extensions/browser/api/async_api_function.h

   1 // Copyright 2014 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 EXTENSIONS_BROWSER_API_ASYNC_API_FUCTION_H_
   6 #define EXTENSIONS_BROWSER_API_ASYNC_API_FUCTION_H_
   7
   8 #include "content/public/browser/browser_thread.h"
   9 #include "extensions/browser/extension_function.h"
  10
  11 namespace extensions {
  12
  13 // AsyncApiFunction provides convenient thread management for APIs that need to
  14 // do essentially all their work on a thread other than the UI thread.
  15 class AsyncApiFunction : public AsyncExtensionFunction {
  16  protected:
  17   AsyncApiFunction();
  18   ~AsyncApiFunction() override;
  19
  20   // Like Prepare(). A useful place to put common work in an ApiFunction
  21   // superclass that multiple API functions want to share.
  22   virtual bool PrePrepare();
  23
  24   // Set up for work (e.g., validate arguments). Guaranteed to happen on UI
  25   // thread.
  26   virtual bool Prepare() = 0;
  27
  28   // Do actual work. Guaranteed to happen on the thread specified in
  29   // work_thread_id_.
  30   virtual void Work();
  31
  32   // Start the asynchronous work. Guraranteed to happen on requested thread.
  33   virtual void AsyncWorkStart();
  34
  35   // Notify AsyncIOApiFunction that the work is completed
  36   void AsyncWorkCompleted();
  37
  38   // Respond. Guaranteed to happen on UI thread.
  39   virtual bool Respond() = 0;
  40
  41   // ExtensionFunction::RunAsync()
  42   bool RunAsync() override;
  43
  44  protected:
  45   content::BrowserThread::ID work_thread_id() const { return work_thread_id_; }
  46   void set_work_thread_id(content::BrowserThread::ID work_thread_id) {
  47     work_thread_id_ = work_thread_id;
  48   }
  49
  50  private:
  51   void WorkOnWorkThread();
  52   void RespondOnUIThread();
  53
  54   // If you don't want your Work() method to happen on the IO thread, then set
  55   // this to the thread that you do want, preferably in Prepare().
  56   content::BrowserThread::ID work_thread_id_;
  57 };
  58
  59 }  // namespace extensions
  60
  61 #endif  // EXTENSIONS_BROWSER_API_ASYNC_API_FUCTION_H_