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arangodb/arangod/Scheduler/Task.h

235 lines
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C++

////////////////////////////////////////////////////////////////////////////////
/// @brief abstract base class for tasks
///
/// @file
/// Tasks are handled by the scheduler. The scheduler calls the task callback
/// as soon as a specific event occurs.
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
/// @author Achim Brandt
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2008-2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGODB_SCHEDULER_TASK_H
#define ARANGODB_SCHEDULER_TASK_H 1
#include "Basics/Common.h"
#include "Scheduler/events.h"
struct TRI_json_t;
namespace triagens {
namespace rest {
class Scheduler;
////////////////////////////////////////////////////////////////////////////////
/// @brief abstract base class for tasks
////////////////////////////////////////////////////////////////////////////////
class Task {
// -----------------------------------------------------------------------------
// --SECTION-- constructors / destructors
// -----------------------------------------------------------------------------
friend class TaskManager;
Task (Task const&) = delete;
Task& operator= (Task const&) = delete;
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief constructs a new task
///
/// Note that the constructor has no access to the event loop. The connection
/// is provided in the method setup and any setup with regards to the event
/// loop must be done there. It is not possible to simply delete a tasks. You
/// must use the method destroy to cleanup the task, remove it from the event
/// loop and delete it. The method cleanup itself will not delete task but
/// remove it from the event loop. It is possible to use setup again to reuse
/// the task.
////////////////////////////////////////////////////////////////////////////////
Task (std::string const& id,
std::string const& name);
////////////////////////////////////////////////////////////////////////////////
/// @brief constructs a new task
////////////////////////////////////////////////////////////////////////////////
explicit Task (std::string const& name);
protected:
////////////////////////////////////////////////////////////////////////////////
/// @brief deletes a task
///
/// The method will only be called from after the task has been cleaned by
/// the method cleanup.
////////////////////////////////////////////////////////////////////////////////
virtual ~Task ();
// -----------------------------------------------------------------------------
// --SECTION-- public methods
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief returns the task name for debugging
////////////////////////////////////////////////////////////////////////////////
std::string const& name () const {
return _name;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief returns the task id
////////////////////////////////////////////////////////////////////////////////
std::string id () const {
return _id;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief returns the internal task identifier
////////////////////////////////////////////////////////////////////////////////
uint64_t taskId () const {
return _taskId;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief get a JSON representation of the task
////////////////////////////////////////////////////////////////////////////////
struct TRI_json_t* toJson () const;
////////////////////////////////////////////////////////////////////////////////
/// @brief whether or not the task is a user task
////////////////////////////////////////////////////////////////////////////////
virtual bool isUserDefined () const;
////////////////////////////////////////////////////////////////////////////////
/// @brief allow thread to run on slave event loop
////////////////////////////////////////////////////////////////////////////////
virtual bool needsMainEventLoop () const;
////////////////////////////////////////////////////////////////////////////////
/// @brief called by scheduler to indicate an event
///
/// The method will only be called from within the scheduler thread, which
/// belongs to the loop parameter.
////////////////////////////////////////////////////////////////////////////////
virtual bool handleEvent (EventToken token, EventType event) = 0;
// -----------------------------------------------------------------------------
// --SECTION-- protected methods
// -----------------------------------------------------------------------------
protected:
////////////////////////////////////////////////////////////////////////////////
/// @brief get a task specific description in JSON format
////////////////////////////////////////////////////////////////////////////////
virtual void getDescription (struct TRI_json_t*) const;
////////////////////////////////////////////////////////////////////////////////
/// @brief called to set up the callback information
///
/// The method will only be called from within the scheduler thread, which
/// belongs to the loop parameter.
////////////////////////////////////////////////////////////////////////////////
virtual bool setup (Scheduler*, EventLoop) = 0;
////////////////////////////////////////////////////////////////////////////////
/// @brief called to clear the callback information
///
/// The method will only be called from within the scheduler thread, which
/// belongs to the loop parameter.
////////////////////////////////////////////////////////////////////////////////
virtual void cleanup () = 0;
// -----------------------------------------------------------------------------
// --SECTION-- protected variables
// -----------------------------------------------------------------------------
protected:
////////////////////////////////////////////////////////////////////////////////
/// @brief scheduler
////////////////////////////////////////////////////////////////////////////////
Scheduler* _scheduler;
////////////////////////////////////////////////////////////////////////////////
/// @brief event loop identifier
////////////////////////////////////////////////////////////////////////////////
EventLoop _loop;
////////////////////////////////////////////////////////////////////////////////
/// @brief task id
////////////////////////////////////////////////////////////////////////////////
uint64_t const _taskId;
// -----------------------------------------------------------------------------
// --SECTION-- private variables
// -----------------------------------------------------------------------------
private:
////////////////////////////////////////////////////////////////////////////////
/// @brief task id
////////////////////////////////////////////////////////////////////////////////
std::string const _id;
////////////////////////////////////////////////////////////////////////////////
/// @brief task name
////////////////////////////////////////////////////////////////////////////////
std::string const _name;
};
}
}
#endif
// -----------------------------------------------------------------------------
// --SECTION-- END-OF-FILE
// -----------------------------------------------------------------------------
// Local Variables:
// mode: outline-minor
// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @page\\|// --SECTION--\\|/// @\\}"
// End: