <thread>
+#include <xcb/xcb_event.h>
+#include <xcb/xcb_icccm.h>
+#include <xcb/xcb_keysyms.h>
+
+#include "args.hh"
+#include "fake_monitor.hh"
+#include "io.hh"
+#include "monitor.hh"
+#include "poll_looper.hh"
+#include "x.hh"
+
+namespace {
+
+struct CairoSurfaceDelete {
+  void operator()(cairo_surface_t* surface) const {
+    cairo_surface_destroy(surface);
+  }
+};
+
+struct CairoDelete {
+  void operator()(cairo_t* cairo) const {
+    cairo_destroy(cairo);
+  }
+};
+
+struct GObjectDelete {
+  void operator()(gpointer ptr) const {
+    g_object_unref(ptr);
+  }
+};
+
+struct PangoFontMetricsDelete {
+  void operator()(PangoFontMetrics* ptr) const {
+    pango_font_metrics_unref(ptr);
+  }
+};
+
+struct CairoPatternDelete {
+  void operator()(cairo_pattern_t* pattern) const {
+    cairo_pattern_destroy(pattern);
+  }
+};
+
+struct CairoPathDelete {
+  void operator()(cairo_path_t* path) const {
+    cairo_path_destroy(path);
+  }
+};
+
+struct MwmHints {
+  uint32_t flags;
+  uint32_t functions;
+  uint32_t decorations;
+  int32_t input_mode;
+  uint32_t status;
+};
+
+class MonMon : virtual Monitor::Observer {
+public:
+  explicit MonMon(std::shared_ptr<PollLooper> const& looper)
+    : looper_(looper), connected_(false), depth_(0), black_pixel_(0),
+      screen_(nullptr), max_jobs_(0), jobs_(0), requests_(0),
+      x_(0), y_(0), w_(0), h_(0),
+      rootpmap_(XCB_ATOM_NONE), desktop_window_(XCB_NONE),
+      desktop_pixmap_(XCB_NONE) {
+    pipe_.open();
+    looper_->add(pipe_.read(), Looper::EV_READ,
+                 std::bind(&MonMon::pipe, this, std::placeholders::_1,
+                           std::placeholders::_2, std::placeholders::_3));
+  }
+
+  ~MonMon() {
+    unset_desktop_window();
+    close_pipe();
+    wnd_.reset();
+  }
+
+  void init(x::shared_connection const& conn, xcb_screen_t const* screen,
+            x::Format format, std::shared_ptr<x::Atoms> const& atoms,
+            std::shared_ptr<x::Ewmh> const& ewmh,
+            uint16_t width, uint16_t height, bool normal, bool black) {
+    screen_ = screen;
+    wnd_.reset(conn);
+    pixmap_.reset(conn);
+    gcontext_.reset(conn);
+
+    uint32_t values[2];
+    values[0] = screen->black_pixel;
+    values[1] = XCB_EVENT_MASK_KEY_PRESS | XCB_EVENT_MASK_EXPOSURE
+      | XCB_EVENT_MASK_STRUCTURE_NOTIFY;
+    xcb_create_window(wnd_.conn(), format.depth,
+                      wnd_.get(), screen->root,
+                      0, 0, width, height, 0,
+                      XCB_WINDOW_CLASS_INPUT_OUTPUT,
+                      format.visual->visual_id,
+                      XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK,
+                      values);
+    if (!normal) {
+      if (atoms->get("_MOTIF_WM_INFO", false) != XCB_ATOM_NONE) {
+        auto atom = atoms->get("_MOTIF_WM_HINTS");
+        MwmHints hints;
+        hints.flags = 1 << 1;  // MWM_HINTS_DECORATIONS
+        hints.decorations = 0;
+        xcb_change_property(wnd_.conn(), XCB_PROP_MODE_REPLACE, wnd_.get(),
+                            atom, atom, 32, sizeof(hints) / 4, &hints);
+      } else {
+#ifndef NDEBUG
+        // There is no way to know how the window manager will implement
+        // utility window type, some might show them without titlebar ...
+        std::cerr << "Warning: No motif support detected, falling back to "
+                  << "NETWM utility window type." << std::endl;
+#endif
+        auto wm = ewmh->conn();
+        if (wm && ewmh->supported(wm->_NET_WM_WINDOW_TYPE_UTILITY)) {
+          xcb_atom_t values[1];
+          values[0] = wm->_NET_WM_WINDOW_TYPE_UTILITY;
+          xcb_ewmh_set_wm_window_type(wm, wnd_.get(), 1, values);
+        } else {
+          // TODO: Fallback to override-redirect?
+        }
+      }
+    }
+    if (!black) {
+      rootpmap_ = atoms->get("_XROOTPMAP_ID", false);
+      if (rootpmap_ == XCB_ATOM_NONE) {
+        std::cerr << "Warning: No support for Eterm style background pixmap"
+                  << std::endl;
+      }
+    }
+    xcb_create_gc(gcontext_.conn(), gcontext_.get(), wnd_.get(), 0, nullptr);
+    auto atom = atoms->get("WM_DELETE_WINDOW");
+    xcb_icccm_set_wm_protocols(wnd_.conn(), wnd_.get(),
+                               atoms->get("WM_PROTOCOLS"),
+                               1, &atom);
+    xcb_create_pixmap(pixmap_.conn(), format.depth, pixmap_.get(), wnd_.get(),
+                      width, height);
+    if (format.render) {
+      surface_.reset(
+          cairo_xcb_surface_create_with_xrender_format(
+              pixmap_.conn(),
+              const_cast<xcb_screen_t*>(screen),
+              pixmap_.get(),
+              format.render,
+              width, height));
+      if (cairo_surface_status(surface_.get()) != CAIRO_STATUS_SUCCESS) {
+        surface_.reset();
+      }
+    }
+    if (!surface_) {
+      surface_.reset(
+          cairo_xcb_surface_create(pixmap_.conn(), pixmap_.get(),
+                                   format.visual, width, height));
+    }
+    cairo_.reset(cairo_create(surface_.get()));
+    layout_.reset(pango_cairo_create_layout(cairo_.get()));
+    pango_layout_set_ellipsize(layout_.get(), PANGO_ELLIPSIZE_MIDDLE);
+    pango_layout_set_alignment(layout_.get(), PANGO_ALIGN_CENTER);
+    pango_layout_set_height(layout_.get(), 0);
+    auto context = pango_layout_get_context(layout_.get());
+    auto metrics = std::unique_ptr<PangoFontMetrics, PangoFontMetricsDelete>(
+        pango_context_get_metrics(context, nullptr, nullptr));
+    box_height_ = static_cast<double>(
+        pango_font_metrics_get_ascent(metrics.get()) +
+        pango_font_metrics_get_descent(metrics.get())) / PANGO_SCALE;
+    x_ = 0;
+    y_ = 0;
+    w_ = width;
+    h_ = height;
+    depth_ = format.depth;
+    black_pixel_ = screen->black_pixel;
+    update_desktop_window();
+    internal_draw();
+    xcb_map_window(wnd_.conn(), wnd_.get());
+    xcb_flush(wnd_.conn());
+  }
+
+  void connect(Args const* args) {
+#if FAKE_MONITOR
+    monitor_.reset(FakeMonitor::create(looper_));
+#else
+    monitor_.reset(Monitor::create(looper_));
+#endif
+    monitor_->add_observer(this);
+    monitor_->connect(args->arg("network", ""),
+                      args->arg("scheduler", ""));
+  }
+
+  void quit_from_xcb() {
+    io::write(pipe_, "q", 1);
+  }
+
+  /*
+  void quit_from_main(std::shared_ptr<x::Atoms> const& atoms) {
+    // Wake up the event thread by sending an event to our window
+    xcb_client_message_event_t event;
+    memset(&event, 0, sizeof(event));
+    event.response_type = XCB_CLIENT_MESSAGE;
+    event.format = 32;
+    event.sequence = 0;
+    event.window = wnd_.get();
+    event.type = atoms->get("__MONMON_QUIT");
+
+    xcb_send_event(wnd_.conn(), false, wnd_.get(), XCB_EVENT_MASK_NO_EVENT,
+                   reinterpret_cast<char*>(&event));
+    xcb_flush(wnd_.conn());
+  }
+  */
+
+  void expose(int16_t x, int16_t y, uint16_t w, uint16_t h) {
+    std::lock_guard<std::mutex> lock(mutex_);
+    xcb_copy_area(wnd_.conn(), pixmap_.get(), wnd_.get(), gcontext_.get(),
+                  x, y, x, y, w, h);
+  }
+
+  bool match(xcb_window_t wnd) const {
+    return wnd == wnd_.get();
+  }
+
+  void configure(int16_t x, int16_t y, uint16_t w, uint16_t h) {
+    bool draw = false;
+    if (rootpmap_ && (x != x_ || y != y_)) {
