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// Copyright 2016 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.
#ifndef BASE_MEMORY_MEMORY_CLIENT_REGISTRY_H_
#define BASE_MEMORY_MEMORY_CLIENT_REGISTRY_H_
#include "base/base_export.h"
#include "base/memory/memory_coordinator_client.h"
#include "base/memory/singleton.h"
#include "base/observer_list_threadsafe.h"
namespace base {
// MemoryCoordinatorClientRegistry is the registry of MemoryCoordinatorClients.
// This class manages clients and provides a way to notify memory state changes
// to clients, but this isn't responsible to determine how/when to change
// memory states.
//
// Threading guarantees:
// This class uses ObserverListThreadsafe internally, which means that
// * Registering/unregistering callbacks are thread-safe.
// * Callbacks are invoked on the same thread on which they are registered.
// See base/observer_list_threadsafe.h for reference.
//
// Ownership management:
// This class doesn't take the ownership of clients. Clients must be
// unregistered before they are destroyed.
class BASE_EXPORT MemoryCoordinatorClientRegistry {
public:
static MemoryCoordinatorClientRegistry* GetInstance();
~MemoryCoordinatorClientRegistry();
// Registers/unregisters a client. Does not take ownership of client.
void Register(MemoryCoordinatorClient* client);
void Unregister(MemoryCoordinatorClient* client);
// Notify clients of a memory state change.
void Notify(MemoryState state);
private:
friend struct DefaultSingletonTraits<MemoryCoordinatorClientRegistry>;
MemoryCoordinatorClientRegistry();
using ClientList = ObserverListThreadSafe<MemoryCoordinatorClient>;
scoped_refptr<ClientList> clients_;
};
} // namespace base
#endif // BASE_MEMORY_MEMORY_CLIENT_REGISTRY_H_
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