thodg/libgit2/src/threadstate.c

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• Hash : 246bc3cc
  Author :
  Date : 2020-10-14T15:05:11
  

  threadstate: rename tlsdata when building w/o threads

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• src/threadstate.c

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #include "threadstate.h"
  #include "runtime.h"
  
  static void threadstate_dispose(git_threadstate *threadstate);
  
  /**
   * Handle the thread-local state
   *
   * `git_threadstate_global_init` will be called as part
   * of `git_libgit2_init` (which itself must be called
   * before calling any other function in the library).
   *
   * This function allocates a TLS index (using pthreads
   * or fiber-local storage in Win32) to store the per-
   * thread state.
   *
   * Any internal method that requires thread-local state
   * will then call `git_threadstate_get()` which returns a
   * pointer to the thread-local state structure; this
   * structure is lazily allocated on each thread.
   *
   * This mechanism will register a shutdown handler
   * (`git_threadstate_global_shutdown`) which will free the
   * TLS index.  This shutdown handler will be called by
   * `git_libgit2_shutdown`.
   *
   * If libgit2 is built without threading support, the
   * `git_threadstate_get()` call returns a pointer to a single,
   * statically allocated global state. The `git_thread_`
   * functions are not available in that case.
   */
  
  #if defined(GIT_THREADS) && defined(GIT_WIN32)
  
  static DWORD fls_index;
  
  static void git_threadstate_global_shutdown(void)
  {
  	FlsFree(fls_index);
  }
  
  static void WINAPI fls_free(void *threadstate)
  {
  	threadstate_dispose(threadstate);
  	git__free(threadstate);
  }
  
  int git_threadstate_global_init(void)
  {
  	if ((fls_index = FlsAlloc(fls_free)) == FLS_OUT_OF_INDEXES)
  		return -1;
  
  	return git_runtime_shutdown_register(git_threadstate_global_shutdown);
  }
  
  git_threadstate *git_threadstate_get(void)
  {
  	git_threadstate *threadstate;
  
  	if ((threadstate = FlsGetValue(fls_index)) != NULL)
  		return threadstate;
  
  	if ((threadstate = git__calloc(1, sizeof(git_threadstate))) == NULL ||
  	    git_buf_init(&threadstate->error_buf, 0) < 0)
  		return NULL;
  
  	FlsSetValue(fls_index, threadstate);
  	return threadstate;
  }
  
  #elif defined(GIT_THREADS) && defined(_POSIX_THREADS)
  
  static pthread_key_t tls_key;
  
  static void git_threadstate_global_shutdown(void)
  {
  	git_threadstate *threadstate;
  
  	threadstate = pthread_getspecific(tls_key);
  	pthread_setspecific(tls_key, NULL);
  
  	threadstate_dispose(threadstate);
  	git__free(threadstate);
  
  	pthread_key_delete(tls_key);
  }
  
  static void tls_free(void *threadstate)
  {
  	threadstate_dispose(threadstate);
  	git__free(threadstate);
  }
  
  int git_threadstate_global_init(void)
  {
  	if (pthread_key_create(&tls_key, &tls_free) != 0)
  		return -1;
  
  	return git_runtime_shutdown_register(git_threadstate_global_shutdown);
  }
  
  git_threadstate *git_threadstate_get(void)
  {
  	git_threadstate *threadstate;
  
  	if ((threadstate = pthread_getspecific(tls_key)) != NULL)
  		return threadstate;
  
  	if ((threadstate = git__calloc(1, sizeof(git_threadstate))) == NULL ||
  	    git_buf_init(&threadstate->error_buf, 0) < 0)
  		return NULL;
  
  	pthread_setspecific(tls_key, threadstate);
  	return threadstate;
  }
  
  #elif defined(GIT_THREADS)
  # error unknown threading model
  #else
  
  static git_threadstate threadstate;
  
  static void git_threadstate_global_shutdown(void)
  {
  	threadstate_dispose(&threadstate);
  	memset(&threadstate, 0, sizeof(git_threadstate));
  }
  
  int git_threadstate_global_init(void)
  {
  	return git_runtime_shutdown_register(git_threadstate_global_shutdown);
  }
  
  git_threadstate *git_threadstate_get(void)
  {
  	return &threadstate;
  }
  
  #endif
  
  static void threadstate_dispose(git_threadstate *threadstate)
  {
  	if (!threadstate)
  		return;
  
  	git__free(threadstate->error_t.message);
  	threadstate->error_t.message = NULL;
  }
  

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