Replace Check for too many pending frames in I420_buffer_pool with returning nullptr. Added histogr…

webrtc/common_video/include/i420_buffer_pool.h

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_COMMON_VIDEO_INCLUDE_I420_BUFFER_POOL_H_
 #define WEBRTC_COMMON_VIDEO_INCLUDE_I420_BUFFER_POOL_H_
 
 #include <list>
+#include <limits>
 
 #include "webrtc/base/race_checker.h"
 #include "webrtc/common_video/include/video_frame_buffer.h"
 
 namespace webrtc {
 
 // Simple buffer pool to avoid unnecessary allocations of I420Buffer objects.
 // The pool manages the memory of the I420Buffer returned from CreateBuffer.
 // When the I420Buffer is destructed, the memory is returned to the pool for use
 // by subsequent calls to CreateBuffer. If the resolution passed to CreateBuffer
 // changes, old buffers will be purged from the pool.
 // Note that CreateBuffer will crash if more than kMaxNumberOfFramesBeforeCrash
 // are created. This is to prevent memory leaks where frames are not returned.
 class I420BufferPool {
  public:
-  I420BufferPool() : I420BufferPool(false) {}
-  explicit I420BufferPool(bool zero_initialize);
+  I420BufferPool()
+      : I420BufferPool(false, std::numeric_limits<size_t>::max()) {}

[magjed_webrtc, 2016/11/04 08:21:36]

nit: this is enough: I420BufferPool(false) {}

+  explicit I420BufferPool(bool zero_initialize)
+      : I420BufferPool(zero_initialize, std::numeric_limits<size_t>::max()) {}
+  I420BufferPool(bool zero_initialze, size_t max_number_of_buffers);
 
-  // Returns a buffer from the pool, or creates a new buffer if no suitable
-  // buffer exists in the pool.
+  // Returns a buffer from the pool. If no suitable buffer exist in the pool
+  // and there are less than |max_number_of_buffers| pending, a buffer is
+  // created. Returns null otherwise.
   rtc::scoped_refptr<I420Buffer> CreateBuffer(int width, int height);
   // Clears buffers_ and detaches the thread checker so that it can be reused
   // later from another thread.
   void Release();
 
  private:
-  static const size_t kMaxNumberOfFramesBeforeCrash;
   // Explicitly use a RefCountedObject to get access to HasOneRef,
   // needed by the pool to check exclusive access.
   using PooledI420Buffer = rtc::RefCountedObject<I420Buffer>;
 
   rtc::RaceChecker race_checker_;
   std::list<rtc::scoped_refptr<PooledI420Buffer>> buffers_;
   // If true, newly allocated buffers are zero-initialized. Note that recycled
   // buffers are not zero'd before reuse. This is required of buffers used by
   // FFmpeg according to http://crbug.com/390941, which only requires it for the
   // initial allocation (as shown by FFmpeg's own buffer allocation code). It
   // has to do with "Use-of-uninitialized-value" on "Linux_msan_chrome".
   bool zero_initialize_;
+  // Max number of buffers this pool can have pending.
+  size_t max_number_of_buffers_;

[magjed_webrtc, 2016/11/04 08:21:36]

It would be nice to have this (and zero_initialize_) const.

 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_VIDEO_INCLUDE_I420_BUFFER_POOL_H_