Collect profiler stats from browser child processes.

chrome/browser/metrics/tracking_synchronizer.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/metrics/tracking_synchronizer.h"
 
 #include "base/bind.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/threading/thread.h"
 #include "base/tracked_objects.h"
 #include "chrome/browser/ui/webui/tracing_ui.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/render_messages.h"
+#include "content/browser/browser_child_process_host.h"
+#include "content/browser/profiler_controller.h"
+#include "content/common/child_process_info.h"
+#include "content/common/child_process_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_process_host.h"
 
 using base::TimeTicks;
 using content::BrowserThread;
 
 namespace chrome_browser_metrics {
 
 // Negative numbers are never used as sequence numbers.  We explicitly pick a
 // negative number that is "so negative" that even when we add one (as is done
 // when we generated the next sequence number) that it will still be negative.
 // We have code that handles wrapping around on an overflow into negative
 // territory.
 static const int kNeverUsableSequenceNumber = -2;
 
 TrackingSynchronizer::TrackingSynchronizer()
     : last_used_sequence_number_(kNeverUsableSequenceNumber) {
   DCHECK(tracking_synchronizer_ == NULL);
   tracking_synchronizer_ = this;
+  ProfilerController::GetInstance()->RegisterSubscriber(this);
 }
 
 TrackingSynchronizer::~TrackingSynchronizer() {
+  ProfilerController::GetInstance()->CancelSubscriber(this);
   // Just in case we have any pending tasks, clear them out.
   while (!outstanding_requests_.empty()) {
     RequestContextMap::iterator it = outstanding_requests_.begin();
     delete it->second;
     outstanding_requests_.erase(it);
   }
 
   tracking_synchronizer_ = NULL;
 }
 
 // static
-TrackingSynchronizer* TrackingSynchronizer::CurrentSynchronizer() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK(tracking_synchronizer_ != NULL);
-  return tracking_synchronizer_;
-}
-
-// static
-void TrackingSynchronizer::FetchTrackingDataAsynchronously(
+void TrackingSynchronizer::FetchProfilerDataAsynchronously(
     const base::WeakPtr<ProfilerUI>& callback_object) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   TrackingSynchronizer* current_synchronizer = CurrentSynchronizer();
   if (current_synchronizer == NULL) {
     // System teardown is happening.
     return;
   }
 
   int sequence_number = current_synchronizer->RegisterAndNotifyAllProcesses(
       callback_object);
 
   // Post a task that would be called after waiting for wait_time.  This acts
   // as a watchdog, to cancel the requests for non-responsive processes.
   BrowserThread::PostDelayedTask(
       BrowserThread::UI, FROM_HERE,
       NewRunnableMethod(
           current_synchronizer,
-          &TrackingSynchronizer::ForceTrackingSynchronizationDoneCallback,
+          &TrackingSynchronizer::ForceProfilerSynchronizationDoneCallback,
           sequence_number),
       60000);
 }
 
 // static
-void TrackingSynchronizer::SetTrackingStatus(bool enable) {
+void TrackingSynchronizer::SetProfilerStatus(bool enable) {
   // To iterate over all processes, or to send messages to the hosts, we need
   // to be on the UI thread.
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   for (content::RenderProcessHost::iterator it(
           content::RenderProcessHost::AllHostsIterator());
        !it.IsAtEnd(); it.Advance()) {
     content::RenderProcessHost* render_process_host = it.GetCurrentValue();
     DCHECK(render_process_host);
     // Ignore processes that don't have a connection, such as crashed tabs.
     if (!render_process_host->HasConnection())
       continue;
 
-    render_process_host->Send(new ChromeViewMsg_SetTrackingStatus(enable));
+    render_process_host->Send(new ChromeViewMsg_SetProfilerStatus(enable));
   }
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(
+          &TrackingSynchronizer::SetProfilerStatusInChildProcesses, enable));
 }
 
