| // 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 <atomic> |
| #include <vector> |
| |
| #include "base/base_export.h" |
| #include "base/trace_event/heap_profiler_allocation_context.h" |
| |
| namespace base { |
| namespace trace_event { |
| |
| // AllocationContextTracker is a thread-local object. Its main purpose is to |
| // keep track of context pointers for memory allocation samples. See |
| // |AllocationContext|. |
| // |
| // A thread-local instance of the context tracker is initialized lazily when it |
| // is first accessed. This might be because a context is pushed or popped, or |
| // because `GetContextSnapshot()` was called when an allocation occurred |
| class BASE_EXPORT AllocationContextTracker { |
| public: |
| enum class CaptureMode : int32_t { |
| DISABLED, // Don't capture anything |
| NATIVE_STACK, // Backtrace has full native backtraces from stack unwinding |
| }; |
| |
| // Globally sets capturing mode. |
| // TODO(primiano): How to guard against *_STACK -> DISABLED -> *_STACK? |
| static void SetCaptureMode(CaptureMode mode); |
| |
| // Returns global capturing mode. |
| inline static CaptureMode capture_mode() { |
| // 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 (capture_mode_.load(std::memory_order_relaxed) == CaptureMode::DISABLED) |
| return CaptureMode::DISABLED; |
| |
| // In the slow path, an acquire load is required to pair with the release |
| // store in |SetCaptureMode|. This is to ensure that the TLS slot for |
| // the thread-local allocation context tracker has been initialized if |
| // |capture_mode| returns something other than DISABLED. |
| return capture_mode_.load(std::memory_order_acquire); |
| } |
| |
| // Returns the thread-local instance, creating one if necessary. Returns |
| // always a valid instance, unless it is called re-entrantly, in which case |
| // returns nullptr in the nested calls. |
| static AllocationContextTracker* GetInstanceForCurrentThread(); |
| |
| // Set the thread name in the AllocationContextTracker of the current thread |
| // if capture is enabled. |
| static void SetCurrentThreadName(const char* name); |
| |
| AllocationContextTracker(const AllocationContextTracker&) = delete; |
| AllocationContextTracker& operator=(const AllocationContextTracker&) = delete; |
| |
| // Starts and ends a new ignore scope between which the allocations are |
| // ignored by the heap profiler. GetContextSnapshot() returns false when |
| // allocations are ignored. |
| void begin_ignore_scope() { ignore_scope_depth_++; } |
| void end_ignore_scope() { |
| if (ignore_scope_depth_) |
| ignore_scope_depth_--; |
| } |
| |
| // Pushes and pops a native stack frame onto thread local tracked stack. |
| void PushNativeStackFrame(const void* pc); |
| void PopNativeStackFrame(const void* pc); |
| |
| // Push and pop current task's context. A stack is used to support nested |
| // tasks and the top of the stack will be used in allocation context. |
| void PushCurrentTaskContext(const char* context); |
| void PopCurrentTaskContext(const char* context); |
| |
| // Returns most recent task context added by ScopedTaskExecutionTracker. |
| const char* TaskContext() const { |
| return task_contexts_.empty() ? nullptr : task_contexts_.back(); |
| } |
| |
| // Fills a snapshot of the current thread-local context. Doesn't fill and |
| // returns false if allocations are being ignored. |
| bool GetContextSnapshot(AllocationContext* snapshot); |
| |
| ~AllocationContextTracker(); |
| |
| private: |
| AllocationContextTracker(); |
| |
| static std::atomic<CaptureMode> capture_mode_; |
| |
| // The pseudo stack where frames are inserted PCs. |
| std::vector<StackFrame> tracked_stack_; |
| |
| // The thread name is used as the first entry in the pseudo stack. |
| const char* thread_name_ = nullptr; |
| |
| // Stack of tasks' contexts. |
| std::vector<const char*> task_contexts_; |
| |
| uint32_t ignore_scope_depth_ = 0; |
| }; |
| |
| } // namespace trace_event |
| } // namespace base |
| |
| #endif // BASE_TRACE_EVENT_HEAP_PROFILER_ALLOCATION_CONTEXT_TRACKER_H_ |