123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122 |
- // Copyright 2019 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 COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_VOTER_H_
- #define COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_VOTER_H_
- #include <array>
- #include "base/callback.h"
- #include "base/memory/memory_pressure_listener.h"
- #include "base/memory/raw_ptr.h"
- #include "base/memory/weak_ptr.h"
- #include "base/sequence_checker.h"
- #include "third_party/abseil-cpp/absl/types/optional.h"
- namespace memory_pressure {
- // Interface used by code which actually monitors memory pressure, to inform
- // a MemoryPressureAggregator when the pressure they observe changes, or they
- // want to trigger a (re-)notification of clients of the current level.
- // Voters must be used only from the same sequence as the Aggregator to which
- // they are attached.
- class MemoryPressureVoter {
- public:
- virtual ~MemoryPressureVoter() {}
- // Called to set a vote / change a vote.
- virtual void SetVote(base::MemoryPressureListener::MemoryPressureLevel level,
- bool notify_listeners) = 0;
- };
- // Collects votes from MemoryPressureVoters and evaluates them to determine the
- // pressure level for the MultiSourceMemoryPressureMonitor, which will own
- // and outlive the aggregator. The pressure level is calculated as the most
- // critical of all votes collected. This class is not thread safe and should be
- // used from a single sequence.
- class MemoryPressureVoteAggregator {
- public:
- class Delegate;
- using MemoryPressureLevel = base::MemoryPressureListener::MemoryPressureLevel;
- explicit MemoryPressureVoteAggregator(Delegate* delegate);
- ~MemoryPressureVoteAggregator();
- MemoryPressureVoteAggregator(const MemoryPressureVoteAggregator&) = delete;
- MemoryPressureVoteAggregator& operator=(const MemoryPressureVoteAggregator&) =
- delete;
- // Creates a MemoryPressureVoter attached to this Aggregator. The returned
- // Voter must not out-live the Aggregator.
- std::unique_ptr<MemoryPressureVoter> CreateVoter();
- void OnVoteForTesting(absl::optional<MemoryPressureLevel> old_vote,
- absl::optional<MemoryPressureLevel> new_vote);
- void NotifyListenersForTesting();
- base::MemoryPressureListener::MemoryPressureLevel EvaluateVotesForTesting();
- void SetVotesForTesting(size_t none_votes,
- size_t moderate_votes,
- size_t critical_votes);
- private:
- friend class MemoryPressureVoterImpl;
- // Invoked by MemoryPressureVoter as it calculates its vote. Optional is
- // used so a voter can pass null as |old_vote| if this is their first vote, or
- // null as |new_vote| if they are removing their vote (e.g. when the voter is
- // being destroyed). |old_vote| and |new_vote| should never both be null.
- void OnVote(absl::optional<MemoryPressureLevel> old_vote,
- absl::optional<MemoryPressureLevel> new_vote);
- // Triggers a notification of the MemoryPressureMonitor's current pressure
- // level, allowing each of the various sources of input on MemoryPressureLevel
- // to maintain their own signalling behavior.
- // TODO(991361): Remove this behavior and standardize across platforms.
- void NotifyListeners();
- // Returns the highest index of |votes_| with a non-zero value, as a
- // MemoryPressureLevel.
- MemoryPressureLevel EvaluateVotes() const;
- MemoryPressureLevel current_pressure_level_ =
- base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
- const raw_ptr<Delegate> delegate_;
- // Array with one bucket for each potential MemoryPressureLevel. The overall
- // MemoryPressureLevel is calculated as the highest index of a non-zero
- // bucket.
- // MEMORY_PRESSURE_LEVEL_CRITICAL + 1 is used in place of adding a kCount
- // value to the MemoryPressureLevel enum as adding another value would require
- // changing every instance of switch(MemoryPressureLevel) in Chromium, and the
- // MemoryPressureLevel system will be changing soon regardless.
- std::array<size_t,
- base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL + 1>
- votes_ = {};
- SEQUENCE_CHECKER(sequence_checker_);
- };
- // Interface used to notify MemoryPressureVoteAggregator's owner of changes to
- // vote aggregation.
- class MemoryPressureVoteAggregator::Delegate {
- public:
- Delegate() = default;
- virtual ~Delegate() = default;
- // Invoked when the aggregate vote has changed.
- virtual void OnMemoryPressureLevelChanged(
- base::MemoryPressureListener::MemoryPressureLevel level) = 0;
- // Invoked when a voter has determined that a notification of the current
- // pressure level is necessary.
- virtual void OnNotifyListenersRequested() = 0;
- };
- } // namespace memory_pressure
- #endif // COMPONENTS_MEMORY_PRESSURE_MEMORY_PRESSURE_VOTER_H_
|