thodg/libgit2/src/threadstate.c

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• Hash : f0e693b1
  Author :
  Date : 2021-09-07T17:53:49
  

  str: introduce `git_str` for internal, `git_buf` is external
  
  libgit2 has two distinct requirements that were previously solved by
  `git_buf`.  We require:
  
  1. A general purpose string class that provides a number of utility APIs
     for manipulating data (eg, concatenating, truncating, etc).
  2. A structure that we can use to return strings to callers that they
     can take ownership of.
  
  By using a single class (`git_buf`) for both of these purposes, we have
  confused the API to the point that refactorings are difficult and
  reasoning about correctness is also difficult.
  
  Move the utility class `git_buf` to be called `git_str`: this represents
  its general purpose, as an internal string buffer class.  The name also
  is an homage to Junio Hamano ("gitstr").
  
  The public API remains `git_buf`, and has a much smaller footprint.  It
  is generally only used as an "out" param with strict requirements that
  follow the documentation.  (Exceptions exist for some legacy APIs to
  avoid breaking callers unnecessarily.)
  
  Utility functions exist to convert a user-specified `git_buf` to a
  `git_str` so that we can call internal functions, then converting it
  back again.
  

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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"
  
  /**
   * 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 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`.
   */
  
  static git_tlsdata_key tls_key;
  
  static void threadstate_dispose(git_threadstate *threadstate)
  {
  	if (!threadstate)
  		return;
  
      if (threadstate->error_t.message != git_str__initstr)
          git__free(threadstate->error_t.message);
  	threadstate->error_t.message = NULL;
  }
  
  static void GIT_SYSTEM_CALL threadstate_free(void *threadstate)
  {
  	threadstate_dispose(threadstate);
  	git__free(threadstate);
  }
  
  static void git_threadstate_global_shutdown(void)
  {
  	git_threadstate *threadstate;
  
  	threadstate = git_tlsdata_get(tls_key);
  	git_tlsdata_set(tls_key, NULL);
  
  	threadstate_dispose(threadstate);
  	git__free(threadstate);
  
  	git_tlsdata_dispose(tls_key);
  }
  
  int git_threadstate_global_init(void)
  {
  	if (git_tlsdata_init(&tls_key, &threadstate_free) != 0)
  		return -1;
  
  	return git_runtime_shutdown_register(git_threadstate_global_shutdown);
  }
  
  git_threadstate *git_threadstate_get(void)
  {
  	git_threadstate *threadstate;
  
  	if ((threadstate = git_tlsdata_get(tls_key)) != NULL)
  		return threadstate;
  
  	if ((threadstate = git__calloc(1, sizeof(git_threadstate))) == NULL ||
  	    git_str_init(&threadstate->error_buf, 0) < 0)
  		return NULL;
  
  	git_tlsdata_set(tls_key, threadstate);
  	return threadstate;
  }
  

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