/src/FreeImage/Source/OpenEXR/IlmImf/ImfThreading.h

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  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
  10. // met:
  11. // * Redistributions of source code must retain the above copyright
  12. // notice, this list of conditions and the following disclaimer.
  13. // * Redistributions in binary form must reproduce the above
  14. // copyright notice, this list of conditions and the following disclaimer
  15. // in the documentation and/or other materials provided with the
  16. // distribution.
  17. // * Neither the name of Industrial Light & Magic nor the names of
  18. // its contributors may be used to endorse or promote products derived
  19. // from this software without specific prior written permission.
  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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  27. // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28. // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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  33. ///////////////////////////////////////////////////////////////////////////
  34. #ifndef INCLUDED_IMF_THREADING_H
  35. #define INCLUDED_IMF_THREADING_H
  36. //-----------------------------------------------------------------------------
  37. //
  38. // Threading support for the IlmImf library
  39. //
  40. // The IlmImf library uses threads to perform reading and writing
  41. // of OpenEXR files in parallel. The thread that calls the library
  42. // always performs the actual file IO (this is usually the main
  43. // application thread) whereas a several worker threads perform
  44. // data compression and decompression. The number of worker
  45. // threads can be any non-negative value (a value of zero reverts
  46. // to single-threaded operation). As long as there is at least
  47. // one worker thread, file IO and compression can potentially be
  48. // done concurrently through pinelining. If there are two or more
  49. // worker threads, then pipelining as well as concurrent compression
  50. // of multiple blocks can be performed.
  51. //
  52. // Threading in the Imf library is controllable at two granularities:
  53. //
  54. // * The functions in this file query and control the total number
  55. // of worker threads, which will be created globally for the whole
  56. // library. Regardless of how many input or output files are
  57. // opened simultaneously, the library will use at most this number
  58. // of worker threads to perform all work. The default number of
  59. // global worker threads is zero (i.e. single-threaded operation;
  60. // everything happens in the thread that calls the library).
  61. //
  62. // * Furthermore, it is possible to set the number of threads that
  63. // each input or output file should keep busy. This number can
  64. // be explicitly set for each file. The default behavior is for
  65. // each file to try to occupy all worker threads in the library's
  66. // thread pool.
  67. //
  68. //-----------------------------------------------------------------------------
  69. namespace Imf {
  70. //-----------------------------------------------------------------------------
  71. // Return the number of Imf-global worker threads used for parallel
  72. // compression and decompression of OpenEXR files.
  73. //-----------------------------------------------------------------------------
  74. int globalThreadCount ();
  75. //-----------------------------------------------------------------------------
  76. // Change the number of Imf-global worker threads
  77. //-----------------------------------------------------------------------------
  78. void setGlobalThreadCount (int count);
  79. } // namespace Imf
  80. #endif