pagespeed/controller/central_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_CENTRAL_CONTROLLER_H_
#define PAGESPEED_CONTROLLER_CENTRAL_CONTROLLER_H_

#include "pagespeed/controller/expensive_operation_callback.h"
#include "pagespeed/controller/schedule_rewrite_callback.h"
#include "pagespeed/kernel/base/basictypes.h"

namespace net_instaweb {

// Abstract interface class that supports various PSOL operations which should
// be performed in a centralized fashion, instead of once per worker process.

class CentralController {
 public:
  virtual ~CentralController();

  // Runs callback at an indeterminate time in the future when it is safe
  // to perform a CPU intensive operation. Or may Cancel the callback at some
  // point if it is determined that the work cannot be performed.
  virtual void ScheduleExpensiveOperation(
      ExpensiveOperationCallback* callback) = 0;

  // Runs callback at an indeterminate time in the future when the associated
  // rewrite should be performed. May Cancel the callback immediately or at
  // some point in the future if the rewrite should not be performed by the
  // caller. Only one rewrite per callback.key() will be scheduled at once.
  virtual void ScheduleRewrite(ScheduleRewriteCallback* callback) = 0;

  // Implementations of this method should try to cancel any pending operations
  // ASAP, and immediately reject new incoming ones. This method should behave
  // safely when called more than once.
  virtual void ShutDown() = 0;

 protected:
  CentralController();

 private:
  DISALLOW_COPY_AND_ASSIGN(CentralController);
};

}  // namespace net_instaweb

#endif  // PAGESPEED_CONTROLLER_CENTRAL_CONTROLLER_H_