+      x_ = x;
+      y_ = y;
+      if (desktop_surface_) {
+        draw = true;
+        io::write(pipe_, "d", 1);
+      }
+    }
+    if (w == w_ && h == h_) return;
+    {
+      std::lock_guard<std::mutex> lock(mutex_);
+      x::unique_pixmap tmp(pixmap_.shared_conn());
+      x::unique_gcontext gc(tmp.shared_conn());
+      cairo_surface_flush(surface_.get());
+      xcb_create_pixmap(tmp.conn(), depth_, tmp.get(), wnd_.get(), w, h);
+      uint32_t value[1];
+      value[0] = black_pixel_;
+      xcb_create_gc(gc.conn(), gc.get(), tmp.get(), XCB_GC_FOREGROUND, value);
+      uint32_t count = 0;
+      xcb_rectangle_t rect[2];
+      uint16_t copy_width, copy_height;
+      if (w > w_) {
+        copy_width = w_;
+        rect[count].x = w_;
+        rect[count].width = w - w_;
+        rect[count].y = 0;
+        rect[count].height = h_;
+        ++count;
+      } else {
+        copy_width = w;
+      }
+      if (h > h_) {
+        copy_height = h_;
+        rect[count].x = 0;
+        rect[count].width = w;
+        rect[count].y = h_;
+        rect[count].height = h - h_;
+        ++count;
+      } else {
+        copy_height = h;
+      }
+      if (count) {
+        xcb_poly_fill_rectangle(tmp.conn(), tmp.get(), gc.get(),
+                                count, rect);
+      }
+      xcb_copy_area(tmp.conn(), pixmap_.get(), tmp.get(), gc.get(), 0, 0, 0, 0,
+                    copy_width, copy_height);
+      cairo_xcb_surface_set_drawable(surface_.get(), tmp.get(), w, h);
+      if (w_ != w) {
+        job_pattern_.reset();
+        w_ = w;
+      }
+      h_ = h;
+      pixmap_ = std::move(tmp);
+      xcb_copy_area(wnd_.conn(), pixmap_.get(), wnd_.get(), gcontext_.get(),
+                    0, 0, 0, 0, w, h);
+    }
+    if (!draw) io::write(pipe_, "d", 1);
+  }
+
+  void update_desktop_window() {
+    if (rootpmap_ == XCB_ATOM_NONE) return;
+
+    xcb_window_t desktop_window = XCB_NONE;
+
+    auto last = wnd_.get();
+    while (true) {
+      auto cookie = xcb_query_tree(wnd_.conn(), last);
+      auto reply = xcb_query_tree_reply(wnd_.conn(), cookie, nullptr);
+      if (!reply) break;
+      auto cookie2 = xcb_get_property(wnd_.conn(), 0, reply->parent, rootpmap_,
+                                      XCB_GET_PROPERTY_TYPE_ANY, 0, 1);
+      auto reply2 = xcb_get_property_reply(wnd_.conn(), cookie2, nullptr);
+      if (reply2) {
+        if (reply2->type != 0 && reply2->format != 0 && reply2->length != 0) {
+          desktop_window = reply->parent;
+          free(reply2);
+          free(reply);
+          break;
+        }
+        free(reply2);
+      }
+      if (reply->parent == reply->root) {
+        free(reply);
+        break;
+      }
+      last = reply->parent;
+      free(reply);
+    }
+
+    if (desktop_window == desktop_window_) return;
+    unset_desktop_window();
+    if (desktop_window == XCB_NONE) return;
+
+    uint32_t values[1];
+    values[0] = XCB_EVENT_MASK_PROPERTY_CHANGE;
+    xcb_change_window_attributes(wnd_.conn(), desktop_window,
+                                 XCB_CW_EVENT_MASK,
+                                 values);
+    desktop_window_ = desktop_window;
+    update_desktop_pixmap();
+  }
+
+  void update_desktop_window(xcb_window_t window, xcb_atom_t property) {
+    if (window != desktop_window_) return;
+    if (property != rootpmap_) return;
+
+    update_desktop_pixmap();
+  }
+
+private:
+  struct Machine {
+    uint32_t id;
+    Monitor::Machine data;
+    unsigned jobs;
+    unsigned requests;
+
+    explicit Machine(uint32_t id)
+      : id(id), jobs(0), requests(0) {
+    }
+
+    bool operator<(Machine const& machine) const {
+      if (data.name < machine.data.name) return true;
+      if (data.name > machine.data.name) return false;
+      return id < machine.id;
+    }
+  };
+
+  void unset_desktop_window() {
+    if (desktop_window_ == XCB_NONE) return;
+    uint32_t values[1];
+    values[0] = 0;
+    xcb_change_window_attributes(wnd_.conn(), desktop_window_,
+                                 XCB_CW_EVENT_MASK,
+                                 values);
+    desktop_window_ = XCB_NONE;
+    update_desktop_pixmap();
+  }
+
+  void update_desktop_pixmap() {
+    xcb_pixmap_t pixmap = XCB_NONE;
+
+    if (desktop_window_ != XCB_NONE) {
+      auto cookie = xcb_get_property(wnd_.conn(), 0, desktop_window_, rootpmap_,
+                                     XCB_GET_PROPERTY_TYPE_ANY, 0, 1);
+      auto reply = xcb_get_property_reply(wnd_.conn(), cookie, nullptr);
+      if (reply) {
+        if (reply->type == XCB_ATOM_PIXMAP) {
+          pixmap = *reinterpret_cast<xcb_pixmap_t*>(
+              xcb_get_property_value(reply));
+        }
+        free(reply);
+      }
+    }
+
+    if (pixmap == desktop_pixmap_) return;
+
+    auto geometry_cookie = xcb_get_geometry(wnd_.conn(), pixmap);
+    auto attr_cookie = xcb_get_window_attributes(wnd_.conn(), desktop_window_);
+
+    auto geometry_reply = xcb_get_geometry_reply(wnd_.conn(), geometry_cookie,
+                                                 nullptr);
+    uint16_t w, h;
+    uint8_t depth;
+    if (geometry_reply) {
+      depth = geometry_reply->depth;
+      w = geometry_reply->width;
+      h = geometry_reply->height;
+      free(geometry_reply);
+    } else {
+      pixmap = XCB_NONE;
+    }
+
+    auto attr_reply = xcb_get_window_attributes_reply(wnd_.conn(), attr_cookie,
+                                                      nullptr);
+    if (attr_reply) {
+      auto iter = xcb_screen_allowed_depths_iterator(screen_);
+      auto count = xcb_screen_allowed_depths_length(screen_);
+      while (count--) {
+        if (iter.data->depth == depth) {
+          auto visuals = xcb_depth_visuals(iter.data);
+          auto visual_count = xcb_depth_visuals_length(iter.data);
+          while (visual_count--) {
+            if (visuals->visual_id == attr_reply->visual) {
+              if (pixmap != XCB_NONE) {
+                desktop_surface_.reset(cairo_xcb_surface_create(
+                                           wnd_.conn(), pixmap,
+                                           visuals, w, h));
+              }
+              break;
+            }
+            ++visuals;
+          }
+        }
+        xcb_depth_next(&iter);
+      }
+      free(attr_reply);
+    } else {
+      pixmap = XCB_NONE;
+    }
+
+    desktop_pixmap_ = pixmap;
+    if (desktop_pixmap_ == XCB_NONE) desktop_surface_.reset();
+
+    io::write(pipe_, "d", 1);
+  }
+
+  void close_pipe() {
+    if (!pipe_) return;
+    looper_->remove(pipe_.read());
+    pipe_.reset();
+  }
+
+  void pipe(Looper*, int, uint8_t event) {
+    if (event & Looper::EV_READ) {
+      char tmp;
+      if (io::read(pipe_, &tmp, 1)) {
+        if (tmp == 'd') {
+          draw();
+          return;
+        }
+      }
+    }
+
+    monitor_->disconnect();
+    looper_->exit_when_empty();
+    close_pipe();
+  }
+
+  void state(Monitor*, Monitor::State state) override {
+    switch (state) {
+    case Monitor::SEARCHING:
+      connected_ = false;
+      machines_.clear();
+      max_jobs_ = 0;
+      jobs_ = 0;
+      requests_ = 0;
+      if (!wnd_) return;
+      draw();
+      break;
+    case Monitor::CONNECTED:
+      connected_ = true;
+      draw();
+      break;
+    }
+  }
+
+  void update(Machine& machine) {
