1 ///////////////////////////////////////////////////////////////////////////
3 // Copyright (c) 2005, Industrial Light & Magic, a division of Lucas
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33 ///////////////////////////////////////////////////////////////////////////
35 #ifndef INCLUDED_ILM_THREAD_POOL_H
36 #define INCLUDED_ILM_THREAD_POOL_H
38 //-----------------------------------------------------------------------------
40 // class Task, class ThreadPool, class TaskGroup
42 // Class ThreadPool manages a set of worker threads and accepts
43 // tasks for processing. Tasks added to the thread pool are
44 // executed concurrently by the worker threads.
46 // Class Thread provides an abstract interface for a task which
47 // a ThreadPool works on. Derived classes need to implement the
48 // execute() function which performs the actual task.
50 // Class TaskTroup allows synchronization on the completion of a set
51 // of tasks. Every task that is added to a ThreadPool belongs to a
52 // single TaskGroup. The destructor of the TaskGroup waits for all
53 // tasks in the group to finish.
55 // Note: if you plan to use the ThreadPool interface in your own
56 // applications note that the implementation of the ThreadPool calls
57 // opertor delete on tasks as they complete. If you define a custom
58 // operator new for your tasks, for instance to use a custom heap,
59 // then you must also write an appropriate operator delete.
61 //-----------------------------------------------------------------------------
73 //-------------------------------------------------------
74 // Constructor -- creates numThreads worker threads which
75 // wait until a task is available.
76 //-------------------------------------------------------
78 ThreadPool (unsigned numThreads = 0);
81 //-----------------------------------------------------------
82 // Destructor -- waits for all tasks to complete, joins all
83 // the threads to the calling thread, and then destroys them.
84 //-----------------------------------------------------------
86 virtual ~ThreadPool ();
89 //--------------------------------------------------------
90 // Query and set the number of worker threads in the pool.
92 // Warning: never call setNumThreads from within a worker
93 // thread as this will almost certainly cause a deadlock
95 //--------------------------------------------------------
97 int numThreads () const;
98 void setNumThreads (int count);
101 //------------------------------------------------------------
102 // Add a task for processing. The ThreadPool can handle any
103 // number of tasks regardless of the number of worker threads.
104 // The tasks are first added onto a queue, and are executed
105 // by threads as they become available, in FIFO order.
106 //------------------------------------------------------------
108 void addTask (Task* task);
111 //-------------------------------------------
112 // Access functions for the global threadpool
113 //-------------------------------------------
115 static ThreadPool& globalThreadPool ();
116 static void addGlobalTask (Task* task);
133 virtual void execute () = 0;
154 } // namespace IlmThread