src/components/metrics/profiler/tracking_synchronizer.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/metrics/profiler/tracking_synchronizer.h"
   6
   7 #include "base/bind.h"
   8 #include "base/metrics/histogram.h"
   9 #include "base/threading/thread.h"
  10 #include "base/tracked_objects.h"
  11 #include "components/metrics/profiler/tracking_synchronizer_observer.h"
  12 #include "content/public/browser/browser_thread.h"
  13 #include "content/public/browser/profiler_controller.h"
  14 #include "content/public/common/process_type.h"
  15
  16 using base::TimeTicks;
  17 using content::BrowserThread;
  18
  19 namespace metrics {
  20
  21 namespace {
  22
  23 // Negative numbers are never used as sequence numbers.  We explicitly pick a
  24 // negative number that is "so negative" that even when we add one (as is done
  25 // when we generated the next sequence number) that it will still be negative.
  26 // We have code that handles wrapping around on an overflow into negative
  27 // territory.
  28 const int kNeverUsableSequenceNumber = -2;
  29
  30 // This singleton instance should be started during the single threaded
  31 // portion of main(). It initializes globals to provide support for all future
  32 // calls. This object is created on the UI thread, and it is destroyed after
  33 // all the other threads have gone away. As a result, it is ok to call it
  34 // from the UI thread, or for about:profiler.
  35 static TrackingSynchronizer* g_tracking_synchronizer = NULL;
  36
  37 }  // namespace
  38
  39 // The "RequestContext" structure describes an individual request received
  40 // from the UI. All methods are accessible on UI thread.
  41 class TrackingSynchronizer::RequestContext {
  42  public:
  43   // A map from sequence_number_ to the actual RequestContexts.
  44   typedef std::map<int, RequestContext*> RequestContextMap;
  45
  46   RequestContext(
  47       const base::WeakPtr<TrackingSynchronizerObserver>& callback_object,
  48       int sequence_number)
  49       : callback_object_(callback_object),
  50         sequence_number_(sequence_number),
  51         received_process_group_count_(0),
  52         processes_pending_(0) {
  53   }
  54   ~RequestContext() {}
  55
  56   void SetReceivedProcessGroupCount(bool done) {
  57     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  58     received_process_group_count_ = done;
  59   }
  60
  61   // Methods for book keeping of processes_pending_.
  62   void IncrementProcessesPending() {
  63     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  64     ++processes_pending_;
  65   }
  66
  67   void AddProcessesPending(int processes_pending) {
  68     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  69     processes_pending_ += processes_pending;
  70   }
  71
  72   void DecrementProcessesPending() {
  73     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  74     --processes_pending_;
  75   }
  76
  77   // Records that we are waiting for one less tracking data from a process for
  78   // the given sequence number. If |received_process_group_count_| and
  79   // |processes_pending_| are zero, then delete the current object by calling
  80   // Unregister.
  81   void DeleteIfAllDone() {
  82     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  83
  84     if (processes_pending_ <= 0 && received_process_group_count_)
  85       RequestContext::Unregister(sequence_number_);
  86   }
  87
  88   // Register |callback_object| in |outstanding_requests_| map for the given
  89   // |sequence_number|.
  90   static RequestContext* Register(
  91       int sequence_number,
  92       const base::WeakPtr<TrackingSynchronizerObserver>& callback_object) {
  93     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  94
  95     RequestContext* request = new RequestContext(
  96         callback_object, sequence_number);
  97     outstanding_requests_.Get()[sequence_number] = request;
  98
  99     return request;
 100   }
 101
 102   // Find the |RequestContext| in |outstanding_requests_| map for the given
 103   // |sequence_number|.
 104   static RequestContext* GetRequestContext(int sequence_number) {
 105     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 106
 107     RequestContextMap::iterator it =
 108         outstanding_requests_.Get().find(sequence_number);
 109     if (it == outstanding_requests_.Get().end())
 110       return NULL;
 111
 112     RequestContext* request = it->second;
 113     DCHECK_EQ(sequence_number, request->sequence_number_);
 114     return request;
 115   }
 116
 117   // Delete the entry for the given |sequence_number| from
 118   // |outstanding_requests_| map. This method is called when all changes have
 119   // been acquired, or when the wait time expires (whichever is sooner).
 120   static void Unregister(int sequence_number) {
 121     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 122
 123     RequestContextMap::iterator it =
 124         outstanding_requests_.Get().find(sequence_number);
 125     if (it == outstanding_requests_.Get().end())
 126       return;
 127
 128     RequestContext* request = it->second;
 129     DCHECK_EQ(sequence_number, request->sequence_number_);
 130     bool received_process_group_count = request->received_process_group_count_;
 131     int unresponsive_processes = request->processes_pending_;
 132
 133     if (request->callback_object_.get())
 134       request->callback_object_->FinishedReceivingProfilerData();
 135
 136     delete request;
 137     outstanding_requests_.Get().erase(it);
 138
 139     UMA_HISTOGRAM_BOOLEAN("Profiling.ReceivedProcessGroupCount",
 140                           received_process_group_count);
 141     UMA_HISTOGRAM_COUNTS("Profiling.PendingProcessNotResponding",
 142                          unresponsive_processes);
 143   }
 144
 145   // Delete all the entries in |outstanding_requests_| map.
 146   static void OnShutdown() {
 147     // Just in case we have any pending tasks, clear them out.
