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- /*
- * Copyright 2013 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #ifndef SkMessageBus_DEFINED
- #define SkMessageBus_DEFINED
- #include "include/core/SkTypes.h"
- #include "include/private/SkMutex.h"
- #include "include/private/SkNoncopyable.h"
- #include "include/private/SkOnce.h"
- #include "include/private/SkTArray.h"
- #include "include/private/SkTDArray.h"
- /**
- * The following method must have a specialization for type 'Message':
- *
- * bool SkShouldPostMessageToBus(const Message&, uint32_t msgBusUniqueID)
- *
- * We may want to consider providing a default template implementation, to avoid this requirement by
- * sending to all inboxes when the specialization for type 'Message' is not present.
- */
- template <typename Message>
- class SkMessageBus : SkNoncopyable {
- public:
- // Post a message to be received by Inboxes for this Message type. Checks
- // SkShouldPostMessageToBus() for each inbox. Threadsafe.
- static void Post(const Message& m);
- class Inbox {
- public:
- Inbox(uint32_t uniqueID = SK_InvalidUniqueID);
- ~Inbox();
- uint32_t uniqueID() const { return fUniqueID; }
- // Overwrite out with all the messages we've received since the last call. Threadsafe.
- void poll(SkTArray<Message>* out);
- private:
- SkTArray<Message> fMessages;
- SkMutex fMessagesMutex;
- uint32_t fUniqueID;
- friend class SkMessageBus;
- void receive(const Message& m); // SkMessageBus is a friend only to call this.
- };
- private:
- SkMessageBus();
- static SkMessageBus* Get();
- SkTDArray<Inbox*> fInboxes;
- SkMutex fInboxesMutex;
- };
- // This must go in a single .cpp file, not some .h, or we risk creating more than one global
- // SkMessageBus per type when using shared libraries. NOTE: at most one per file will compile.
- #define DECLARE_SKMESSAGEBUS_MESSAGE(Message) \
- template <> \
- SkMessageBus<Message>* SkMessageBus<Message>::Get() { \
- static SkOnce once; \
- static SkMessageBus<Message>* bus; \
- once([] { bus = new SkMessageBus<Message>(); }); \
- return bus; \
- }
- // ----------------------- Implementation of SkMessageBus::Inbox -----------------------
- template<typename Message>
- SkMessageBus<Message>::Inbox::Inbox(uint32_t uniqueID) : fUniqueID(uniqueID) {
- // Register ourselves with the corresponding message bus.
- SkMessageBus<Message>* bus = SkMessageBus<Message>::Get();
- SkAutoMutexExclusive lock(bus->fInboxesMutex);
- bus->fInboxes.push_back(this);
- }
- template<typename Message>
- SkMessageBus<Message>::Inbox::~Inbox() {
- // Remove ourselves from the corresponding message bus.
- SkMessageBus<Message>* bus = SkMessageBus<Message>::Get();
- SkAutoMutexExclusive lock(bus->fInboxesMutex);
- // This is a cheaper fInboxes.remove(fInboxes.find(this)) when order doesn't matter.
- for (int i = 0; i < bus->fInboxes.count(); i++) {
- if (this == bus->fInboxes[i]) {
- bus->fInboxes.removeShuffle(i);
- break;
- }
- }
- }
- template<typename Message>
- void SkMessageBus<Message>::Inbox::receive(const Message& m) {
- SkAutoMutexExclusive lock(fMessagesMutex);
- fMessages.push_back(m);
- }
- template<typename Message>
- void SkMessageBus<Message>::Inbox::poll(SkTArray<Message>* messages) {
- SkASSERT(messages);
- messages->reset();
- SkAutoMutexExclusive lock(fMessagesMutex);
- fMessages.swap(*messages);
- }
- // ----------------------- Implementation of SkMessageBus -----------------------
- template <typename Message>
- SkMessageBus<Message>::SkMessageBus() {}
- template <typename Message>
- /*static*/ void SkMessageBus<Message>::Post(const Message& m) {
- SkMessageBus<Message>* bus = SkMessageBus<Message>::Get();
- SkAutoMutexExclusive lock(bus->fInboxesMutex);
- for (int i = 0; i < bus->fInboxes.count(); i++) {
- if (SkShouldPostMessageToBus(m, bus->fInboxes[i]->fUniqueID)) {
- bus->fInboxes[i]->receive(m);
- }
- }
- }
- #endif // SkMessageBus_DEFINED
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