+    auto old = machine.data.max_jobs;
+    machine.data = monitor_->machine(machine.id);
+    if (old < machine.data.max_jobs) {
+      max_jobs_ += machine.data.max_jobs - old;
+    } else if (old > machine.data.max_jobs) {
+      max_jobs_ -= old - machine.data.max_jobs;
+    }
+  }
+
+  void draw() {
+    internal_draw();
+    xcb_flush(wnd_.conn());
+  }
+
+  static void rounded_path(cairo_t* cr, double x, double y,
+                           double width, double height) {
+    auto radius = height / 10.0;
+    auto degrees = M_PI / 180.0;
+
+    cairo_new_sub_path(cr);
+    cairo_arc(cr, x + width - radius, y + radius, radius,
+              -90 * degrees, 0 * degrees);
+    cairo_arc(cr, x + width - radius, y + height - radius, radius,
+              0 * degrees, 90 * degrees);
+    cairo_arc(cr, x + radius, y + height - radius, radius,
+              90 * degrees, 180 * degrees);
+    cairo_arc(cr, x + radius, y + radius, radius, 180 * degrees, 270 * degrees);
+    cairo_close_path(cr);
+  }
+
+  void internal_draw() {
+    std::lock_guard<std::mutex> lock(mutex_);
+    if (!desktop_surface_) {
+      cairo_set_source_rgb(cairo_.get(), 0, 0, 0);
+    } else {
+      cairo_set_source_surface(cairo_.get(), desktop_surface_.get(),
+                               -x_, -y_);
+    }
+    cairo_rectangle(cairo_.get(), 0, 0, w_, h_);
+    cairo_fill(cairo_.get());
+    auto pad_x = std::min(9.0, w_ / 20.0), pad_y = pad_x;
+    auto margin_x = std::min(7.5, w_ / 20.0), margin_y = margin_x;
+    auto y = pad_y;
+    auto box_width = w_ - pad_x * 2;
+    auto box_height = box_height_ + margin_y * 2;
+    if (!job_pattern_) {
+      job_pattern_.reset(cairo_pattern_create_linear(0.0, 0.0, box_width, 0.0));
+      cairo_pattern_add_color_stop_rgb(job_pattern_.get(), 0.000000,
+                                       0.000000, 0.000000, 0.000000);
+      cairo_pattern_add_color_stop_rgb(job_pattern_.get(), 0.594324,
+                                       0.729412, 0.000000, 0.000000);
+      cairo_pattern_add_color_stop_rgb(job_pattern_.get(), 0.809683,
+                                       1.000000, 0.545098, 0.196078);
+      cairo_pattern_add_color_stop_rgb(job_pattern_.get(), 0.899833,
+                                       0.972549, 0.937255, 0.074510);
+      cairo_pattern_add_color_stop_rgb(job_pattern_.get(), 1.000000,
+                                       0.976471, 0.968627, 0.831373);
+    }
+    pango_layout_set_width(layout_.get(),
+                           (box_width - margin_x * 2) * PANGO_SCALE);
+    for (auto const& machine : machines_) {
+      pango_layout_set_text(layout_.get(), machine.data.name.data(),
+                            machine.data.name.size());
+      rounded_path(cairo_.get(), pad_x, y, box_width, box_height);
+      cairo_set_source_rgba(cairo_.get(), 0.1, 0.1, 0.1, 0.7);
+
+      if (machine.jobs > 0) {
+        cairo_fill_preserve(cairo_.get());
+        auto old = std::unique_ptr<cairo_path_t, CairoPathDelete>(cairo_copy_path(cairo_.get()));
+        cairo_new_path(cairo_.get());
+        cairo_rectangle(cairo_.get(), pad_x, y,
+                        (machine.jobs * box_width) / machine.data.max_jobs,
+                        box_height);
+        cairo_clip(cairo_.get());
+        cairo_append_path(cairo_.get(), old.get());
+        cairo_set_source(cairo_.get(), job_pattern_.get());
+        cairo_fill(cairo_.get());
+        cairo_reset_clip(cairo_.get());
+      } else {
+        cairo_fill(cairo_.get());
+      }
+      if (machine.requests > 0) {
+        cairo_set_line_width(cairo_.get(), 1.5);
+        cairo_new_path(cairo_.get());
+        cairo_move_to(cairo_.get(), pad_x + box_width, y);
+        cairo_rel_line_to(cairo_.get(),
+                          -(machine.requests * box_width) / requests_, 0);
+        cairo_set_source_rgb(cairo_.get(), 0, 0.6, 0);
+        cairo_stroke(cairo_.get());
+      }
+
+      cairo_move_to(cairo_.get(), pad_x + margin_x, y + margin_y);
+      pango_cairo_layout_path(cairo_.get(), layout_.get());
+      cairo_set_source_rgb(cairo_.get(), 0.0, 0.0, 0.0);
+      cairo_set_line_cap(cairo_.get(), CAIRO_LINE_CAP_ROUND);
+      cairo_set_line_width(cairo_.get(), 2.0);
+      cairo_stroke(cairo_.get());
+      cairo_set_source_rgb(cairo_.get(), 1.0, 1.0, 1.0);
+      cairo_move_to(cairo_.get(), pad_x + margin_x, y + margin_y);
+      pango_cairo_show_layout(cairo_.get(), layout_.get());
+      y += box_height + pad_y * 2;
+      if (y >= h_) break;
+    }
+    cairo_surface_flush(surface_.get());
+    xcb_copy_area(wnd_.conn(), pixmap_.get(), wnd_.get(), gcontext_.get(),
+                  0, 0, 0, 0, w_, h_);
+  }
+
+  void added_machine(Monitor*, uint32_t id) override {
+    Machine machine(id);
+    update(machine);
+    machines_.insert(
+        std::lower_bound(machines_.begin(), machines_.end(), machine),
+        machine);
+    draw();
+  }
+
+  void updated_machine(Monitor*, uint32_t id) override {
+    for (auto& machine : machines_) {
+      if (machine.id == id) {
+        auto old = machine.data.name;
+        update(machine);
+        if (machine.data.name != old) {
+          // TODO: Perhaps remove and insert instead?
+          std::sort(machines_.begin(), machines_.end());
+        }
+        draw();
+        return;
+      }
+    }
+    assert(false);
+  }
+
+  void removed_machine(Monitor*, uint32_t id) override {
+    for (auto it = machines_.begin(); it != machines_.end(); ++it) {
+      if (it->id == id) {
+        max_jobs_ -= it->data.max_jobs;
+        requests_ -= it->requests;
+        jobs_ -= it->jobs;
+        machines_.erase(it);
+        draw();
+        return;
+      }
+    }
+    assert(false);
+  }
+
+  void added_job(Monitor*, uint32_t source, uint32_t target) override {
+    if (source == target) {
+      for (auto& machine : machines_) {
+        if (machine.id == source) {
+          ++machine.jobs;
+        }
+      }
+    } else {
+      for (auto& machine : machines_) {
+        if (machine.id == source) {
+          ++machine.requests;
+        }
+        if (machine.id == target) {
+          ++machine.jobs;
+        }
+      }
+      ++requests_;
+    }
+    ++jobs_;
+    draw();
+  }
+
+  void removed_job(Monitor*, uint32_t source, uint32_t target) override {
+    if (source == target) {
+      for (auto& machine : machines_) {
+        if (machine.id == source) {
+          --machine.jobs;
+        }
+      }
+    } else {
+      for (auto& machine : machines_) {
+        if (machine.id == source) {
+          --machine.requests;
+        }
+        if (machine.id == target) {
+          --machine.jobs;
+        }
+      }
+      --requests_;
+    }
+    --jobs_;
+    draw();
+  }
+
+  std::shared_ptr<PollLooper> looper_;
+  std::unique_ptr<Monitor> monitor_;
+  bool connected_;
+  io::pipe pipe_;
+  std::shared_ptr<x::Atoms> atoms_;
+  x::unique_window wnd_;
+  x::unique_gcontext gcontext_;
+  uint8_t depth_;
+  uint32_t black_pixel_;
+  xcb_screen_t const* screen_;
+  double box_height_;
+  std::vector<Machine> machines_;
+  unsigned max_jobs_;
+  unsigned jobs_;
+  unsigned requests_;
+  std::mutex mutex_;
+  std::unique_ptr<cairo_surface_t, CairoSurfaceDelete> surface_;
+  std::unique_ptr<cairo_t, CairoDelete> cairo_;
+  std::unique_ptr<cairo_pattern_t, CairoPatternDelete> job_pattern_;
