125 lines
4.7 KiB
C++
125 lines
4.7 KiB
C++
/*
|
|
* Copyright 2014 The WebRTC Project Authors. All rights reserved.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license
|
|
* that can be found in the LICENSE file in the root of the source
|
|
* tree. An additional intellectual property rights grant can be found
|
|
* in the file PATENTS. All contributing project authors may
|
|
* be found in the AUTHORS file in the root of the source tree.
|
|
*/
|
|
|
|
#include "rtc_base/async_invoker.h"
|
|
|
|
#include "rtc_base/checks.h"
|
|
#include "rtc_base/logging.h"
|
|
|
|
namespace rtc {
|
|
|
|
AsyncInvoker::AsyncInvoker()
|
|
: pending_invocations_(0),
|
|
invocation_complete_(new RefCountedObject<Event>()),
|
|
destroying_(false) {}
|
|
|
|
AsyncInvoker::~AsyncInvoker() {
|
|
destroying_.store(true, std::memory_order_relaxed);
|
|
// Messages for this need to be cleared *before* our destructor is complete.
|
|
ThreadManager::Clear(this);
|
|
// And we need to wait for any invocations that are still in progress on
|
|
// other threads. Using memory_order_acquire for synchronization with
|
|
// AsyncClosure destructors.
|
|
while (pending_invocations_.load(std::memory_order_acquire) > 0) {
|
|
// If the destructor was called while AsyncInvoke was being called by
|
|
// another thread, WITHIN an AsyncInvoked functor, it may do another
|
|
// Thread::Post even after we called ThreadManager::Clear(this). So
|
|
// we need to keep calling Clear to discard these posts.
|
|
Thread::Current()->Clear(this);
|
|
invocation_complete_->Wait(Event::kForever);
|
|
}
|
|
}
|
|
|
|
void AsyncInvoker::OnMessage(Message* msg) {
|
|
// Get the AsyncClosure shared ptr from this message's data.
|
|
ScopedMessageData<AsyncClosure>* data =
|
|
static_cast<ScopedMessageData<AsyncClosure>*>(msg->pdata);
|
|
// Execute the closure and trigger the return message if needed.
|
|
data->inner_data().Execute();
|
|
delete data;
|
|
}
|
|
|
|
void AsyncInvoker::Flush(Thread* thread, uint32_t id /*= MQID_ANY*/) {
|
|
// If the destructor is waiting for invocations to finish, don't start
|
|
// running even more tasks.
|
|
if (destroying_.load(std::memory_order_relaxed))
|
|
return;
|
|
|
|
// Run this on |thread| to reduce the number of context switches.
|
|
if (Thread::Current() != thread) {
|
|
thread->Invoke<void>(RTC_FROM_HERE,
|
|
Bind(&AsyncInvoker::Flush, this, thread, id));
|
|
return;
|
|
}
|
|
|
|
MessageList removed;
|
|
thread->Clear(this, id, &removed);
|
|
for (MessageList::iterator it = removed.begin(); it != removed.end(); ++it) {
|
|
// This message was pending on this thread, so run it now.
|
|
thread->Send(it->posted_from, it->phandler, it->message_id, it->pdata);
|
|
}
|
|
}
|
|
|
|
void AsyncInvoker::Clear() {
|
|
ThreadManager::Clear(this);
|
|
}
|
|
|
|
void AsyncInvoker::DoInvoke(const Location& posted_from,
|
|
Thread* thread,
|
|
std::unique_ptr<AsyncClosure> closure,
|
|
uint32_t id) {
|
|
if (destroying_.load(std::memory_order_relaxed)) {
|
|
// Note that this may be expected, if the application is AsyncInvoking
|
|
// tasks that AsyncInvoke other tasks. But otherwise it indicates a race
|
|
// between a thread destroying the AsyncInvoker and a thread still trying
|
|
// to use it.
|
|
RTC_LOG(LS_WARNING) << "Tried to invoke while destroying the invoker.";
|
|
return;
|
|
}
|
|
thread->Post(posted_from, this, id,
|
|
new ScopedMessageData<AsyncClosure>(std::move(closure)));
|
|
}
|
|
|
|
void AsyncInvoker::DoInvokeDelayed(const Location& posted_from,
|
|
Thread* thread,
|
|
std::unique_ptr<AsyncClosure> closure,
|
|
uint32_t delay_ms,
|
|
uint32_t id) {
|
|
if (destroying_.load(std::memory_order_relaxed)) {
|
|
// See above comment.
|
|
RTC_LOG(LS_WARNING) << "Tried to invoke while destroying the invoker.";
|
|
return;
|
|
}
|
|
thread->PostDelayed(posted_from, delay_ms, this, id,
|
|
new ScopedMessageData<AsyncClosure>(std::move(closure)));
|
|
}
|
|
|
|
AsyncClosure::AsyncClosure(AsyncInvoker* invoker)
|
|
: invoker_(invoker), invocation_complete_(invoker_->invocation_complete_) {
|
|
invoker_->pending_invocations_.fetch_add(1, std::memory_order_relaxed);
|
|
}
|
|
|
|
AsyncClosure::~AsyncClosure() {
|
|
// Using memory_order_release for synchronization with the AsyncInvoker
|
|
// destructor.
|
|
invoker_->pending_invocations_.fetch_sub(1, std::memory_order_release);
|
|
|
|
// After |pending_invocations_| is decremented, we may need to signal
|
|
// |invocation_complete_| in case the AsyncInvoker is being destroyed and
|
|
// waiting for pending tasks to complete.
|
|
//
|
|
// It's also possible that the destructor finishes before "Set()" is called,
|
|
// which is safe because the event is reference counted (and in a thread-safe
|
|
// way).
|
|
invocation_complete_->Set();
|
|
}
|
|
|
|
} // namespace rtc
|