xref: /onnv-gate/usr/src/lib/libslp/clib/slp_queue.c (revision 0:68f95e015346)
1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate  * CDDL HEADER START
3*0Sstevel@tonic-gate  *
4*0Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate  * with the License.
8*0Sstevel@tonic-gate  *
9*0Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate  * and limitations under the License.
13*0Sstevel@tonic-gate  *
14*0Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate  *
20*0Sstevel@tonic-gate  * CDDL HEADER END
21*0Sstevel@tonic-gate  */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24*0Sstevel@tonic-gate  * Use is subject to license terms.
25*0Sstevel@tonic-gate  */
26*0Sstevel@tonic-gate 
27*0Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
28*0Sstevel@tonic-gate 
29*0Sstevel@tonic-gate /*
30*0Sstevel@tonic-gate  * A synchronized FIFO queue for inter-thread producer-consumer semantics.
31*0Sstevel@tonic-gate  * This queue will handle multiple writers and readers simultaneously.
32*0Sstevel@tonic-gate  *
33*0Sstevel@tonic-gate  * The following operations are provided:
34*0Sstevel@tonic-gate  * slp_new_queue:	create a new queue
35*0Sstevel@tonic-gate  * slp_enqueue:		place a message at the end of the queue
36*0Sstevel@tonic-gate  * slp_enqueue_at_head:	place a message the the start of the queue
37*0Sstevel@tonic-gate  * slp_dequeue:		remove and return the next message on the queue
38*0Sstevel@tonic-gate  *				(waits indefinately)
39*0Sstevel@tonic-gate  * slp_dequeue_timed:	remove and return the next message on the queue
40*0Sstevel@tonic-gate  *				(waits only for a specified time)
41*0Sstevel@tonic-gate  * slp_flush_queue:	flushes and frees all messages on a queue
42*0Sstevel@tonic-gate  * slp_destroy_queue:	frees an empty queue.
43*0Sstevel@tonic-gate  */
44*0Sstevel@tonic-gate 
45*0Sstevel@tonic-gate #include <stdio.h>
46*0Sstevel@tonic-gate #include <stdlib.h>
47*0Sstevel@tonic-gate #include <thread.h>
48*0Sstevel@tonic-gate #include <synch.h>
49*0Sstevel@tonic-gate #include <syslog.h>
50*0Sstevel@tonic-gate #include <slp.h>
51*0Sstevel@tonic-gate #include <slp-internal.h>
52*0Sstevel@tonic-gate 
53*0Sstevel@tonic-gate /* Private implementation details */
54*0Sstevel@tonic-gate struct queue_entry {
55*0Sstevel@tonic-gate 	void *msg;
56*0Sstevel@tonic-gate 	struct queue_entry *next;
57*0Sstevel@tonic-gate };
58*0Sstevel@tonic-gate typedef struct queue_entry slp_queue_entry_t;
59*0Sstevel@tonic-gate 
60*0Sstevel@tonic-gate struct queue {
61*0Sstevel@tonic-gate 	slp_queue_entry_t *head;
62*0Sstevel@tonic-gate 	slp_queue_entry_t *tail;
63*0Sstevel@tonic-gate 	mutex_t *lock;
64*0Sstevel@tonic-gate 	cond_t *wait;
65*0Sstevel@tonic-gate 	int count;
66*0Sstevel@tonic-gate };
67*0Sstevel@tonic-gate 
68*0Sstevel@tonic-gate /*
69*0Sstevel@tonic-gate  * Creates, initializes, and returns a new queue.
70*0Sstevel@tonic-gate  * If an initialization error occured, returns NULL and sets err to
71*0Sstevel@tonic-gate  * the appropriate SLP error code.
72*0Sstevel@tonic-gate  * queues can operate in one of two modes: timed-wait, and infinite
73*0Sstevel@tonic-gate  * wait. The timeout parameter specifies which of these modes should
74*0Sstevel@tonic-gate  * be enabled for the new queue.
