summaryrefslogtreecommitdiffstats
path: root/xpcom/base/nsMemoryReporterManager.h
blob: 8899d322d29f504b7030c30898ddecf22627957e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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__