Bug 803414 - Part 3: Add EncodedBufferCache. r=roc

content/media/EncodedBufferCache.cpp

@@ -0,0 +1,73 @@
+/* -*- 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 "EncodedBufferCache.h"
+#include "nsAnonymousTemporaryFile.h"
+#include "nsLocalFile.h"
+
+namespace mozilla {
+
+void
+EncodedBufferCache::AppendBuffer(nsTArray<uint8_t> & aBuf)
+{
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+  mDataSize += aBuf.Length();
+
+  mEncodedBuffers.AppendElement()->SwapElements(aBuf);
+
+  if (!mTempFileEnabled && mDataSize > mMaxMemoryStorage) {
+    nsresult rv = NS_OpenAnonymousTemporaryFile(&mFD);
+    if (!NS_FAILED(rv)) {
+      mTempFileEnabled = true;
+    }
+  }
+
+  if (mTempFileEnabled) {
+    // has created temporary file, write buffer in it
+    for (uint32_t i = 0; i < mEncodedBuffers.Length(); i++) {
+      int64_t amount = PR_Write(mFD, mEncodedBuffers.ElementAt(i).Elements(), mEncodedBuffers.ElementAt(i).Length());
+      if (amount <  mEncodedBuffers.ElementAt(i).Length()) {
+        NS_WARNING("Failed to write media cache block!");
+      }
+    }
+    mEncodedBuffers.Clear();
+  }
+
+}
+
+already_AddRefed<nsIDOMBlob>
+EncodedBufferCache::ExtractBlob(const nsAString &aContentType)
+{
+  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
+  nsCOMPtr<nsIDOMBlob> blob;
+  if (mTempFileEnabled) {
+    // generate new temporary file to write
+    blob = new nsDOMTemporaryFileBlob(mFD, 0, mDataSize, aContentType);
+    // fallback to memory blob
+    mTempFileEnabled = false;
+    mDataSize = 0;
+    mFD = nullptr;
+  } else {
+    void* blobData = moz_malloc(mDataSize);
+    NS_ASSERTION(blobData, "out of memory!!");
+
+    if (blobData) {
+      for (uint32_t i = 0, offset = 0; i < mEncodedBuffers.Length(); i++) {
+        memcpy((uint8_t*)blobData + offset, mEncodedBuffers.ElementAt(i).Elements(),
+               mEncodedBuffers.ElementAt(i).Length());
+        offset += mEncodedBuffers.ElementAt(i).Length();
+      }
+      blob = new nsDOMMemoryFile(blobData, mDataSize,
+                                 aContentType);
+      mEncodedBuffers.Clear();
+    } else
+      return nullptr;
+  }
+  mDataSize = 0;
+  return blob.forget();
+}
+
+} //end namespace

content/media/EncodedBufferCache.h

@@ -0,0 +1,60 @@
+/* -*- 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 "nsTArray.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "prio.h"
+#include "nsDOMFile.h"
+
+namespace mozilla {
+
+class ReentrantMonitor;
+/**
+ * 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:
+  EncodedBufferCache(uint32_t aMaxMemoryStorage)
+  : mFD(nullptr),
+    mReentrantMonitor("EncodedBufferCache.Data.Monitor"),
+    mDataSize(0),
+    mMaxMemoryStorage(aMaxMemoryStorage),
+    mTempFileEnabled(false) { }
+  ~EncodedBufferCache()
+  {
+    NS_ASSERTION(mDataSize == 0, "still has data in EncodedBuffers!");
+  }
+  // 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<nsIDOMBlob> ExtractBlob(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.
+  ReentrantMonitor mReentrantMonitor;
+  // 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