[tracing] Track number of allocations in heap profiler

third_party/WebKit/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp

 // Copyright 2015 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 "platform/heap/BlinkGCMemoryDumpProvider.h"
 
 #include "base/trace_event/heap_profiler_allocation_context_tracker.h"
 #include "base/trace_event/heap_profiler_allocation_register.h"
 #include "base/trace_event/trace_event_memory_overhead.h"
 #include "platform/heap/Handle.h"
@@ skipping 46 matching lines @@
 {
     // In the case of a detailed dump perform a mark-only GC pass to collect
     // more detailed stats.
     if (levelOfDetail == WebMemoryDumpLevelOfDetail::Detailed)
         Heap::collectGarbage(BlinkGC::NoHeapPointersOnStack, BlinkGC::TakeSnapshot, BlinkGC::ForcedGC);
     dumpMemoryTotals(memoryDump);
 
     if (m_isHeapProfilingEnabled) {
         // Overhead should always be reported, regardless of light vs. heavy.
         base::trace_event::TraceEventMemoryOverhead overhead;
-        base::hash_map<base::trace_event::AllocationContext, size_t> bytesByContext;
+        base::hash_map<base::trace_event::AllocationContext, base::trace_event::AllocationsSizeAndCount> metricsByContext;
         {
             MutexLocker locker(m_allocationRegisterMutex);
             if (levelOfDetail == WebMemoryDumpLevelOfDetail::Detailed) {
-                for (const auto& allocSize : *m_allocationRegister)
-                    bytesByContext[allocSize.context] += allocSize.size;
+                for (const auto& allocSize : *m_allocationRegister) {
+                    metricsByContext[allocSize.context].size += allocSize.size;
+                    metricsByContext[allocSize.context].count++;

[Dmitry Skiba, 2016/04/14 19:07:30]

Avoid second lookup.

[ssid, 2016/04/14 20:17:11]

Done.

+                }
             }
             m_allocationRegister->EstimateTraceMemoryOverhead(&overhead);
         }
-        memoryDump->dumpHeapUsage(bytesByContext, overhead, "blink_gc");
+        memoryDump->dumpHeapUsage(metricsByContext, overhead, "blink_gc");
     }
 
     // Merge all dumps collected by Heap::collectGarbage.
     if (levelOfDetail == WebMemoryDumpLevelOfDetail::Detailed)
         memoryDump->takeAllDumpsFrom(m_currentProcessMemoryDump.get());
     return true;
 }
 
 void BlinkGCMemoryDumpProvider::onHeapProfilingEnabled(bool enabled)
 {
@@ skipping 38 matching lines @@
 }
 
 void BlinkGCMemoryDumpProvider::remove(Address address)
 {
     MutexLocker locker(m_allocationRegisterMutex);
     if (m_allocationRegister)
         m_allocationRegister->Remove(address);
 }
 
 } // namespace blink