+  std::unique_ptr<PangoLayout, GObjectDelete> layout_;
+  x::unique_pixmap pixmap_;
+  int16_t x_, y_;
+  uint16_t w_, h_;
+  xcb_atom_t rootpmap_;
+  xcb_window_t desktop_window_;
+  xcb_pixmap_t desktop_pixmap_;
+  std::unique_ptr<cairo_surface_t, CairoSurfaceDelete> desktop_surface_;
+};
+
+struct XcbKeySymbolsDelete {
+  void operator()(xcb_key_symbols_t* ptr) const {
+    if (ptr) xcb_key_symbols_free(ptr);
+  }
+};
+
+struct XcbGenericEventDelete {
+  void operator()(xcb_generic_event_t* ptr) const {
+    free(ptr);
+  }
+};
+
+void xcb_event_loop(x::shared_connection const& conn,
+                    std::shared_ptr<x::Atoms> const& atoms,
+                    std::shared_ptr<MonMon> const& monmon) {
+  std::unique_ptr<xcb_key_symbols_t, XcbKeySymbolsDelete> syms;
+  syms.reset(xcb_key_symbols_alloc(conn.get()));
+  std::unique_ptr<xcb_generic_event_t, XcbGenericEventDelete> event;
+  auto const quit = atoms->get("__MONMON_QUIT");
+  auto const wm_protocols = atoms->get("WM_PROTOCOLS");
+  auto const wm_delete_window = atoms->get("WM_DELETE_WINDOW");
+  while (true) {
+    event.reset(xcb_wait_for_event(conn.get()));
+    if (!event) {
+      std::cerr << "fatal error: "
+                << xcb_connection_has_error(conn.get()) << std::endl;
+      monmon->quit_from_xcb();
+      return;
+    }
+    if (event->response_type == 0) {
+      auto e = reinterpret_cast<xcb_generic_error_t*>(event.get());
+#ifndef NDEBUG
+      std::cerr << "error: " << xcb_event_get_error_label(e->error_code)
+                << std::endl;
+#endif
+      continue;
+    }
+    switch (XCB_EVENT_RESPONSE_TYPE(event)) {
+    case XCB_EXPOSE: {
+      auto e = reinterpret_cast<xcb_expose_event_t*>(event.get());
+      if (monmon->match(e->window)) {
+        monmon->expose(e->x, e->y, e->width, e->height);
+      }
+      if (e->count != 0) continue;  // Only flush for e->count == 0
+      break;
+    }
+    case XCB_KEY_PRESS: {
+      auto e = reinterpret_cast<xcb_key_press_event_t*>(event.get());
+      auto sym = xcb_key_press_lookup_keysym(syms.get(), e, 0);
+      switch (sym) {
+      case 'Q':
+      case 'q':
+      case 0xff1b: {  // escape
+        if (monmon->match(e->event)) {
+          monmon->quit_from_xcb();
+          return;
+        }
+        break;
+      }
+      }
+      break;
+    }
+    case XCB_DESTROY_NOTIFY: {
+      auto e = reinterpret_cast<xcb_destroy_notify_event_t*>(event.get());
+      if (monmon->match(e->window)) {
+        monmon->quit_from_xcb();
+        return;
+      }
+      break;
+    }
+    case XCB_CONFIGURE_NOTIFY: {
+      auto e = reinterpret_cast<xcb_configure_notify_event_t*>(event.get());
+      if (monmon->match(e->window)) {
+        monmon->configure(e->x, e->y, e->width, e->height);
+      }
+      break;
+    }
+    case XCB_CLIENT_MESSAGE: {
+      auto e = reinterpret_cast<xcb_client_message_event_t*>(event.get());
+      if (e->format == 32
+          && e->type == wm_protocols
+          && e->data.data32[0] == wm_delete_window) {
+        if (monmon->match(e->window)) {
+          monmon->quit_from_xcb();
+          return;
+        }
+      } else if (e->format == 32 && e->type == quit) {
+        // Do not call quit_from_xcb() here, only reason to end up
+        // here is if main already called quit_from_main()
+        return;
+      }
+      break;
+    }
+    case XCB_MAPPING_NOTIFY: {
+      auto e = reinterpret_cast<xcb_mapping_notify_event_t*>(event.get());
+      xcb_refresh_keyboard_mapping(syms.get(), e);
+      break;
+    }
+    case XCB_REPARENT_NOTIFY: {
+      auto e = reinterpret_cast<xcb_reparent_notify_event_t*>(event.get());
+      if (monmon->match(e->window)) {
+        monmon->update_desktop_window();
+      }
+      break;
+    }
+    case XCB_PROPERTY_NOTIFY: {
+      auto e = reinterpret_cast<xcb_property_notify_event_t*>(event.get());
+      monmon->update_desktop_window(e->window, e->atom);
+      break;
+    }
+    }
+    xcb_flush(conn.get());
+  }
+}
+
+}  // namespace
+
+int main(int argc, char** argv) {
+  std::unique_ptr<Args> args(Args::create());
+  args->add("network", "NETNAME",
+            "monitor NETNAME instead of default ICECREAM");
+  args->add("scheduler", "HOST",
+            "connect to scheduler at HOST instead of broadcasting");
+  args->add("display", "HOST:VS", "connect to X server at [HOST]:[VS]");
+  args->add("no-render", "do not use render extension even if available");
+  args->add("titlebar", "create a normal window instead of the default without"
+            " titlebar (or other WM addons)");
+  args->add("black", "use black background instead of background pixmap");
+  args->add("help", "display this text and exit.");
+  if (!args->run(argc, argv)) {
+    std::cout << "Try `monmon --help` for usage." << std::endl;
+    return EXIT_FAILURE;
+  }
+  if (args->is_set("help")) {
+    std::cout << "Usage: `monmon [OPTIONS...]`\n"
+              << "icecream (icecc) monitor\n"
+              << "\n";
+    args->print_help(std::cout);
+    return EXIT_FAILURE;
+  }
+  int screen_index;
+  x::shared_connection conn(
+      xcb_connect(args->arg("display", nullptr), &screen_index));
+  if (xcb_connection_has_error(conn.get())) {
+    std::cerr << "Unable to connect to X server." << std::endl;
+    return EXIT_FAILURE;
+  }
+  x::prefetch_extensions(conn.get());
+  auto screen = x::get_screen(conn.get(), screen_index);
+  auto format = x::get_best_format(conn.get(), screen,
+                                   !args->is_set("no-render"));
+  if (!format.good()) {
+    std::cerr << "Unable to find a good X visual." << std::endl;
+    return EXIT_FAILURE;
+  }
+  std::shared_ptr<PollLooper> looper(PollLooper::create());
+  std::shared_ptr<x::Atoms> atoms(x::Atoms::create(conn));
+  atoms->preload("WM_DELETE_WINDOW");
+  atoms->preload("WM_PROTOCOLS");
+  atoms->preload("__MONMON_QUIT");
+  atoms->preload("_MOTIF_WM_INFO", false);
+  atoms->preload("_MOTIF_WM_HINTS");
+  atoms->preload("_XROOTPMAP_ID", false);
+  std::shared_ptr<x::Ewmh> ewmh(x::Ewmh::create(conn, screen_index));
+  auto monmon = std::make_shared<MonMon>(looper);
+  monmon->init(conn, screen, format, atoms, ewmh, 400, 400,
+               args->is_set("titlebar"), args->is_set("black"));
+  monmon->connect(args.get());
+  std::thread xcb_thread(xcb_event_loop, conn, atoms, monmon);
+  conn.reset();
+  looper->run();
+  xcb_thread.join();
+  return EXIT_SUCCESS;
+}
diff --git a/src/monitor.cc b/src/monitor.cc
new file mode 100644
index 0000000..e5a231d
--- /dev/null
+++ b/src/monitor.cc
@@ -0,0 +1,410 @@
+#include "common.hh"
+
+#include <icecc/comm.h>
+#include <iostream>
+#include <unordered_map>
+#include <vector>
+
+#include "looper.hh"
+#include "monitor.hh"
+
+namespace {
+
+class MonitorImpl : public Monitor {
+public:
+  explicit MonitorImpl(std::shared_ptr<Looper> const& looper)
+    : looper_(looper), discover_timer_(0), connect_(false), discover_fd_(-1),
+      port_(0) {
+  }
+
+  ~MonitorImpl() override {
+    disconnect();
+  }
+
+  void connect(std::string const& netname,
+               std::string const& hostname,
+               uint16_t port) override {
+    netname_ = netname;
+    hostname_ = hostname;
+    port_ = port;
+
+    if (channel_) {
+      // TODO(the_jk): Should we reconnect here?
