1///////////////////////////////////////////////////////////////////////////
2//
3// Copyright (c) 2005, Industrial Light & Magic, a division of Lucas
4// Digital Ltd. LLC
5//
6// All rights reserved.
7//
8// Redistribution and use in source and binary forms, with or without
9// modification, are permitted provided that the following conditions are
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12// notice, this list of conditions and the following disclaimer.
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14// copyright notice, this list of conditions and the following disclaimer
15// in the documentation and/or other materials provided with the
16// distribution.
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18// its contributors may be used to endorse or promote products derived
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20//
21// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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33///////////////////////////////////////////////////////////////////////////
34
35#ifndef INCLUDED_IMF_THREADING_H
36#define INCLUDED_IMF_THREADING_H
37
38#include "ImfExport.h"
39#include "ImfNamespace.h"
40
41//-----------------------------------------------------------------------------
42//
43// Threading support for the IlmImf library
44//
45// The IlmImf library uses threads to perform reading and writing
46// of OpenEXR files in parallel. The thread that calls the library
47// always performs the actual file IO (this is usually the main
48// application thread) whereas a several worker threads perform
49// data compression and decompression. The number of worker
50// threads can be any non-negative value (a value of zero reverts
51// to single-threaded operation). As long as there is at least
52// one worker thread, file IO and compression can potentially be
53// done concurrently through pinelining. If there are two or more
54// worker threads, then pipelining as well as concurrent compression
55// of multiple blocks can be performed.
56//
57// Threading in the Imf library is controllable at two granularities:
58//
59// * The functions in this file query and control the total number
60// of worker threads, which will be created globally for the whole
61// library. Regardless of how many input or output files are
62// opened simultaneously, the library will use at most this number
63// of worker threads to perform all work. The default number of
64// global worker threads is zero (i.e. single-threaded operation;
65// everything happens in the thread that calls the library).
66//
67// * Furthermore, it is possible to set the number of threads that
68// each input or output file should keep busy. This number can
69// be explicitly set for each file. The default behavior is for
70// each file to try to occupy all worker threads in the library's
71// thread pool.
72//
73//-----------------------------------------------------------------------------
74
75OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER
76
77
78//-----------------------------------------------------------------------------
79// Return the number of Imf-global worker threads used for parallel
80// compression and decompression of OpenEXR files.
81//-----------------------------------------------------------------------------
82
83IMF_EXPORT int globalThreadCount ();
84
85
86//-----------------------------------------------------------------------------
87// Change the number of Imf-global worker threads
88//-----------------------------------------------------------------------------
89
90IMF_EXPORT void setGlobalThreadCount (int count);
91
92
93OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT
94
95#endif
96