Implement evictFrames() to support MSE's coded frame eviction algorithm.

media/filters/source_buffer_stream.cc

 // Copyright (c) 2012 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.
 
 #include "media/filters/source_buffer_stream.h"
 
 #include <algorithm>
 #include <map>
 #include <sstream>
 
@@ skipping 330 matching lines @@
   // are appended to the range covered by |track_buffer_|.
   if (!track_buffer_.empty()) {
     DecodeTimestamp keyframe_timestamp =
         FindKeyframeAfterTimestamp(track_buffer_.front()->GetDecodeTimestamp());
     if (keyframe_timestamp != kNoDecodeTimestamp())
       PruneTrackBuffer(keyframe_timestamp);
   }
 
   SetSelectedRangeIfNeeded(next_buffer_timestamp);
 
-  GarbageCollectIfNeeded();
-
   DVLOG(1) << __FUNCTION__ << " " << GetStreamTypeName()
            << ": done. ranges_=" << RangesToString(ranges_);
   DCHECK(IsRangeListSorted(ranges_));
   DCHECK(OnlySelectedRangeIsSeeked());
   return true;
 }
 
 void SourceBufferStream::Remove(base::TimeDelta start, base::TimeDelta end,
                                 base::TimeDelta duration) {
   DVLOG(1) << __FUNCTION__ << " " << GetStreamTypeName()
@@ skipping 213 matching lines @@
   }
 }
 
 void SourceBufferStream::SetConfigIds(const BufferQueue& buffers) {
   for (BufferQueue::const_iterator itr = buffers.begin();
        itr != buffers.end(); ++itr) {
     (*itr)->SetConfigId(append_config_index_);
   }
 }
 
-void SourceBufferStream::GarbageCollectIfNeeded() {
+bool SourceBufferStream::GarbageCollectIfNeeded(DecodeTimestamp media_time) {
   // Compute size of |ranges_|.
   int ranges_size = 0;
   for (RangeList::iterator itr = ranges_.begin(); itr != ranges_.end(); ++itr)
     ranges_size += (*itr)->size_in_bytes();
 
   // Return if we're under or at the memory limit.
   if (ranges_size <= memory_limit_)
-    return;
+    return true;
 
   int bytes_to_free = ranges_size - memory_limit_;
 
   DVLOG(2) << __FUNCTION__ << " " << GetStreamTypeName() << ": Before GC"
            << " ranges_size=" << ranges_size
            << " ranges_=" << RangesToString(ranges_)
            << " memory_limit_=" << memory_limit_;
 
   // Begin deleting after the last appended buffer.
   int bytes_freed = FreeBuffersAfterLastAppended(bytes_to_free);
 
   // Begin deleting from the front.
   if (bytes_to_free - bytes_freed > 0)
-    bytes_freed += FreeBuffers(bytes_to_free - bytes_freed, false);
+    bytes_freed += FreeBuffers(bytes_to_free - bytes_freed, media_time, false);
 
-  // Begin deleting from the back.
   if (bytes_to_free - bytes_freed > 0)
-    bytes_freed += FreeBuffers(bytes_to_free - bytes_freed, true);
+    bytes_freed += FreeBuffers(bytes_to_free - bytes_freed, media_time, true);
 
   DVLOG(2) << __FUNCTION__ << " " << GetStreamTypeName() << ": After GC"
            << " bytes_freed=" << bytes_freed
            << " ranges_=" << RangesToString(ranges_);
+
+  return bytes_freed >= bytes_to_free;
 }
 
 int SourceBufferStream::FreeBuffersAfterLastAppended(int total_bytes_to_free) {
   DecodeTimestamp next_buffer_timestamp = GetNextBufferTimestamp();
   if (last_appended_buffer_timestamp_ == kNoDecodeTimestamp() ||
       next_buffer_timestamp == kNoDecodeTimestamp() ||
       last_appended_buffer_timestamp_ >= next_buffer_timestamp) {
     return 0;
   }
 
@@ skipping 42 matching lines @@
 
     int bytes_removed = range->GetRemovalGOP(
         start_timestamp, end_timestamp, bytes_to_free, removal_end_timestamp);
     bytes_to_free -= bytes_removed;
     bytes_freed += bytes_removed;
   }
   return bytes_freed;
 }
 
 int SourceBufferStream::FreeBuffers(int total_bytes_to_free,
+                                    DecodeTimestamp media_time,
                                     bool reverse_direction) {
   TRACE_EVENT2("media", "SourceBufferStream::FreeBuffers",
                "total bytes to free", total_bytes_to_free,
                "reverse direction", reverse_direction);
 
   DCHECK_GT(total_bytes_to_free, 0);
   int bytes_to_free = total_bytes_to_free;
   int bytes_freed = 0;
 
   // This range will save the last GOP appended to |range_for_next_append_|
@@ skipping 11 matching lines @@
         DCHECK_EQ(current_range, selected_range_);
         break;
       }
       bytes_deleted = current_range->DeleteGOPFromBack(&buffers);
     } else {
       current_range = ranges_.front();
       if (current_range->FirstGOPContainsNextBufferPosition()) {
         DCHECK_EQ(current_range, selected_range_);
         break;
       }
+      if (media_time != kNoDecodeTimestamp() &&
+          !current_range->FirstGOPEarlierThanMediaTime(media_time)) {
+        break;
+      }
       bytes_deleted = current_range->DeleteGOPFromFront(&buffers);
     }
 
     // Check to see if we've just deleted the GOP that was last appended.
     DecodeTimestamp end_timestamp = buffers.back()->GetDecodeTimestamp();
     if (end_timestamp == last_appended_buffer_timestamp_) {
       DCHECK(last_appended_buffer_timestamp_ != kNoDecodeTimestamp());
       DCHECK(!new_range_for_append);
+
       // Create a new range containing these buffers.
       new_range_for_append = new SourceBufferRange(
           TypeToGapPolicy(GetType()),
           buffers, kNoDecodeTimestamp(),
           base::Bind(&SourceBufferStream::GetMaxInterbufferDistance,
                      base::Unretained(this)));
       range_for_next_append_ = ranges_.end();
     } else {
       bytes_to_free -= bytes_deleted;
       bytes_freed += bytes_deleted;
     }
 
     if (current_range->size_in_bytes() == 0) {
       DCHECK_NE(current_range, selected_range_);
       DCHECK(range_for_next_append_ == ranges_.end() ||
              *range_for_next_append_ != current_range);
       delete current_range;
       reverse_direction ? ranges_.pop_back() : ranges_.pop_front();
     }
+
+    if (reverse_direction && new_range_for_append) {
+      // We don't want to delete any further, or we'll be creating gaps
+      break;
+    }
   }
 
   // Insert |new_range_for_append| into |ranges_|, if applicable.
   if (new_range_for_append) {
     range_for_next_append_ = AddToRanges(new_range_for_append);
     DCHECK(range_for_next_append_ != ranges_.end());
 
     // Check to see if we need to merge |new_range_for_append| with the range
     // before or after it. |new_range_for_append| is created whenever the last
     // GOP appended is encountered, regardless of whether any buffers after it
@@ skipping 815 matching lines @@
     return false;
 
   DCHECK_NE(have_splice_buffers, have_preroll_buffer);
   splice_buffers_index_ = 0;
   pending_buffer_.swap(*out_buffer);
   pending_buffers_complete_ = false;
   return true;
 }
 
 }  // namespace media