gecko-dev/xpcom/base/nsMemoryReporterManager.h
Nicholas Nethercote 9d5a878581 Bug 1291970 (part 1) - Use MOZ_MUST_USE in nsMemoryReporterManager. r=erahm.
--HG--
extra : rebase_source : 11223e1aadb08c2ce71f783d68b37c135fe4bee5
2016-08-04 12:14:14 +10:00

289 lines
11 KiB
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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 http://mozilla.org/MPL/2.0/. */
#ifndef nsMemoryReporterManager_h__
#define nsMemoryReporterManager_h__
#include "mozilla/Mutex.h"
#include "nsHashKeys.h"
#include "nsIMemoryReporter.h"
#include "nsITimer.h"
#include "nsServiceManagerUtils.h"
#include "nsTHashtable.h"
namespace mozilla {
namespace dom {
class ContentParent;
class MemoryReport;
} // namespace dom
} // namespace mozilla
class nsITimer;
class nsMemoryReporterManager final : public nsIMemoryReporterManager
{
virtual ~nsMemoryReporterManager();
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIMEMORYREPORTERMANAGER
nsMemoryReporterManager();
// Gets the memory reporter manager service.
static nsMemoryReporterManager* GetOrCreate()
{
nsCOMPtr<nsIMemoryReporterManager> imgr =
do_GetService("@mozilla.org/memory-reporter-manager;1");
return static_cast<nsMemoryReporterManager*>(imgr.get());
}
typedef nsDataHashtable<nsRefPtrHashKey<nsIMemoryReporter>, bool> StrongReportersTable;
typedef nsDataHashtable<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;
mozilla::InfallibleAmountFn mJSMainRuntimeTemporaryPeak;
mozilla::InfallibleAmountFn mJSMainRuntimeCompartmentsSystem;
mozilla::InfallibleAmountFn mJSMainRuntimeCompartmentsUser;
mozilla::InfallibleAmountFn mImagesContentUsedUncompressed;
mozilla::InfallibleAmountFn mStorageSQLite;
mozilla::InfallibleAmountFn mLowMemoryEventsVirtual;
mozilla::InfallibleAmountFn mLowMemoryEventsPhysical;
mozilla::InfallibleAmountFn mGhostWindows;
AmountFns()
{
mozilla::PodZero(this);
}
};
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.
static int64_t ResidentUnique();
// Functions that measure per-tab memory consumption.
struct SizeOfTabFns
{
mozilla::JSSizeOfTabFn mJS;
mozilla::NonJSSizeOfTabFn mNonJS;
SizeOfTabFns()
{
mozilla::PodZero(this);
}
};
SizeOfTabFns mSizeOfTabFns;
private:
MOZ_MUST_USE nsresult
RegisterReporterHelper(nsIMemoryReporter* aReporter,
bool aForce, bool aStrongRef, bool aIsAsync);
MOZ_MUST_USE nsresult StartGettingReports();
// No MOZ_MUST_USE 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 = 50000;
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::dom::ContentParent>> 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.
FILE* mDMDFile;
PendingReportersState(nsIFinishReportingCallback* aFinishReporting,
nsISupports* aFinishReportingData,
FILE* aDMDFile)
: mReportsPending(0)
, mFinishReporting(aFinishReporting)
, mFinishReportingData(aFinishReportingData)
, 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;
PendingProcessesState* GetStateForGeneration(uint32_t aGeneration);
static MOZ_MUST_USE bool
StartChildReport(mozilla::dom::ContentParent* aChild,
const PendingProcessesState* aState);
};
#define NS_MEMORY_REPORTER_MANAGER_CID \
{ 0xfb97e4f5, 0x32dd, 0x497a, \
{ 0xba, 0xa2, 0x7d, 0x1e, 0x55, 0x7, 0x99, 0x10 } }
#endif // nsMemoryReporterManager_h__