| // Copyright 2017 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. |
| |
| #include "mojo/public/cpp/bindings/sync_event_watcher.h" |
| |
| #include <algorithm> |
| |
| #include "base/containers/stack_container.h" |
| #include "base/logging.h" |
| |
| namespace mojo { |
| |
| SyncEventWatcher::SyncEventWatcher(base::WaitableEvent* event, |
| const base::Closure& callback) |
| : event_(event), |
| callback_(callback), |
| registry_(SyncHandleRegistry::current()), |
| destroyed_(new base::RefCountedData<bool>(false)) {} |
| |
| SyncEventWatcher::~SyncEventWatcher() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| if (registered_) |
| registry_->UnregisterEvent(event_, callback_); |
| destroyed_->data = true; |
| } |
| |
| void SyncEventWatcher::AllowWokenUpBySyncWatchOnSameThread() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| IncrementRegisterCount(); |
| } |
| |
| bool SyncEventWatcher::SyncWatch(const bool** stop_flags, |
| size_t num_stop_flags) { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| IncrementRegisterCount(); |
| if (!registered_) { |
| DecrementRegisterCount(); |
| return false; |
| } |
| |
| // This object may be destroyed during the Wait() call. So we have to preserve |
| // the boolean that Wait uses. |
| auto destroyed = destroyed_; |
| |
| constexpr size_t kFlagStackCapacity = 4; |
| base::StackVector<const bool*, kFlagStackCapacity> should_stop_array; |
| should_stop_array.container().push_back(&destroyed->data); |
| std::copy(stop_flags, stop_flags + num_stop_flags, |
| std::back_inserter(should_stop_array.container())); |
| bool result = registry_->Wait(should_stop_array.container().data(), |
| should_stop_array.container().size()); |
| |
| // This object has been destroyed. |
| if (destroyed->data) |
| return false; |
| |
| DecrementRegisterCount(); |
| return result; |
| } |
| |
| void SyncEventWatcher::IncrementRegisterCount() { |
| register_request_count_++; |
| if (!registered_) { |
| registry_->RegisterEvent(event_, callback_); |
| registered_ = true; |
| } |
| } |
| |
| void SyncEventWatcher::DecrementRegisterCount() { |
| DCHECK_GT(register_request_count_, 0u); |
| register_request_count_--; |
| if (register_request_count_ == 0 && registered_) { |
| registry_->UnregisterEvent(event_, callback_); |
| registered_ = false; |
| } |
| } |
| |
| } // namespace mojo |