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