thodg/libgit2/src/git/thread-utils.h

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• Hash : a1d34bc0
  Author :
  Date : 2008-12-30T21:49:38
  

  Support building on Mac OS X by using pthread_getspecific for TLS
  
  The Mach-O format does not permit gcc to implement the __thread
  TLS specification, so we must instead emulate it using a single
  int cell allocated from memory and stored inside of the thread
  specific data associated with the current pthread.
  
  What makes this tricky is git_errno must be a valid lvalue, so
  we really need to return a pointer to the caller and deference it
  as part of the git_errno macro.
  
  The GCC-specific __attribute__((constructor)) extension is used
  to ensure the pthread_key_t is allocated before any Git functions
  are executed in the library, as this is necessary to access our
  thread specific storage.
  
  Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
  

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• src/git/thread-utils.h

• #ifndef INCLUDE_git_thread_utils_h__
  #define INCLUDE_git_thread_utils_h__
  
  /*
   * How TLS works is compiler+platform dependant
   * Sources: http://en.wikipedia.org/wiki/Thread-Specific_Storage
   *          http://predef.sourceforge.net/precomp.html
   */
  
  #define GIT_HAS_TLS 1
  
  #if defined(__APPLE__) && defined(__MACH__)
  # undef GIT_TLS
  # define GIT_HAS_PTHREAD
  
  #elif defined(__GNUC__) || \
        defined(__SUNPRO_C) || \
        defined(__SUNPRO_CC) || \
        defined(__xlc__) || \
        defined(__xlC__)
  # define GIT_TLS __thread
  
  #elif defined(__INTEL_COMPILER)
  # if defined(_WIN32) || defined(_WIN32_CE)
  #  define GIT_TLS __declspec(thread)
  # else
  #  define GIT_TLS __thread
  # endif
  
  #elif defined(_WIN32) || \
        defined(_WIN32_CE) || \
        defined(__BORLANDC__)
  # define GIT_TLS __declspec(thread)
  
  #else
  # undef GIT_HAS_TLS
  # define GIT_TLS /* nothing: tls vars are thread-global */
  #endif
  
  /* sparse and cygwin don't grok thread-local variables */
  #if defined(__CHECKER__) || defined(__CYGWIN__)
  # undef GIT_HAS_TLS
  # undef GIT_TLS
  # define GIT_TLS
  #endif
  
  #endif /* INCLUDE_git_thread_utils_h__ */
  

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