From 6232d13f5321b87ddf12a1aa36b4545da45f173d Mon Sep 17 00:00:00 2001
From: Joel Klinghed <the_jk@spawned.biz>
Date: Wed, 17 Nov 2021 22:34:57 +0100
Subject: Travel3: Simple image and video display site

Reads the images and videos from filesystem and builds a site in
memroy.
---
 src/task_runner_thread.cc | 73 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 src/task_runner_thread.cc

(limited to 'src/task_runner_thread.cc')

diff --git a/src/task_runner_thread.cc b/src/task_runner_thread.cc
new file mode 100644
index 0000000..6e1a06f
--- /dev/null
+++ b/src/task_runner_thread.cc
@@ -0,0 +1,73 @@
+#include "common.hh"
+
+#include <algorithm>
+#include <condition_variable>
+#include <deque>
+#include <mutex>
+#include <thread>
+
+#include "task_runner.hh"
+
+namespace {
+
+class TaskRunnerThread : public TaskRunner {
+public:
+  explicit TaskRunnerThread(size_t threads)
+    : threads_(std::max<size_t>(1, threads)) {
+    thread_ = std::make_unique<std::thread[]>(threads_);
+    for (size_t i = 0; i < threads_; ++i)
+      thread_[i] = std::thread(&TaskRunnerThread::thread, this);
+  }
+
+  ~TaskRunnerThread() override {
+    {
+      std::lock_guard<std::mutex> lock(mutex_);
+      quit_ = true;
+    }
+    cond_.notify_all();
+    for (size_t i = 0; i < threads_; ++i)
+      thread_[i].join();
+  }
+
+  void post(std::function<void()> callback) override {
+    {
+      std::lock_guard<std::mutex> lock(mutex_);
+      queue_.push_back(std::move(callback));
+    }
+    cond_.notify_one();
+  }
+
+private:
+  void thread() {
+    while (true) {
+      std::function<void()> callback;
+      while (true) {
+        std::unique_lock<std::mutex> lock(mutex_);
+        if (queue_.empty()) {
+          if (quit_)
+            return;
+          cond_.wait(lock);
+        } else {
+          callback = std::move(queue_.front());
+          queue_.pop_front();
+          break;
+        }
+      }
+
+      callback();
+    }
+  }
+
+  size_t const threads_;
+  bool quit_{false};
+  std::condition_variable cond_;
+  std::mutex mutex_;
+  std::deque<std::function<void()>> queue_;
+  std::unique_ptr<std::thread[]> thread_;
+};
+
+}  // namespace
+
+std::unique_ptr<TaskRunner> TaskRunner::create(size_t threads) {
+  return std::make_unique<TaskRunnerThread>(threads);
+}
-- 
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