 // static
-void TrackingSynchronizer::IsTrackingEnabled(int process_id) {
+void TrackingSynchronizer::IsProfilerEnabledForRenderer(
+    int renderer_process_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   // To find the process, or to send messages to the hosts, we need to be on the
   // UI thread.
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(
-          &TrackingSynchronizer::SetTrackingStatusInProcess, process_id));
+          &TrackingSynchronizer::SendRendererSetProfilerStatusOnUI,
+          renderer_process_id));
 }
 
 // static
-void TrackingSynchronizer::SetTrackingStatusInProcess(int process_id) {
+void TrackingSynchronizer::OnRendererProfilerDatatCollected(
+    int sequence_number,
+    const std::string& profiler_data) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&TrackingSynchronizer::OnRendererProfilerDatatCollectedOnUI,
+                 sequence_number,
+                 profiler_data));
+}
+
+void TrackingSynchronizer::OnBrowserChildProfilerDataCollected(
+    int sequence_number,
+    const std::string& profiler_data) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  base::Value* value =
+      base::JSONReader().JsonToValue(profiler_data, false, true);
+  DCHECK(value->GetType() == base::Value::TYPE_DICTIONARY);
+  base::DictionaryValue* dictionary_value =
+      static_cast<DictionaryValue*>(value);
+
+  DecrementPendingProcessesAndSendDataOnIO(sequence_number, dictionary_value);
+}
+
+void TrackingSynchronizer::OnIsProfilerEnabledForChildProcess(
+    base::ProcessId child_process_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   // To find the process, or to send messages to the hosts, we need to be on the
-  // UI thread.
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  bool enable = tracked_objects::ThreadData::tracking_status();
-
-  content::RenderProcessHost* process =
-      content::RenderProcessHost::FromID(process_id);
-  // Ignore processes that don't have a connection, such as crashed tabs.
-  if (!process || !process->HasConnection())
-    return;
-  process->Send(new ChromeViewMsg_SetTrackingStatus(enable));
+  // IO thread. We post a task to set the status.
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(
+          &TrackingSynchronizer::SendChildSetProfilerStatusOnIO,
+          child_process_id));
 }
 
 // static
-void TrackingSynchronizer::DeserializeTrackingList(
-    int sequence_number,
-    const std::string& tracking_data,
-    ChildProcessInfo::ProcessType process_type) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  BrowserThread::PostTask(
-      BrowserThread::UI, FROM_HERE,
-      base::Bind(
-          &TrackingSynchronizer::DeserializeTrackingListOnUI,
-          sequence_number, tracking_data, process_type));
-}
-
-// static
-void TrackingSynchronizer::DeserializeTrackingListOnUI(
-    int sequence_number,
-    const std::string& tracking_data,
-    ChildProcessInfo::ProcessType process_type) {
+TrackingSynchronizer* TrackingSynchronizer::CurrentSynchronizer() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  TrackingSynchronizer* current_synchronizer = CurrentSynchronizer();
-  if (current_synchronizer == NULL)
-    return;
-
-  base::Value* value =
-      base::JSONReader().JsonToValue(tracking_data, false, true);
-  DCHECK(value->GetType() == base::Value::TYPE_DICTIONARY);
-  base::DictionaryValue* dictionary_value =
-      static_cast<DictionaryValue*>(value);
-  dictionary_value->SetString(
-      "process_type", ChildProcessInfo::GetTypeNameInEnglish(process_type));
-
-  current_synchronizer->DecrementPendingProcessesAndSendData(
-      sequence_number, dictionary_value);
+  DCHECK(tracking_synchronizer_ != NULL);
+  return tracking_synchronizer_;
 }
 
 int TrackingSynchronizer::RegisterAndNotifyAllProcesses(
     const base::WeakPtr<ProfilerUI>& callback_object) {
   // To iterate over all processes, or to send messages to the hosts, we need
   // to be on the UI thread.
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   int sequence_number = GetNextAvailableSequenceNumber();
 
