[tracing] Adding task information to heap profiler

base/trace_event/heap_profiler_allocation_context_tracker.cc

 // 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 "base/trace_event/heap_profiler_allocation_context_tracker.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/atomicops.h"
 #include "base/threading/thread_local_storage.h"
 #include "base/trace_event/heap_profiler_allocation_context.h"
 
 namespace base {
 namespace trace_event {
 
 subtle::Atomic32 AllocationContextTracker::capture_enabled_ = 0;
 
 namespace {
 
 const size_t kMaxStackDepth = 128u;
+const size_t kMaxTaskDepth = 16u;
 AllocationContextTracker* const kInitializingSentinel =
     reinterpret_cast<AllocationContextTracker*>(-1);
 
 ThreadLocalStorage::StaticSlot g_tls_alloc_ctx_tracker = TLS_INITIALIZER;
 
 // This function is added to the TLS slot to clean up the instance when the
 // thread exits.
 void DestructAllocationContextTracker(void* alloc_ctx_tracker) {
   delete static_cast<AllocationContextTracker*>(alloc_ctx_tracker);
 }
@@ skipping 12 matching lines @@
     g_tls_alloc_ctx_tracker.Set(kInitializingSentinel);
     tracker = new AllocationContextTracker();
     g_tls_alloc_ctx_tracker.Set(tracker);
   }
 
   return tracker;
 }
 
 AllocationContextTracker::AllocationContextTracker() : thread_name_(nullptr) {
   pseudo_stack_.reserve(kMaxStackDepth);
+  task_contexts_.reserve(kMaxTaskDepth);
 }
 AllocationContextTracker::~AllocationContextTracker() {}
 
 // static
 void AllocationContextTracker::SetCurrentThreadName(const char* name) {
   if (name && capture_enabled()) {
     GetInstanceForCurrentThread()->thread_name_ = name;
   }
 }
 
@@ skipping 28 matching lines @@
 
   // Assert that pushes and pops are nested correctly. This DCHECK can be
   // hit if some TRACE_EVENT macro is unbalanced (a TRACE_EVENT_END* call
   // without a corresponding TRACE_EVENT_BEGIN).
   DCHECK_EQ(frame, pseudo_stack_.back())
       << "Encountered an unmatched TRACE_EVENT_END";
 
   pseudo_stack_.pop_back();
 }
 
+void AllocationContextTracker::PushCurrentTaskContext(const char* context) {
+  DCHECK(context);
+  if (task_contexts_.size() < kMaxTaskDepth)
+    task_contexts_.push_back(context);
+  else
+    NOTREACHED();
+}
+
+void AllocationContextTracker::PopCurrentTaskContext(const char* context) {
+  DCHECK_EQ(context, task_contexts_.back())
+      << "Encountered an unmatched context end";
+  task_contexts_.pop_back();
+}
+
 // static
 AllocationContext AllocationContextTracker::GetContextSnapshot() {
   AllocationContext ctx;
 
   // Fill the backtrace.
   {
     auto src = pseudo_stack_.begin();
     auto dst = std::begin(ctx.backtrace.frames);
     auto src_end = pseudo_stack_.end();
     auto dst_end = std::end(ctx.backtrace.frames);
 
     // Add the thread name as the first enrty in the backtrace.
     if (thread_name_) {
       *dst = thread_name_;
       ++dst;
     }
 
     // Copy as much of the bottom of the pseudo stack into the backtrace as
     // possible.
     for (; src != src_end && dst != dst_end; src++, dst++)
       *dst = *src;
 
     // If there is room for more, fill the remaining slots with empty frames.
     std::fill(dst, dst_end, nullptr);
   }
 
-  ctx.type_name = nullptr;
+  // TODO(ssid): Fix crbug.com/594803 to add file name as 3rd dimension
+  // (component name) in the heap profiler and not piggy back on the type name.
+  ctx.type_name = task_contexts_.empty() ? nullptr : task_contexts_.back();
 
   return ctx;
 }
 
 }  // namespace trace_event
 }  // namespace base