glibc/linuxthreads/queue.h

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/* Linuxthreads - a simple clone()-based implementation of Posix */
/* threads for Linux. */
/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
/* */
/* This program is free software; you can redistribute it and/or */
/* modify it under the terms of the GNU Library 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 Library General Public License for more details. */
/* Waiting queues */
/* Waiting queues are represented by lists of thread descriptors
linked through their p_nextwaiting field. The lists are kept
sorted by decreasing priority, and then decreasing waiting time. */
static inline void enqueue(pthread_descr * q, pthread_descr th)
{
int prio = th->p_priority;
ASSERT(th->p_nextwaiting == NULL);
for (; *q != NULL; q = &((*q)->p_nextwaiting)) {
if (prio > (*q)->p_priority) {
th->p_nextwaiting = *q;
*q = th;
return;
}
}
*q = th;
}
static inline pthread_descr dequeue(pthread_descr * q)
{
pthread_descr th;
th = *q;
if (th != NULL) {
*q = th->p_nextwaiting;
th->p_nextwaiting = NULL;
}
return th;
}
static inline int remove_from_queue(pthread_descr * q, pthread_descr th)
{
for (; *q != NULL; q = &((*q)->p_nextwaiting)) {
if (*q == th) {
*q = th->p_nextwaiting;
th->p_nextwaiting = NULL;
return 1;
}
}
return 0;
}
static inline int queue_is_empty(pthread_descr * q)
{
return *q == NULL;
}