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// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_ANDROID_SELF_COMPACTION_MANAGER_H_
#define BASE_ANDROID_SELF_COMPACTION_MANAGER_H_
// TODO(thiabaud): remove this include once we have separated the locks
// between these two classes.
#include "base/android/pre_freeze_background_memory_trimmer.h"
#include "base/debug/proc_maps_linux.h"
#include "base/no_destructor.h"
#include "base/profiler/sample_metadata.h"
namespace base::android {
BASE_EXPORT BASE_DECLARE_FEATURE(kShouldFreezeSelf);
BASE_EXPORT BASE_DECLARE_FEATURE(kUseRunningCompact);
// These values are persisted to logs. Entries should not be renumbered and
// numeric values should never be reused.
enum class CompactCancellationReason {
kAppFreezer,
kPageResumed,
kTimeout,
kMaxValue = kTimeout
};
class BASE_EXPORT SelfCompactionManager {
public:
using CompactCancellationReason = CompactCancellationReason;
static void OnSelfFreeze();
static void OnRunningCompact();
// If we are currently doing self compaction, cancel it. If it was running,
// record a metric with the reason for the cancellation.
static void MaybeCancelCompaction(
CompactCancellationReason cancellation_reason);
// The callback runs in the thread pool. The caller cannot make any thread
// safety assumptions for the callback execution (e.g. it could run
// concurrently with the thread that registered it).
static void SetOnStartSelfCompactionCallback(base::RepeatingClosure callback)
LOCKS_EXCLUDED(lock());
class CompactionMetric final : public RefCountedThreadSafe<CompactionMetric> {
public:
CompactionMetric(const std::string& name,
base::TimeTicks triggered_at,
base::TimeTicks started_at);
void RecordDelayedMetrics();
void RecordTimeMetrics(base::TimeTicks compaction_last_finished,
base::TimeTicks compaction_last_cancelled);
void RecordBeforeMetrics();
void MaybeRecordCompactionMetrics() LOCKS_EXCLUDED(lock());
private:
friend class RefCountedThreadSafe<CompactionMetric>;
~CompactionMetric();
void RecordSmapsRollup(std::optional<debug::SmapsRollup>* target)
LOCKS_EXCLUDED(lock());
void RecordSmapsRollupWithDelay(std::optional<debug::SmapsRollup>* target,
base::TimeDelta delay);
std::string GetMetricName(std::string_view name) const;
std::string GetMetricName(std::string_view name,
std::string_view suffix) const;
void RecordCompactionMetrics(const debug::SmapsRollup& value,
std::string_view suffix);
void RecordCompactionMetric(size_t value_bytes,
std::string_view metric_name,
std::string_view suffix);
void RecordCompactionDiffMetrics(const debug::SmapsRollup& before,
const debug::SmapsRollup& after,
std::string_view suffix);
void RecordCompactionDiffMetric(size_t before_value_bytes,
size_t after_value_bytes,
std::string_view name,
std::string_view suffix);
const std::string name_;
// When the self compaction was first triggered. There is a delay between
// this time and when we actually begin the compaction.
const base::TimeTicks compaction_triggered_at_;
// When the self compaction first started. This should generally be
// |compaction_triggered_at_ +
// kShouldFreezeSelfDelayAfterPreFreezeTasks.Get()|, but may be longer if
// the task was delayed.
const base::TimeTicks compaction_started_at_;
// We use std::optional here because:
// - We record these incrementally.
// - We may stop recording at some point.
// - We only want to emit histograms if all values were recorded.
