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/* -*- 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 */
#ifndef nsMemoryReporterManager_h__
#define nsMemoryReporterManager_h__
#include "mozilla/Mutex.h"
#include "nsTHashMap.h"
#include "nsHashKeys.h"
#include "nsIMemoryReporter.h"
#include "nsISupports.h"
#include "nsServiceManagerUtils.h"
#ifdef XP_WIN
# include <windows.h>
#endif // XP_WIN
namespace mozilla {
class MemoryReportingProcess;
namespace dom {
class MemoryReport;
} // namespace dom
} // namespace mozilla
class mozIDOMWindowProxy;
class nsIEventTarget;
class nsIRunnable;
class nsITimer;
class nsMemoryReporterManager final : public nsIMemoryReporterManager,
public nsIMemoryReporter {
virtual ~nsMemoryReporterManager();
// Gets the memory reporter manager service.
static already_AddRefed<nsMemoryReporterManager> GetOrCreate() {
nsCOMPtr<nsIMemoryReporterManager> imgr =
return imgr.forget().downcast<nsMemoryReporterManager>();
typedef nsTHashMap<nsRefPtrHashKey<nsIMemoryReporter>, bool>
typedef nsTHashMap<nsPtrHashKey<nsIMemoryReporter>, bool> WeakReportersTable;
// Inter-process memory reporting proceeds as follows.
// - GetReports() (declared within NS_DECL_NSIMEMORYREPORTERMANAGER)
// synchronously gets memory reports for the current process, sets up some
// state (mPendingProcessesState) for when child processes report back --
// including a timer -- and starts telling child processes to get memory
// reports. Control then returns to the main event loop.
// The number of concurrent child process reports is limited by the pref
// "memory.report_concurrency" in order to prevent the memory overhead of
// memory reporting from causing problems, especially on B2G when swapping
// to compressed RAM; see bug 1154053.
// - HandleChildReport() is called (asynchronously) once per child process
// reporter callback.
// - EndProcessReport() is called (asynchronously) once per process that
// finishes reporting back, including the parent. If all processes do so
// before time-out, the timer is cancelled. If there are child processes
// whose requests have not yet been sent, they will be started until the
// concurrency limit is (again) reached.
// - TimeoutCallback() is called (asynchronously) if all the child processes
// don't respond within the time threshold.
// - FinishReporting() finishes things off. It is *always* called -- either
// from EndChildReport() (if all child processes have reported back) or
// from TimeoutCallback() (if time-out occurs).
// All operations occur on the main thread.
// The above sequence of steps is a "request". A partially-completed request
// is described as "in flight".
// Each request has a "generation", a unique number that identifies it. This
// is used to ensure that each reports from a child process corresponds to
// the appropriate request from the parent process. (It's easier to
// implement a generation system than to implement a child report request
// cancellation mechanism.)
// Failures are mostly ignored, because it's (a) typically the most sensible
// thing to do, and (b) often hard to do anything else. The following are
// the failure cases of note.
// - If a request is made while the previous request is in flight, the new
// request is ignored, as per getReports()'s specification. No error is
// reported, because the previous request will complete soon enough.
// - If one or more child processes fail to respond within the time limit,
// things will proceed as if they don't exist. No error is reported,
// because partial information is better than nothing.
// - If a child process reports after the time-out occurs, it is ignored.
// (Generation checking will ensure it is ignored even if a subsequent
// request is in flight; this is the main use of generations.) No error
// is reported, because there's nothing sensible to be done about it at
// this late stage.
// - If the time-out occurs after a child process has sent some reports but
// before it has signaled completion (see bug 1151597), then what it
// successfully sent will be included, with no explicit indication that it
// is incomplete.
// Now, what what happens if a child process is created/destroyed in the
// middle of a request? Well, PendingProcessesState is initialized with an
// array of child process actors as of when the report started. So...
// - If a process is created after reporting starts, it won't be sent a
// request for reports. So the reported data will reflect how things were
// when the request began.
// - If a process is destroyed before it starts reporting back, the reported
// data will reflect how things are when the request ends.
// - If a process is destroyed after it starts reporting back but before it
// finishes, the reported data will contain a partial report for it.
// - If a process is destroyed after reporting back, but before all other
// child processes have reported back, it will be included in the reported
// data. So the reported data will reflect how things were when the
// request began.
// The inconsistencies between these cases are unfortunate but difficult to
// avoid. It's enough of an edge case to not be worth doing more.
void HandleChildReport(uint32_t aGeneration,
const mozilla::dom::MemoryReport& aChildReport);
void EndProcessReport(uint32_t aGeneration, bool aSuccess);
// Functions that (a) implement distinguished amounts, and (b) are outside of
// this module.
struct AmountFns {
mozilla::InfallibleAmountFn mJSMainRuntimeGCHeap = nullptr;
mozilla::InfallibleAmountFn mJSMainRuntimeTemporaryPeak = nullptr;
mozilla::InfallibleAmountFn mJSMainRuntimeCompartmentsSystem = nullptr;
mozilla::InfallibleAmountFn mJSMainRuntimeCompartmentsUser = nullptr;
mozilla::InfallibleAmountFn mJSMainRuntimeRealmsSystem = nullptr;
mozilla::InfallibleAmountFn mJSMainRuntimeRealmsUser = nullptr;
mozilla::InfallibleAmountFn mImagesContentUsedUncompressed = nullptr;
mozilla::InfallibleAmountFn mStorageSQLite = nullptr;
mozilla::InfallibleAmountFn mLowMemoryEventsPhysical = nullptr;
mozilla::InfallibleAmountFn mGhostWindows = nullptr;
AmountFns mAmountFns;
// Convenience function to get RSS easily from other code. This is useful
// when debugging transient memory spikes with printf instrumentation.
static int64_t ResidentFast();
// Convenience function to get peak RSS easily from other code.
static int64_t ResidentPeak();
// Convenience function to get USS easily from other code. This is useful
// when debugging unshared memory pages for forked processes.
