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// -*- mode: c++; c-basic-offset: 2; -*-
#include "common.hh"
#include <condition_variable>
#include <cstring>
#include <fcntl.h>
#include <mutex>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <thread>
#include <vector>
#include "io.hh"
#include "looper.hh"
#include "resolver.hh"
namespace {
size_t const WORKERS = 4;
class ResolverImpl : public Resolver {
public:
ResolverImpl(Looper* looper)
: looper_(looper), request_(nullptr), buf_(new char[sizeof(Request*)]),
fill_(0), quit_(false) {
while (threads_.size() < WORKERS) {
threads_.emplace_back(std::bind(&ResolverImpl::worker, this));
}
if (pipe_.open() && fcntl(pipe_.read(), F_SETFL, O_NONBLOCK) == 0) {
looper_->add(pipe_.read(),
Looper::EVENT_READ,
std::bind(&ResolverImpl::event, this,
std::placeholders::_1, std::placeholders::_2));
} else {
assert(false);
}
}
~ResolverImpl() override {
quit_ = true;
cond_.notify_all();
for (auto& thread : threads_) {
thread.join();
}
}
void* request(std::string const& host, uint16_t port,
Callback const& callback) override {
auto req = new Request();
req->host = host;
req->port = port;
req->callback = callback;
req->canceled = false;
std::unique_lock<std::mutex> lock(mutex_);
req->next = request_;
request_ = req;
cond_.notify_one();
return req;
}
void cancel(void* ptr) override {
auto req = reinterpret_cast<Request*>(ptr);
req->canceled = true;
std::unique_lock<std::mutex> lock(mutex_);
if (request_ == req) {
request_ = req->next;
delete req;
} else {
for (auto r = request_; r->next; r = r->next) {
if (r->next == req) {
r->next = req->next;
delete req;
return;
}
}
}
}
protected:
struct Request {
Request* next;
std::string host;
uint16_t port;
Callback callback;
bool canceled;
io::auto_fd fd;
bool connected;
std::string error;
};
void event(int fd, uint8_t event) {
assert(fd == pipe_.read());
if (event & Looper::EVENT_READ) {
while (true) {
auto ret = io::read(fd, buf_.get() + fill_, sizeof(Request*) - fill_);
if (ret == -1) {
if (errno == EAGAIN || errno == EWOULDBLOCK) return;
assert(false);
return;
} else if (ret == 0) {
assert(false);
return;
}
fill_ += ret;
if (fill_ == sizeof(Request*)) {
fill_ = 0;
auto req = *reinterpret_cast<Request**>(buf_.get());
if (!req->canceled) {
auto err = req->fd ? nullptr : req->error.c_str();
req->callback(req->fd.release(), req->connected, err);
}
delete req;
} else {
break;
}
}
} else {
assert(false);
}
}
void report(Request* req, int fd, bool connected, char const* errmsg) {
req->fd.reset(fd);
req->connected = connected;
if (errmsg) req->error = errmsg;
io::write_all(pipe_.write(), &req, sizeof(Request*));
}
void worker() {
struct addrinfo hints;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_V4MAPPED | AI_ADDRCONFIG | AI_NUMERICSERV;
char tmp[10];
while (true) {
Request* req;
{
std::unique_lock<std::mutex> lock(mutex_);
while (!quit_ && !request_) {
cond_.wait(lock);
}
if (quit_) return;
auto pr = &request_;
while ((*pr)->next) {
pr = &((*pr)->next);
}
req = *pr;
*pr = nullptr;
}
snprintf(tmp, sizeof(tmp), "%u", static_cast<unsigned int>(req->port));
struct addrinfo* result;
auto ret = getaddrinfo(req->host.c_str(), tmp, &hints, &result);
if (ret != 0) {
report(req, -1, false, gai_strerror(ret));
continue;
}
auto rp = result;
for (; rp; rp = rp->ai_next) {
io::auto_fd fd(socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol));
if (!fd) continue;
fcntl(fd.get(), F_SETFL, O_NONBLOCK);
while (true) {
ret = connect(fd.get(), rp->ai_addr, rp->ai_addrlen);
if (ret == 0 || errno != EINTR) break;
}
if (ret == 0) {
report(req, fd.release(), true, nullptr);
break;
}
if (errno == EINPROGRESS) {
report(req, fd.release(), false, nullptr);
break;
}
}
if (!rp) {
freeaddrinfo(result);
report(req, -1, false, strerror(errno));
continue;
}
freeaddrinfo(result);
}
}
Looper* const looper_;
Request* request_;
io::auto_pipe pipe_;
std::mutex mutex_;
std::condition_variable cond_;
std::unique_ptr<char[]> buf_;
size_t fill_;
bool quit_;
std::vector<std::thread> threads_;
};
} // namespace
// static
Resolver* Resolver::create(Looper* looper) {
return new ResolverImpl(looper);
}
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