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arangodb/lib/Dispatcher/DispatcherQueue.h

362 lines
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C++

////////////////////////////////////////////////////////////////////////////////
/// @brief dispatcher queue
///
/// @file
///
/// 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 Martin Schoenert
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2009-2014, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGODB_DISPATCHER_DISPATCHER_QUEUE_H
#define ARANGODB_DISPATCHER_DISPATCHER_QUEUE_H 1
#include "Basics/Common.h"
#include "Basics/ConditionVariable.h"
#include "Dispatcher/Dispatcher.h"
// -----------------------------------------------------------------------------
// --SECTION-- forward declarations
// -----------------------------------------------------------------------------
namespace triagens {
namespace rest {
class DispatcherThread;
class Job;
// -----------------------------------------------------------------------------
// --SECTION-- class DispatcherQueue
// -----------------------------------------------------------------------------
////////////////////////////////////////////////////////////////////////////////
/// @brief dispatcher queue
////////////////////////////////////////////////////////////////////////////////
class DispatcherQueue {
friend class Dispatcher;
friend class DispatcherThread;
private:
DispatcherQueue (DispatcherQueue const&);
DispatcherQueue& operator= (DispatcherQueue const&);
// -----------------------------------------------------------------------------
// --SECTION-- constructors and destructors
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief constructs a new dispatcher queue
////////////////////////////////////////////////////////////////////////////////
DispatcherQueue (Scheduler*,
Dispatcher*,
std::string const& name,
Dispatcher::newDispatcherThread_fptr,
void* threadData,
size_t nrThreads,
size_t maxSize);
////////////////////////////////////////////////////////////////////////////////
/// @brief destructor
////////////////////////////////////////////////////////////////////////////////
~DispatcherQueue ();
// -----------------------------------------------------------------------------
// --SECTION-- public methods
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief adds a job
////////////////////////////////////////////////////////////////////////////////
bool addJob (Job*);
////////////////////////////////////////////////////////////////////////////////
/// @brief tries to cancel a job
////////////////////////////////////////////////////////////////////////////////
bool cancelJob (uint64_t);
////////////////////////////////////////////////////////////////////////////////
/// @brief downgrades the thread to special
////////////////////////////////////////////////////////////////////////////////
void specializeThread (DispatcherThread*);
////////////////////////////////////////////////////////////////////////////////
/// @brief indicates that thread is doing a blocking operation
////////////////////////////////////////////////////////////////////////////////
void blockThread (DispatcherThread* thread);
////////////////////////////////////////////////////////////////////////////////
/// @brief indicates that thread has resumed work
////////////////////////////////////////////////////////////////////////////////
void unblockThread (DispatcherThread* thread);
////////////////////////////////////////////////////////////////////////////////
/// @brief starts a queue
////////////////////////////////////////////////////////////////////////////////
bool start ();
////////////////////////////////////////////////////////////////////////////////
/// @brief begins the shutdown sequence the queue
////////////////////////////////////////////////////////////////////////////////
void beginShutdown ();
////////////////////////////////////////////////////////////////////////////////
/// @brief shut downs the queue
////////////////////////////////////////////////////////////////////////////////
void shutdown ();
////////////////////////////////////////////////////////////////////////////////
/// @brief checks if the dispatcher queues are up and running
////////////////////////////////////////////////////////////////////////////////
bool isStarted ();
////////////////////////////////////////////////////////////////////////////////
/// @brief is the queue still active
////////////////////////////////////////////////////////////////////////////////
bool isRunning ();
////////////////////////////////////////////////////////////////////////////////
/// @brief starts a new queue thread
////////////////////////////////////////////////////////////////////////////////
bool startQueueThread ();
// -----------------------------------------------------------------------------
// --SECTION-- private variables
// -----------------------------------------------------------------------------
private:
////////////////////////////////////////////////////////////////////////////////
/// @brief name
////////////////////////////////////////////////////////////////////////////////
std::string const _name;
////////////////////////////////////////////////////////////////////////////////
/// @brief thread data
////////////////////////////////////////////////////////////////////////////////
void* _threadData;
////////////////////////////////////////////////////////////////////////////////
/// @brief monopolistic jobs
////////////////////////////////////////////////////////////////////////////////
basics::ConditionVariable _accessQueue;
////////////////////////////////////////////////////////////////////////////////
/// @brief list of ready jobs
////////////////////////////////////////////////////////////////////////////////
std::list<Job*> _readyJobs;
////////////////////////////////////////////////////////////////////////////////
/// @brief current running job
////////////////////////////////////////////////////////////////////////////////
std::set<Job*> _runningJobs;
////////////////////////////////////////////////////////////////////////////////
/// @brief maximum queue size (number of jobs)
////////////////////////////////////////////////////////////////////////////////
size_t _maxSize;
////////////////////////////////////////////////////////////////////////////////
/// @brief queue is shutting down
////////////////////////////////////////////////////////////////////////////////
volatile sig_atomic_t _stopping;
////////////////////////////////////////////////////////////////////////////////
/// @brief monopolistic job
////////////////////////////////////////////////////////////////////////////////
DispatcherThread* _monopolizer;
////////////////////////////////////////////////////////////////////////////////
/// @brief list of started threads
////////////////////////////////////////////////////////////////////////////////
std::set<DispatcherThread*> _startedThreads;
////////////////////////////////////////////////////////////////////////////////
/// @brief list of stopped threads
////////////////////////////////////////////////////////////////////////////////
std::list<DispatcherThread*> _stoppedThreads;
////////////////////////////////////////////////////////////////////////////////
/// @brief number of started jobs
///
/// Whenever a new thread is started, this number is increased by 1. As soon as
/// the thread enters its main event loop, this number is decreased by 1 and
/// the number running threads _nrRunning is increased by 1.
