import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/media/fmp4/MP4Stream.cpp

@@ -0,0 +1,103 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MP4Stream.h"
+#include "MediaResource.h"
+
+namespace mozilla {
+
+MP4Stream::MP4Stream(MediaResource* aResource)
+  : mResource(aResource)
+  , mPinCount(0)
+{
+  MOZ_COUNT_CTOR(MP4Stream);
+  MOZ_ASSERT(aResource);
+}
+
+MP4Stream::~MP4Stream()
+{
+  MOZ_COUNT_DTOR(MP4Stream);
+  MOZ_ASSERT(mPinCount == 0);
+}
+
+bool
+MP4Stream::BlockingReadIntoCache(int64_t aOffset, size_t aCount, Monitor* aToUnlock)
+{
+  MOZ_ASSERT(mPinCount > 0);
+  CacheBlock block(aOffset, aCount);
+  if (!block.Init()) {
+    return false;
+  }
+
+  uint32_t bytesRead = 0;
+  {
+    MonitorAutoUnlock unlock(*aToUnlock);
+    nsresult rv = mResource.ReadAt(aOffset, block.Buffer(), aCount, &bytesRead);
+    if (NS_FAILED(rv)) {
+      return false;
+    }
+  }
+
+  MOZ_ASSERT(block.mCount >= bytesRead);
+  block.mCount = bytesRead;
+
+  mCache.AppendElement(Move(block));
+  return true;
+}
+
+// We surreptitiously reimplement the supposedly-blocking ReadAt as a non-
+// blocking CachedReadAt, and record when it fails. This allows MP4Reader
+// to retry the read as an actual blocking read without holding the lock.
+bool
+MP4Stream::ReadAt(int64_t aOffset, void* aBuffer, size_t aCount,
+                  size_t* aBytesRead)
+{
+  if (mFailedRead.isSome()) {
+    mFailedRead.reset();
+  }
+
+  if (!CachedReadAt(aOffset, aBuffer, aCount, aBytesRead)) {
+    mFailedRead.emplace(aOffset, aCount);
+    return false;
+  }
+
+  return true;
+}
+
+bool
+MP4Stream::CachedReadAt(int64_t aOffset, void* aBuffer, size_t aCount,
+                        size_t* aBytesRead)
+{
+  // First, check our local cache.
+  for (size_t i = 0; i < mCache.Length(); ++i) {
+    if (mCache[i].mOffset == aOffset && mCache[i].mCount >= aCount) {
+      memcpy(aBuffer, mCache[i].Buffer(), aCount);
+      *aBytesRead = aCount;
+      return true;
+    }
+  }
+
+  nsresult rv =
+    mResource.GetResource()->ReadFromCache(reinterpret_cast<char*>(aBuffer),
+                                           aOffset, aCount);
+  if (NS_FAILED(rv)) {
+    *aBytesRead = 0;
+    return false;
+  }
+  *aBytesRead = aCount;
+  return true;
+}
+
+bool
+MP4Stream::Length(int64_t* aSize)
+{
+  if (mResource.GetLength() < 0)
+    return false;
+  *aSize = mResource.GetLength();
+  return true;
+}
+
+} // namespace mozilla