// Returns 0 if, for some reason, the resident unique memory cannot be
// determined - typically if there is a race between us and someone else
// closing the process and we lost that race.
#ifdef XP_WIN
static int64_t ResidentUnique(HANDLE aProcess = nullptr);
static int64_t ResidentUnique(mach_port_t aPort = 0);
static int64_t ResidentUnique(pid_t aPid = 0);
#endif // XP_{WIN, MACOSX, LINUX, *}
// Functions that measure per-tab memory consumption.
struct SizeOfTabFns {
mozilla::JSSizeOfTabFn mJS = nullptr;
mozilla::NonJSSizeOfTabFn mNonJS = nullptr;
SizeOfTabFns mSizeOfTabFns;
[[nodiscard]] nsresult RegisterReporterHelper(nsIMemoryReporter* aReporter,
bool aForce, bool aStrongRef,
bool aIsAsync);
[[nodiscard]] nsresult StartGettingReports();
// No [[nodiscard]] here because ignoring the result is common and reasonable.
nsresult FinishReporting();
void DispatchReporter(nsIMemoryReporter* aReporter, bool aIsAsync,
nsIHandleReportCallback* aHandleReport,
nsISupports* aHandleReportData, bool aAnonymize);
static void TimeoutCallback(nsITimer* aTimer, void* aData);
// Note: this timeout needs to be long enough to allow for the
// possibility of DMD reports and/or running on a low-end phone.
static const uint32_t kTimeoutLengthMS = 180000;
mozilla::Mutex mMutex;
bool mIsRegistrationBlocked;
StrongReportersTable* mStrongReporters;
WeakReportersTable* mWeakReporters;
// These two are only used for testing purposes.
StrongReportersTable* mSavedStrongReporters;
WeakReportersTable* mSavedWeakReporters;
uint32_t mNextGeneration;
// Used to keep track of state of which processes are currently running and
// waiting to run memory reports. Holds references to parameters needed when
// requesting a memory report and finishing reporting.
struct PendingProcessesState {
uint32_t mGeneration;
bool mAnonymize;
bool mMinimize;
nsCOMPtr<nsITimer> mTimer;
nsTArray<RefPtr<mozilla::MemoryReportingProcess>> mChildrenPending;
uint32_t mNumProcessesRunning;
uint32_t mNumProcessesCompleted;
uint32_t mConcurrencyLimit;
nsCOMPtr<nsIHandleReportCallback> mHandleReport;
nsCOMPtr<nsISupports> mHandleReportData;
nsCOMPtr<nsIFinishReportingCallback> mFinishReporting;
nsCOMPtr<nsISupports> mFinishReportingData;
nsString mDMDDumpIdent;
PendingProcessesState(uint32_t aGeneration, bool aAnonymize, bool aMinimize,
uint32_t aConcurrencyLimit,
nsIHandleReportCallback* aHandleReport,
nsISupports* aHandleReportData,
nsIFinishReportingCallback* aFinishReporting,
nsISupports* aFinishReportingData,
const nsAString& aDMDDumpIdent);
// Used to keep track of the state of the asynchronously run memory
// reporters. The callback and file handle used when all memory reporters
// have finished are also stored here.
struct PendingReportersState {
// Number of memory reporters currently running.
uint32_t mReportsPending;
// Callback for when all memory reporters have completed.
nsCOMPtr<nsIFinishReportingCallback> mFinishReporting;
nsCOMPtr<nsISupports> mFinishReportingData;
// File handle to write a DMD report to if requested.
PendingReportersState(nsIFinishReportingCallback* aFinishReporting,
nsISupports* aFinishReportingData, FILE* aDMDFile)
: mReportsPending(0),
mDMDFile(aDMDFile) {}
// When this is non-null, a request is in flight. Note: We use manual
// new/delete for this because its lifetime doesn't match block scope or
// anything like that.
PendingProcessesState* mPendingProcessesState;
// This is reinitialized each time a call to GetReports is initiated.
PendingReportersState* mPendingReportersState;
// Used in GetHeapAllocatedAsync() to run jemalloc_stats async.
nsCOMPtr<nsIEventTarget> mThreadPool;
PendingProcessesState* GetStateForGeneration(uint32_t aGeneration);
[[nodiscard]] static bool StartChildReport(
mozilla::MemoryReportingProcess* aChild,
const PendingProcessesState* aState);
{ \
0xfb97e4f5, 0x32dd, 0x497a, { \
0xba, 0xa2, 0x7d, 0x1e, 0x55, 0x7, 0x99, 0x10 \
} \
#endif // nsMemoryReporterManager_h__