chromium/components/performance_manager/execution_context_priority/boosting_vote_aggregator.h

// 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_EXECUTION_CONTEXT_PRIORITY_BOOSTING_VOTE_AGGREGATOR_H_
#define COMPONENTS_PERFORMANCE_MANAGER_EXECUTION_CONTEXT_PRIORITY_BOOSTING_VOTE_AGGREGATOR_H_

#include <map>
#include <optional>
#include <set>

#include "base/memory/raw_ptr.h"
#include "base/task/task_traits.h"
#include "components/performance_manager/public/execution_context_priority/execution_context_priority.h"

namespace performance_manager {
namespace execution_context_priority {

class BoostingVoteAggregator;

// A BoostingVote is a special kind of relative vote that allows a voter to
// express that "execution context X should have the same or greater priority
// than execution context Y". It allows implementing priority boost semantics to
// avoid priority inversions for access to shared resources. BoostingVotes must
// be registered with a BoostingVoteAggregator. Similar to a VoteReceipt, they
// are a move-only type and their vote will be removed with their destruction.
//
// A BoostingVote is considered "active" if it is associated with an aggregator
// (the result of calling "aggregator()" is non-null).
//
// See comments in the implementation for details on how the algorithm works.
class BoostingVote { … };

// The BoostingVoteAggregator allows for incoming votes to be modified via a
// collection of registered "relative boosting votes" that express relationships
// such as "execution context X should have the same or greater priority than
// execution context Y". It is intended to serve as the root of a tree of voters
// and aggregators, allowing priority boost semantics to be implemented. This
// class must outlive all boosting votes registered with it.
class BoostingVoteAggregator : public VoteObserver { … };

}  // namespace execution_context_priority
}  // namespace performance_manager

#endif  // COMPONENTS_PERFORMANCE_MANAGER_EXECUTION_CONTEXT_PRIORITY_BOOSTING_VOTE_AGGREGATOR_H_