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/* Copyright (c) 2015, Linaro Limited
* All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
/**
* @file
*
* ODP recursive read/write lock
*/
#ifndef ODP_API_RWLOCK_RECURSIVE_H_
#define ODP_API_RWLOCK_RECURSIVE_H_
#include <odp/visibility_begin.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @addtogroup odp_locks
* @details
* <b> Recursive reader/writer lock (odp_rwlock_recursive_t) </b>
*
* This is recursive version of the reader/writer lock.
* A thread can read- or write-acquire a recursive read-write lock multiple
* times without a deadlock. To release the lock, the thread must unlock it
* the same number of times. Recursion is supported only for a pure series of
* read or write lock calls. Read and write lock calls must not be mixed when
* recursing.
*
* For example, these are supported...
* * read_lock(); read_lock(); read_unlock(); read_unlock();
* * write_lock(); write_lock(); write_unlock(); write_unlock();
*
* ... but this is not supported.
* * read_lock(); write_lock(); write_unlock(); read_unlock();
*
* The trylock variants can be used to avoid blocking when the lock
* is not immediately available.
* @{
*/
/**
* @typedef odp_rwlock_recursive_t
* Recursive rwlock
*/
/**
* Initialize recursive rwlock
*
* @param lock Pointer to a lock
*/
void odp_rwlock_recursive_init(odp_rwlock_recursive_t *lock);
/**
* Acquire recursive rwlock for reading
*
* This call allows the thread to acquire the same lock multiple times for
* reading. The lock cannot be acquired for writing while holding it
* for reading.
*
* @param lock Pointer to a lock
*/
void odp_rwlock_recursive_read_lock(odp_rwlock_recursive_t *lock);
/**
* Try to acquire recursive rwlock for reading
*
* @param lock Pointer to a lock
*
* @retval 0 Lock was not available for read access
* @retval !0 Read access to lock acquired
*/
int odp_rwlock_recursive_read_trylock(odp_rwlock_recursive_t *lock);
/**
* Release recursive rwlock after reading
*
* @param lock Pointer to a lock
*/
void odp_rwlock_recursive_read_unlock(odp_rwlock_recursive_t *lock);
/**
* Acquire recursive rwlock for writing
*
* This call allows the thread to acquire the same lock multiple times for
* writing. The lock cannot be acquired for reading while holding it
* for writing.
*
* @param lock Pointer to a lock
*/
void odp_rwlock_recursive_write_lock(odp_rwlock_recursive_t *lock);
/**
* Try to acquire recursive rwlock for writing
*
* @param lock Pointer to a lock
*
* @retval 0 Lock was not available for write access
* @retval !0 Write access to lock acquired
*/
int odp_rwlock_recursive_write_trylock(odp_rwlock_recursive_t *lock);
/**
* Release recursive rwlock after writing
*
* @param lock Pointer to a lock
*/
void odp_rwlock_recursive_write_unlock(odp_rwlock_recursive_t *lock);
/**
* @}
*/
#ifdef __cplusplus
}
#endif
#include <odp/visibility_end.h>
#endif
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