pagespeed/kernel/thread/sequence.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.
 */

//
// Abstraction for a sequence of tasks.

#ifndef PAGESPEED_KERNEL_THREAD_SEQUENCE_H_
#define PAGESPEED_KERNEL_THREAD_SEQUENCE_H_

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

namespace net_instaweb {

class Function;

// Interface for a holding and adding to a sequence of tasks.
// The mechanism for executing the tasks must be defined by
// implementations of this interface.
class Sequence {
 public:
  Sequence();
  virtual ~Sequence();

  // Adds 'function' to a sequence.  Note that this can occur at any time
  // the sequence is live -- you can add functions to a sequence that has
  // already started processing.  The caller is expected to ensure Function
  // will be cleaned up after Run or Cancel.
  //
  // 'function' can be called any time after Add(), and may in fact be
  // called before Add() returns.  It's OK for the function to call Add
  // again.
  //
  // If the sequence is destructed after Add, but before the function has
  // been run, function->Cancel() will be called when the Sequence is destroyed.
  virtual void Add(Function* function) = 0;

 private:
  DISALLOW_COPY_AND_ASSIGN(Sequence);
};

}  // namespace net_instaweb

#endif  // PAGESPEED_KERNEL_THREAD_SEQUENCE_H_