| OLD | NEW |
| (Empty) |
| 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_EDK_SYSTEM_WAITER_H_ | |
| 6 #define MOJO_EDK_SYSTEM_WAITER_H_ | |
| 7 | |
| 8 #include <stdint.h> | |
| 9 | |
| 10 #include "base/macros.h" | |
| 11 #include "base/synchronization/condition_variable.h" | |
| 12 #include "base/synchronization/lock.h" | |
| 13 #include "mojo/edk/system/awakable.h" | |
| 14 #include "mojo/edk/system/system_impl_export.h" | |
| 15 #include "mojo/public/c/system/types.h" | |
| 16 | |
| 17 namespace mojo { | |
| 18 namespace system { | |
| 19 | |
| 20 // IMPORTANT (all-caps gets your attention, right?): |Waiter| methods are called | |
| 21 // under other locks, in particular, |Dispatcher::lock_|s, so |Waiter| methods | |
| 22 // must never call out to other objects (in particular, |Dispatcher|s). This | |
| 23 // class is thread-safe. | |
| 24 class MOJO_SYSTEM_IMPL_EXPORT Waiter : public Awakable { | |
| 25 public: | |
| 26 Waiter(); | |
| 27 ~Waiter(); | |
| 28 | |
| 29 // A |Waiter| can be used multiple times; |Init()| should be called before | |
| 30 // each time it's used. | |
| 31 void Init(); | |
| 32 | |
| 33 // Waits until a suitable |Awake()| is called. (|context| may be null, in | |
| 34 // which case, obviously no context is ever returned.) | |
| 35 // Returns: | |
| 36 // - The result given to the first call to |Awake()| (possibly before this | |
| 37 // call to |Wait()|); in this case, |*context| is set to the value passed | |
| 38 // to that call to |Awake()|. | |
| 39 // - |MOJO_RESULT_DEADLINE_EXCEEDED| if the deadline was exceeded; in this | |
| 40 // case |*context| is not modified. | |
| 41 // | |
| 42 // Usually, the context passed to |Awake()| will be the value passed to | |
| 43 // |Dispatcher::AddAwakable()|, which is usually the index to the array of | |
| 44 // handles passed to |MojoWaitMany()| (or 0 for |MojoWait()|). | |
| 45 // | |
| 46 // Typical |Awake()| results are: | |
| 47 // - |MOJO_RESULT_OK| if one of the flags passed to | |
| 48 // |MojoWait()|/|MojoWaitMany()| (hence |Dispatcher::AddAwakable()|) was | |
| 49 // satisfied; | |
| 50 // - |MOJO_RESULT_CANCELLED| if a handle (on which | |
| 51 // |MojoWait()|/|MojoWaitMany()| was called) was closed (hence the | |
| 52 // dispatcher closed); and | |
| 53 // - |MOJO_RESULT_FAILED_PRECONDITION| if one of the set of flags passed to | |
| 54 // |MojoWait()|/|MojoWaitMany()| cannot or can no longer be satisfied by | |
| 55 // the corresponding handle (e.g., if the other end of a message or data | |
| 56 // pipe is closed). | |
| 57 MojoResult Wait(MojoDeadline deadline, uint32_t* context); | |
| 58 | |
| 59 // Wake the waiter up with the given result and context (or no-op if it's been | |
| 60 // woken up already). | |
| 61 bool Awake(MojoResult result, uintptr_t context) override; | |
| 62 | |
| 63 private: | |
| 64 base::ConditionVariable cv_; // Associated to |lock_|. | |
| 65 base::Lock lock_; // Protects the following members. | |
| 66 #ifndef NDEBUG | |
| 67 bool initialized_; | |
| 68 #endif | |
| 69 bool awoken_; | |
| 70 MojoResult awake_result_; | |
| 71 uintptr_t awake_context_; | |
| 72 | |
| 73 DISALLOW_COPY_AND_ASSIGN(Waiter); | |
| 74 }; | |
| 75 | |
| 76 } // namespace system | |
| 77 } // namespace mojo | |
| 78 | |
| 79 #endif // MOJO_EDK_SYSTEM_WAITER_H_ | |
| OLD | NEW |