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Diffstat (limited to '')
| -rw-r--r-- | xpcom/base/AvailableMemoryWatcherMac.cpp | 625 |
1 files changed, 625 insertions, 0 deletions
diff --git a/xpcom/base/AvailableMemoryWatcherMac.cpp b/xpcom/base/AvailableMemoryWatcherMac.cpp new file mode 100644 index 0000000000..452b32a149 --- /dev/null +++ b/xpcom/base/AvailableMemoryWatcherMac.cpp @@ -0,0 +1,625 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include <sys/sysctl.h> +#include <sys/types.h> +#include <time.h> + +#include "AvailableMemoryWatcher.h" +#include "Logging.h" +#include "mozilla/Preferences.h" +#include "nsICrashReporter.h" +#include "nsISupports.h" +#include "nsITimer.h" +#include "nsMemoryPressure.h" +#include "nsPrintfCString.h" + +#define MP_LOG(...) MOZ_LOG(gMPLog, mozilla::LogLevel::Debug, (__VA_ARGS__)) +static mozilla::LazyLogModule gMPLog("MemoryPressure"); + +namespace mozilla { + +/* + * The Mac AvailableMemoryWatcher works as follows. When the OS memory pressure + * level changes on macOS, nsAvailableMemoryWatcher::OnMemoryPressureChanged() + * is called with the new memory pressure level. The level is represented in + * Gecko by a MacMemoryPressureLevel instance and represents the states of + * normal, warning, or critical which correspond to the native levels. When the + * browser launches, the initial level is determined using a sysctl. Which + * actions are taken in the browser in response to memory pressure, and the + * level (warning or critical) which trigger the reponse is configurable with + * prefs to make it easier to perform experiments to study how the response + * affects the user experience. + * + * By default, the browser responds by attempting to reduce memory use when the + * OS transitions to the critical level and while it stays in the critical + * level. i.e., "critical" OS memory pressure is the default threshold for the + * low memory response. Setting pref "browser.lowMemoryResponseOnWarn" to true + * changes the memory response to occur at the "warning" level which is less + * severe than "critical". When entering the critical level, we begin polling + * the memory pressure level every 'n' milliseconds (specified via the pref + * "browser.lowMemoryPollingIntervalMS"). Each time the poller wakes up and + * finds the OS still under memory pressure, the low memory response is + * executed. + * + * By default, the memory pressure response is, in order, to + * 1) call nsITabUnloader::UnloadTabAsync(), + * 2) if no tabs could be unloaded, issue a Gecko + * MemoryPressureState::LowMemory notification. + * The response can be changed via the pref "browser.lowMemoryResponseMask" to + * limit the actions to only tab unloading or Gecko memory pressure + * notifications. + * + * Polling occurs on the main thread because, at each polling interval, we + * call into the tab unloader which requires being on the main thread. + * Polling only occurs while under OS memory pressure at the critical (by + * default) level. + */ +class nsAvailableMemoryWatcher final : public nsITimerCallback, + public nsINamed, + public nsAvailableMemoryWatcherBase { + public: + NS_DECL_ISUPPORTS_INHERITED + NS_DECL_NSIOBSERVER + NS_DECL_NSITIMERCALLBACK + NS_DECL_NSINAMED + + nsAvailableMemoryWatcher(); + nsresult Init() override; + + void OnMemoryPressureChanged(MacMemoryPressureLevel aLevel) override; + void AddChildAnnotations( + const UniquePtr<ipc::CrashReporterHost>& aCrashReporter) override; + + private: + ~nsAvailableMemoryWatcher(){}; + + void OnMemoryPressureChangedInternal(MacMemoryPressureLevel aNewLevel, + bool aIsInitialLevel); + + // Override