import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/media/EncodedBufferCache.h

@@ -0,0 +1,63 @@
+/* -*- 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/. */
+
+#ifndef EncodedBufferCache_h_
+#define EncodedBufferCache_h_
+
+#include "nsCOMPtr.h"
+#include "nsTArray.h"
+#include "mozilla/Mutex.h"
+
+struct PRFileDesc;
+
+namespace mozilla {
+
+namespace dom {
+class Blob;
+} // namespace dom
+
+/**
+ * Data is moved into a temporary file when it grows beyond
+ * the maximal size passed in the Init function.
+ * The AppendBuffer and ExtractBlob methods are thread-safe and can be called on
+ * different threads at the same time.
+ */
+class EncodedBufferCache
+{
+public:
+  explicit EncodedBufferCache(uint32_t aMaxMemoryStorage)
+  : mFD(nullptr),
+    mMutex("EncodedBufferCache.Data.Mutex"),
+    mDataSize(0),
+    mMaxMemoryStorage(aMaxMemoryStorage),
+    mTempFileEnabled(false) { }
+  ~EncodedBufferCache()
+  {
+  }
+  // Append buffers in cache, check if the queue is too large then switch to write buffer to file system
+  // aBuf will append to mEncodedBuffers or temporary File, aBuf also be cleared
+  void AppendBuffer(nsTArray<uint8_t> & aBuf);
+  // Read all buffer from memory or file System, also Remove the temporary file or clean the buffers in memory.
+  already_AddRefed<dom::Blob> ExtractBlob(nsISupports* aParent, const nsAString &aContentType);
+
+private:
+  //array for storing the encoded data.
+  nsTArray<nsTArray<uint8_t> > mEncodedBuffers;
+  // File handle for the temporary file
+  PRFileDesc* mFD;
+  // Used to protect the mEncodedBuffer for avoiding AppendBuffer/Consume on different thread at the same time.
+  Mutex mMutex;
+  // the current buffer size can be read
+  uint64_t mDataSize;
+  // The maximal buffer allowed in memory
+  uint32_t mMaxMemoryStorage;
+  // indicate the buffer is stored on temporary file or not
+  bool mTempFileEnabled;
+};
+
+} // namespace mozilla
+
+#endif