Extract Awakable from Waiter

mojo/edk/system/waiter.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_EDK_SYSTEM_WAITER_H_
 #define MOJO_EDK_SYSTEM_WAITER_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
+#include "mojo/edk/system/awakable.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/c/system/types.h"
 
 namespace mojo {
 namespace system {
 
 // IMPORTANT (all-caps gets your attention, right?): |Waiter| methods are called
 // under other locks, in particular, |Dispatcher::lock_|s, so |Waiter| methods
 // must never call out to other objects (in particular, |Dispatcher|s). This
 // class is thread-safe.
-class MOJO_SYSTEM_IMPL_EXPORT Waiter {
+class MOJO_SYSTEM_IMPL_EXPORT Waiter : public Awakable {
  public:
   Waiter();
   ~Waiter();

[viettrungluu, 2014/12/03 22:31:27]

Maybe this should be declared virtual.

(It's not really needed, since no one should delete it from an Awakable*. Maybe
that means that Awakable should have a protected, non-virtual destructor
declared.)

[Hajime Morrita, 2014/12/03 22:47:11]

Added protected ~Awakable() to make it clear that Awakable won't be deleted.

 
   // A |Waiter| can be used multiple times; |Init()| should be called before
   // each time it's used.
   void Init();
 
   // Waits until a suitable |Awake()| is called. (|context| may be null, in
   // which case, obviously no context is ever returned.)
   // Returns:
   //   - The result given to the first call to |Awake()| (possibly before this
   //     call to |Wait()|); in this case, |*context| is set to the value passed
@@ skipping 13 matching lines @@
   //     |MojoWait()|/|MojoWaitMany()| was called) was closed (hence the
   //     dispatcher closed); and
   //   - |MOJO_RESULT_FAILED_PRECONDITION| if one of the set of flags passed to
   //     |MojoWait()|/|MojoWaitMany()| cannot or can no longer be satisfied by
   //     the corresponding handle (e.g., if the other end of a message or data
   //     pipe is closed).
   MojoResult Wait(MojoDeadline deadline, uint32_t* context);
 
   // Wake the waiter up with the given result and context (or no-op if it's been
   // woken up already).
-  void Awake(MojoResult result, uint32_t context);
+  void Awake(MojoResult result, uintptr_t context) override;
 
  private:
   base::ConditionVariable cv_;  // Associated to |lock_|.
   base::Lock lock_;             // Protects the following members.
 #ifndef NDEBUG
   bool initialized_;
 #endif
   bool awoken_;
   MojoResult awake_result_;
   // This is a |uint32_t| because we really only need to store an index (for

[viettrungluu, 2014/12/03 22:31:27]

Remove this comment.

   // |MojoWaitMany()|). But in tests, it's convenient to use this for other
   // purposes (e.g., to distinguish between different wake-up reasons).
-  uint32_t awake_context_;
+  uintptr_t awake_context_;
 
   DISALLOW_COPY_AND_ASSIGN(Waiter);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_WAITER_H_