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209 lines
5.8 KiB
C++
209 lines
5.8 KiB
C++
//
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// ThreadPool.h
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//
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// Library: Foundation
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// Package: Threading
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// Module: ThreadPool
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//
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// Definition of the ThreadPool class.
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//
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// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_ThreadPool_INCLUDED
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#define Foundation_ThreadPool_INCLUDED
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#include "Poco/Foundation.h"
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#include "Poco/Thread.h"
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#include "Poco/Mutex.h"
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#include <vector>
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namespace Poco {
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class Runnable;
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class PooledThread;
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class Foundation_API ThreadPool
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/// A thread pool always keeps a number of threads running, ready
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/// to accept work.
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/// Creating and starting a threads can impose a significant runtime
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/// overhead to an application. A thread pool helps to improve
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/// the performance of an application by reducing the number
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/// of threads that have to be created (and destroyed again).
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/// Threads in a thread pool are re-used once they become
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/// available again.
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/// The thread pool always keeps a minimum number of threads
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/// running. If the demand for threads increases, additional
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/// threads are created. Once the demand for threads sinks
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/// again, no-longer used threads are stopped and removed
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/// from the pool.
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{
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public:
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ThreadPool(int minCapacity = 2,
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int maxCapacity = 16,
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int idleTime = 60,
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int stackSize = POCO_THREAD_STACK_SIZE);
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/// Creates a thread pool with minCapacity threads.
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/// If required, up to maxCapacity threads are created
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/// a NoThreadAvailableException exception is thrown.
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/// If a thread is running idle for more than idleTime seconds,
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/// and more than minCapacity threads are running, the thread
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/// is killed. Threads are created with given stack size.
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ThreadPool(const std::string& name,
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int minCapacity = 2,
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int maxCapacity = 16,
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int idleTime = 60,
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int stackSize = POCO_THREAD_STACK_SIZE);
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/// Creates a thread pool with the given name and minCapacity threads.
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/// If required, up to maxCapacity threads are created
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/// a NoThreadAvailableException exception is thrown.
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/// If a thread is running idle for more than idleTime seconds,
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/// and more than minCapacity threads are running, the thread
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/// is killed. Threads are created with given stack size.
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~ThreadPool();
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/// Currently running threads will remain active
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/// until they complete.
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void addCapacity(int n);
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/// Increases (or decreases, if n is negative)
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/// the maximum number of threads.
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int capacity() const;
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/// Returns the maximum capacity of threads.
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void setStackSize(int stackSize);
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/// Sets the stack size for threads.
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/// New stack size applies only for newly created threads.
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int getStackSize() const;
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/// Returns the stack size used to create new threads.
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int used() const;
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/// Returns the number of currently used threads.
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int allocated() const;
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/// Returns the number of currently allocated threads.
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int available() const;
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/// Returns the number available threads.
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void start(Runnable& target);
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/// Obtains a thread and starts the target.
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/// Throws a NoThreadAvailableException if no more
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/// threads are available.
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void start(Runnable& target, const std::string& name);
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/// Obtains a thread and starts the target.
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/// Assigns the given name to the thread.
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/// Throws a NoThreadAvailableException if no more
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/// threads are available.
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void startWithPriority(Thread::Priority priority, Runnable& target);
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/// Obtains a thread, adjusts the thread's priority, and starts the target.
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/// Throws a NoThreadAvailableException if no more
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/// threads are available.
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void startWithPriority(Thread::Priority priority, Runnable& target, const std::string& name);
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/// Obtains a thread, adjusts the thread's priority, and starts the target.
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/// Assigns the given name to the thread.
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/// Throws a NoThreadAvailableException if no more
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/// threads are available.
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void stopAll();
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/// Stops all running threads and waits for their completion.
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///
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/// Will also delete all thread objects.
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/// If used, this method should be the last action before
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/// the thread pool is deleted.
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///
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/// Note: If a thread fails to stop within 10 seconds
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/// (due to a programming error, for example), the
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/// underlying thread object will not be deleted and
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/// this method will return anyway. This allows for a
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/// more or less graceful shutdown in case of a misbehaving
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/// thread.
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void joinAll();
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/// Waits for all threads to complete.
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///
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/// Note that this will not actually join() the underlying
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/// thread, but rather wait for the thread's runnables
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/// to finish.
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void collect();
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/// Stops and removes no longer used threads from the
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/// thread pool. Can be called at various times in an
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/// application's life time to help the thread pool
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/// manage its threads. Calling this method is optional,
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/// as the thread pool is also implicitly managed in
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/// calls to start(), addCapacity() and joinAll().
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const std::string& name() const;
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/// Returns the name of the thread pool,
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/// or an empty string if no name has been
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/// specified in the constructor.
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static ThreadPool& defaultPool();
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/// Returns a reference to the default
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/// thread pool.
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protected:
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PooledThread* getThread();
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PooledThread* createThread();
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void housekeep();
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private:
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ThreadPool(const ThreadPool& pool);
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ThreadPool& operator = (const ThreadPool& pool);
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typedef std::vector<PooledThread*> ThreadVec;
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std::string _name;
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int _minCapacity;
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int _maxCapacity;
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int _idleTime;
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int _serial;
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int _age;
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int _stackSize;
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ThreadVec _threads;
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mutable FastMutex _mutex;
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};
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//
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// inlines
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//
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inline void ThreadPool::setStackSize(int stackSize)
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{
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_stackSize = stackSize;
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}
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inline int ThreadPool::getStackSize() const
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{
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return _stackSize;
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}
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inline const std::string& ThreadPool::name() const
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{
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return _name;
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}
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} // namespace Poco
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#endif // Foundation_ThreadPool_INCLUDED
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