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///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2005-2012, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
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///////////////////////////////////////////////////////////////////////////
#ifndef INCLUDED_ILM_THREAD_POOL_H
#define INCLUDED_ILM_THREAD_POOL_H
//-----------------------------------------------------------------------------
//
// class Task, class ThreadPool, class TaskGroup
//
// Class ThreadPool manages a set of worker threads and accepts
// tasks for processing. Tasks added to the thread pool are
// executed concurrently by the worker threads.
//
// Class Task provides an abstract interface for a task which
// a ThreadPool works on. Derived classes need to implement the
// execute() function which performs the actual task.
//
// Class TaskGroup allows synchronization on the completion of a set
// of tasks. Every task that is added to a ThreadPool belongs to a
// single TaskGroup. The destructor of the TaskGroup waits for all
// tasks in the group to finish.
//
// Note: if you plan to use the ThreadPool interface in your own
// applications note that the implementation of the ThreadPool calls
// operator delete on tasks as they complete. If you define a custom
// operator new for your tasks, for instance to use a custom heap,
// then you must also write an appropriate operator delete.
//
//-----------------------------------------------------------------------------
#include "IlmThreadNamespace.h"
#include "IlmThreadExport.h"
ILMTHREAD_INTERNAL_NAMESPACE_HEADER_ENTER
class TaskGroup;
class Task;
class ILMTHREAD_EXPORT ThreadPool
{
public:
//-------------------------------------------------------
// Constructor -- creates numThreads worker threads which
// wait until a task is available.
//-------------------------------------------------------
ThreadPool (unsigned numThreads = 0);
//-----------------------------------------------------------
// Destructor -- waits for all tasks to complete, joins all
// the threads to the calling thread, and then destroys them.
//-----------------------------------------------------------
virtual ~ThreadPool ();
//--------------------------------------------------------
// Query and set the number of worker threads in the pool.
//
// Warning: never call setNumThreads from within a worker
// thread as this will almost certainly cause a deadlock
// or crash.
//--------------------------------------------------------
int numThreads () const;
void setNumThreads (int count);
//------------------------------------------------------------
// Add a task for processing. The ThreadPool can handle any
// number of tasks regardless of the number of worker threads.
// The tasks are first added onto a queue, and are executed
// by threads as they become available, in FIFO order.
//------------------------------------------------------------
void addTask (Task* task);
//-------------------------------------------
// Access functions for the global threadpool
//-------------------------------------------
static ThreadPool& globalThreadPool ();
static void addGlobalTask (Task* task);
struct Data;
protected:
Data * _data;
};
class ILMTHREAD_EXPORT Task
{
public:
Task (TaskGroup* g);
virtual ~Task ();
virtual void execute () = 0;
TaskGroup * group();
protected:
TaskGroup * _group;
};
class ILMTHREAD_EXPORT TaskGroup
{
public:
TaskGroup();
~TaskGroup();
struct Data;
Data* const _data;
};
ILMTHREAD_INTERNAL_NAMESPACE_HEADER_EXIT
#endif // INCLUDED_ILM_THREAD_POOL_H
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