Leak detector posts notifications to task runner

components/metrics/leak_detector/leak_detector.h

 // Copyright 2016 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 COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_H_
 #define COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <list>
 #include <memory>
 #include <vector>
 
 #include "base/feature_list.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "base/synchronization/lock.h"
+#include "base/task_runner.h"
 #include "base/threading/thread_checker.h"
 #include "components/metrics/proto/memory_leak_report.pb.h"
 
 namespace base {
 template <typename T>
 struct DefaultLazyInstanceTraits;
 }
 
 namespace metrics {
 
@@ skipping 25 matching lines @@
     virtual ~Observer() {}
 
     // Called by leak detector to report leaks.
     virtual void OnLeaksFound(
         const std::vector<MemoryLeakReportProto>& reports) = 0;
   };
 
   // Returns the sole instance, or creates it if it hasn't already been created.
   static LeakDetector* GetInstance();
 
-  // Initializes leak detector with a set of params given by |params|. See the
-  // definition of MemoryLeakReportProto::Params for info about individual
-  // parameters.
-  void Init(const MemoryLeakReportProto::Params& params);
+  // Initializes leak detector. Args:
+  // - |params| is a set of parameters used by the leak detector. See definition
+  //   of MemoryLeakReportProto::Params for info about individual parameters.
+  // - |task_runner| is a TaskRunner to which NotifyObservers() should be
+  //   posted, if it is initally called from a different thread than the one on
+  //   which |task_runner| runs.
+  void Init(const MemoryLeakReportProto::Params& params,
+            scoped_refptr<base::TaskRunner> task_runner);
 
   // Add |observer| to the list of stored Observers, i.e. |observers_|, to which
   // the leak detector will report leaks.
   void AddObserver(Observer* observer);
 
   // Remove |observer| from |observers_|.
   void RemoveObserver(Observer* observer);
 
  private:
   friend base::DefaultLazyInstanceTraits<LeakDetector>;
@@ skipping 12 matching lines @@
   // Allocator hook function that processes each free. Performs sampling and
   // passes the allocation address |ptr| to |impl_|.
   static void FreeHook(const void* ptr);
 
   // Give an pointer |ptr|, computes a hash of the pointer value and compares it
   // against |sampling_factor_| to determine if it should be sampled. This
   // allows the same pointer to be sampled during both alloc and free.
   bool ShouldSample(const void* ptr) const;
 
   // Notifies all Observers in |observers_| with the given vector of leak
-  // report protobufs.
+  // report protobufs. If it is not currently on the thread that corresponds to
+  // |task_runner_|, it will post the call as task to |task_runner_|.
   void NotifyObservers(const std::vector<MemoryLeakReportProto>& reports);
 
   // List of observers to notify when there's a leak report.
   // TODO(sque): Consider using ObserverListThreadSafe instead.
   base::ObserverList<Observer> observers_;
 
   // For atomic access to |observers_|.
   base::Lock observers_lock_;
 
   // Handles leak detection logic. Must be called under lock as LeakDetectorImpl
   // uses shared resources.
   std::unique_ptr<leak_detector::LeakDetectorImpl> impl_;
 
   // For thread safety.
   base::ThreadChecker thread_checker_;
 
+  // For posting leak report notifications.
+  scoped_refptr<base::TaskRunner> task_runner_;
+
   // Total number of bytes allocated, computed before sampling.
   size_t total_alloc_size_;
 
   // The value of |total_alloc_size_| the last time there was a leak analysis,
   // rounded down to the nearest multiple of |analysis_interval_bytes_|.
   size_t last_analysis_alloc_size_;
 
   // For atomic access to |impl_|, |total_alloc_size_| and
   // |last_analysis_alloc_size_|.
   base::Lock recording_lock_;
 
   // Perform a leak analysis each time this many bytes have been allocated since
   // the previous analysis.
   size_t analysis_interval_bytes_;
 
   // When unwinding call stacks, unwind no more than this number of frames.
   size_t max_call_stack_unwind_depth_;
 
   // Sampling factor used by ShouldSample(). It's full range of values
   // corresponds to the allowable range of |sampling_rate| passed in during
   // initialization: [0.0f, 1.0f] -> [0, UINT64_MAX].
   uint64_t sampling_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(LeakDetector);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_H_