75*0Sstevel@tonic-gate  */
slp_new_queue(SLPError * err)76*0Sstevel@tonic-gate slp_queue_t *slp_new_queue(SLPError *err) {
77*0Sstevel@tonic-gate 	mutex_t *lock;
78*0Sstevel@tonic-gate 	cond_t *wait;
79*0Sstevel@tonic-gate 	struct queue *q;
80*0Sstevel@tonic-gate 
81*0Sstevel@tonic-gate 	*err = SLP_OK;
82*0Sstevel@tonic-gate 
83*0Sstevel@tonic-gate 	/* initialize new mutex and semaphore */
84*0Sstevel@tonic-gate 	if ((lock = calloc(1, sizeof (*lock))) == NULL) {
85*0Sstevel@tonic-gate 		*err = SLP_MEMORY_ALLOC_FAILED;
86*0Sstevel@tonic-gate 		slp_err(LOG_CRIT, 0, "slp_new_queue", "out of memory");
87*0Sstevel@tonic-gate 		return (NULL);
88*0Sstevel@tonic-gate 	}
89*0Sstevel@tonic-gate 
90*0Sstevel@tonic-gate 	/* intialize condition vars */
91*0Sstevel@tonic-gate 	if (!(wait = calloc(1, sizeof (*wait)))) {
92*0Sstevel@tonic-gate 		*err = SLP_MEMORY_ALLOC_FAILED;
93*0Sstevel@tonic-gate 		slp_err(LOG_CRIT, 0, "slp_new_queue", "out of memory");
94*0Sstevel@tonic-gate 		return (NULL);
95*0Sstevel@tonic-gate 	}
96*0Sstevel@tonic-gate 	(void) cond_init(wait, NULL, NULL);
97*0Sstevel@tonic-gate 
98*0Sstevel@tonic-gate 	/* create the queue */
99*0Sstevel@tonic-gate 	if ((q = malloc(sizeof (*q))) == NULL) {
100*0Sstevel@tonic-gate 		*err = SLP_MEMORY_ALLOC_FAILED;
101*0Sstevel@tonic-gate 		slp_err(LOG_CRIT, 0, "slp_new_queue", "out of memory");
102*0Sstevel@tonic-gate 		return (NULL);
103*0Sstevel@tonic-gate 	}
104*0Sstevel@tonic-gate 
105*0Sstevel@tonic-gate 	q->head = NULL;
106*0Sstevel@tonic-gate 	q->lock = lock;
107*0Sstevel@tonic-gate 	q->wait = wait;
108*0Sstevel@tonic-gate 	q->count = 0;
109*0Sstevel@tonic-gate 
110*0Sstevel@tonic-gate 	return (q);
111*0Sstevel@tonic-gate }
112*0Sstevel@tonic-gate 
113*0Sstevel@tonic-gate /*
114*0Sstevel@tonic-gate  * Adds msg to the tail of queue q.
115*0Sstevel@tonic-gate  * Returns an SLP error code: SLP_OK for no error, or SLP_MEMORY_ALLOC_FAILED
116*0Sstevel@tonic-gate  * if it couldn't allocate memory.
117*0Sstevel@tonic-gate  */
slp_enqueue(slp_queue_t * qa,void * msg)118*0Sstevel@tonic-gate SLPError slp_enqueue(slp_queue_t *qa, void *msg) {
119*0Sstevel@tonic-gate 	slp_queue_entry_t *qe;
120*0Sstevel@tonic-gate 	struct queue *q = qa;
121*0Sstevel@tonic-gate 
122*0Sstevel@tonic-gate 	if ((qe = malloc(sizeof (*qe))) == NULL) {
123*0Sstevel@tonic-gate 		slp_err(LOG_CRIT, 0, "slp_enqueue", "out of memory");
124*0Sstevel@tonic-gate 		return (SLP_MEMORY_ALLOC_FAILED);
125*0Sstevel@tonic-gate 	}
126*0Sstevel@tonic-gate 
127*0Sstevel@tonic-gate 	(void) mutex_lock(q->lock);
128*0Sstevel@tonic-gate 	qe->msg = msg;
129*0Sstevel@tonic-gate 	qe->next = NULL;
130*0Sstevel@tonic-gate 	if (q->head != NULL) {	/* queue is not emptry */
131*0Sstevel@tonic-gate 		q->tail->next = qe;
132*0Sstevel@tonic-gate 		q->tail = qe;
133*0Sstevel@tonic-gate 	} else {		/* queue is empty */
134*0Sstevel@tonic-gate 		q->head = q->tail = qe;
135*0Sstevel@tonic-gate 	}
136*0Sstevel@tonic-gate 	q->count++;
137*0Sstevel@tonic-gate 	(void) mutex_unlock(q->lock);
138*0Sstevel@tonic-gate 	(void) cond_signal(q->wait);
139*0Sstevel@tonic-gate 
140*0Sstevel@tonic-gate 	return (SLP_OK);
141*0Sstevel@tonic-gate }
142*0Sstevel@tonic-gate 
143*0Sstevel@tonic-gate /*
144*0Sstevel@tonic-gate  * Inserts a message at the head of the queue. This is useful for inserting
145*0Sstevel@tonic-gate  * things like cancel messages.