-  // Initialize processes_pending with one because we are going to send
-  // browser's ThreadData.
+  // ui_processes_pending is initialized to 1 to send browser's data.
+  // io_processes_pending is initialized to 1 for browser child processes.
+  // threads_pending is set to 2 to wait for data from UI thread (for renderer
+  // processes) and IO thread (for browser child processes).
   RequestContext* request = new RequestContext(
-      callback_object, sequence_number, 1, TimeTicks::Now());
+      callback_object, sequence_number, 1, 1, 2, TimeTicks::Now());
   outstanding_requests_[sequence_number] = request;
 
-  DCHECK_GT(request->processes_pending_, 0);
+  NotifyAllRendererProcesses(request);
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(
+          &TrackingSynchronizer::NotifyAllChildProcesses,
+          base::Unretained(this), request));
+
+  // Get the ThreadData for the browser process and send it back.
+  base::DictionaryValue* value = tracked_objects::ThreadData::ToValue();
+  const std::string process_type =
+      ChildProcessInfo::GetTypeNameInEnglish(ChildProcessInfo::BROWSER_PROCESS);
+  value->SetString("process_type", process_type);
+  value->SetInteger("process_id", base::GetCurrentProcId());
+  DCHECK_GE(request->ui_processes_pending_, 1);
+  DecrementPendingProcessesAndSendDataOnUI(sequence_number, value);
+
+  return sequence_number;
+}
+
+void TrackingSynchronizer::NotifyAllRendererProcesses(RequestContext* request) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK_EQ(request->ui_processes_pending_, 1);
+
+  const std::string render_process_type =
+      ChildProcessInfo::GetTypeNameInEnglish(ChildProcessInfo::RENDER_PROCESS);
+
   for (content::RenderProcessHost::iterator it(
           content::RenderProcessHost::AllHostsIterator());
        !it.IsAtEnd(); it.Advance()) {
     content::RenderProcessHost* render_process_host = it.GetCurrentValue();
     DCHECK(render_process_host);
     // Ignore processes that don't have a connection, such as crashed tabs.
     if (!render_process_host->HasConnection())
       continue;
 
-    ++request->processes_pending_;
-    if (!render_process_host->Send(
-        new ChromeViewMsg_GetRendererTrackedData(sequence_number))) {
-      DecrementPendingProcesses(sequence_number);
+    ++request->ui_processes_pending_;
+    if (!render_process_host->Send(new ChromeViewMsg_GetRendererProfilerData(
+        request->sequence_number_, render_process_type))) {
+      DecrementPendingProcessesAndSendDataOnUI(request->sequence_number_, NULL);
+    }
+  }
+  DCHECK_GE(request->ui_processes_pending_, 1);
+}
+
+void TrackingSynchronizer::NotifyAllChildProcesses(RequestContext* request) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK_EQ(1, request->io_processes_pending_);
+
+  // Default constr references a singleton.

[jam, 2011/11/19 23:36:25]

nit: this comment, and below, seem unnecessary. i.e. they're explaining what
someone can see when reading the code, which is not what we should be using
comments for (explaining tricky parts)

[ramant (doing other things), 2011/11/25 23:59:48]

Done.

+  for (BrowserChildProcessHost::Iterator child_process_host;
+       !child_process_host.Done(); ++child_process_host) {
+    const std::string process_type =
+      ChildProcessInfo::GetTypeNameInEnglish(child_process_host->type());
+
+    ++request->io_processes_pending_;
+    if (!child_process_host->Send(new ChildProcessMsg_GetChildProfilerData(
+        request->sequence_number_, process_type))) {
+      DecrementPendingProcessesAndSendDataOnIO(request->sequence_number_, NULL);
     }
   }
 
