commit-bot@chromium.org | 50a3043 | 2013-10-24 17:44:27 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2013 Google Inc. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license that can be |
| 5 | * found in the LICENSE file. |
| 6 | */ |
| 7 | |
| 8 | #ifndef SkMessageBus_DEFINED |
| 9 | #define SkMessageBus_DEFINED |
| 10 | |
| 11 | #include "SkOnce.h" |
| 12 | #include "SkTDArray.h" |
| 13 | #include "SkThread.h" |
| 14 | #include "SkTypes.h" |
| 15 | |
| 16 | template <typename Message> |
| 17 | class SkMessageBus : SkNoncopyable { |
| 18 | public: |
| 19 | // Post a message to be received by all Inboxes for this Message type. Threadsafe. |
| 20 | static void Post(const Message& m); |
| 21 | |
| 22 | class Inbox { |
| 23 | public: |
| 24 | Inbox(); |
| 25 | ~Inbox(); |
| 26 | |
| 27 | // Overwrite out with all the messages we've received since the last call. Threadsafe. |
| 28 | void poll(SkTDArray<Message>* out); |
| 29 | |
| 30 | private: |
| 31 | SkTDArray<Message> fMessages; |
| 32 | SkMutex fMessagesMutex; |
| 33 | |
| 34 | friend class SkMessageBus; |
| 35 | void receive(const Message& m); // SkMessageBus is a friend only to call this. |
| 36 | }; |
| 37 | |
| 38 | private: |
| 39 | SkMessageBus(); |
| 40 | static SkMessageBus* Get(); |
| 41 | static void New(SkMessageBus**); |
| 42 | |
| 43 | SkTDArray<Inbox*> fInboxes; |
| 44 | SkMutex fInboxesMutex; |
| 45 | }; |
| 46 | |
| 47 | // ----------------------- Implementation of SkMessageBus::Inbox ----------------------- |
| 48 | |
| 49 | template<typename Message> |
| 50 | SkMessageBus<Message>::Inbox::Inbox() { |
| 51 | // Register ourselves with the corresponding message bus. |
| 52 | SkMessageBus<Message>* bus = SkMessageBus<Message>::Get(); |
| 53 | SkAutoMutexAcquire lock(bus->fInboxesMutex); |
| 54 | bus->fInboxes.push(this); |
| 55 | } |
| 56 | |
| 57 | template<typename Message> |
| 58 | SkMessageBus<Message>::Inbox::~Inbox() { |
| 59 | // Remove ourselves from the corresponding message bus. |
| 60 | SkMessageBus<Message>* bus = SkMessageBus<Message>::Get(); |
| 61 | SkAutoMutexAcquire lock(bus->fInboxesMutex); |
| 62 | // This is a cheaper fInboxes.remove(fInboxes.find(this)) when order doesn't matter. |
| 63 | for (int i = 0; i < bus->fInboxes.count(); i++) { |
| 64 | if (this == bus->fInboxes[i]) { |
| 65 | bus->fInboxes.removeShuffle(i); |
| 66 | break; |
| 67 | } |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | template<typename Message> |
| 72 | void SkMessageBus<Message>::Inbox::receive(const Message& m) { |
| 73 | SkAutoMutexAcquire lock(fMessagesMutex); |
| 74 | fMessages.push(m); |
| 75 | } |
| 76 | |
| 77 | template<typename Message> |
| 78 | void SkMessageBus<Message>::Inbox::poll(SkTDArray<Message>* messages) { |
| 79 | SkASSERT(NULL != messages); |
| 80 | messages->reset(); |
| 81 | SkAutoMutexAcquire lock(fMessagesMutex); |
| 82 | messages->swap(fMessages); |
| 83 | } |
| 84 | |
| 85 | // ----------------------- Implementation of SkMessageBus ----------------------- |
| 86 | |
| 87 | template <typename Message> |
| 88 | SkMessageBus<Message>::SkMessageBus() {} |
| 89 | |
| 90 | template <typename Message> |
| 91 | /*static*/ void SkMessageBus<Message>::New(SkMessageBus<Message>** bus) { |
| 92 | *bus = new SkMessageBus<Message>(); |
| 93 | } |
| 94 | |
| 95 | template <typename Message> |
| 96 | /*static*/ SkMessageBus<Message>* SkMessageBus<Message>::Get() { |
| 97 | // The first time this method is called, create the singleton bus for this message type. |
| 98 | static SkMessageBus<Message>* bus = NULL; |
| 99 | SK_DECLARE_STATIC_ONCE(once); |
| 100 | SkOnce(&once, &New, &bus); |
| 101 | |
| 102 | SkASSERT(bus != NULL); |
| 103 | return bus; |
| 104 | } |
| 105 | |
| 106 | template <typename Message> |
| 107 | /*static*/ void SkMessageBus<Message>::Post(const Message& m) { |
| 108 | SkMessageBus<Message>* bus = SkMessageBus<Message>::Get(); |
| 109 | SkAutoMutexAcquire lock(bus->fInboxesMutex); |
| 110 | for (int i = 0; i < bus->fInboxes.count(); i++) { |
| 111 | bus->fInboxes[i]->receive(m); |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | #endif // SkMessageBus_DEFINED |