Replace Check for too many pending frames in I420_buffer_pool with returning nullptr. Added histograms for when this happens in VP8Impl.

BUG=chromium:542522
R=tommi@webrtc.org

Review URL: https://codereview.webrtc.org/2474783005 .

Cr-Commit-Position: refs/heads/master@{#14930}

webrtc/common_video/i420_buffer_pool.cc

@@ -14,10 +14,10 @@
 
 namespace webrtc {
 
-const size_t I420BufferPool::kMaxNumberOfFramesBeforeCrash = 300;
-
-I420BufferPool::I420BufferPool(bool zero_initialize)
-    : zero_initialize_(zero_initialize) {}
+I420BufferPool::I420BufferPool(bool zero_initialize,
+                               size_t max_number_of_buffers)
+    : zero_initialize_(zero_initialize),
+      max_number_of_buffers_(max_number_of_buffers) {}
 
 void I420BufferPool::Release() {
   buffers_.clear();
@@ -26,8 +26,6 @@ void I420BufferPool::Release() {
 rtc::scoped_refptr<I420Buffer> I420BufferPool::CreateBuffer(int width,
                                                             int height) {
   RTC_DCHECK_RUNS_SERIALIZED(&race_checker_);
-  RTC_CHECK_LT(buffers_.size(), kMaxNumberOfFramesBeforeCrash)
-      << "I420BufferPool too big.";
   // Release buffers with wrong resolution.
   for (auto it = buffers_.begin(); it != buffers_.end();) {
     if ((*it)->width() != width || (*it)->height() != height)
@@ -44,6 +42,9 @@ rtc::scoped_refptr<I420Buffer> I420BufferPool::CreateBuffer(int width,
     if (buffer->HasOneRef())
       return buffer;
   }
+
+  if (buffers_.size() >= max_number_of_buffers_)
+    return nullptr;
   // Allocate new buffer.
   rtc::scoped_refptr<PooledI420Buffer> buffer =
       new PooledI420Buffer(width, height);

webrtc/common_video/i420_buffer_pool_unittest.cc

@@ -63,4 +63,11 @@ TEST(TestI420BufferPool, FrameValidAfterPoolDestruction) {
   memset(buffer->MutableDataY(), 0xA5, 16 * buffer->StrideY());
 }
 
+TEST(TestI420BufferPool, MaxNumberOfBuffers) {
+  I420BufferPool pool(false, 1);
+  rtc::scoped_refptr<VideoFrameBuffer> buffer1 = pool.CreateBuffer(16, 16);
+  EXPECT_NE(nullptr, buffer1.get());
+  EXPECT_EQ(nullptr, pool.CreateBuffer(16, 16).get());
+}
+
 }  // namespace webrtc

webrtc/common_video/include/i420_buffer_pool.h

@@ -12,6 +12,7 @@
 #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"
@@ -27,18 +28,21 @@ namespace webrtc {
 // 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()) {}
+  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>;
@@ -51,6 +55,8 @@ class I420BufferPool {
   // 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_;
 };
 
 }  // namespace webrtc

webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc

@@ -31,6 +31,7 @@
 #include "webrtc/modules/video_coding/codecs/vp8/temporal_layers.h"
 #include "webrtc/modules/video_coding/utility/simulcast_rate_allocator.h"
 #include "webrtc/system_wrappers/include/clock.h"
+#include "webrtc/system_wrappers/include/metrics.h"
 
 namespace webrtc {
 namespace {
@@ -1055,7 +1056,8 @@ int VP8EncoderImpl::RegisterEncodeCompleteCallback(
 }
 
 VP8DecoderImpl::VP8DecoderImpl()
-    : decode_complete_callback_(NULL),
+    : buffer_pool_(false, 300 /* max_number_of_buffers*/),
+      decode_complete_callback_(NULL),
       inited_(false),
       feedback_mode_(false),
       decoder_(NULL),
@@ -1270,6 +1272,12 @@ int VP8DecoderImpl::ReturnFrame(const vpx_image_t* img,
   // Allocate memory for decoded image.
   rtc::scoped_refptr<I420Buffer> buffer =
       buffer_pool_.CreateBuffer(img->d_w, img->d_h);
+  if (!buffer.get()) {
+    // Pool has too many pending frames.
+    RTC_HISTOGRAM_BOOLEAN("WebRTC.Video.VP8DecoderImpl.TooManyPendingFrames",
+                          1);
+    return WEBRTC_VIDEO_CODEC_NO_OUTPUT;
+  }
 
   libyuv::I420Copy(img->planes[VPX_PLANE_Y], img->stride[VPX_PLANE_Y],
                    img->planes[VPX_PLANE_U], img->stride[VPX_PLANE_U],