std::optional<debug::SmapsRollup> smaps_before_;
std::optional<debug::SmapsRollup> smaps_after_;
std::optional<debug::SmapsRollup> smaps_after_1s_;
std::optional<debug::SmapsRollup> smaps_after_10s_;
std::optional<debug::SmapsRollup> smaps_after_60s_;
};
class CompactionState {
public:
CompactionState(scoped_refptr<SequencedTaskRunner> task_runner,
base::TimeTicks triggered_at,
uint64_t max_bytes);
virtual ~CompactionState();
virtual bool IsFeatureEnabled() const = 0;
virtual std::string GetMetricName(std::string_view name) const = 0;
void MaybeReadProcMaps();
virtual scoped_refptr<CompactionMetric> MakeCompactionMetric(
base::TimeTicks started_at) const = 0;
virtual base::TimeDelta GetDelayAfterPreFreezeTasks() const = 0;
scoped_refptr<SequencedTaskRunner> task_runner_;
std::vector<debug::MappedMemoryRegion> regions_;
const base::TimeTicks triggered_at_;
const uint64_t max_bytes_;
};
private:
friend class base::NoDestructor<SelfCompactionManager>;
friend class PreFreezeBackgroundMemoryTrimmer;
friend class SelfCompactionState;
friend class RunningCompactionState;
friend class PreFreezeSelfCompactionTest;
friend class PreFreezeSelfCompactionTestWithParam;
FRIEND_TEST_ALL_PREFIXES(PreFreezeSelfCompactionTestWithParam, Disabled);
FRIEND_TEST_ALL_PREFIXES(PreFreezeSelfCompactionTestWithParam, TimeoutCancel);
FRIEND_TEST_ALL_PREFIXES(PreFreezeSelfCompactionTestWithParam, Cancel);
FRIEND_TEST_ALL_PREFIXES(PreFreezeSelfCompactionTest, NotCanceled);
FRIEND_TEST_ALL_PREFIXES(PreFreezeSelfCompactionTest, OnSelfFreezeCancel);
SelfCompactionManager();
~SelfCompactionManager();
static SelfCompactionManager& Instance();
static Lock& lock() LOCK_RETURNED(PreFreezeBackgroundMemoryTrimmer::lock()) {
return PreFreezeBackgroundMemoryTrimmer::lock();
}
static bool CompactionIsSupported();
static bool TimeoutExceeded();
static base::TimeDelta GetDelayBetweenCompaction();
static bool ShouldContinueCompaction(const CompactionState& state)
LOCKS_EXCLUDED(lock());
static bool ShouldContinueCompaction(base::TimeTicks compaction_triggered_at)
LOCKS_EXCLUDED(lock());
void MaybeCancelCompactionInternal(
CompactCancellationReason cancellation_reason)
EXCLUSIVE_LOCKS_REQUIRED(lock());
// Compacts the memory for the process.
static void CompactSelf(std::unique_ptr<CompactionState> state);
template <class State>
void OnTriggerCompact(scoped_refptr<SequencedTaskRunner> task_runner);
void OnTriggerCompact(std::unique_ptr<CompactionState> state)
EXCLUSIVE_LOCKS_REQUIRED(lock());
void StartCompaction(std::unique_ptr<CompactionState> state)
LOCKS_EXCLUDED(lock());
void MaybePostCompactionTask(std::unique_ptr<CompactionState> state,
scoped_refptr<CompactionMetric> metric)
LOCKS_EXCLUDED(lock());
void CompactionTask(std::unique_ptr<CompactionState> state,
scoped_refptr<CompactionMetric> metric)
LOCKS_EXCLUDED(lock());
void FinishCompaction(std::unique_ptr<CompactionState> state,
scoped_refptr<CompactionMetric> metric)
LOCKS_EXCLUDED(lock());
static std::optional<uint64_t> CompactMemory(
std::vector<debug::MappedMemoryRegion>* regions,
const uint64_t max_bytes);
static std::optional<uint64_t> CompactRegion(
debug::MappedMemoryRegion region);
void MaybeRunOnSelfCompactCallback() EXCLUSIVE_LOCKS_REQUIRED(lock());
static void ResetCompactionForTesting();
static std::unique_ptr<CompactionState> GetSelfCompactionStateForTesting(
scoped_refptr<SequencedTaskRunner> task_runner,
const TimeTicks& triggered_at);
static std::unique_ptr<CompactionState> GetRunningCompactionStateForTesting(
scoped_refptr<SequencedTaskRunner> task_runner,
const TimeTicks& triggered_at);
// Whether or not we should continue self compaction. There are two reasons
// why we would cancel:
// (1) We have resumed, meaning we are likely to touch much of the process
// memory soon, and we do not want to waste CPU time with compaction,
// since it can block other work that needs to be done.
// (2) We are going to be frozen by App Freezer, which will do the compaction
// work for us. This situation should be relatively rare, because we
// attempt to not do self compaction if we know that we are going to
// frozen by App Freezer.
base::TimeTicks compaction_last_cancelled_ GUARDED_BY(lock()) =
base::TimeTicks::Min();
// When we last triggered self compaction. Used to record metrics.
base::TimeTicks compaction_last_triggered_ GUARDED_BY(lock()) =
base::TimeTicks::Min();
// When we last started self compaction. Used to know if we should cancel
// compaction due to it taking too long.
base::TimeTicks compaction_last_started_ GUARDED_BY(lock()) =
base::TimeTicks::Min();
// When we last finished self compaction (either successfully, or from
// being cancelled). Used to record metrics.
base::TimeTicks compaction_last_finished_ GUARDED_BY(lock()) =
base::TimeTicks::Min();
base::RepeatingClosure on_self_compact_callback_ GUARDED_BY(lock());
std::optional<base::ScopedSampleMetadata> process_compacted_metadata_
GUARDED_BY(lock());
};
} // namespace base::android
#endif // BASE_ANDROID_SELF_COMPACTION_MANAGER_H_
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