146*0Sstevel@tonic-gate  */
slp_enqueue_at_head(slp_queue_t * qa,void * msg)147*0Sstevel@tonic-gate SLPError slp_enqueue_at_head(slp_queue_t *qa, void *msg) {
148*0Sstevel@tonic-gate 	slp_queue_entry_t *qe;
149*0Sstevel@tonic-gate 	struct queue *q = qa;
150*0Sstevel@tonic-gate 
151*0Sstevel@tonic-gate 	if ((qe = malloc(sizeof (*qe))) == NULL) {
152*0Sstevel@tonic-gate 		slp_err(LOG_CRIT, 0, "slp_enqueue", "out of memory");
153*0Sstevel@tonic-gate 		return (SLP_MEMORY_ALLOC_FAILED);
154*0Sstevel@tonic-gate 	}
155*0Sstevel@tonic-gate 
156*0Sstevel@tonic-gate 	(void) mutex_lock(q->lock);
157*0Sstevel@tonic-gate 	qe->msg = msg;
158*0Sstevel@tonic-gate 	qe->next = q->head;
159*0Sstevel@tonic-gate 	q->head = qe;
160*0Sstevel@tonic-gate 
161*0Sstevel@tonic-gate 	q->count++;
162*0Sstevel@tonic-gate 	(void) mutex_unlock(q->lock);
163*0Sstevel@tonic-gate 	(void) cond_signal(q->wait);
164*0Sstevel@tonic-gate 
165*0Sstevel@tonic-gate 	return (SLP_OK);
166*0Sstevel@tonic-gate }
167*0Sstevel@tonic-gate 
168*0Sstevel@tonic-gate /*
169*0Sstevel@tonic-gate  * The core functionality for dequeue.
170*0Sstevel@tonic-gate  */
dequeue_nolock(struct queue * q)171*0Sstevel@tonic-gate static void *dequeue_nolock(struct queue *q) {
172*0Sstevel@tonic-gate 	void *msg;
173*0Sstevel@tonic-gate 	slp_queue_entry_t *qe = q->head;
174*0Sstevel@tonic-gate 
175*0Sstevel@tonic-gate 	if (!qe)
176*0Sstevel@tonic-gate 		return (NULL);	/* shouldn't get here */
177*0Sstevel@tonic-gate 	msg = qe->msg;
178*0Sstevel@tonic-gate 	if (!qe->next)		/* last one in queue */
179*0Sstevel@tonic-gate 		q->head = q->tail = NULL;
180*0Sstevel@tonic-gate 	else
181*0Sstevel@tonic-gate 		q->head = qe->next;
182*0Sstevel@tonic-gate 	free(qe);
183*0Sstevel@tonic-gate 	q->count--;
184*0Sstevel@tonic-gate 	return (msg);
185*0Sstevel@tonic-gate }
186*0Sstevel@tonic-gate 
187*0Sstevel@tonic-gate /*
188*0Sstevel@tonic-gate  * Returns the first message waiting or arriving in the queue, or if no
189*0Sstevel@tonic-gate  * message is available after waiting the amount of time specified in
190*0Sstevel@tonic-gate  * 'to', returns NULL, and sets 'etimed' to true. If an error occured,
191*0Sstevel@tonic-gate  * returns NULL and sets 'etimed' to false.