+      return;
+    }
+    close_discover();
+    schedule_discover((rand() % 1000) / 1000.0);
+  }
+
+  void disconnect() override {
+    close_discover();
+    disconnect_channel();
+  }
+
+  size_t machines() const override {
+    return machines_.size();
+  }
+
+  uint32_t id(size_t index) const override {
+    auto it = machines_.begin();
+    while (index--) ++it;
+    if (it == machines_.end()) {
+      assert(false);
+      return 0xffffffff;
+    }
+    return it->first;
+  }
+
+  Machine machine_at(size_t index) const override {
+    auto it = machines_.begin();
+    while (index--) ++it;
+    if (it == machines_.end()) {
+      assert(false);
+      return EMPTY;
+    }
+    return it->second;
+  }
+
+  Machine machine(uint32_t id) const override {
+    auto it = machines_.find(id);
+    if (it == machines_.end()) {
+      assert(false);
+      return EMPTY;
+    }
+    return it->second;
+  }
+
+  void add_observer(Observer* observer) override {
+    observers_.push_back(observer);
+  }
+
+private:
+  static Machine const EMPTY;
+
+  struct Job {
+    uint32_t source;
+    uint32_t target;
+  };
+
+  void schedule_discover(double delay) {
+    if (discover_timer_) return;
+    discover_timer_ = looper_->schedule(delay,
+                                        std::bind(&MonitorImpl::discover,
+                                                  this,
+                                                  std::placeholders::_1,
+                                                  std::placeholders::_2));
+  }
+
+  void discover(Looper*, uint32_t timer) {
+    assert(discover_timer_ == timer);
+    discover_timer_ = 0;
+    check_discover();
+  }
+
+  void close_discover() {
+    if (discover_timer_) {
+      looper_->cancel(discover_timer_);
+      discover_timer_ = 0;
+    }
+    if (!discover_) return;
+    connect_ = false;
+    if (discover_fd_ >= 0) {
+      looper_->remove(discover_fd_);
+      discover_fd_ = -1;
+    }
+    discover_.reset();
+  }
+
+  void check_discover() {
+    if (channel_) return;
+
+    if (!discover_) {
+      discover_.reset(new DiscoverSched(netname_, 2, hostname_, port_));
+    }
+
+    channel_.reset(discover_->try_get_scheduler());
+
+    if (channel_) {
+      connected();
+      return;
+    }
+
+    if (discover_->timed_out()) {
+      close_discover();
+      check_discover();
+      return;
+    }
+
+    if (discover_fd_ < 0) {
+      auto fd = discover_->connect_fd();
+      if (!connect_ && fd >= 0) {
+        discover_fd_ = fd;
+        connect_ = true;
+        looper_->add(fd, Looper::EV_WRITE,
+                     std::bind(&MonitorImpl::discover_fd, this,
+                               std::placeholders::_1,
+                               std::placeholders::_2,
+                               std::placeholders::_3));
+        // Use connect() timeout
+        return;
+      }
+      fd = discover_->listen_fd();
+      if (fd >= 0) {
+        discover_fd_ = fd;
+        connect_ = false;
+        looper_->add(fd, Looper::EV_READ,
+                     std::bind(&MonitorImpl::discover_fd, this,
+                               std::placeholders::_1,
+                               std::placeholders::_2,
+                               std::placeholders::_3));
+      }
+    }
+
+    schedule_discover(1.0 + (rand() % 1000) / 1000.0);
+  }
+
+  void discover_fd(Looper*, int fd, uint8_t) {
+    assert(fd == discover_fd_);
+    looper_->remove(discover_fd_);
+    discover_fd_ = -1;
+    check_discover();
+  }
+
+  void connected() {
+    std::cerr << "connected" << std::endl;
+    current_netname_ = discover_->schedulerName();
+    current_hostname_ = discover_->networkName();
+
+    channel_->setBulkTransfer();
+
+    close_discover();
+
+    looper_->add(channel_->fd, Looper::EV_READ,
+                 std::bind(&MonitorImpl::msg, this, std::placeholders::_1,
+                           std::placeholders::_2, std::placeholders::_3));
+
+    if (!channel_->send_msg(MonLoginMsg())) {
+      std::cerr << "login failed" << std::endl;
+      disconnect_channel();
+      schedule_discover(0.0);
+      return;
+    }
+
+    for (auto* observer : observers_) {
+      observer->state(this, CONNECTED);
+    }
+  }
+
+  void disconnect_channel() {
+    if (!channel_) return;
+    std::cerr << "disconnect" << std::endl;
+    looper_->remove(channel_->fd);
+    channel_.reset();
+
+    for (auto* observer : observers_) {
+      observer->state(this, SEARCHING);
+    }
+  }
+
+  void msg(Looper*, int, uint8_t event) {
+    if (event & Looper::EV_ERR) {
+      disconnect();
+      schedule_discover(0.0);
+      return;
+    }
+
+    while (true) {
+      if (!channel_->read_a_bit()) {
+        disconnect();
+        schedule_discover(0.0);
+        return;
+      }
+      if (!channel_->has_msg()) break;
+      std::unique_ptr<Msg> msg(channel_->get_msg());
+      if (!msg) {
+        disconnect();
+        schedule_discover(0.0);
+        return;
+      }
+      switch (msg->type) {
+      case M_END:
+        disconnect();
+        schedule_discover(1.0);
+        return;
+      case M_MON_STATS:
+        handle_stats(static_cast<MonStatsMsg*>(msg.get()));
+        break;
+      case M_MON_GET_CS:
+        handle_job(static_cast<MonGetCSMsg*>(msg.get()));
+        break;
+      case M_MON_JOB_BEGIN:
+        handle_job(static_cast<MonJobBeginMsg*>(msg.get()));
+        break;
+      case M_MON_JOB_DONE:
+        handle_job(static_cast<MonJobDoneMsg*>(msg.get()));
+        break;
+      case M_MON_LOCAL_JOB_BEGIN:
+        handle_local_job(static_cast<MonLocalJobBeginMsg*>(msg.get()));
+        break;
+      case M_JOB_LOCAL_DONE:
+        handle_local_job(static_cast<JobLocalDoneMsg*>(msg.get()));
+        break;
+      default:
+        break;
+      }
+    }
+  }
+
+  void handle_job(MonGetCSMsg const* msg) {
+    pending_jobs_[msg->job_id] = msg->clientid;
+  }
+
+  void handle_job(MonJobBeginMsg const* msg) {
+    auto it = pending_jobs_.find(msg->job_id);
+    if (it == pending_jobs_.end()) {
+      assert(false);
+      return;
+    }
+    auto source = it->second;
+    pending_jobs_.erase(it);
+    job_begin(msg->job_id, source, msg->hostid);
+  }
+
+  void handle_job(MonJobDoneMsg const* msg) {
+    job_done(msg->job_id);
+  }
+
+  void handle_local_job(MonLocalJobBeginMsg const* msg) {
+    job_begin(msg->job_id, msg->hostid, msg->hostid);
+  }
+
+  void handle_local_job(JobLocalDoneMsg const* msg) {
+    job_done(msg->job_id);
+  }
+
+  void job_begin(uint32_t job_id, uint32_t source, uint32_t target) {
+    auto& job = active_jobs_[job_id];
+    job.source = source;
+    job.target = target;
+    for (auto* observer : observers_) {
+      observer->added_job(this, job.source, job.target);
+    }
+  }
+
+  void job_done(uint32_t job_id) {
+    auto it = active_jobs_.find(job_id);
+    if (it == active_jobs_.end()) {
+      assert(false);
+      return;
+    }
+    auto source = it->second.source;
+    auto target = it->second.target;
+    active_jobs_.erase(it);
+    for (auto* observer : observers_) {
+      observer->removed_job(this, source, target);
+    }
+  }
+
+  void handle_stats(MonStatsMsg const* msg) {
+    std::cerr << msg->hostid << " " << msg->statmsg << "***" << std::endl;
+
+    auto& machine = machines_[msg->hostid];
+    auto const known = !machine.name.empty();
+    if (update(msg->statmsg, &machine)) {
+      if (machine.name.empty()) {
+        machines_.erase(msg->hostid);
+        if (known) {
+          for (auto* observer : observers_) {
+            observer->removed_machine(this, msg->hostid);
+          }
+        }
+      } else {
+        if (known) {
+          for (auto* observer : observers_) {
+            observer->updated_machine(this, msg->hostid);
+          }
+        } else {
+          for (auto* observer : observers_) {
+            observer->added_machine(this, msg->hostid);
+          }
+        }
+      }
+    } else {
+      if (!known) {
+        machines_.erase(msg->hostid);
+      }
+    }
+  }
+
+  bool update(std::string const& msg, Machine* machine) {
+    std::string name, ip;
+    unsigned max_jobs = 0;
+
+    size_t last = 0;
+    while (true) {
+      auto pos = msg.find(':', last);
+      if (pos == std::string::npos) break;
+      auto end = msg.find('\n', pos + 1);
+      if (end == std::string::npos) end = msg.size();
+      auto key = msg.substr(last, pos - last);
+      if (key == "Name") {
+        name = msg.substr(pos + 1, end - pos - 1);
+        auto dot = name.find('.');
+        if (dot != std::string::npos) name = name.substr(0, dot);