OnUnloadAttemptCompleted() so that we can control whether + // or not a Gecko memory-pressure event is sent after a tab unload attempt. + // This method is called externally by the tab unloader after a tab unload + // attempt. It is used internally when tab unloading is disabled in + // mResponseMask. + nsresult OnUnloadAttemptCompleted(nsresult aResult) override; + + void OnShutdown(); + void OnPrefChange(); + + void InitParentAnnotations(); + void UpdateParentAnnotations(); + + void AddParentAnnotation(CrashReporter::Annotation aAnnotation, + nsAutoCString aString) { + CrashReporter::AnnotateCrashReport(aAnnotation, aString); + } + void AddParentAnnotation(CrashReporter::Annotation aAnnotation, + uint32_t aData) { + CrashReporter::AnnotateCrashReport(aAnnotation, aData); + } + + void LowMemoryResponse(); + void StartPolling(); + void StopPolling(); + void RestartPolling(); + inline bool IsPolling() { return mTimer; } + + void ReadSysctls(); + + // This enum represents the allowed values for the pref that controls + // the low memory response - "browser.lowMemoryResponseMask". Specifically, + // whether or not we unload tabs and/or issue the Gecko "memory-pressure" + // internal notification. For tab unloading, the pref + // "browser.tabs.unloadOnLowMemory" must also be set. + enum ResponseMask { + eNone = 0x0, + eTabUnload = 0x1, + eInternalMemoryPressure = 0x2, + eAll = 0x3, + }; + static constexpr char kResponseMask[] = "browser.lowMemoryResponseMask"; + static const uint32_t kResponseMaskDefault; + static const uint32_t kResponseMaskMax; + + // Pref for controlling how often we wake up during an OS memory pressure + // time period. At each wakeup, we unload tabs and issue the Gecko + // "memory-pressure" internal notification. When not under OS memory pressure, + // polling is disabled. + static constexpr char kPollingIntervalMS[] = + "browser.lowMemoryPollingIntervalMS"; + static const uint32_t kPollingIntervalMaxMS; + static const uint32_t kPollingIntervalMinMS; + static const uint32_t kPollingIntervalDefaultMS; + + static constexpr char kResponseOnWarn[] = "browser.lowMemoryResponseOnWarn"; + static const bool kResponseLevelOnWarnDefault = false; + + // Init has been called. + bool mInitialized; + + // The memory pressure reported to the application by macOS. + MacMemoryPressureLevel mLevel; + + // The OS memory pressure level that triggers the response. + MacMemoryPressureLevel mResponseLevel; + + // The value of the kern.memorystatus_vm_pressure_level sysctl. The OS + // notifies the application when the memory pressure level changes, + // but the sysctl value can be read at any time. Unofficially, the sysctl + // value corresponds to the OS memory pressure level with 4=>critical, + // 2=>warning, and 1=>normal (values from kernel event.h file). + uint32_t mLevelSysctl; + static const int kSysctlLevelNormal = 0x1; + static const int kSysctlLevelWarning = 0x2; + static const int kSysctlLevelCritical = 0x4; + + // The value of the kern.memorystatus_level sysctl. Unofficially, + // this is the percentage of available memory. (Also readable + // via the undocumented memorystatus_get_level syscall.) + int mAvailMemSysctl; + + // The string representation of `mLevel`. i.e., normal, warning, or critical. + // Set to "unset" until a memory pressure change is reported to the process + // by the OS. + nsAutoCString mLevelStr; + + // Timestamps for memory pressure level changes. Specifically, the Unix + // time in string form. Saved as Unix time to allow comparisons with + // the crash time. + nsAutoCString mNormalTimeStr; + nsAutoCString mWarningTimeStr; + nsAutoCString