import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

gfx/layers/ipc/SynchronousTask.h

@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_SYNCHRONOUSTASK_H
+#define MOZILLA_GFX_SYNCHRONOUSTASK_H
+
+#include "mozilla/ReentrantMonitor.h"   // for ReentrantMonitor, etc
+
+namespace mozilla {
+namespace layers {
+
+// Helper that creates a monitor and a "done" flag, then enters the monitor.
+// This can go away when we switch ImageBridge to an XPCOM thread.
+class MOZ_STACK_CLASS SynchronousTask
+{
+  friend class AutoCompleteTask;
+
+public:
+  explicit SynchronousTask(const char* name)
+   : mMonitor(name),
+     mAutoEnter(mMonitor),
+     mDone(false)
+  {}
+
+  void Wait() {
+    while (!mDone) {
+      mMonitor.Wait();
+    }
+  }
+
+private:
+  void Complete() {
+    mDone = true;
+    mMonitor.NotifyAll();
+  }
+
+private:
+  ReentrantMonitor mMonitor;
+  ReentrantMonitorAutoEnter mAutoEnter;
+  bool mDone;
+};
+
+class MOZ_STACK_CLASS AutoCompleteTask
+{
+public:
+  explicit AutoCompleteTask(SynchronousTask* aTask)
+   : mTask(aTask),
+     mAutoEnter(aTask->mMonitor)
+  {
+  }
+  ~AutoCompleteTask() {
+    mTask->Complete();
+  }
+
+private:
+  SynchronousTask* mTask;
+  ReentrantMonitorAutoEnter mAutoEnter;
+};
+
+}
+}
+
+#endif