+      } else if (key == "IP") {
+        ip = msg.substr(pos + 1, end - pos - 1);
+      } else if (key == "MaxJobs") {
+        errno = 0;
+        char* end_ptr;
+        auto tmp = strtoul(msg.c_str() + pos + 1, &end_ptr, 10);
+        if (errno == 0 && tmp > 0 && end_ptr == msg.c_str() + end) {
+          max_jobs = static_cast<unsigned>(tmp);
+        }
+      }
+      last = end + 1;
+    }
+
+    if (name.empty()) name = ip;
+
+    bool changed = false;
+    if (name != machine->name) {
+      machine->name = name;
+      changed = true;
+    }
+    if (max_jobs != machine->max_jobs) {
+      machine->max_jobs = max_jobs;
+      changed = true;
+    }
+    return changed;
+  }
+
+  std::shared_ptr<Looper> looper_;
+  std::vector<Observer*> observers_;
+  std::unique_ptr<MsgChannel> channel_;
+  std::unique_ptr<DiscoverSched> discover_;
+  uint32_t discover_timer_;
+  bool connect_;
+  int discover_fd_;
+
+  // Requested netname, hostname and port
+  std::string netname_;
+  std::string hostname_;
+  uint16_t port_;
+
+  // Actually connected netname and hostname
+  std::string current_netname_;
+  std::string current_hostname_;
+
+  std::unordered_map<uint32_t, Machine> machines_;
+  std::unordered_map<uint32_t, Job> active_jobs_;
+  std::unordered_map<uint32_t, uint32_t> pending_jobs_;
+};
+
+Monitor::Machine const MonitorImpl::EMPTY;
+
+}  // namespace
+
+// static
+Monitor* Monitor::create(std::shared_ptr<Looper> const& looper) {
+  return new MonitorImpl(looper);
+}
diff --git a/src/monitor.hh b/src/monitor.hh
new file mode 100644
index 0000000..99e172b
--- /dev/null
+++ b/src/monitor.hh
@@ -0,0 +1,62 @@
+#ifndef MONITOR_HH
+#define MONITOR_HH
+
+#include <memory>
+#include <string>
+
+class Looper;
+
+class Monitor {
+public:
+  enum State {
+    SEARCHING,
+    CONNECTED,
+  };
+
+  struct Machine {
+    std::string name;
+    unsigned max_jobs;
+
+    Machine()
+      : max_jobs(0) {
+    }
+  };
+
+  class Observer {
+  public:
+    virtual ~Observer() {}
+    virtual void state(Monitor* monitor, State state) = 0;
+    virtual void added_machine(Monitor* monitor, uint32_t id) = 0;
+    virtual void updated_machine(Monitor* monitor, uint32_t id) = 0;
+    virtual void removed_machine(Monitor* monitor, uint32_t id) = 0;
+    virtual void added_job(Monitor* monitor, uint32_t source_id,
+                           uint32_t target_id) = 0;
+    virtual void removed_job(Monitor* monitor, uint32_t source_id,
+                             uint32_t target_id) = 0;
+
+  protected:
+    Observer() {}
+  };
+
+  virtual ~Monitor() {}
+
+  static Monitor* create(std::shared_ptr<Looper> const& looper);
+
+  virtual void connect(std::string const& netname = std::string(),
+                       std::string const& scheduler = std::string(),
+                       uint16_t port = 0) = 0;
+  virtual void disconnect() = 0;
+  virtual size_t machines() const = 0;
+  virtual uint32_t id(size_t index) const = 0;
+  virtual Machine machine_at(size_t index) const = 0;
+  virtual Machine machine(uint32_t id) const = 0;
+
+  virtual void add_observer(Observer* observer) = 0;
+
+protected:
+  Monitor() {}
+  Monitor(Monitor const&) = delete;
+  Monitor& operator=(Monitor const&) = delete;
+};
+
+#endif  // MONITOR_HH
diff --git a/src/poll_looper.cc b/src/poll_looper.cc
new file mode 100644
index 0000000..71788e0
--- /dev/null
+++ b/src/poll_looper.cc
@@ -0,0 +1,249 @@
+#include "common.hh"
+
+#include <poll.h>
+#include <string.h>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "clock.hh"
+#include "poll_looper.hh"
+
+namespace {
+
+void empty_callback(Looper*, int, uint8_t) {
+  assert(false);
+}
+
+int const READ_POLL_MASK = POLLIN | POLLPRI;
+int const WRITE_POLL_MASK = POLLOUT;
+
+class PollLooperImpl : public PollLooper {
+public:
+  PollLooperImpl()
+    : next_id_(0), active_(0), exit_(false) {
+  }
+
+  void add(int fd, uint8_t events,
+           std::function<void(Looper*, int, uint8_t)> const& callback)
+    override {
+    if (fd < 0) {
+      assert(false);
+      return;
+    }
+    auto it = fds_.find(fd);
+    if (it != fds_.end()) {
+      if (!removed_.count(it->second)) {
+        modify(fd, events);
+        return;
+      }
+    }
+    struct pollfd poll;
+    poll.fd = fd;
+    poll.events = 0;
+    if (events & EV_READ) {
+      poll.events |= READ_POLL_MASK;
+    }
+    if (events & EV_WRITE) {
+      poll.events |= WRITE_POLL_MASK;
+    }
+    if (free_.empty()) {
+      fds_[fd] = poll_.size();
+      callback_.push_back(callback);
+      poll_.push_back(poll);
+    } else {
+      auto it = free_.begin();
+      auto index = *it;
+      free_.erase(it);
+      fds_[fd] = index;
+      callback_[index] = callback;
+      poll_[index] = poll;
+    }
+  }
+
+  void modify(int fd, uint8_t events) override {
+    auto it = fds_.find(fd);
+    if (it == fds_.end()) {
+      assert(false);
+      return;
+    }
+    auto& poll = poll_[it->second];
+    poll.events = 0;
+    if (events & EV_READ) {
+      poll.events |= READ_POLL_MASK;
+    }
+    if (events & EV_WRITE) {
+      poll.events |= WRITE_POLL_MASK;
+    }
+  }
+
+  void remove(int fd) override {
+    auto it = fds_.find(fd);
+    if (it == fds_.end()) {
+      assert(false);
+      return;
+    }
+    if (it->second < active_) {
+      removed_.insert(it->second);
+    } else {
+      free_.insert(it->second);
+      poll_[it->second].fd = -1;
+      poll_[it->second].events = 0;
+      callback_[it->second] = empty_callback;
+      fds_.erase(it);
+    }
+  }
+
+  uint32_t schedule(double delay,
+                    std::function<void(Looper*, uint32_t)> const& callback)
+    override {
+    assert(delay >= 0.0);
+    uint32_t id = next_id();
+    auto target = clk::steady() + delay;
+    std::vector<Timer>::iterator insert = timer_.end();
+    if (timer_.empty() || timer_.back().target >= target) {
+      auto it = timer_.begin();
+      for (; it != timer_.end(); ++it) {
+        if (it->target >= target) {
+          insert = it;
+          break;
+        }
+      }
+    }
+    timer_.emplace(insert, id, target, callback);
+    return id;
+  }
+
+  void cancel(uint32_t id) override {
+    auto active = active_ids_.find(id);
+    if (active == active_ids_.end()) {
+      assert(false);
+      return;
+    }
+    for (auto it = timer_.begin(); it != timer_.end(); ++it) {
+      if (it->id == id) {
+        active_ids_.erase(active);
+        timer_.erase(it);
+        break;
+      }
+    }
+  }
+
+  void exit_when_empty() override {
+    exit_ = true;
+  }
+
+  void run() override {
+    while (true) {
+      auto now = clk::steady();
+      while (true) {
+        if (timer_.empty()) {
+          now = -1.0;
+          break;
+        }
+        if (now < timer_.front().target) {
+          now = timer_.front().target - clk::steady();
+          if (now < 0.0) now = 0.0;
+          break;
+        }
+        auto id = timer_.front().id;
+        auto callback = timer_.front().callback;
+        timer_.erase(timer_.begin());
+        active_ids_.erase(id);
+        callback(this, id);
+      }
+      active_ = poll_.size();
+      while (active_ > 0 && poll_[active_ - 1].fd < 0) --active_;
+      if (exit_ && now < 0.0 && active_ == 0) return;
+      auto ret = poll(&poll_[0], active_, now < 0.0 ? -1 : now * 1000);
+      if (ret < 0) {
+        if (errno == EINTR) continue;
+        return;
+      }
+      for (size_t i = 0; ret && i < active_; ++i) {
+        if (poll_[i].revents) {
+          --ret;
+          if (removed_.count(i)) continue;
+          uint8_t events = 0;
+          if (poll_[i].revents & READ_POLL_MASK
+              && poll_[i].events & READ_POLL_MASK) {
+            events |= EV_READ;
+          }
+          if (poll_[i].revents & WRITE_POLL_MASK
+              && poll_[i].events & WRITE_POLL_MASK) {
+            events |= EV_WRITE;
+          }
+          if (poll_[i].revents & POLLHUP) {
+            if (poll_[i].events & READ_POLL_MASK) {
+              events |= EV_READ;
+            } else {
+              events |= EV_ERR;
+            }
+          }
+          if (poll_[i].revents & POLLERR) {
+            events |= EV_ERR;
+          }
+          if (poll_[i].revents & POLLNVAL) {
+            events |= EV_ERR;
+            removed_.insert(i);
+          }
+          if (events) {
+            callback_[i](this, poll_[i].fd, events);
+          }
+        }
+      }
+
+      active_ = 0;
+      while (!removed_.empty()) {
+        auto index = *removed_.begin();
+        removed_.erase(removed_.begin());