mCriticalTimeStr; + + nsCOMPtr<nsITimer> mTimer; // non-null indicates the timer is active + + // Saved pref values. + uint32_t mPollingInterval; + uint32_t mResponseMask; +}; + +const uint32_t nsAvailableMemoryWatcher::kResponseMaskDefault = + ResponseMask::eAll; +const uint32_t nsAvailableMemoryWatcher::kResponseMaskMax = ResponseMask::eAll; + +// 10 seconds +const uint32_t nsAvailableMemoryWatcher::kPollingIntervalDefaultMS = 10'000; +// 10 minutes +const uint32_t nsAvailableMemoryWatcher::kPollingIntervalMaxMS = 600'000; +// 100 milliseconds +const uint32_t nsAvailableMemoryWatcher::kPollingIntervalMinMS = 100; + +NS_IMPL_ISUPPORTS_INHERITED(nsAvailableMemoryWatcher, + nsAvailableMemoryWatcherBase, nsIObserver, + nsITimerCallback, nsINamed) + +nsAvailableMemoryWatcher::nsAvailableMemoryWatcher() + : mInitialized(false), + mLevel(MacMemoryPressureLevel::Value::eUnset), + mResponseLevel(MacMemoryPressureLevel::Value::eCritical), + mLevelSysctl(0xFFFFFFFF), + mAvailMemSysctl(-1), + mLevelStr("Unset"), + mNormalTimeStr("Unset"), + mWarningTimeStr("Unset"), + mCriticalTimeStr("Unset"), + mPollingInterval(0), + mResponseMask(ResponseMask::eAll) {} + +nsresult nsAvailableMemoryWatcher::Init() { + nsresult rv = nsAvailableMemoryWatcherBase::Init(); + if (NS_FAILED(rv)) { + return rv; + } + + // Users of nsAvailableMemoryWatcher should use + // nsAvailableMemoryWatcherBase::GetSingleton() and not call Init directly. + MOZ_ASSERT(!mInitialized); + if (mInitialized) { + return NS_ERROR_ALREADY_INITIALIZED; + } + + // Read polling frequency pref + mPollingInterval = + Preferences::GetUint(kPollingIntervalMS, kPollingIntervalDefaultMS); + mPollingInterval = std::clamp(mPollingInterval, kPollingIntervalMinMS, + kPollingIntervalMaxMS); + + // Read response bitmask pref which (along with the main tab unloading + // preference) controls whether or not tab unloading and Gecko (internal) + // memory pressure notifications will be sent. The main tab unloading + // preference must also be enabled for tab unloading to occur. + mResponseMask = Preferences::GetUint(kResponseMask, kResponseMaskDefault); + if (mResponseMask > kResponseMaskMax) { + mResponseMask = kResponseMaskMax; + } + + // Read response level pref + if (Preferences::GetBool(kResponseOnWarn, kResponseLevelOnWarnDefault)) { + mResponseLevel = MacMemoryPressureLevel::Value::eWarning; + } else { + mResponseLevel = MacMemoryPressureLevel::Value::eCritical; + } + + ReadSysctls(); + MP_LOG("Initial memory pressure sysctl: %d", mLevelSysctl); + MP_LOG("Initial available memory sysctl: %d", mAvailMemSysctl); + + // Set the initial state of all annotations for parent crash reports. + // Content process crash reports are set when a crash occurs and + // AddChildAnnotations() is called. + CrashReporter::AnnotateCrashReport( + CrashReporter::Annotation::MacMemoryPressure, mLevelStr); + CrashReporter::AnnotateCrashReport( + CrashReporter::Annotation::MacMemoryPressureNormalTime, mNormalTimeStr); + CrashReporter::AnnotateCrashReport( + CrashReporter::Annotation::MacMemoryPressureWarningTime, mWarningTimeStr); + CrashReporter::AnnotateCrashReport( + CrashReporter::Annotation::MacMemoryPressureCriticalTime, + mCriticalTimeStr); + CrashReporter::AnnotateCrashReport( + CrashReporter::Annotation::MacMemoryPressureSysctl, mLevelSysctl); + CrashReporter::AnnotateCrashReport( + CrashReporter::Annotation::MacAvailableMemorySysctl, mAvailMemSysctl); + + // To support running experiments, handle pref + // changes without requiring a browser restart. + rv = Preferences::AddStrongObserver(this, kResponseMask); + if (NS_FAILED(rv)) { + NS_WARNING( + nsPrintfCString("Failed to add %s