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// 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.
#ifndef BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_TRACKER_H_
#define BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_TRACKER_H_
#include <vector>
#include "base/atomicops.h"
#include "base/base_export.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/trace_event/heap_profiler_allocation_context.h"
namespace base {
namespace trace_event {
// The allocation context tracker keeps track of thread-local context for heap
// profiling. It includes a pseudo stack of trace events. On every allocation
// the tracker provides a snapshot of its context in the form of an
// |AllocationContext| that is to be stored together with the allocation
// details.
class BASE_EXPORT AllocationContextTracker {
public:
// Globally enables capturing allocation context.
// TODO(ruuda): Should this be replaced by |EnableCapturing| in the future?
// Or at least have something that guards agains enable -> disable -> enable?
static void SetCaptureEnabled(bool enabled);
// Returns whether capturing allocation context is enabled globally.
inline static bool capture_enabled() {
// A little lag after heap profiling is enabled or disabled is fine, it is
// more important that the check is as cheap as possible when capturing is
// not enabled, so do not issue a memory barrier in the fast path.
if (subtle::NoBarrier_Load(&capture_enabled_) == 0)
return false;
// In the slow path, an acquire load is required to pair with the release
// store in |SetCaptureEnabled|. This is to ensure that the TLS slot for
// the thread-local allocation context tracker has been initialized if
// |capture_enabled| returns true.
return subtle::Acquire_Load(&capture_enabled_) != 0;
}
// Pushes a frame onto the thread-local pseudo stack.
static void PushPseudoStackFrame(StackFrame frame);
// Pops a frame from the thread-local pseudo stack.
static void PopPseudoStackFrame(StackFrame frame);
// Returns a snapshot of the current thread-local context.
static AllocationContext GetContextSnapshot();
~AllocationContextTracker();
private:
AllocationContextTracker();
static AllocationContextTracker* GetThreadLocalTracker();
static subtle::Atomic32 capture_enabled_;
// The pseudo stack where frames are |TRACE_EVENT| names.
std::vector<StackFrame> pseudo_stack_;
DISALLOW_COPY_AND_ASSIGN(AllocationContextTracker);
};
} // namespace trace_event
} // namespace base
#endif // BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_TRACKER_H_
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