-  // Get the ThreadData for the browser process and send it back.
-  base::DictionaryValue* value = tracked_objects::ThreadData::ToValue();
-  const std::string process_type =
-      ChildProcessInfo::GetTypeNameInEnglish(ChildProcessInfo::BROWSER_PROCESS);
-  value->SetString("process_type", process_type);
-  value->SetInteger("process_id", base::GetCurrentProcId());
-  DCHECK_GT(request->processes_pending_, 0);
-  DecrementPendingProcessesAndSendData(sequence_number, value);
+  DCHECK_GE(request->io_processes_pending_, 1);
+  if (--request->io_processes_pending_ == 0) {
+    // We are done because we are not waiting for any browser child processes.
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(&TrackingSynchronizer::DeleteIfAllDone,
+                   base::Unretained(this), request));
+  }
+}
 
-  return sequence_number;
+// static
+void TrackingSynchronizer::OnRendererProfilerDatatCollectedOnUI(
+    int sequence_number,
+    const std::string& profiler_data) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  TrackingSynchronizer* current_synchronizer = CurrentSynchronizer();
+  if (current_synchronizer == NULL)
+    return;
+
+  base::Value* value =
+      base::JSONReader().JsonToValue(profiler_data, false, true);
+  DCHECK(value->GetType() == base::Value::TYPE_DICTIONARY);
+  base::DictionaryValue* dictionary_value =
+      static_cast<DictionaryValue*>(value);
+
+  current_synchronizer->DecrementPendingProcessesAndSendDataOnUI(
+      sequence_number, dictionary_value);
+}
+
+void TrackingSynchronizer::DecrementPendingProcessesAndSendDataOnUI(
+    int sequence_number,
+    base::DictionaryValue* value) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  DecrementProcessesCallback decrement_pending_process_cb =
+        base::Bind(&TrackingSynchronizer::DecrementUIProcesses,
+                   base::Unretained(this));
+
+  DecrementPendingProcessesAndSendData(sequence_number,
+                                       value,
+                                       MessageLoop::current(),
+                                       decrement_pending_process_cb);
+}
+
+void TrackingSynchronizer::DecrementPendingProcessesAndSendDataOnIO(
+    int sequence_number,
+    base::DictionaryValue* value) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  DecrementProcessesCallback decrement_pending_process_cb =
+        base::Bind(&TrackingSynchronizer::DecrementIOProcesses,
+                   base::Unretained(this));
+
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(
+          &TrackingSynchronizer::DecrementPendingProcessesAndSendData,
+          base::Unretained(this),
+          sequence_number,
+          value,
+          MessageLoop::current(),
+          decrement_pending_process_cb));
 }
 
 void TrackingSynchronizer::DecrementPendingProcessesAndSendData(
     int sequence_number,
-    base::DictionaryValue* value) {
+    base::DictionaryValue* value,
+    MessageLoop* callback_thread,
+    const DecrementProcessesCallback& decrement_pending_process_cb) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   RequestContextMap::iterator it =
       outstanding_requests_.find(sequence_number);
   if (it == outstanding_requests_.end()) {
     delete value;
     return;
   }
 
   RequestContext* request = NULL;
   request = it->second;
   DCHECK(sequence_number == request->sequence_number_);
 
   if (value && request->callback_object_) {
     // Transfers ownership of |value| to |callback_object_|.
     request->callback_object_->ReceivedData(value);
   } else {
     delete value;
   }
 
-  if (--request->processes_pending_ <= 0)
-    ForceTrackingSynchronizationDoneCallback(sequence_number);
+  callback_thread->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &TrackingSynchronizer::RunDecrementProcessesCallback,
+          this, decrement_pending_process_cb, request));
 }
 
-void TrackingSynchronizer::DecrementPendingProcesses(int sequence_number) {
-  DecrementPendingProcessesAndSendData(sequence_number, NULL);
+void TrackingSynchronizer::DecrementUIProcesses(RequestContext* request) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK_GT(request->ui_processes_pending_, 0);
+  if (--request->ui_processes_pending_ <= 0) {
+    DeleteIfAllDone(request);
+  }
 }
 