observer", kResponseMask).get()); + } + rv = Preferences::AddStrongObserver(this, kPollingIntervalMS); + if (NS_FAILED(rv)) { + NS_WARNING( + nsPrintfCString("Failed to add %s observer", kPollingIntervalMS).get()); + } + rv = Preferences::AddStrongObserver(this, kResponseOnWarn); + if (NS_FAILED(rv)) { + NS_WARNING( + nsPrintfCString("Failed to add %s observer", kResponseOnWarn).get()); + } + + // Use the memory pressure sysctl to initialize our memory pressure state. + MacMemoryPressureLevel initialLevel; + switch (mLevelSysctl) { + case kSysctlLevelNormal: + initialLevel = MacMemoryPressureLevel::Value::eNormal; + break; + case kSysctlLevelWarning: + initialLevel = MacMemoryPressureLevel::Value::eWarning; + break; + case kSysctlLevelCritical: + initialLevel = MacMemoryPressureLevel::Value::eCritical; + break; + default: + initialLevel = MacMemoryPressureLevel::Value::eUnexpected; + } + + OnMemoryPressureChangedInternal(initialLevel, /* aIsInitialLevel */ true); + mInitialized = true; + return NS_OK; +} + +already_AddRefed<nsAvailableMemoryWatcherBase> CreateAvailableMemoryWatcher() { + // Users of nsAvailableMemoryWatcher should use + // nsAvailableMemoryWatcherBase::GetSingleton(). + RefPtr watcher(new nsAvailableMemoryWatcher()); + watcher->Init(); + return watcher.forget(); +} + +// Update the memory pressure level, level change timestamps, and sysctl +// level crash report annotations. +void nsAvailableMemoryWatcher::UpdateParentAnnotations() { + // Generate a string representation of the current Unix time. + time_t timeChanged = time(NULL); + nsAutoCString timeChangedString; + timeChangedString = + nsPrintfCString("%" PRIu64, static_cast<uint64_t>(timeChanged)); + + nsAutoCString pressureLevelString; + Maybe<CrashReporter::Annotation> pressureLevelKey; + + switch (mLevel.GetValue()) { + case MacMemoryPressureLevel::Value::eNormal: + mNormalTimeStr = timeChangedString; + pressureLevelString = "Normal"; + pressureLevelKey.emplace( + CrashReporter::Annotation::MacMemoryPressureNormalTime); + break; + case MacMemoryPressureLevel::Value::eWarning: + mWarningTimeStr = timeChangedString; + pressureLevelString = "Warning"; + pressureLevelKey.emplace( + CrashReporter::Annotation::MacMemoryPressureWarningTime); + break; + case MacMemoryPressureLevel::Value::eCritical: + mCriticalTimeStr = timeChangedString; + pressureLevelString = "Critical"; + pressureLevelKey.emplace( + CrashReporter::Annotation::MacMemoryPressureCriticalTime); + break; + default: + pressureLevelString = "Unexpected"; + break; + } + + // Save the current memory pressure level. + AddParentAnnotation(CrashReporter::Annotation::MacMemoryPressure, + pressureLevelString); + + // Save the time we transitioned to the current memory pressure level. + if (pressureLevelKey.isSome()) { + AddParentAnnotation(pressureLevelKey.value(), timeChangedString); + } + + AddParentAnnotation(CrashReporter::Annotation::MacMemoryPressureSysctl, + mLevelSysctl); + AddParentAnnotation(CrashReporter::Annotation::MacAvailableMemorySysctl, + mAvailMemSysctl); +} + +void nsAvailableMemoryWatcher::ReadSysctls() { + // Pressure level + uint32_t level; + size_t size = sizeof(level); + if (sysctlbyname("kern.memorystatus_vm_pressure_level", &level, &size, NULL, + 0) == -1) { + MP_LOG("Failure reading memory pressure sysctl"); + } + mLevelSysctl = level; + + // Available memory percent + int availPercent; + size = sizeof(availPercent); + if (sysctlbyname("kern.memorystatus_level", &availPercent, &size, NULL, 0) == + -1) { + MP_LOG("Failure reading available memory level"); + } + mAvailMemSysctl = availPercent; +} + +/* virtual */ +void