systems-assistant[bot]
857e5ef3ce
Co-authored-by: Eisuke Kawashima <e-kwsm@users.noreply.github.com> Co-authored-by: systems-assistant[bot] <systems-assistant[bot]@users.noreply.github.com> Co-authored-by: Maisam Arif <Maisam.Arif@amd.com>
92 строки
4.0 KiB
C
92 строки
4.0 KiB
C
/*
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Modifications Copyright © 2019 – 2020 Advanced Micro Devices, Inc. All Rights
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Reserved.
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Copyright (c) 2018 Oleg Yamnikov
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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#ifndef SRC_SHARED_MUTEX_SHARED_MUTEX_H_
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#define SRC_SHARED_MUTEX_SHARED_MUTEX_H_
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#include <sys/stat.h>
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#include <pthread.h> // pthread_mutex_t, pthread_mutexattr_t,
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// pthread_mutexattr_init, pthread_mutexattr_setpshared,
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// pthread_mutex_init, pthread_mutex_destroy
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// Structure of a shared mutex.
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typedef struct shared_mutex_t {
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pthread_mutex_t *ptr; // Pointer to the pthread mutex and
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// shared memory segment.
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int shm_fd; // Descriptor of shared memory object.
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char* name; // Name of the mutex and associated
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// shared memory object.
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int created; // Equals 1 (true) if initialization
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// of this structure caused creation
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// of a new shared mutex.
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// Equals 0 (false) if this mutex was
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// just retrieved from shared memory.
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} shared_mutex_t;
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// Initialize a new shared mutex with given `name`. If a mutex
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// with such name exists in the system, it will be loaded.
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// Otherwise a new mutes will by created.
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//
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// In case of any error, it will be printed into the standard output
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// and the returned structure will have `ptr` equal `NULL`.
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// `errno` wil not be reset in such case, so you may used it.
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//
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// **NOTE:** In case when the mutex appears to be uncreated,
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// this function becomes *non-thread-safe*. If multiple threads
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// call it at one moment, there occur several race conditions,
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// in which one call might recreate another's shared memory
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// object or rewrite another's pthread mutex in the shared memory.
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// There is no workaround currently, except to run first
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// initialization only before multi-threaded or multi-process
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// functionality.
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shared_mutex_t shared_mutex_init(const char *name, mode_t mode, bool retried=false);
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// Close access to the shared mutex and free all the resources,
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// used by the structure.
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//
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// Returns 0 in case of success. If any error occurs, it will be
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// printed into the standard output and the function will return -1.
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// `errno` wil not be reset in such case, so you may used it.
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//
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// **NOTE:** It will not destroy the mutex. The mutex would not
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// only be available to other processes using it right now,
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// but also to any process which might want to use it later on.
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// For complete desctruction use `shared_mutex_destroy` instead.
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//
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// **NOTE:** It will not unlock locked mutex.
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int shared_mutex_close(shared_mutex_t mutex);
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// Close and destroy shared mutex.
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// Any open pointers to it will be invalidated.
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//
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// Returns 0 in case of success. If any error occurs, it will be
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// printed into the standard output and the function will return -1.
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// `errno` wil not be reset in such case, so you may used it.
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//
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// **NOTE:** It will not unlock locked mutex.
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int shared_mutex_destroy(shared_mutex_t mutex);
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#endif // SRC_SHARED_MUTEX_SHARED_MUTEX_H_
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