192*0Sstevel@tonic-gate  */
slp_dequeue_timed(slp_queue_t * qa,timestruc_t * to,SLPBoolean * etimed)193*0Sstevel@tonic-gate void *slp_dequeue_timed(slp_queue_t *qa, timestruc_t *to, SLPBoolean *etimed) {
194*0Sstevel@tonic-gate 	int err;
195*0Sstevel@tonic-gate 	void *ans;
196*0Sstevel@tonic-gate 	struct queue *q = qa;
197*0Sstevel@tonic-gate 
198*0Sstevel@tonic-gate 	if (etimed)
199*0Sstevel@tonic-gate 		*etimed = SLP_FALSE;
200*0Sstevel@tonic-gate 
201*0Sstevel@tonic-gate 	(void) mutex_lock(q->lock);
202*0Sstevel@tonic-gate 	if (q->count > 0) {
203*0Sstevel@tonic-gate 		/* something's in the q, so no need to wait */
204*0Sstevel@tonic-gate 		goto msg_available;
205*0Sstevel@tonic-gate 	}
206*0Sstevel@tonic-gate 
207*0Sstevel@tonic-gate 	/* else wait */
208*0Sstevel@tonic-gate 	while (q->count == 0) {
209*0Sstevel@tonic-gate 		if (to) {
210*0Sstevel@tonic-gate 			err = cond_timedwait(q->wait, q->lock, to);
211*0Sstevel@tonic-gate 		} else {
212*0Sstevel@tonic-gate 			err = cond_wait(q->wait, q->lock);
213*0Sstevel@tonic-gate 		}
214*0Sstevel@tonic-gate 		if (err == ETIME) {
215*0Sstevel@tonic-gate 			(void) mutex_unlock(q->lock);
216*0Sstevel@tonic-gate 			*etimed = SLP_TRUE;
217*0Sstevel@tonic-gate 			return (NULL);
218*0Sstevel@tonic-gate 		}
219*0Sstevel@tonic-gate 	}
220*0Sstevel@tonic-gate 
221*0Sstevel@tonic-gate msg_available:
222*0Sstevel@tonic-gate 	ans = dequeue_nolock(q);
223*0Sstevel@tonic-gate 	(void) mutex_unlock(q->lock);
224*0Sstevel@tonic-gate 	return (ans);
225*0Sstevel@tonic-gate }
226*0Sstevel@tonic-gate 
227*0Sstevel@tonic-gate /*
228*0Sstevel@tonic-gate  * Removes the first message from the queue and returns it.
229*0Sstevel@tonic-gate  * Returns NULL only on internal error.
230*0Sstevel@tonic-gate  */
slp_dequeue(slp_queue_t * qa)231*0Sstevel@tonic-gate void *slp_dequeue(slp_queue_t *qa) {
232*0Sstevel@tonic-gate 	return (slp_dequeue_timed(qa, NULL, NULL));
233*0Sstevel@tonic-gate }
234*0Sstevel@tonic-gate 
235*0Sstevel@tonic-gate /*
236*0Sstevel@tonic-gate  * Flushes the queue, using the caller-specified free function to
237*0Sstevel@tonic-gate  * free each message in the queue.
238*0Sstevel@tonic-gate  */
slp_flush_queue(slp_queue_t * qa,void (* free_f)(void *))239*0Sstevel@tonic-gate void slp_flush_queue(slp_queue_t *qa, void (*free_f)(void *)) {
240*0Sstevel@tonic-gate 	slp_queue_entry_t *p, *pn;
241*0Sstevel@tonic-gate 	struct queue *q = qa;
242*0Sstevel@tonic-gate 
243*0Sstevel@tonic-gate 	for (p = q->head; p; p = pn) {
244*0Sstevel@tonic-gate 		pn = p->next;
245*0Sstevel@tonic-gate 		free_f(p);
246*0Sstevel@tonic-gate 	}
247*0Sstevel@tonic-gate }
248*0Sstevel@tonic-gate 
249*0Sstevel@tonic-gate /*
250*0Sstevel@tonic-gate  * Frees a queue.
251*0Sstevel@tonic-gate  * The queue must be empty before it can be destroyed; slp_flush_queue
252*0Sstevel@tonic-gate  * can be used to empty a queue.
253*0Sstevel@tonic-gate  */
slp_destroy_queue(slp_queue_t * qa)254*0Sstevel@tonic-gate void slp_destroy_queue(slp_queue_t *qa) {
255*0Sstevel@tonic-gate 	struct queue *q = qa;
256*0Sstevel@tonic-gate 
257*0Sstevel@tonic-gate 	(void) mutex_destroy(q->lock);
258*0Sstevel@tonic-gate 	(void) cond_destroy(q->wait);
259*0Sstevel@tonic-gate 	free(q->lock);
260*0Sstevel@tonic-gate 	free(q->wait);
261*0Sstevel@tonic-gate 	free(q);
262*0Sstevel@tonic-gate }
263