nsAvailableMemoryWatcher::OnMemoryPressureChanged( + MacMemoryPressureLevel aNewLevel) { + MOZ_ASSERT(mInitialized); + OnMemoryPressureChangedInternal(aNewLevel, /* aIsInitialLevel */ false); +} + +void nsAvailableMemoryWatcher::OnMemoryPressureChangedInternal( + MacMemoryPressureLevel aNewLevel, bool aIsInitialLevel) { + MOZ_ASSERT(mInitialized || aIsInitialLevel); + MP_LOG("MemoryPressureChange: existing level: %s, new level: %s", + mLevel.ToString(), aNewLevel.ToString()); + + // If 'aNewLevel' is not one of normal, warning, or critical, ASSERT + // here so we can debug this scenario. For non-debug builds, ignore + // the unexpected value which will be logged in crash reports. + MOZ_ASSERT(aNewLevel.IsNormal() || aNewLevel.IsWarningOrAbove()); + + if (mLevel == aNewLevel) { + return; + } + + // Start the memory pressure response if the new level is high enough + // and the existing level was not. + if ((mLevel < mResponseLevel) && (aNewLevel >= mResponseLevel)) { + UpdateLowMemoryTimeStamp(); + LowMemoryResponse(); + if (mResponseMask) { + StartPolling(); + } + } + + // End the memory pressure reponse if the new level is not high enough. + if ((mLevel >= mResponseLevel) && (aNewLevel < mResponseLevel)) { + RecordTelemetryEventOnHighMemory(); + StopPolling(); + MP_LOG("Issuing MemoryPressureState::NoPressure"); + NS_NotifyOfMemoryPressure(MemoryPressureState::NoPressure); + } + + mLevel = aNewLevel; + + if (!aIsInitialLevel) { + // Sysctls are already read by ::Init(). + ReadSysctls(); + MP_LOG("level sysctl: %d, available memory: %d percent", mLevelSysctl, + mAvailMemSysctl); + } + UpdateParentAnnotations(); +} + +/* virtual */ +// Add all annotations to the provided crash reporter instance. +void nsAvailableMemoryWatcher::AddChildAnnotations( + const UniquePtr<ipc::CrashReporterHost>& aCrashReporter) { + aCrashReporter->AddAnnotation(CrashReporter::Annotation::MacMemoryPressure, + mLevelStr); + aCrashReporter->AddAnnotation( + CrashReporter::Annotation::MacMemoryPressureNormalTime, mNormalTimeStr); + aCrashReporter->AddAnnotation( + CrashReporter::Annotation::MacMemoryPressureWarningTime, mWarningTimeStr); + aCrashReporter->AddAnnotation( + CrashReporter::Annotation::MacMemoryPressureCriticalTime, + mCriticalTimeStr); + aCrashReporter->AddAnnotation( + CrashReporter::Annotation::MacMemoryPressureSysctl, mLevelSysctl); + aCrashReporter->AddAnnotation( + CrashReporter::Annotation::MacAvailableMemorySysctl, mAvailMemSysctl); +} + +void nsAvailableMemoryWatcher::LowMemoryResponse() { + if (mResponseMask & ResponseMask::eTabUnload) { + MP_LOG("Attempting tab unload"); + mTabUnloader->UnloadTabAsync(); + } else { + // Re-use OnUnloadAttemptCompleted() to issue the internal + // memory pressure event. + OnUnloadAttemptCompleted(NS_ERROR_NOT_AVAILABLE); + } +} + +NS_IMETHODIMP +nsAvailableMemoryWatcher::Notify(nsITimer* aTimer) { + MOZ_ASSERT(NS_IsMainThread()); + MOZ_ASSERT(mLevel >= mResponseLevel); + LowMemoryResponse(); + return NS_OK; +} + +// Override OnUnloadAttemptCompleted() so that we can issue Gecko memory +// pressure notifications only if eInternalMemoryPressure is set in +// mResponseMask. When called from the tab unloader, an |aResult| value of +// NS_OK indicates the tab unloader successfully unloaded a tab. +// NS_ERROR_NOT_AVAILABLE indicates the tab unloader did not unload any tabs. +NS_IMETHODIMP +nsAvailableMemoryWatcher::OnUnloadAttemptCompleted(nsresult aResult) { + switch (aResult) { + // A tab was unloaded successfully. + case NS_OK: + MP_LOG("Tab unloaded"); + ++mNumOfTabUnloading; + break; + + // Either the tab unloader found no unloadable tabs OR we've been called + // locally to explicitly issue the