chromium/mojo/public/cpp/bindings/sequence_local_sync_event_watcher.h

// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MOJO_PUBLIC_CPP_BINDINGS_SEQUENCE_LOCAL_SYNC_EVENT_WATCHER_H_
#define MOJO_PUBLIC_CPP_BINDINGS_SEQUENCE_LOCAL_SYNC_EVENT_WATCHER_H_

#include "base/component_export.h"
#include "base/functional/callback.h"
#include "base/memory/weak_ptr.h"

namespace mojo {

// This encapsulates a SyncEventWatcher watching an event shared by all
// |SequenceLocalSyncEventWatcher| on the same sequence. This class is NOT
// sequence-safe in general, but |SignalEvent()| is safe to call from any
// sequence.
//
// Interfaces which support sync messages use a WaitableEvent to block and
// be signaled when messages are available, but having a WaitableEvent for every
// such interface endpoint would cause the number of WaitableEvents to grow
// arbitrarily large.
//
// Some platform constraints may limit the number of WaitableEvents the bindings
// layer can wait upon concurrently, so this type is used to keep the number
// of such events fixed at a small constant value per sequence regardless of the
// number of active interface endpoints supporting sync messages on that
// sequence.
class COMPONENT_EXPORT(MOJO_CPP_BINDINGS) SequenceLocalSyncEventWatcher { … };

}  // namespace mojo

#endif  // MOJO_PUBLIC_CPP_BINDINGS_SEQUENCE_LOCAL_SYNC_EVENT_WATCHER_H_