thodg/libgit2/src/thread.c

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• Hash : 971b7187
  Author :
  Date : 2020-08-06T16:24:18
  

  Implement generic TLS interface
  
  This adds a generic TLS interface for anyone to store TLS data. It is designed to work regardless of whether threading support is built into the library or not.
  
  Nobody in the library should directly interface with the data on the TLS struct, so it's been built to be opaque even in the library.
  
  Requires the allocator to be initialized before use.
  

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• src/thread.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 "common.h"
  
  #ifndef GIT_THREADS
  
  struct git_tls_data {
  	void GIT_CALLBACK(free_fn)(void *payload);
  	void *storage;
  };
  
  int git_tls_data__init(git_tls_data **out,
  	void GIT_CALLBACK(free_fn)(void *storage))
  {
  	struct git_tls_data *tls = git__malloc(sizeof(struct git_tls_data));
  	GIT_ERROR_CHECK_ALLOC(tls);
  
  	tls->storage = NULL;
  	tls->free_fn = free_fn;
  	*out = tls;
  
  	return 0;
  }
  
  int git_tls_data__set(git_tls_data *tls, void *payload)
  {
  	tls->storage = payload;
  	return 0;
  }
  
  void *git_tls_data__get(git_tls_data *tls)
  {
  	return tls->storage;
  }
  
  void git_tls_data__free(git_tls_data *tls)
  {
  	tls->free_fn(tls->storage);
  	git__free(tls);
  }
  
  #elif defined(GIT_WIN32)
  
  struct git_tls_data {
  	void GIT_CALLBACK(free_fn)(void *payload);
  	DWORD fls_index;
  };
  
  struct git_tls_cell {
  	void GIT_CALLBACK(free_fn)(void *storage);
  	void *storage;
  };
  
  static void WINAPI git_tls_cell__free(void *sc)
  {
    struct git_tls_cell *storage_cell = sc;
  	if (storage_cell == NULL) {
  		return;
  	}
  
  	storage_cell->free_fn(storage_cell->storage);
  	git__free(storage_cell);
  }
  
  int git_tls_data__init(git_tls_data **out,
  	void GIT_CALLBACK(free_fn)(void *payload))
  {
  	struct git_tls_data *tls = git__malloc(sizeof(struct git_tls_data));
  	GIT_ERROR_CHECK_ALLOC(tls);
  
  	if ((tls->fls_index = FlsAlloc(git_tls_cell__free)) == FLS_OUT_OF_INDEXES) {
  		git__free(tls);
  		return -1;
  	}
  
  	tls->free_fn = free_fn;
  	*out = tls;
  
  	return 0;
  }
  
  int git_tls_data__set(git_tls_data *tls, void *payload)
  {
  	struct git_tls_cell *storage_cell;
  
  	if (payload == NULL) {
  		if ((storage_cell = FlsGetValue(tls->fls_index)) != NULL)
  			git_tls_cell__free(storage_cell);
  
  		if (FlsSetValue(tls->fls_index, NULL) == 0)
  			return -1;
  
  		return 0;
  	}
  
  	storage_cell = git__malloc(sizeof(struct git_tls_cell));
  	GIT_ERROR_CHECK_ALLOC(storage_cell);
  
  	storage_cell->free_fn = tls->free_fn;
  	storage_cell->storage = payload;
  
  	if (FlsSetValue(tls->fls_index, storage_cell) == 0) {
  		git__free(storage_cell);
  		return -1;
  	}
  
  	return 0;
  }
  
  void *git_tls_data__get(git_tls_data *tls)
  {
  	struct git_tls_cell *storage_cell = FlsGetValue(tls->fls_index);
  	if (storage_cell == NULL)
  		return NULL;
  
  	return storage_cell->storage;
  }
  
  void git_tls_data__free(git_tls_data *tls)
  {
  	FlsFree(tls->fls_index);
  	tls->free_fn = NULL;
  	git__free(tls);
  }
  
  #elif defined(_POSIX_THREADS)
  
  struct git_tls_data {
  	void GIT_CALLBACK(free_fn)(void *payload);
  	pthread_key_t tls_key;
  };
  
  struct git_tls_cell {
  	void GIT_CALLBACK(free_fn)(void *storage);
  	void *storage;
  };
  
  static void git_tls_cell__free(void *sc)
  {
    struct git_tls_cell *storage_cell = sc;
  	storage_cell->free_fn(storage_cell->storage);
  	git__free(storage_cell);
  }
  
  int git_tls_data__init(git_tls_data **out,
  	void GIT_CALLBACK(free_fn)(void *payload))
  {
  	struct git_tls_data *tls = git__malloc(sizeof(struct git_tls_data));
  	GIT_ERROR_CHECK_ALLOC(tls);
  
  	if (pthread_key_create(&tls->tls_key, git_tls_cell__free) != 0) {
  		git__free(tls);
  		return -1;
  	}
  
  	tls->free_fn = free_fn;
  	*out = tls;
  
  	return 0;
  }
  
  int git_tls_data__set(git_tls_data *tls, void *payload)
  {
  	struct git_tls_cell *storage_cell;
  
  	if (payload == NULL) {
  		if ((storage_cell = pthread_getspecific(tls->tls_key)) != NULL)
  			git_tls_cell__free(storage_cell);
  
  		if (pthread_setspecific(tls->tls_key, NULL) != 0)
  			return -1;
  
  		return 0;
  	}
  
  	storage_cell = git__malloc(sizeof(struct git_tls_cell));
  	GIT_ERROR_CHECK_ALLOC(storage_cell);
  
  	storage_cell->free_fn = tls->free_fn;
  	storage_cell->storage = payload;
  
  	if (pthread_setspecific(tls->tls_key, storage_cell) != 0) {
  		git__free(storage_cell);
  		return -1;
  	}
  
  	return 0;
  }
  
  void *git_tls_data__get(git_tls_data *tls)
  {
  	struct git_tls_cell *storage_cell = pthread_getspecific(tls->tls_key);
  	if (storage_cell == NULL)
  		return NULL;
  
  	return storage_cell->storage;
  }
  
  void git_tls_data__free(git_tls_data *tls)
  {
  	git_tls_data__set(tls, NULL);
  	pthread_key_delete(tls->tls_key);
  	git__free(tls);
  }
  
  #else
  #  error unknown threading model
  #endif
  

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