internal memory pressure event because + // tab unloading is disabled in |mResponseMask|. In either case, attempt + // to reduce memory use using the internal memory pressure notification. + case NS_ERROR_NOT_AVAILABLE: + if (mResponseMask & ResponseMask::eInternalMemoryPressure) { + ++mNumOfMemoryPressure; + MP_LOG("Tab not unloaded"); + MP_LOG("Issuing MemoryPressureState::LowMemory"); + NS_NotifyOfEventualMemoryPressure(MemoryPressureState::LowMemory); + } + break; + + // There was a pending task to unload a tab. + case NS_ERROR_ABORT: + break; + + default: + MOZ_ASSERT_UNREACHABLE("Unexpected aResult"); + break; + } + return NS_OK; +} + +NS_IMETHODIMP +nsAvailableMemoryWatcher::Observe(nsISupports* aSubject, const char* aTopic, + const char16_t* aData) { + nsresult rv = nsAvailableMemoryWatcherBase::Observe(aSubject, aTopic, aData); + if (NS_FAILED(rv)) { + return rv; + } + + if (strcmp(aTopic, "xpcom-shutdown") == 0) { + OnShutdown(); + } else if (strcmp(aTopic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID) == 0) { + OnPrefChange(); + } + return NS_OK; +} + +void nsAvailableMemoryWatcher::OnShutdown() { + StopPolling(); + Preferences::RemoveObserver(this, kResponseMask); + Preferences::RemoveObserver(this, kPollingIntervalMS); +} + +void nsAvailableMemoryWatcher::OnPrefChange() { + MP_LOG("OnPrefChange()"); + // Handle the polling interval changing. + uint32_t pollingInterval = Preferences::GetUint(kPollingIntervalMS); + if (pollingInterval != mPollingInterval) { + mPollingInterval = std::clamp(pollingInterval, kPollingIntervalMinMS, + kPollingIntervalMaxMS); + RestartPolling(); + } + + // Handle the response mask changing. + uint32_t responseMask = Preferences::GetUint(kResponseMask); + if (mResponseMask != responseMask) { + mResponseMask = std::min(responseMask, kResponseMaskMax); + + // Do we need to turn on polling? + if (mResponseMask && (mLevel >= mResponseLevel) && !IsPolling()) { + StartPolling(); + } + + // Do we need to turn off polling? + if (!mResponseMask && IsPolling()) { + StopPolling(); + } + } + + // Handle the response level changing. + MacMemoryPressureLevel newResponseLevel; + if (Preferences::GetBool(kResponseOnWarn, kResponseLevelOnWarnDefault)) { + newResponseLevel = MacMemoryPressureLevel::Value::eWarning; + } else { + newResponseLevel = MacMemoryPressureLevel::Value::eCritical; + } + if (newResponseLevel == mResponseLevel) { + return; + } + + // Do we need to turn on polling? + if (mResponseMask && (newResponseLevel <= mLevel)) { + UpdateLowMemoryTimeStamp(); + LowMemoryResponse(); + StartPolling(); + } + + // Do we need to turn off polling? + if (IsPolling() && (newResponseLevel > mLevel)) { + RecordTelemetryEventOnHighMemory(); + StopPolling(); + MP_LOG("Issuing MemoryPressureState::NoPressure"); + NS_NotifyOfMemoryPressure(MemoryPressureState::NoPressure); + } + mResponseLevel = newResponseLevel; +} + +void nsAvailableMemoryWatcher::StartPolling() { + MOZ_ASSERT(NS_IsMainThread()); + if (!mTimer) { + MP_LOG("Starting poller"); + mTimer = NS_NewTimer(); + if (mTimer) { + mTimer->InitWithCallback(this, mPollingInterval, + nsITimer::TYPE_REPEATING_SLACK); + } + } +} + +void nsAvailableMemoryWatcher::StopPolling() { + MOZ_ASSERT(NS_IsMainThread()); + if (mTimer) { + MP_LOG("Pausing poller"); + mTimer->Cancel(); + mTimer = nullptr; + } +} + +void nsAvailableMemoryWatcher::RestartPolling() { + if (IsPolling()) { + StopPolling(); + StartPolling(); + } else { + MOZ_ASSERT(!mTimer); + } +} + +NS_IMETHODIMP +nsAvailableMemoryWatcher::GetName(nsACString& aName) { + aName.AssignLiteral("nsAvailableMemoryWatcher"); + return NS_OK; +} + +} // namespace mozilla |