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arangodb/arangod/Dispatcher/DispatcherQueue.h

367 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 <boost/lockfree/queue.hpp>
#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 {
DispatcherQueue (DispatcherQueue const&) = delete;
DispatcherQueue& operator= (DispatcherQueue const&) = delete;
friend class Dispatcher;
friend class DispatcherThread;
// -----------------------------------------------------------------------------
// --SECTION-- constructors and destructors
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief constructs a new dispatcher queue
////////////////////////////////////////////////////////////////////////////////
DispatcherQueue (Scheduler*,
Dispatcher*,
size_t id,
Dispatcher::newDispatcherThread_fptr,
size_t nrThreads,
size_t maxSize);
////////////////////////////////////////////////////////////////////////////////
/// @brief destructor
////////////////////////////////////////////////////////////////////////////////
~DispatcherQueue ();
// -----------------------------------------------------------------------------
// --SECTION-- public methods
// -----------------------------------------------------------------------------
public:
////////////////////////////////////////////////////////////////////////////////
/// @brief adds a job
////////////////////////////////////////////////////////////////////////////////
int addJob (Job*);
////////////////////////////////////////////////////////////////////////////////
/// @brief removes a job
////////////////////////////////////////////////////////////////////////////////
void removeJob (Job*);
////////////////////////////////////////////////////////////////////////////////
/// @brief tries to cancel a job
////////////////////////////////////////////////////////////////////////////////
bool cancelJob (uint64_t);
////////////////////////////////////////////////////////////////////////////////
/// @brief indicates that thread is doing a blocking operation
////////////////////////////////////////////////////////////////////////////////
void blockThread ();
////////////////////////////////////////////////////////////////////////////////
/// @brief indicates that thread has resumed work
////////////////////////////////////////////////////////////////////////////////
void unblockThread ();
////////////////////////////////////////////////////////////////////////////////
/// @brief begins the shutdown sequence the queue
////////////////////////////////////////////////////////////////////////////////
void beginShutdown ();
////////////////////////////////////////////////////////////////////////////////
/// @brief shut downs the queue
////////////////////////////////////////////////////////////////////////////////
void shutdown ();
////////////////////////////////////////////////////////////////////////////////
/// @brief starts a new queue thread
////////////////////////////////////////////////////////////////////////////////
void startQueueThread ();
////////////////////////////////////////////////////////////////////////////////
/// @brief called when a thread has stopped
////////////////////////////////////////////////////////////////////////////////
void removeStartedThread (DispatcherThread* thread);
////////////////////////////////////////////////////////////////////////////////
/// @brief checks if we have too many threads
////////////////////////////////////////////////////////////////////////////////
bool tooManyThreads ();
////////////////////////////////////////////////////////////////////////////////
/// @brief checks if we have enough threads
////////////////////////////////////////////////////////////////////////////////
bool notEnoughThreads ();
////////////////////////////////////////////////////////////////////////////////
/// @brief sets the process affinity
////////////////////////////////////////////////////////////////////////////////
void setProcessorAffinity (const std::vector<size_t>& cores);
// -----------------------------------------------------------------------------
// --SECTION-- private methods
// -----------------------------------------------------------------------------
private:
////////////////////////////////////////////////////////////////////////////////
/// @brief deletes old threads
////////////////////////////////////////////////////////////////////////////////
void deleteOldThreads ();
// -----------------------------------------------------------------------------
// --SECTION-- private variables
// -----------------------------------------------------------------------------
private:
////////////////////////////////////////////////////////////////////////////////
/// @brief name
////////////////////////////////////////////////////////////////////////////////
const size_t _id;
////////////////////////////////////////////////////////////////////////////////
/// @brief total number of threads
///
/// This number is fixed. It is the number of pre-configured threads from the
/// configuration file and is the initial number of threads started. The
/// dispatcher queues will try to have at least this many running threads.
