gecko/xpcom/base/nsMemoryReporterManager.h
Nicholas Nethercote 2efdc47a99 Bug 929797 - Implement proper memory reporting for child processes. r=khuey.
--HG--
extra : rebase_source : f0788757afc2097830295170120e1e2094993cc7
2013-10-22 22:26:24 -07:00

197 lines
7.6 KiB
C++

/* -*- 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 "nsIMemoryReporter.h"
#include "mozilla/Mutex.h"
#include "nsTHashtable.h"
#include "nsHashKeys.h"
using mozilla::Mutex;
class nsITimer;
namespace mozilla {
namespace dom {
class MemoryReport;
}
}
class nsMemoryReporterManager : public nsIMemoryReporterManager
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIMEMORYREPORTERMANAGER
nsMemoryReporterManager();
virtual ~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());
}
void IncrementNumChildProcesses();
void DecrementNumChildProcesses();
// Inter-process memory reporting proceeds as follows.
//
// - GetReports() (declared within NS_DECL_NSIMEMORYREPORTERMANAGER)
// synchronously gets memory reports for the current process, tells all
// child processes to get memory reports, and sets up some state
// (mGetReportsState) for when the child processes report back, including a
// timer. Control then returns to the main event loop.
//
// - HandleChildReports() is called (asynchronously) once per child process
// that reports back. If all child processes report back before time-out,
// the timer is cancelled. (The number of child processes is part of the
// saved request state.)
//
// - 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 HandleChildReports() (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.
//
// Now, what what happens if a child process is created/destroyed in the
// middle of a request? Well, GetReportsState contains a copy of
// mNumChildProcesses which it uses to determine finished-ness. So...
//
// - If a process is created, it won't have received the request for reports,
// and the GetReportsState's mNumChildProcesses won't account for it. So
// the reported data will reflect how things were when the request began.
//
// - If a process is destroyed before reporting back, we'll just hit the
// time-out, because we'll have received reports (barring other errors)
// from N-1 child process. So the reported data will reflect how things
// are when the request ends.
//
// - 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 three cases are unfortunate but
// difficult to avoid. It's enough of an edge case to not be worth doing
// more.
//
void HandleChildReports(
const uint32_t& generation,
const InfallibleTArray<mozilla::dom::MemoryReport>& aChildReports);
void FinishReporting();
// 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;
// Functions that measure per-tab memory consumption.
struct SizeOfTabFns {
mozilla::JSSizeOfTabFn mJS;
mozilla::NonJSSizeOfTabFn mNonJS;
SizeOfTabFns() { mozilla::PodZero(this); }
};
SizeOfTabFns mSizeOfTabFns;
private:
nsresult RegisterReporterHelper(nsIMemoryReporter* aReporter, bool aForce);
static void TimeoutCallback(nsITimer* aTimer, void* aData);
static const uint32_t kTimeoutLengthMS = 5000;
nsTHashtable<nsISupportsHashKey> mReporters;
Mutex mMutex;
bool mIsRegistrationBlocked;
uint32_t mNumChildProcesses;
uint32_t mNextGeneration;
struct GetReportsState {
uint32_t mGeneration;
nsCOMPtr<nsITimer> mTimer;
uint32_t mNumChildProcesses;
uint32_t mNumChildProcessesCompleted;
nsCOMPtr<nsIHandleReportCallback> mHandleReport;
nsCOMPtr<nsISupports> mHandleReportData;
nsCOMPtr<nsIFinishReportingCallback> mFinishReporting;
nsCOMPtr<nsISupports> mFinishReportingData;
GetReportsState(uint32_t aGeneration, nsITimer* aTimer,
uint32_t aNumChildProcesses,
nsIHandleReportCallback* aHandleReport,
nsISupports* aHandleReportData,
nsIFinishReportingCallback* aFinishReporting,
nsISupports* aFinishReportingData)
: mGeneration(aGeneration),
mTimer(aTimer),
mNumChildProcesses(aNumChildProcesses),
mNumChildProcessesCompleted(0),
mHandleReport(aHandleReport),
mHandleReportData(aHandleReportData),
mFinishReporting(aFinishReporting),
mFinishReportingData(aFinishReportingData)
{}
};
// 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.
GetReportsState* mGetReportsState;
};
#define NS_MEMORY_REPORTER_MANAGER_CID \
{ 0xfb97e4f5, 0x32dd, 0x497a, \
{ 0xba, 0xa2, 0x7d, 0x1e, 0x55, 0x7, 0x99, 0x10 } }