content/public/child/worker_thread.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_PUBLIC_CHILD_WORKER_THREAD_H_
   6 #define CONTENT_PUBLIC_CHILD_WORKER_THREAD_H_
   7
   8 #include "base/callback.h"
   9 #include "base/macros.h"
  10 #include "content/common/content_export.h"
  11
  12 namespace content {
  13
  14 // Utility functions for worker threads, for example service worker threads.
  15 //
  16 // This allows getting the thread IDs for service worker threads, then later
  17 // posting tasks back to them.
  18 class CONTENT_EXPORT WorkerThread {
  19  public:
  20   // Observes worker thread lifetime.
  21   class CONTENT_EXPORT Observer {
  22    public:
  23     virtual ~Observer() {}
  24
  25     // Notifies the observer that the current worker thread is about to be
  26     // stopped.
  27     //
  28     // The worker state may have already been destroyed. To observe that, use
  29     // ContentRendererClient::WillDestroyServiceWorkerContextOnWorkerThread.
  30     virtual void WillStopCurrentWorkerThread() {}
  31   };
  32
  33   // Adds/removes an Observer. Observers are stored per-thread, so it is only
  34   // valid to call these from a worker thread, and events will be dispatched on
  35   // that worker's thread.
  36   static void AddObserver(Observer* observer);
  37   static void RemoveObserver(Observer* observer);
  38
  39   // Returns the thread ID for the current worker thread, or 0 if this is not a
  40   // worker thread (for example, the render thread). Worker thread IDs will
  41   // always be > 0.
  42   static int GetCurrentId();
  43
  44   // Posts a task to the worker thread with ID |id|. ID must be > 0.
  45   static void PostTask(int id, const base::Closure& task);
  46
  47  private:
  48   WorkerThread(){};
  49   DISALLOW_COPY_AND_ASSIGN(WorkerThread);
  50 };
  51
  52 }  // namespace content
  53
  54 #endif  // CONTENT_PUBLIC_CHILD_WORKER_THREAD_H_