pagespeed/controller/schedule_rewrite_controller.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_CONTROLLER_SCHEDULE_REWRITE_CONTROLLER_H_
#define PAGESPEED_CONTROLLER_SCHEDULE_REWRITE_CONTROLLER_H_

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

namespace net_instaweb {

// Abstract interface class that supports PSOL operations for controlling
// which rewrites should be run when. Ensures that only one rewrite will
// run concurrently for each supplied key. For use in CentralController.

class ScheduleRewriteController {
 public:
  virtual ~ScheduleRewriteController() { }

  // Run callback at an indeterminate time in the future when the rewrite
  // for the supplied key should be performed. Will call Cancel immediately
  // if the supplied key is currently in progress. May also call Cancel at
  // some point in the future, for instance if it decides the key isn't worth
  // rewriting.
  virtual void ScheduleRewrite(const GoogleString& key, Function* callback) = 0;

  // Inform controller that the rewrite has been completed. Should only be
  // called if Run() was invoked on callback above. Controller implemenations
  // may wish to behave differently depending on success or failure of the
  // result, for instance by retrying failures ASAP. Failure should not be
  // used in the case of permanent failure, such as a badly formed input.
  virtual void NotifyRewriteComplete(const GoogleString& key) = 0;
  virtual void NotifyRewriteFailed(const GoogleString& key) = 0;

  // Implementations of this method should try to cancel any pending operations
  // ASAP, and configure the object to immediately reject new incoming ones.
  //
  // Default implementation does nothing.
  virtual void ShutDown() { }

 protected:
  ScheduleRewriteController() { }

 private:
  DISALLOW_COPY_AND_ASSIGN(ScheduleRewriteController);
};

}  // namespace net_instaweb

#endif  // PAGESPEED_CONTROLLER_SCHEDULE_REWRITE_CONTROLLER_H_