src/threadstate.c

   1 /*
   2  * Copyright (C) the libgit2 contributors. All rights reserved.
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7
   8 #include "threadstate.h"
   9 #include "runtime.h"
  10
  11 /**
  12  * Handle the thread-local state
  13  *
  14  * `git_threadstate_global_init` will be called as part
  15  * of `git_libgit2_init` (which itself must be called
  16  * before calling any other function in the library).
  17  *
  18  * This function allocates a TLS index to store the per-
  19  * thread state.
  20  *
  21  * Any internal method that requires thread-local state
  22  * will then call `git_threadstate_get()` which returns a
  23  * pointer to the thread-local state structure; this
  24  * structure is lazily allocated on each thread.
  25  *
  26  * This mechanism will register a shutdown handler
  27  * (`git_threadstate_global_shutdown`) which will free the
  28  * TLS index.  This shutdown handler will be called by
  29  * `git_libgit2_shutdown`.
  30  */
  31
  32 static git_tlsdata_key tls_key;
  33
  34 static void threadstate_dispose(git_threadstate *threadstate)
  35 {
  36         if (!threadstate)
  37                 return;
  38
  39     if (threadstate->error_t.message != git_buf__initbuf)
  40         git__free(threadstate->error_t.message);
  41         threadstate->error_t.message = NULL;
  42 }
  43
  44 static void GIT_SYSTEM_CALL threadstate_free(void *threadstate)
  45 {
  46         threadstate_dispose(threadstate);
  47         git__free(threadstate);
  48 }
  49
  50 static void git_threadstate_global_shutdown(void)
  51 {
  52         git_threadstate *threadstate;
  53
  54         threadstate = git_tlsdata_get(tls_key);
  55         git_tlsdata_set(tls_key, NULL);
  56
  57         threadstate_dispose(threadstate);
  58         git__free(threadstate);
  59
  60         git_tlsdata_dispose(tls_key);
  61 }
  62
  63 int git_threadstate_global_init(void)
  64 {
  65         if (git_tlsdata_init(&tls_key, &threadstate_free) != 0)
  66                 return -1;
  67
  68         return git_runtime_shutdown_register(git_threadstate_global_shutdown);
  69 }
  70
  71 git_threadstate *git_threadstate_get(void)
  72 {
  73         git_threadstate *threadstate;
  74
  75         if ((threadstate = git_tlsdata_get(tls_key)) != NULL)
  76                 return threadstate;
  77
  78         if ((threadstate = git__calloc(1, sizeof(git_threadstate))) == NULL ||
  79             git_buf_init(&threadstate->error_buf, 0) < 0)
  80                 return NULL;
  81
  82         git_tlsdata_set(tls_key, threadstate);
  83         return threadstate;
  84 }