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// Copyright 2021 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_NODE_STATE_H_
#define COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_NODE_STATE_H_
namespace performance_manager {
// The state of a node. Nodes transition from the states linearly from top
// to bottom. For the full lifecycle of the node, see class comments on
// NodeBase.
//
// Each state has a set of flags:
// * Edges visible: Public methods that return pointers to other nodes will
// return pointers to nodes in the graph. If false, these methods will return
// nullptr.
// * Property changes allowed: Changes to properties that don't point to other
// nodes are allowed, but they must not cause notifications to be sent unless
// "Notifications allowed" is also true.
// * Edge changes allowed: Changes to properties that point to other nodes are
// allowed, but they must not cause notifications to be sent unless
// "Notifications allowed" is also true.
// * Notifications allowed: Public observer methods can be called with this
// node as a parameter. Except for the OnBeforeNodeAdded and OnNodeRemoved
// methods, all public observer methods expect the graph to be in a
// consistent state, with all nodes in their parameters reachable and all
// graph connections symmetrical.
enum class NodeState {
// The node is in an uninitialized state, and does not belong to a graph. This
// is the state of a newly constructed node, and one that has been removed
// from the graph and uninitialized but not yet destroyed.
kNotInGraph,
// The node is initializing but not yet in the graph. Nodes will be in this
// state during public OnBeforeNodeAdded observer methods.
//
// Property changes allowed.
kInitializingNotInGraph,
// The node is initializing edges. Nodes will not be in this state during any
// public observer methods, because the public API must always see graph edges
// in a consistent state.
//
// Property changes allowed.
// Edge changes allowed.
kInitializingEdges,
// The node is being added to the graph. Incoming and outgoing edges have been
// initialized. Nodes will be in this state during public OnNodeAdded observer
// methods.
//
// Edges visible.
kJoiningGraph,
// The node is active in the graph. Nodes will be in this state during most
// public observer methods.
//
// Edges visible.
// Property changes allowed.
// Edge changes allowed.
// Notifications allowed.
kActiveInGraph,
// The node is being removed from the graph. Incoming and outgoing edges are
// still set. Nodes will be in this state during public OnBeforeNodeRemoved
// observer methods.
//
// Edges visible.
kLeavingGraph,
// The node is uninitializing edges. Nodes will not be in this state during
// any public observer methods, because the public API must always see graph
// edges in a consistent state.
//
// Property changes allowed.
// Edge changes allowed.
kUninitializingEdges,
// The node is no longer in the graph. Its properties are still valid except
// for those that point to other graph nodes, which are all null. Nodes will
// be in this state during public OnNodeRemoved observer methods.
//
// Unlike kInitializingNotInGraph, property changes are not allowed, because
// the node is about to be deleted so they would have no effect.
kLeftGraph,
};
} // namespace performance_manager
#endif // COMPONENTS_PERFORMANCE_MANAGER_PUBLIC_GRAPH_NODE_STATE_H_
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