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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_SYSTEM_NODE_H_
#define COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_SYSTEM_NODE_H_
#include "base/memory/memory_pressure_listener.h"
#include "base/observer_list_types.h"
#include "components/performance_manager/public/graph/node.h"
namespace performance_manager {
class SystemNodeObserver;
// The SystemNode represents system-wide state. Each graph owns exactly one
// system node. This node has the same lifetime has the graph that owns it.
class SystemNode : public TypedNode<SystemNode> {
public:
using MemoryPressureLevel = base::MemoryPressureListener::MemoryPressureLevel;
static constexpr NodeTypeEnum Type() { return NodeTypeEnum::kSystem; }
SystemNode();
SystemNode(const SystemNode&) = delete;
SystemNode& operator=(const SystemNode&) = delete;
~SystemNode() override;
};
// Observer interface for the system node.
class SystemNodeObserver : public base::CheckedObserver {
public:
SystemNodeObserver();
SystemNodeObserver(const SystemNodeObserver&) = delete;
SystemNodeObserver& operator=(const SystemNodeObserver&) = delete;
~SystemNodeObserver() override;
// Called when a new set of process memory metrics is available.
//
// Note: This is only valid if at least one component has expressed interest
// for process memory metrics by calling
// ProcessMetricsDecorator::RegisterInterestForProcessMetrics.
virtual void OnProcessMemoryMetricsAvailable(const SystemNode* system_node) {}
// Called before OnMemoryPressure(). This can be used to track state before
// memory start being released in response to memory pressure.
//
// Note: This is guaranteed to be invoked before OnMemoryPressure(), but
// will not necessarily be called before base::MemoryPressureListeners
// are notified.
virtual void OnBeforeMemoryPressure(
base::MemoryPressureListener::MemoryPressureLevel new_level) {}
// Called when the system is under memory pressure. Observers may start
// releasing memory in response to memory pressure.
//
// NOTE: This isn't called for a transition to the MEMORY_PRESSURE_LEVEL_NONE
// level. For this reason there's no corresponding property in this node and
// the response to these notifications should be stateless.
virtual void OnMemoryPressure(
base::MemoryPressureListener::MemoryPressureLevel new_level) {}
};
} // namespace performance_manager
#endif // COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_SYSTEM_NODE_H_
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