 148     while (!outstanding_requests_.Get().empty()) {
 149       RequestContextMap::iterator it = outstanding_requests_.Get().begin();
 150       delete it->second;
 151       outstanding_requests_.Get().erase(it);
 152     }
 153   }
 154
 155   // Requests are made to asynchronously send data to the |callback_object_|.
 156   base::WeakPtr<TrackingSynchronizerObserver> callback_object_;
 157
 158   // The sequence number used by the most recent update request to contact all
 159   // processes.
 160   int sequence_number_;
 161
 162   // Indicates if we have received all pending processes count.
 163   bool received_process_group_count_;
 164
 165   // The number of pending processes (browser, all renderer processes and
 166   // browser child processes) that have not yet responded to requests.
 167   int processes_pending_;
 168
 169   // Map of all outstanding RequestContexts, from sequence_number_ to
 170   // RequestContext.
 171   static base::LazyInstance<RequestContextMap>::Leaky outstanding_requests_;
 172 };
 173
 174 // static
 175 base::LazyInstance
 176     <TrackingSynchronizer::RequestContext::RequestContextMap>::Leaky
 177         TrackingSynchronizer::RequestContext::outstanding_requests_ =
 178             LAZY_INSTANCE_INITIALIZER;
 179
 180 // TrackingSynchronizer methods and members.
 181
 182 TrackingSynchronizer::TrackingSynchronizer()
 183     : last_used_sequence_number_(kNeverUsableSequenceNumber) {
 184   DCHECK(!g_tracking_synchronizer);
 185   g_tracking_synchronizer = this;
 186   content::ProfilerController::GetInstance()->Register(this);
 187 }
 188
 189 TrackingSynchronizer::~TrackingSynchronizer() {
 190   content::ProfilerController::GetInstance()->Unregister(this);
 191
 192   // Just in case we have any pending tasks, clear them out.
 193   RequestContext::OnShutdown();
 194
 195   g_tracking_synchronizer = NULL;
 196 }
 197
 198 // static
 199 void TrackingSynchronizer::FetchProfilerDataAsynchronously(
 200     const base::WeakPtr<TrackingSynchronizerObserver>& callback_object) {
 201   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 202
 203   if (!g_tracking_synchronizer) {
 204     // System teardown is happening.
 205     return;
 206   }
 207
 208   int sequence_number = g_tracking_synchronizer->RegisterAndNotifyAllProcesses(
 209       callback_object);
 210
 211   // Post a task that would be called after waiting for wait_time.  This acts
 212   // as a watchdog, to cancel the requests for non-responsive processes.
 213   BrowserThread::PostDelayedTask(
 214       BrowserThread::UI, FROM_HERE,
 215       base::Bind(&RequestContext::Unregister, sequence_number),
 216       base::TimeDelta::FromMinutes(1));
 217 }
 218
 219 void TrackingSynchronizer::OnPendingProcesses(int sequence_number,
 220                                               int pending_processes,
 221                                               bool end) {
 222   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 223
 224   RequestContext* request = RequestContext::GetRequestContext(sequence_number);
 225   if (!request)
 226     return;
 227   request->AddProcessesPending(pending_processes);
 228   request->SetReceivedProcessGroupCount(end);
 229   request->DeleteIfAllDone();
 230 }
 231
 232 void TrackingSynchronizer::OnProfilerDataCollected(
 233     int sequence_number,
 234     const tracked_objects::ProcessDataSnapshot& profiler_data,
 235     int process_type) {
 236   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 237   DecrementPendingProcessesAndSendData(sequence_number, profiler_data,
 238                                        process_type);
 239 }
 240
 241 int TrackingSynchronizer::RegisterAndNotifyAllProcesses(
 242     const base::WeakPtr<TrackingSynchronizerObserver>& callback_object) {
 243   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 244
 245   int sequence_number = GetNextAvailableSequenceNumber();
 246
 247   RequestContext* request =
 248       RequestContext::Register(sequence_number, callback_object);
 249
 250   // Increment pending process count for sending browser's profiler data.
 251   request->IncrementProcessesPending();
 252
 253   // Get profiler data from renderer and browser child processes.
 254   content::ProfilerController::GetInstance()->GetProfilerData(sequence_number);
 255
 256   // Send profiler_data from browser process.
 257   tracked_objects::ProcessDataSnapshot process_data;
 258   tracked_objects::ThreadData::Snapshot(false, &process_data);
 259   DecrementPendingProcessesAndSendData(sequence_number, process_data,
 260                                        content::PROCESS_TYPE_BROWSER);
 261
 262   return sequence_number;
 263 }
 264
 265 void TrackingSynchronizer::DecrementPendingProcessesAndSendData(
 266     int sequence_number,
 267     const tracked_objects::ProcessDataSnapshot& profiler_data,
 268     int process_type) {
 269   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 270
 271   RequestContext* request = RequestContext::GetRequestContext(sequence_number);
 272   if (!request)
 273     return;
 274
 275   if (request->callback_object_.get()) {
 276     request->callback_object_
 277         ->ReceivedProfilerData(profiler_data, process_type);
 278   }
 279
 280   // Delete request if we have heard back from all child processes.
 281   request->DecrementProcessesPending();
 282   request->DeleteIfAllDone();
 283 }
 284
 285 int TrackingSynchronizer::GetNextAvailableSequenceNumber() {
 286   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 287
 288   ++last_used_sequence_number_;
 289
 290   // Watch out for wrapping to a negative number.
 291   if (last_used_sequence_number_ < 0)
 292     last_used_sequence_number_ = 1;
 293   return last_used_sequence_number_;
 294 }
 295
 296 }  // namespace metrics