pagespeed/kernel/base/chunking_writer.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#ifndef PAGESPEED_KERNEL_BASE_CHUNKING_WRITER_H_
#define PAGESPEED_KERNEL_BASE_CHUNKING_WRITER_H_

#include "pagespeed/kernel/base/basictypes.h"
#include "pagespeed/kernel/base/string_util.h"
#include "pagespeed/kernel/base/writer.h"

namespace net_instaweb {

class MessageHandler;

// Wraps around an another writer forcing periodic flushes, and making sure
// writes are not too long.
class ChunkingWriter : public Writer {
 public:
  // This writer will force a flush every flush_limit bytes.
  // If the flush_limit is <= 0 no extra flushing will be performed.
  // This does NOT take ownership of passed-in writer.
  ChunkingWriter(Writer* writer, int flush_limit);
  ~ChunkingWriter() override;

  bool Write(const StringPiece& str, MessageHandler* handler) override;
  bool Flush(MessageHandler* handler) override;

 private:
  // Flushes output if we have enough queued; returns false on Flush failure
  bool FlushIfNeeded(MessageHandler* handler);

  Writer* const writer_;
  const int flush_limit_;
  int unflushed_bytes_;

  DISALLOW_COPY_AND_ASSIGN(ChunkingWriter);
};

}  // namespace net_instaweb

#endif  // PAGESPEED_KERNEL_BASE_CHUNKING_WRITER_H_