mojo/common/handle_watcher.h

   1 // Copyright 2013 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 MOJO_COMMON_HANDLE_WATCHER_H_
   6 #define MOJO_COMMON_HANDLE_WATCHER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/callback_forward.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "mojo/common/mojo_common_export.h"
  12 #include "mojo/public/system/core_cpp.h"
  13
  14 namespace base {
  15 class Thread;
  16 class TickClock;
  17 class TimeTicks;
  18 }
  19
  20 namespace mojo {
  21 namespace common {
  22 namespace test {
  23 class HandleWatcherTest;
  24 }
  25
  26 // HandleWatcher is used to asynchronously wait on a handle and notify a Closure
  27 // when the handle is ready, or the deadline has expired.
  28 class MOJO_COMMON_EXPORT HandleWatcher {
  29  public:
  30   HandleWatcher();
  31   ~HandleWatcher();
  32
  33   // Starts listening for |handle|. This implicitly invokes Stop(). In other
  34   // words, Start() performs one asynchronous watch at a time. It is ok to call
  35   // Start() multiple times, but it cancels any existing watches. |callback| is
  36   // notified when the handle is ready, invalid or deadline has passed and is
  37   // notified on the thread Start() was invoked on.
  38   void Start(const Handle& handle,
  39              MojoWaitFlags wait_flags,
  40              MojoDeadline deadline,
  41              const base::Callback<void(MojoResult)>& callback);
  42
  43   // Stops listening. Does nothing if not in the process of listening.
  44   void Stop();
  45
  46   // Returns now. Used internally; generally not useful.
  47   static base::TimeTicks NowTicks();
  48
  49   // Converts a MojoDeadline into a TimeTicks.
  50   static base::TimeTicks MojoDeadlineToTimeTicks(MojoDeadline deadline);
  51
  52  private:
  53   friend class test::HandleWatcherTest;
  54   struct StartState;
  55
  56   // See description of |StartState::weak_factory| for details.
  57   void OnHandleReady(MojoResult result);
  58
  59   // If non-NULL Start() has been invoked.
  60   scoped_ptr<StartState> start_state_;
  61
  62   // Used for getting the time. Only set by tests.
  63   static base::TickClock* tick_clock_;
  64
  65   DISALLOW_COPY_AND_ASSIGN(HandleWatcher);
  66 };
  67
  68 }  // namespace common
  69 }  // namespace mojo
  70
  71 #endif  // MOJO_COMMON_HANDLE_WATCHER_H_