Issue 3595 - Get rid of detached threads for setTimeout

src/DefaultTimer.h

+/*
+* This file is part of Adblock Plus <https://adblockplus.org/>,
+* Copyright (C) 2006-2017 eyeo GmbH
+*
+* Adblock Plus is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License version 3 as
+* published by the Free Software Foundation.
+*
+* Adblock Plus is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef ADBLOCK_PLUS_DEFAULT_TIMER_H
+#define ADBLOCK_PLUS_DEFAULT_TIMER_H
+
+#include <AdblockPlus/ITimer.h>
+#include <mutex>
+#include <condition_variable>
+#include <queue>
+#include <atomic>
+#include <thread>
+
+namespace AdblockPlus
+{
+  class DefaultTimer : public ITimer
+  {
+    struct TimerUnit {
+      std::chrono::steady_clock::time_point fireAt;
+      TimerCallback callback;
+    };
+    struct TimerUnitComparator {
+      typedef bool result_type;
+      typedef TimerUnit first_argument_type;
+      typedef TimerUnit second_argument_type;
+      bool operator()(const first_argument_type& t1, const second_argument_type& t2) const {
+        // pay attention 2 < 1 because we need the smallest time at the top.
+        return t2.fireAt < t1.fireAt;
+      }
+    };
+    typedef std::priority_queue<TimerUnit, std::vector<TimerUnit>, TimerUnitComparator> TimerUnits;
+  public:
+    DefaultTimer();
+    ~DefaultTimer();
+    void SetTimer(const std::chrono::milliseconds& timeout, const TimerCallback& timerCallback) override;
+  private:
+    void ThreadFunc();
+  private:
+    std::mutex mutex;
+    std::condition_variable conditionVariable;
+    TimerUnits timers;
+    std::atomic<bool> shouldThreadStop;
+    std::thread m_thread;
+  };
+}
+
+#endif