-void TrackingSynchronizer::ForceTrackingSynchronizationDoneCallback(
+void TrackingSynchronizer::DecrementIOProcesses(RequestContext* request) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK_GT(request->io_processes_pending_, 0);
+  if (--request->io_processes_pending_ <= 0) {
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(&TrackingSynchronizer::DeleteIfAllDone,
+                   base::Unretained(this), request));
+  }
+}
+
+void TrackingSynchronizer::DeleteIfAllDone(RequestContext* request) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(request);
+  // Return if we still need to hear from other threads.
+  if (--request->threads_pending_)
+    return;
+
+  DCHECK_EQ(0, request->ui_processes_pending_);
+  DCHECK_EQ(0, request->io_processes_pending_);
+  ForceProfilerSynchronizationDoneCallback(request->sequence_number_);
+}
+
+void TrackingSynchronizer::ForceProfilerSynchronizationDoneCallback(
     int sequence_number) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  int unresponsive_processes;
   RequestContextMap::iterator it =
       outstanding_requests_.find(sequence_number);
   if (it == outstanding_requests_.end())
     return;
 
   RequestContext* request = it->second;
 
   DCHECK(sequence_number == request->sequence_number_);
 
-  unresponsive_processes = request->processes_pending_;
+  int unresponsive_processes = request->ui_processes_pending_;
 
   delete it->second;
   outstanding_requests_.erase(it);
 
-  UMA_HISTOGRAM_COUNTS("Tracking.ProcessNotRespondingAsynchronous",
+  UMA_HISTOGRAM_COUNTS("Profiler.ProcessNotRespondingAsynchronous",
                        unresponsive_processes);
 }
 
 int TrackingSynchronizer::GetNextAvailableSequenceNumber() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   ++last_used_sequence_number_;
 
   // Watch out for wrapping to a negative number.
   if (last_used_sequence_number_ < 0)
     last_used_sequence_number_ = 1;
   return last_used_sequence_number_;
 }
 
+void TrackingSynchronizer::RunDecrementProcessesCallback(
+    const DecrementProcessesCallback& decrement_pending_process_cb,
+    RequestContext* request) {
+  decrement_pending_process_cb.Run(request);
+}
+
+// static
+void TrackingSynchronizer::SetProfilerStatusInChildProcesses(bool enable) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // Default constr references a singleton.
+  for (BrowserChildProcessHost::Iterator child_process_host;
+       !child_process_host.Done(); ++child_process_host) {
+    child_process_host->Send(new ChildProcessMsg_SetProfilerStatus(enable));
+  }
+}
+
+// static
+void TrackingSynchronizer::SendRendererSetProfilerStatusOnUI(
+    int renderer_process_id) {
+  // To find the process, or to send messages to the hosts, we need to be on the
+  // UI thread.
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  bool enable = tracked_objects::ThreadData::tracking_status();
+
+  content::RenderProcessHost* process =
+      content::RenderProcessHost::FromID(renderer_process_id);
+  // Ignore processes that don't have a connection, such as crashed tabs.
+  if (!process || !process->HasConnection())
+    return;
+  process->Send(new ChromeViewMsg_SetProfilerStatus(enable));
+}
+
+// static
+void TrackingSynchronizer::SendChildSetProfilerStatusOnIO(
+    base::ProcessId child_process_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  bool enable = tracked_objects::ThreadData::tracking_status();
+
+  // Default constr references a singleton.
+  for (BrowserChildProcessHost::Iterator child_process_host;
+       !child_process_host.Done(); ++child_process_host) {
+    if (base::GetProcId(child_process_host->handle()) == child_process_id)
+      child_process_host->Send(new ChildProcessMsg_SetProfilerStatus(enable));
+  }
+}
+
 // static
 TrackingSynchronizer* TrackingSynchronizer::tracking_synchronizer_ = NULL;
 
 }  // namespace chrome_browser_metrics