74 lines
2.3 KiB
C++
74 lines
2.3 KiB
C++
// Copyright 2017 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef MOJO_PUBLIC_CPP_BINDINGS_SYNC_EVENT_WATCHER_H_
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#define MOJO_PUBLIC_CPP_BINDINGS_SYNC_EVENT_WATCHER_H_
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#include <stddef.h>
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#include "base/callback.h"
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#include "base/macros.h"
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#include "base/memory/ref_counted.h"
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#include "base/sequence_checker.h"
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#include "base/synchronization/waitable_event.h"
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#include "mojo/public/cpp/bindings/bindings_export.h"
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#include "mojo/public/cpp/bindings/sync_handle_registry.h"
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namespace mojo {
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// SyncEventWatcher supports waiting on a base::WaitableEvent to signal while
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// also allowing other SyncEventWatchers and SyncHandleWatchers on the same
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// sequence to wake up as needed.
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//
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// This class is not thread safe.
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class MOJO_CPP_BINDINGS_EXPORT SyncEventWatcher {
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public:
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SyncEventWatcher(base::WaitableEvent* event, const base::Closure& callback);
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~SyncEventWatcher();
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// Registers |event_| with SyncHandleRegistry, so that when others perform
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// sync watching on the same sequence, |event_| will be watched along with
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// them.
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void AllowWokenUpBySyncWatchOnSameThread();
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// Waits on |event_| plus all other events and handles registered with this
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// sequence's SyncHandleRegistry, running callbacks synchronously for any
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// ready events and handles.
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//
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// |stop_flags| is treated as an array of |const bool*| with |num_stop_flags|
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// entries.
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//
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// This method:
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// - returns true when any flag in |stop_flags| is set to |true|.
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// - return false when any error occurs, including this object being
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// destroyed during a callback.
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bool SyncWatch(const bool** stop_flags, size_t num_stop_flags);
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private:
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void IncrementRegisterCount();
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void DecrementRegisterCount();
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base::WaitableEvent* const event_;
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const base::Closure callback_;
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// Whether |event_| has been registered with SyncHandleRegistry.
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bool registered_ = false;
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// If non-zero, |event_| should be registered with SyncHandleRegistry.
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size_t register_request_count_ = 0;
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scoped_refptr<SyncHandleRegistry> registry_;
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scoped_refptr<base::RefCountedData<bool>> destroyed_;
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SEQUENCE_CHECKER(sequence_checker_);
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DISALLOW_COPY_AND_ASSIGN(SyncEventWatcher);
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};
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} // namespace mojo
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#endif // MOJO_PUBLIC_CPP_BINDINGS_SYNC_EVENT_WATCHER_H_
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