fully cache small audio/video

media/blink/multibuffer_data_source.cc

 // Copyright 2013 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/blink/multibuffer_data_source.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 487 matching lines @@
     media_log_->SetBooleanProperty("single_origin", single_origin_);
     media_log_->SetBooleanProperty("passed_cors_access_check",
                                    DidPassCORSAccessCheck());
     media_log_->SetBooleanProperty("range_header_supported",
                                    url_data_->range_supported());
   }
 
   render_task_runner_->PostTask(
       FROM_HERE, base::Bind(base::ResetAndReturn(&init_cb_), success));
 
+  UpdateBufferSizes();
+
   // Even if data is cached, say that we're loading at this point for
   // compatibility.
   UpdateLoadingState_Locked(true);
 }
 
 void MultibufferDataSource::ProgressCallback(int64_t begin, int64_t end) {
   DVLOG(1) << __func__ << "(" << begin << ", " << end << ")";
   DCHECK(render_task_runner_->BelongsToCurrentThread());
 
   if (assume_fully_buffered())
@@ skipping 85 matching lines @@
   int64_t pin_forward = std::max(preload_high, kDefaultPinSize);
 
   // Note that the buffer size is advisory as only non-pinned data is allowed
   // to be thrown away. Most of the time we pin a region that is larger than
   // |buffer_size|, which only makes sense because most of the time, some of
   // the data in pinned region is not present in the cache.
   int64_t buffer_size =
       std::min((kTargetSecondsBufferedAhead + kTargetSecondsBufferedBehind) *
                    bytes_per_second,
                preload_high + pin_backward);
+
+  if (url_data_->FullyCached() ||
+      (url_data_->length() != kPositionNotSpecified &&
+       url_data_->length() < kDefaultPinSize)) {
+    pin_forward = url_data_->length() * 2;

[DaleCurtis, 2017/05/26 16:43:57]

Why x2?

[hubbe, 2017/05/26 17:39:45]

I just wanted to avoid any problems at the edges.
Stuff like: Oh, I managed to seek slightly beyond the end of the file, so now
it's ok to throw away the first block...

[DaleCurtis, 2017/05/26 18:19:33]

Okay, please add a comment to that effect since it's not obvious why you'd
choose these values.

[hubbe, 2017/05/26 18:45:12]

Done.

+    pin_backward = url_data_->length() * 2;
+    buffer_size = url_data_->length();
+  }
+
   reader_->SetMaxBuffer(buffer_size);
   reader_->SetPinRange(pin_backward, pin_forward);
 
   if (preload_ == METADATA) {
     reader_->SetPreload(0, 0);
   } else {
     reader_->SetPreload(preload_high, preload);
   }
 }
 
 }  // namespace media