Thread-local trace-event buffers

content/browser/tracing/trace_controller_impl.cc

 // Copyright (c) 2012 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 "content/browser/tracing/trace_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 130 matching lines @@
 
   return true;
 }
 
 bool TraceControllerImpl::EndTracingAsync(TraceSubscriber* subscriber) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (!can_end_tracing() || subscriber != subscriber_)
     return false;
 
+  // Disable local trace early to avoid traces during end-tracing process from
+  // interfering with the process.
+  TraceLog::GetInstance()->SetDisabled();
+
   // There could be a case where there are no child processes and filters_
   // is empty. In that case we can immediately tell the subscriber that tracing
   // has ended. To avoid recursive calls back to the subscriber, we will just
   // use the existing asynchronous OnEndTracingAck code.
   // Count myself (local trace) in pending_end_ack_count_, acked below.
   pending_end_ack_count_ = filters_.size() + 1;
 
   // Handle special case of zero child processes.
   if (pending_end_ack_count_ == 1) {
     // Ack asynchronously now, because we don't have any children to wait for.
@@ skipping 133 matching lines @@
     return;
   }
 
   // Merge known_category_groups with known_category_groups_
   known_category_groups_.insert(known_category_groups.begin(),
                                 known_category_groups.end());
 
   if (pending_end_ack_count_ == 0)
     return;
 
-  if (--pending_end_ack_count_ == 0) {
-    // All acks have been received.
+
+  if (--pending_end_ack_count_ == 1) {
+    // All acks from subprocesses have been received. Now flush the local trace.
+    // During or after this call, our OnLocalTraceDataCollected will be
+    // called with the last of the local trace data.
+    TraceLog::GetInstance()->Flush(
+        base::Bind(&TraceControllerImpl::OnLocalTraceDataCollected,
+                   base::Unretained(this)));
+  }
+
+  if (pending_end_ack_count_ == 0) {
+    // All acks (including from the subprocesses and the local trace) have been
+    // received.
     is_tracing_ = false;
 
-    // Disable local trace.
-    TraceLog::GetInstance()->SetDisabled();
-
-    // During this call, our OnTraceDataCollected will be
-    // called with the last of the local trace data. Since we are on the UI
-    // thread, the call to OnTraceDataCollected will be synchronous, so we can
-    // immediately call OnEndTracingComplete below.
-    TraceLog::GetInstance()->Flush(
-        base::Bind(&TraceControllerImpl::OnTraceDataCollected,
-                   base::Unretained(this)));
-
     // Trigger callback if one is set.
     if (subscriber_) {
       if (is_get_category_groups_)
         subscriber_->OnKnownCategoriesCollected(known_category_groups_);
       else
         subscriber_->OnEndTracingComplete();
       // Clear subscriber so that others can use TraceController.
       subscriber_ = NULL;
     }
 
     is_get_category_groups_ = false;
   }
-
-  if (pending_end_ack_count_ == 1) {
-    // The last ack represents local trace, so we need to ack it now. Note that
-    // this code only executes if there were child processes.
-    std::vector<std::string> category_groups;
-    TraceLog::GetInstance()->GetKnownCategoryGroups(&category_groups);
-    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-        base::Bind(&TraceControllerImpl::OnEndTracingAck,
-                   base::Unretained(this), category_groups));
-  }
 }
 
 void TraceControllerImpl::OnTraceDataCollected(
     const scoped_refptr<base::RefCountedString>& events_str_ptr) {
   // OnTraceDataCollected may be called from any browser thread, either by the
   // local event trace system or from child processes via TraceMessageFilter.
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
         base::Bind(&TraceControllerImpl::OnTraceDataCollected,
                    base::Unretained(this), events_str_ptr));
     return;
   }
 
   // Drop trace events if we are just getting categories.
   if (subscriber_ && !is_get_category_groups_)
     subscriber_->OnTraceDataCollected(events_str_ptr);
 }
 
+void TraceControllerImpl::OnLocalTraceDataCollected(
+    const scoped_refptr<base::RefCountedString>& events_str_ptr,
+    bool has_more_events) {
+  if (events_str_ptr->data().size())
+    OnTraceDataCollected(events_str_ptr);
+
+  if (!has_more_events) {
+    // Simulate an EndTrackingAck for the local trace.
+    std::vector<std::string> category_groups;
+    TraceLog::GetInstance()->GetKnownCategoryGroups(&category_groups);
+    OnEndTracingAck(category_groups);
+  }
+}
+
 void TraceControllerImpl::OnTraceNotification(int notification) {
   // OnTraceNotification may be called from any browser thread, either by the
   // local event trace system or from child processes via TraceMessageFilter.
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
         base::Bind(&TraceControllerImpl::OnTraceNotification,
                    base::Unretained(this), notification));
     return;
   }
 
@@ skipping 31 matching lines @@
     // The last ack represents local trace, so we need to ack it now. Note that
     // this code only executes if there were child processes.
     float bpf = TraceLog::GetInstance()->GetBufferPercentFull();
     BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
         base::Bind(&TraceControllerImpl::OnTraceBufferPercentFullReply,
                    base::Unretained(this), bpf));
   }
 }
 
 }  // namespace content