+        auto it = fds_.find(poll_[index].fd);
+        if (it == fds_.end() || it->second != index) {
+          free_.insert(index);
+          poll_[index].fd = -1;
+          poll_[index].events = 0;
+          callback_[index] = empty_callback;
+        } else {
+          remove(it->first);
+        }
+      }
+    }
+  }
+
+private:
+  struct Timer {
+    uint32_t id;
+    double target;
+    std::function<void(Looper*, uint32_t)> callback;
+
+    Timer(uint32_t id, double target,
+          std::function<void(Looper*, uint32_t)> const& callback)
+      : id(id), target(target), callback(callback) {
+    }
+  };
+
+  uint32_t next_id() {
+    uint32_t ret = ++next_id_;
+    if (ret == 0) return next_id();
+    if (!active_ids_.emplace(ret).second) return next_id();
+    return ret;
+  }
+
+  std::vector<Timer> timer_;
+  uint32_t next_id_;
+  std::unordered_set<uint32_t> active_ids_;
+  std::vector<struct pollfd> poll_;
+  std::vector<std::function<void(Looper*, int, uint8_t)>> callback_;
+  std::unordered_set<size_t> free_;
+  std::unordered_map<int, size_t> fds_;
+  std::unordered_set<size_t> removed_;
+  size_t active_;
+  bool exit_;
+};
+
+}  // namespace
+
+// static
+PollLooper* PollLooper::create() {
+  return new PollLooperImpl();
+}
diff --git a/src/poll_looper.hh b/src/poll_looper.hh
new file mode 100644
index 0000000..16097fe
--- /dev/null
+++ b/src/poll_looper.hh
@@ -0,0 +1,15 @@
+#ifndef POLL_LOOPER_HH
+#define POLL_LOOPER_HH
+
+#include "looper.hh"
+
+class PollLooper : public Looper {
+public:
+  static PollLooper* create();
+
+  virtual void run() = 0;
+
+  virtual void exit_when_empty() = 0;
+};
+
+#endif  // POLL_LOOPER_HH
diff --git a/src/x.cc b/src/x.cc
new file mode 100644
index 0000000..4af1230
--- /dev/null
+++ b/src/x.cc
@@ -0,0 +1,312 @@
+#include "common.hh"
+
+#include <mutex>
+#include <unordered_map>
+
+#include "x.hh"
+
+namespace x {
+
+namespace {
+
+class AtomsImpl : public Atoms {
+public:
+  explicit AtomsImpl(shared_connection const& conn)
+    : conn_(conn) {
+  }
+
+  void preload(std::string const& name, bool create) override {
+    std::lock_guard<std::mutex> lock(mutex_);
+    auto& entry = data_[name];
+    if (entry.state_ == UNINITIALIZED) {
+      entry.cookie_ = xcb_intern_atom(
+          conn_.get(), create ? 0 : 1, name.size(), name.c_str());
+      entry.state_ = REQUESTED;
+    }
+  }
+
+  xcb_atom_t get(std::string const& name, bool create) override {
+    std::lock_guard<std::mutex> lock(mutex_);
+    return get_locked(name, create);
+  }
+
+private:
+  enum State {
+    UNINITIALIZED = 0,
+    REQUESTED,
+    RESOLVED,
+  };
+
+  struct Entry {
+    State state_;
+    xcb_atom_t atom_;
+    xcb_intern_atom_cookie_t cookie_;
+
+    Entry()
+      : state_(UNINITIALIZED) {
+    }
+  };
+
+  xcb_atom_t get_locked(std::string const& name, bool create) {
+    auto& entry = data_[name];
+    switch (entry.state_) {
+    case UNINITIALIZED:
+      entry.cookie_ = xcb_intern_atom(
+          conn_.get(), create ? 0 : 1, name.size(), name.c_str());
+      entry.state_ = REQUESTED;
+      // Fallthrough
+    case REQUESTED: {
+      auto reply = xcb_intern_atom_reply(conn_.get(), entry.cookie_, nullptr);
+      if (reply) {
+        entry.atom_ = reply->atom;
+        free(reply);
+      }
+      entry.state_ = RESOLVED;
+      // Fallthrough
+    }
+    case RESOLVED:
+      if (create && entry.atom_ == XCB_ATOM_NONE) {
+        entry.state_ = UNINITIALIZED;
+        return get_locked(name, create);
+      }
+      break;
+    }
+    return entry.atom_;
+  }
+
+  shared_connection conn_;
+  std::mutex mutex_;
+  std::unordered_map<std::string, Entry> data_;
+};
+
+class EwmhImpl : public Ewmh {
+public:
+  EwmhImpl(shared_connection const& conn, int screen)
+    : conn_(conn), screen_(screen) {
+    if (conn_) {
+      cookies_ = xcb_ewmh_init_atoms(conn_.get(), &ewmh_);
+    } else {
+      cookies_ = nullptr;
+    }
+  }
+
+  ~EwmhImpl() override {
+    ensure_cookies();
+    if (supported_) xcb_ewmh_get_atoms_reply_wipe(supported_.get());
+    if (conn_) xcb_ewmh_connection_wipe(&ewmh_);
+  }
+
+  xcb_ewmh_connection_t* conn() override {
+    ensure_supported();
+    return conn_ ? &ewmh_ : nullptr;
+  }
+
+  bool supported(xcb_atom_t atom) override {
+    ensure_supported();
+    if (!conn_) return false;
+    for (uint32_t i = 0; i < supported_->atoms_len; i++) {
+      if (supported_->atoms[i] == atom) return true;
+    }
+    return false;
+  }
+
+private:
+  void ensure_cookies() {
+    if (!cookies_) return;
+    if (!xcb_ewmh_init_atoms_replies(&ewmh_, cookies_, nullptr)) {
+      conn_.reset();
+    }
+    cookies_ = nullptr;
+  }
+
+  void ensure_supported() {
+    if (supported_ || !conn_) return;
+    ensure_cookies();
+    auto cookie = xcb_ewmh_get_supported(&ewmh_, screen_);
+    supported_.reset(new xcb_ewmh_get_atoms_reply_t());
+    if (!xcb_ewmh_get_supported_reply(&ewmh_, cookie, supported_.get(),
+                                      nullptr)) {
+      conn_.reset();
+    }
+  }
+
+  shared_connection conn_;
+  int const screen_;
+  xcb_ewmh_connection_t ewmh_;
+  xcb_intern_atom_cookie_t* cookies_;
+  std::unique_ptr<xcb_ewmh_get_atoms_reply_t> supported_;
+};
+
+}  // namespace
+
+// static
+Atoms* Atoms::create(shared_connection const& conn) {
+  return new AtomsImpl(conn);
+}
+
+// static
+Ewmh* Ewmh::create(shared_connection const& conn, int screen) {
+  return new EwmhImpl(conn, screen);
+}
+
+xcb_screen_t const* get_screen(xcb_connection_t* conn, int screen) {
+  auto setup = xcb_get_setup(conn);
+  xcb_screen_iterator_t iter = xcb_setup_roots_iterator(setup);
+  while (screen--) {
+    xcb_screen_next(&iter);
+  }
+  return iter.data;
+}
+
+void prefetch_extensions(xcb_connection_t* conn) {
+  xcb_prefetch_extension_data(conn, &xcb_render_id);
+}
+
+enum PixelFormat {
+  ABGR_8888,
+  ARGB_8888,
+  BGRA_8888,
+  RGBA_8888,
+};
+
+Format get_best_format(xcb_connection_t* conn, xcb_screen_t const* screen,
+                       bool allow_render) {
+  assert(conn);
+  uint8_t depth = 0;
+  xcb_visualtype_t* visual = nullptr;
+  xcb_render_pictforminfo_t* render = nullptr;
+  xcb_render_pictforminfo_t* render_alpha = nullptr;
+  xcb_render_query_pict_formats_reply_t* render_formats = nullptr;
+  PixelFormat format;
+
+  auto render_reply = xcb_get_extension_data(conn, &xcb_render_id);
+  if (render_reply && allow_render && render_reply->present) {
+    auto version = xcb_render_query_version_unchecked(
+        conn, XCB_RENDER_MAJOR_VERSION, XCB_RENDER_MINOR_VERSION);
+    auto formats = xcb_render_query_pict_formats_unchecked(conn);
+    auto version_reply = xcb_render_query_version_reply(conn, version, nullptr);
+    if (!version_reply || (version_reply->major_version == 0
+                           && version_reply->minor_version < 6)) {
+      xcb_discard_reply(conn, formats.sequence);
+    } else {
+      render_formats = xcb_render_query_pict_formats_reply(
+          conn, formats, nullptr);
+    }
+    free(version_reply);
+  }
+  auto count = xcb_screen_allowed_depths_length(screen);
+  if (count == 0) {
+    free(render_formats);
+    return Format();
+  }
+  auto iter = xcb_screen_allowed_depths_iterator(screen);
+  while (count--) {
+    auto d = iter.data;
+    if (d->depth <= depth) continue;
+    auto visuals_count = xcb_depth_visuals_length(d);
+    if (visuals_count == 0) continue;
+    auto v = xcb_depth_visuals(d);
+    for (; visuals_count--; ++v) {
+      switch (v->_class) {
+      case XCB_VISUAL_CLASS_TRUE_COLOR:
+      case XCB_VISUAL_CLASS_DIRECT_COLOR:
+        break;
+      default:
+        continue;
+      }
+      PixelFormat f;
+      if (v->bits_per_rgb_value != 8) continue;
+      if (v->red_mask == 0xff0000 && v->green_mask == 0xff00
+          && v->blue_mask == 0xff) {
+        f = ARGB_8888;
+      } else if (v->red_mask == 0xff && v->green_mask == 0xff00
+                 && v->blue_mask == 0xff0000) {
+        f = ABGR_8888;
+      } else if (v->red_mask == 0xff000000 && v->green_mask == 0xff0000
+                 && v->blue_mask == 0xff00) {
+        f = RGBA_8888;
+      } else if (v->red_mask == 0xff00 && v->green_mask == 0xff0000
+                 && v->blue_mask == 0xff000000) {
+        f = BGRA_8888;
+      } else {
+        continue;
+      }
+      visual = v;
+      format = f;
+      depth = d->depth;
+      if (!render_formats) break;
+      auto info = xcb_render_query_pict_formats_formats(render_formats);
+      auto count = xcb_render_query_pict_formats_formats_length(render_formats);
