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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