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/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
/**
* @file cbuff.c
* @brief Implementation of a ring buffer
*
* @copyright 2013 The FreeRADIUS server project
* @copyright 2013 Arran Cudbard-Bell <a.cudbardb@freeradius.org>
*/
RCSID("$Id$")
#include <freeradius-devel/libradius.h>
#ifdef HAVE_PTHREAD_H
# define PTHREAD_MUTEX_LOCK(_x) if (_x->lock) pthread_mutex_lock(&((_x)->mutex))
# define PTHREAD_MUTEX_UNLOCK(_x) if (_x->lock) pthread_mutex_unlock(&((_x)->mutex))
#else
# define PTHREAD_MUTEX_LOCK(_x)
# define PTHREAD_MUTEX_UNLOCK(_x)
#endif
/** Standard thread safe circular buffer
*
*/
struct fr_cbuff {
void const *end; //!< End of allocated memory
uint32_t size;
uint32_t in; //!< Write index
uint32_t out; //!< Read index
void **elem; //!< Ring buffer data
bool lock; //!< Perform thread synchronisation
pthread_mutex_t mutex; //!< Thread synchronisation mutex
};
/** Initialise a new circular buffer
*
* @param ctx to allocate the buffer in.
* @param size of buffer to allocate.
* @param lock If true, insert and next operations will lock the buffer.
* @return new cbuff, or NULL on error.
*/
#ifdef HAVE_PTHREAD_H
fr_cbuff_t *fr_cbuff_alloc(TALLOC_CTX *ctx, uint32_t size, bool lock)
#else
fr_cbuff_t *fr_cbuff_alloc(TALLOC_CTX *ctx, uint32_t size, UNUSED bool lock)
#endif
{
fr_cbuff_t *cbuff;
uint32_t pow;
/*
* Find the nearest power of 2 (rounding up)
*/
for (pow = 0x00000001;
pow < size;
pow <<= 1);
size = pow;
size--;
cbuff = talloc_zero(ctx, fr_cbuff_t);
if (!cbuff) {
return NULL;
}
cbuff->elem = talloc_zero_array(cbuff, void *, size);
if (!cbuff->elem) {
return NULL;
}
cbuff->size = size;
#ifdef HAVE_PTHREAD_H
if (lock) {
cbuff->lock = true;
pthread_mutex_init(&cbuff->mutex, NULL);
}
#endif
return cbuff;
}
/** Insert a new element into the buffer, and steal it from it's original context
*
* cbuff will steal obj and insert it into it's own context.
*
* @param cbuff to insert element into
* @param obj to insert, must of been allocated with talloc
*/
void fr_cbuff_rp_insert(fr_cbuff_t *cbuff, void *obj)
{
PTHREAD_MUTEX_LOCK(cbuff);
if (cbuff->elem[cbuff->in]) {
TALLOC_FREE(cbuff->elem[cbuff->in]);
}
cbuff->elem[cbuff->in] = talloc_steal(cbuff, obj);
cbuff->in = (cbuff->in + 1) & cbuff->size;
/* overwrite - out is advanced ahead of in */
if (cbuff->in == cbuff->out) {
cbuff->out = (cbuff->out + 1) & cbuff->size;
}
PTHREAD_MUTEX_UNLOCK(cbuff);
}
/** Remove an item from the buffer, and reparent to ctx
*
* @param cbuff to remove element from
* @param ctx to hang obj off.
* @return NULL if no elements in the buffer, else an element from the buffer reparented to ctx.
*/
void *fr_cbuff_rp_next(fr_cbuff_t *cbuff, TALLOC_CTX *ctx)
{
void *obj = NULL;
PTHREAD_MUTEX_LOCK(cbuff);
/* Buffer is empty */
if (cbuff->out == cbuff->in) goto done;
obj = talloc_steal(ctx, cbuff->elem[cbuff->out]);
cbuff->out = (cbuff->out + 1) & cbuff->size;
done:
PTHREAD_MUTEX_UNLOCK(cbuff);
return obj;
}
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