///
/// Therefore _nrStarted and _nrRunning is the number of threads which are or
/// soon be available for the dispatcher queue.
////////////////////////////////////////////////////////////////////////////////
size_t _nrStarted;
////////////////////////////////////////////////////////////////////////////////
/// @brief number of threads that are up
///
/// As soon as a thread enters its main event loop, this number is increased by
/// 1. As soon as the thread leaves its main event loop, this number is
/// decreased by 1.
///
/// This indicates the current number of threads currently within their main
/// event loop. The difference to _nrRunning is, that _nrRunning is decreased by
/// 1, if a thread enters a special job.
////////////////////////////////////////////////////////////////////////////////
size_t _nrUp;
////////////////////////////////////////////////////////////////////////////////
/// @brief number of running jobs
///
/// As soon as a thread enters its main event loop, this number is increased by
/// one. As soon as the thread leaves its main event loop or works on a special
/// job, this number is decreaes by 1.
////////////////////////////////////////////////////////////////////////////////
size_t _nrRunning;
////////////////////////////////////////////////////////////////////////////////
/// @brief number of waiting jobs
///
/// Whenever a threads waits for more work, this number is increased by 1. As
/// soon as the thread leaves the wait because it received a broadcast, this
/// number is decreased by 1.
////////////////////////////////////////////////////////////////////////////////
size_t _nrWaiting;
////////////////////////////////////////////////////////////////////////////////
/// @brief number of stopped jobs
///
/// As soon as a thread leaves its main event loop, this number is increased by
/// 1 and the thread is put onto a cleanup list. Eventually all threads on that
/// list are deleted and the number is reset to zero.
////////////////////////////////////////////////////////////////////////////////
size_t _nrStopped;
////////////////////////////////////////////////////////////////////////////////
/// @brief number of special jobs
///
/// This is the number of special jobs. We start with 0 special jobs. Whenever a
/// job of type SPECIAL_JOB is started or a running job is specialized, this
/// number is increased by 1. The number _nrRunning of running jobs is decreased
/// by 1.
///
/// If a special job is started or a running job is specialized, a new thread is
/// started. This will increase the number _nrStarted.
////////////////////////////////////////////////////////////////////////////////
size_t _nrSpecial;
////////////////////////////////////////////////////////////////////////////////
/// @brief number of blocked threads
///
/// The number of threads, that are blocked for some reason.
////////////////////////////////////////////////////////////////////////////////
size_t _nrBlocked;
////////////////////////////////////////////////////////////////////////////////
/// @brief total number of threads
///
/// This number is fixed. It is the number of pre-configured threads from the
/// configuration file.
///
/// The following hold, after startup and before shutdown:
///
/// _nrRunning + _nrStarted = _nrThreads
/// _nrRunning + _nrSpecial + _nrWaiting = _nrUp
////////////////////////////////////////////////////////////////////////////////
size_t _nrThreads;
////////////////////////////////////////////////////////////////////////////////
/// @brief last time we created or deleted a queue thread
////////////////////////////////////////////////////////////////////////////////
double _lastChanged;
////////////////////////////////////////////////////////////////////////////////
/// @brief grace period before shuting down queue threads
////////////////////////////////////////////////////////////////////////////////
double _gracePeriod;
////////////////////////////////////////////////////////////////////////////////
/// @brief scheduler
////////////////////////////////////////////////////////////////////////////////
Scheduler* _scheduler;
////////////////////////////////////////////////////////////////////////////////
/// @brief dispatcher
////////////////////////////////////////////////////////////////////////////////
Dispatcher* _dispatcher;
////////////////////////////////////////////////////////////////////////////////
/// @brief thread creator function
////////////////////////////////////////////////////////////////////////////////
Dispatcher::newDispatcherThread_fptr createDispatcherThread;
};
}
}
#endif
// -----------------------------------------------------------------------------
// --SECTION-- END-OF-FILE
// -----------------------------------------------------------------------------
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