+      for (; count--; ++info) {
+        if (info->type != XCB_RENDER_PICT_TYPE_DIRECT) continue;
+        if (info->depth != d->depth) continue;
+        if (info->direct.alpha_mask != 0
+            || (static_cast<uint32_t>(info->direct.red_mask)
+                << info->direct.red_shift) != visual->red_mask
+            || (static_cast<uint32_t>(info->direct.green_mask)
+                << info->direct.green_shift) != visual->green_mask
+            || (static_cast<uint32_t>(info->direct.blue_mask)
+                << info->direct.blue_shift) != visual->blue_mask) continue;
+        render = info;
+        break;
+      }
+      if (render) break;
+    }
+    xcb_depth_next(&iter);
+  }
+  if (!depth) {
+    free(render_formats);
+    return Format();
+  }
+  if (render && render_formats) {
+    auto info = xcb_render_query_pict_formats_formats(render_formats);
+    auto count = xcb_render_query_pict_formats_formats_length(render_formats);
+    for (; count--; ++info) {
+      if (info->type != XCB_RENDER_PICT_TYPE_DIRECT) continue;
+      if (info->depth != 32) continue;
+      if (info->direct.alpha_mask != 0xff
+          || info->direct.red_mask != 0xff
+          || info->direct.green_mask != 0xff
+          || info->direct.blue_mask != 0xff) continue;
+
+      PixelFormat f;
+      if (info->direct.red_shift == 0
+          && info->direct.green_shift == 8
+          && info->direct.blue_shift == 16
+          && info->direct.alpha_shift == 24) {
+        f = ABGR_8888;
+      } else if (info->direct.red_shift == 16
+                 && info->direct.green_shift == 8
+                 && info->direct.blue_shift == 0
+                 && info->direct.alpha_shift == 24) {
+        f = ARGB_8888;
+      } else if (info->direct.red_shift == 8
+                 && info->direct.green_shift == 16
+                 && info->direct.blue_shift == 24
+                 && info->direct.alpha_shift == 0) {
+        f = BGRA_8888;
+      } else if (info->direct.red_shift == 24
+                 && info->direct.green_shift == 16
+                 && info->direct.blue_shift == 8
+                 && info->direct.alpha_shift == 0) {
+        f = RGBA_8888;
+      } else {
+        continue;
+      }
+
+      if (!render_alpha || f == format) {
+        render = info;
+      }
+    }
+    if (!render) {
+      render = nullptr;
+    }
+  }
+  // Leak render_formats here to be able to return render and render_alpha
+  // as xcb_render_pictforminfo_t pointers
+  // free(render_formats);
+
+  return Format(depth, visual, render, render_alpha);
+}
+
+}  // namespace x
diff --git a/src/x.hh b/src/x.hh
new file mode 100644
index 0000000..ce4f812
--- /dev/null
+++ b/src/x.hh
@@ -0,0 +1,255 @@
+#ifndef X_HH
+#define X_HH
+
+#include <memory>
+#include <xcb/render.h>
+#include <xcb/xcb.h>
+#include <xcb/xcb_ewmh.h>
+#include <xcb/xproto.h>
+#include <xcb/render.h>
+
+namespace x {
+
+namespace priv {
+struct XcbConnectionDelete {
+  void operator()(xcb_connection_t* ptr) const {
+    xcb_disconnect(ptr);
+  }
+};
+
+struct XcbWindowDelete {
+  void operator()(xcb_connection_t* conn, xcb_window_t id) const {
+    xcb_destroy_window(conn, id);
+  }
+};
+
+struct XcbPixmapDelete {
+  void operator()(xcb_connection_t* conn, xcb_window_t id) const {
+    xcb_free_pixmap(conn, id);
+  }
+};
+
+struct XcbGContextDelete {
+  void operator()(xcb_connection_t* conn, xcb_gcontext_t id) const {
+    xcb_free_gc(conn, id);
+  }
+};
+
+struct XcbRenderPictureDelete {
+  void operator()(xcb_connection_t* conn, xcb_render_picture_t pic) const {
+    xcb_render_free_picture(conn, pic);
+  }
+};
+
+}  // priv
+
+class shared_connection {
+public:
+  shared_connection() {
+  }
+  shared_connection(std::nullptr_t) {
+  }
+  explicit shared_connection(xcb_connection_t* conn)
+    : shared_(conn, priv::XcbConnectionDelete()) {
+  }
+  shared_connection(shared_connection const& shared)
+    : shared_(shared.shared_) {
+  }
+  shared_connection(shared_connection&& shared)
+    : shared_(std::move(shared.shared_)) {
+  }
+
+  shared_connection& operator=(shared_connection const& shared) {
+    shared_ = shared.shared_;
+    return *this;
+  }
+
+  shared_connection& operator=(shared_connection&& shared) {
+    shared_ = std::move(shared.shared_);
+    return *this;
+  }
+
+  void swap(shared_connection& shared) {
+    shared_.swap(shared.shared_);
+  }
+
+  void reset() {
+    shared_.reset();
+  }
+
+  void reset(xcb_connection_t* ptr) {
+    shared_.reset(ptr, priv::XcbConnectionDelete());
+  }
+
+  xcb_connection_t* get() const {
+    return shared_.get();
+  }
+
+  explicit operator bool() const {
+    return shared_.get() != nullptr;
+  }
+
+private:
+  std::shared_ptr<xcb_connection_t> shared_;
+};
+
+template<typename T, typename D>
+class unique_resource {
+public:
+  unique_resource()
+    : id_(XCB_NONE) {
+  }
+  explicit unique_resource(shared_connection const& conn)
+    : conn_(conn), id_(conn ? xcb_generate_id(conn.get()) : XCB_NONE) {
+  }
+  unique_resource(shared_connection const& conn, T id)
+    : conn_(conn), id_(id) {
+    if (id_ == XCB_NONE) conn_.reset();
+  }
+  unique_resource(unique_resource&& res)
+    : conn_(res.conn_), id_(res.release()) {
+  }
+
+  ~unique_resource() {
+    destroy();
+  }
+
+  unique_resource& operator=(shared_connection const& conn) {
+    reset(conn);
+    return *this;
+  }
+
+  unique_resource& operator=(unique_resource&& res) {
+    swap(res);
+    return *this;
+  }
+
+  xcb_connection_t* conn() const {
+    return conn_.get();
+  }
+
+  shared_connection const& shared_conn() const {
+    return conn_;
+  }
+
+  T get() const {
+    return id_;
+  }
+
+  explicit operator bool() const {
+    return id_ != XCB_NONE;
+  }
+
+  void reset() {
+    destroy();
+    conn_.reset();
+    id_ = XCB_NONE;
+  }
+
+  void reset(shared_connection const& conn) {
+    if (conn) {
+      reset(conn, xcb_generate_id(conn.get()));
+    } else {
+      reset();
+    }
+  }
+
+  void reset(shared_connection const& conn, T id) {
+    destroy();
+    conn_ = conn;
+    id_ = id;
+    if (id_ == XCB_NONE) conn_.reset();
+  }
+
+  void swap(unique_resource& res) {
+    conn_.swap(res.conn_);
+    auto tmp = id_;
+    id_ = res.id_;
+    res.id_ = tmp;
+  }
+
+private:
+  unique_resource(unique_resource const&) = delete;
+  unique_resource& operator=(unique_resource const&) = delete;
+
+  void destroy() {
+    if (id_ == XCB_NONE) return;
+    D()(conn_.get(), id_);
+  }
+
+  T release() {
+    T ret = id_;
+    id_ = XCB_NONE;
+    conn_.reset();
+    return ret;
+  }
+
+  shared_connection conn_;
+  T id_;
+};
+
+typedef unique_resource<xcb_window_t, priv::XcbWindowDelete> unique_window;
+typedef unique_resource<xcb_pixmap_t, priv::XcbPixmapDelete> unique_pixmap;
+typedef unique_resource<xcb_gcontext_t,
+                        priv::XcbGContextDelete> unique_gcontext;
+typedef unique_resource<xcb_render_picture_t,
+                        priv::XcbRenderPictureDelete> unique_picture;
+
+struct Format {
+  uint8_t depth;
+  xcb_visualtype_t* visual;
+  xcb_render_pictforminfo_t* render;
+  xcb_render_pictforminfo_t* render_alpha;
+
+  bool good() const {
+    return depth > 0 && visual;
+  }
+
+  Format(uint8_t depth, xcb_visualtype_t* visual,
+         xcb_render_pictforminfo_t* render,
+         xcb_render_pictforminfo_t* render_alpha)
+    : depth(depth), visual(visual), render(render), render_alpha(render_alpha) {
+  }
+  Format()
+    : depth(0), visual(nullptr), render(nullptr), render_alpha(nullptr) {
+  }
+};
+
+xcb_screen_t const* get_screen(xcb_connection_t* conn, int screen);
+void prefetch_extensions(xcb_connection_t* conn);
+Format get_best_format(xcb_connection_t* conn, xcb_screen_t const* screen,
+                       bool allow_render = true);
+
+class Atoms {
+public:
+  virtual ~Atoms() {}
+
+  static Atoms* create(shared_connection const& conn);
+
+  virtual void preload(std::string const& name, bool create = true) = 0;
+  virtual xcb_atom_t get(std::string const& name, bool create = true) = 0;
+
+protected:
+  Atoms() {}
+  Atoms(Atoms const&) = delete;
+  Atoms& operator=(Atoms const&) = delete;
+};
+
+class Ewmh {
+public:
+  virtual ~Ewmh() {}
+
+  static Ewmh* create(shared_connection const& conn, int screen);
+
+  virtual xcb_ewmh_connection_t* conn() = 0;
+  virtual bool supported(xcb_atom_t atom) = 0;
+
+protected:
+  Ewmh() {}
+  Ewmh(Ewmh const&) = delete;
+  Ewmh& operator=(Ewmh const&) = delete;
+};
+
+}  // namespace x
+
+#endif  // X_HH
-- 
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