////////////////////////////////////////////////////////////////////////////////
const size_t _nrThreads;
////////////////////////////////////////////////////////////////////////////////
/// @brief maximum queue size (number of jobs)
////////////////////////////////////////////////////////////////////////////////
const size_t _maxSize;
////////////////////////////////////////////////////////////////////////////////
/// @brief waker for sleeping threads
////////////////////////////////////////////////////////////////////////////////
basics::ConditionVariable _waitLock;
////////////////////////////////////////////////////////////////////////////////
/// @brief list of ready jobs
////////////////////////////////////////////////////////////////////////////////
boost::lockfree::queue<Job*> _readyJobs;
////////////////////////////////////////////////////////////////////////////////
/// @brief guard for hazard pointer
////////////////////////////////////////////////////////////////////////////////
basics::Mutex _hazardLock;
////////////////////////////////////////////////////////////////////////////////
/// @brief hazard pointer for jobs
////////////////////////////////////////////////////////////////////////////////
std::atomic<Job*> _hazardPointer;
////////////////////////////////////////////////////////////////////////////////
/// @brief queue is shutting down
////////////////////////////////////////////////////////////////////////////////
std::atomic<bool> _stopping;
////////////////////////////////////////////////////////////////////////////////
/// @brief guard for _startedThreads
////////////////////////////////////////////////////////////////////////////////
basics::Mutex _threadsLock;
////////////////////////////////////////////////////////////////////////////////
/// @brief list of started threads
////////////////////////////////////////////////////////////////////////////////
std::set<DispatcherThread*> _startedThreads;
////////////////////////////////////////////////////////////////////////////////
/// @brief list of stopped threads
////////////////////////////////////////////////////////////////////////////////
boost::lockfree::queue<DispatcherThread*> _stoppedThreads;
////////////////////////////////////////////////////////////////////////////////
/// @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, this number is
/// decreaes by 1.
///
/// Note that we ignore race conditions, the worst that can happen is that we
/// start one thread too many or shutdown a thread too early. This variable is
/// accessed using "memory_order_seq_cst".
////////////////////////////////////////////////////////////////////////////////
std::atomic<ssize_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 signal, this
/// number is decreased by 1.
///
/// This variable is accessed using "memory_order_seq_cst".
////////////////////////////////////////////////////////////////////////////////
std::atomic<ssize_t> _nrWaiting;
////////////////////////////////////////////////////////////////////////////////
/// @brief number of blocked threads
///
/// The number of threads, that are blocked for some reason.
///
/// Note that we ignore race conditions, the worst that can happen is that we
/// start one thread too many or shutdown a thread too early. This variable is
/// accessed using "memory_order_seq_cst".
////////////////////////////////////////////////////////////////////////////////
std::atomic<ssize_t> _nrBlocked;
////////////////////////////////////////////////////////////////////////////////
/// @brief last time we created or deleted a queue thread
///
/// Note that we ignore race conditions, the worst that can happen is that we
/// start one thread too many or shutdown a thread too early. This variable is
/// accessed using "memory_order_seq_cst".
////////////////////////////////////////////////////////////////////////////////
std::atomic<double> _lastChanged;
////////////////////////////////////////////////////////////////////////////////
/// @brief grace period before shuting down queue threads
////////////////////////////////////////////////////////////////////////////////
const double _gracePeriod;
////////////////////////////////////////////////////////////////////////////////
/// @brief scheduler
////////////////////////////////////////////////////////////////////////////////
Scheduler* const _scheduler;
////////////////////////////////////////////////////////////////////////////////
/// @brief dispatcher
////////////////////////////////////////////////////////////////////////////////
Dispatcher* const _dispatcher;
////////////////////////////////////////////////////////////////////////////////
/// @brief thread creator function
////////////////////////////////////////////////////////////////////////////////
Dispatcher::newDispatcherThread_fptr createDispatcherThread;
////////////////////////////////////////////////////////////////////////////////
/// @brief cores to use for affinity
////////////////////////////////////////////////////////////////////////////////
std::vector<size_t> _affinityCores;
////////////////////////////////////////////////////////////////////////////////
/// @brief next affinity core to use
////////////////////////////////////////////////////////////////////////////////
size_t _affinityPos;
////////////////////////////////////////////////////////////////////////////////
/// @brief list of jobs
///
/// There are at most _maxSize jobs.
////////////////////////////////////////////////////////////////////////////////
std::atomic<Job*>* _jobs;
////////////////////////////////////////////////////////////////////////////////
/// @brief list of free job positions
///
/// There are at most _maxSize jobs. But _maxSize is only known at runtime.
////////////////////////////////////////////////////////////////////////////////
boost::lockfree::queue<size_t> _jobPositions;
};
}
}
#endif
// -----------------------------------------------------------------------------
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// -----------------------------------------------------------------------------
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