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/*
* include/haproxy/port_range.h
* This file defines everything needed to manage port ranges
*
* Copyright (C) 2000-2020 Willy Tarreau - w@1wt.eu
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _HAPROXY_PORT_RANGE_H
#define _HAPROXY_PORT_RANGE_H
#include <stdlib.h>
#include <haproxy/api.h>
#include <haproxy/port_range-t.h>
#define GET_NEXT_OFF(range, off) ((off) == (range)->size - 1 ? 0 : (off) + 1)
/* return an available port from range <range>, or zero if none is left */
static inline int port_range_alloc_port(struct port_range *range)
{
int ret;
int get;
int put;
get = _HA_ATOMIC_LOAD(&range->get);
do {
/* barrier to make sure get is loaded before put */
__ha_barrier_atomic_load();
put = _HA_ATOMIC_LOAD(&range->put_t);
if (unlikely(put == get))
return 0;
ret = range->ports[get];
} while (!(_HA_ATOMIC_CAS(&range->get, &get, GET_NEXT_OFF(range, get))));
return ret;
}
/* release port <port> into port range <range>. Does nothing if <port> is zero
* nor if <range> is null. The caller is responsible for marking the port
* unused by either setting the port to zero or the range to NULL.
*/
static inline void port_range_release_port(struct port_range *range, int port)
{
int put;
if (!port || !range)
return;
put = range->put_h;
/* put_h is reserved for producers, so that they can each get a
* free slot, put_t is what is used by consumers to know if there's
* elements available or not
*/
/* First reserve or slot, we know the ring buffer can't be full,
* as we will only ever release port we allocated before
*/
while (!(_HA_ATOMIC_CAS(&range->put_h, &put, GET_NEXT_OFF(range, put))));
_HA_ATOMIC_STORE(&range->ports[put], port);
/* Barrier to make sure the new port is visible before we change put_t */
__ha_barrier_atomic_store();
/* Wait until all the threads that got a slot before us are done */
while ((volatile int)range->put_t != put)
__ha_compiler_barrier();
/* Let the world know we're done, and any potential consumer they
* can use that port.
*/
_HA_ATOMIC_STORE(&range->put_t, GET_NEXT_OFF(range, put));
}
/* return a new initialized port range of N ports. The ports are not
* filled in, it's up to the caller to do it.
*/
static inline struct port_range *port_range_alloc_range(int n)
{
struct port_range *ret;
ret = calloc(1, sizeof(struct port_range) +
(n + 1) * sizeof(((struct port_range *)0)->ports[0]));
if (!ret)
return NULL;
ret->size = n + 1;
/* Start at the first free element */
ret->put_h = ret->put_t = n;
return ret;
}
#endif /* _HAPROXY_PORT_RANGE_H */
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/
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