1 /*-
2 * Copyright (c) 2006, Maxime Henrion <mux@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD$
27 */
28
29 #include <assert.h>
30 #include <pthread.h>
31 #include <stdlib.h>
32 #include <string.h>
33
34 #include "fixups.h"
35 #include "misc.h"
36 #include "queue.h"
37
38 /*
39 * A synchronized queue to implement fixups. The updater thread adds
40 * fixup requests to the queue with fixups_put() when a checksum
41 * mismatch error occurred. It then calls fixups_close() when he's
42 * done requesting fixups. The detailer thread gets the fixups with
43 * fixups_get() and then send the requests to the server.
44 *
45 * The queue is synchronized with a mutex and a condition variable.
46 */
47
48 struct fixups {
49 pthread_mutex_t lock;
50 pthread_cond_t cond;
51 STAILQ_HEAD(, fixup) fixupq;
52 struct fixup *cur;
53 size_t size;
54 int closed;
55 };
56
57 static void fixups_lock(struct fixups *);
58 static void fixups_unlock(struct fixups *);
59
60 static struct fixup *fixup_new(struct coll *, const char *);
61 static void fixup_free(struct fixup *);
62
63 static void
fixups_lock(struct fixups * f)64 fixups_lock(struct fixups *f)
65 {
66 int error;
67
68 error = pthread_mutex_lock(&f->lock);
69 assert(!error);
70 }
71
72 static void
fixups_unlock(struct fixups * f)73 fixups_unlock(struct fixups *f)
74 {
75 int error;
76
77 error = pthread_mutex_unlock(&f->lock);
78 assert(!error);
79 }
80
81 static struct fixup *
fixup_new(struct coll * coll,const char * name)82 fixup_new(struct coll *coll, const char *name)
83 {
84 struct fixup *fixup;
85
86 fixup = xmalloc(sizeof(struct fixup));
87 fixup->f_name = xstrdup(name);
88 fixup->f_coll = coll;
89 return (fixup);
90 }
91
92 static void
fixup_free(struct fixup * fixup)93 fixup_free(struct fixup *fixup)
94 {
95
96 free(fixup->f_name);
97 free(fixup);
98 }
99
100 /* Create a new fixup queue. */
101 struct fixups *
fixups_new(void)102 fixups_new(void)
103 {
104 struct fixups *f;
105
106 f = xmalloc(sizeof(struct fixups));
107 f->size = 0;
108 f->closed = 0;
109 f->cur = NULL;
110 STAILQ_INIT(&f->fixupq);
111 pthread_mutex_init(&f->lock, NULL);
112 pthread_cond_init(&f->cond, NULL);
113 return (f);
114 }
115
116 /* Add a fixup request to the queue. */
117 void
fixups_put(struct fixups * f,struct coll * coll,const char * name)118 fixups_put(struct fixups *f, struct coll *coll, const char *name)
119 {
120 struct fixup *fixup;
121 int dosignal;
122
123 dosignal = 0;
124 fixup = fixup_new(coll, name);
125 fixups_lock(f);
126 assert(!f->closed);
127 STAILQ_INSERT_TAIL(&f->fixupq, fixup, f_link);
128 if (f->size++ == 0)
129 dosignal = 1;
130 fixups_unlock(f);
131 if (dosignal)
132 pthread_cond_signal(&f->cond);
133 }
134
135 /* Get a fixup request from the queue. */
136 struct fixup *
fixups_get(struct fixups * f)137 fixups_get(struct fixups *f)
138 {
139 struct fixup *fixup, *tofree;
140
141 fixups_lock(f);
142 while (f->size == 0 && !f->closed)
143 pthread_cond_wait(&f->cond, &f->lock);
144 if (f->closed && f->size == 0) {
145 fixups_unlock(f);
146 return (NULL);
147 }
148 assert(f->size > 0);
149 fixup = STAILQ_FIRST(&f->fixupq);
150 tofree = f->cur;
151 f->cur = fixup;
152 STAILQ_REMOVE_HEAD(&f->fixupq, f_link);
153 f->size--;
154 fixups_unlock(f);
155 if (tofree != NULL)
156 fixup_free(tofree);
157 return (fixup);
158 }
159
160 /* Close the writing end of the queue. */
161 void
fixups_close(struct fixups * f)162 fixups_close(struct fixups *f)
163 {
164 int dosignal;
165
166 dosignal = 0;
167 fixups_lock(f);
168 if (f->size == 0 && !f->closed)
169 dosignal = 1;
170 f->closed = 1;
171 fixups_unlock(f);
172 if (dosignal)
173 pthread_cond_signal(&f->cond);
174 }
175
176 /* Free a fixups queue. */
177 void
fixups_free(struct fixups * f)178 fixups_free(struct fixups *f)
179 {
180 struct fixup *fixup, *fixup2;
181
182 assert(f->closed);
183 /*
184 * Free any fixup that has been left on the queue.
185 * This can happen if we have been aborted prematurely.
186 */
187 fixup = STAILQ_FIRST(&f->fixupq);
188 while (fixup != NULL) {
189 fixup2 = STAILQ_NEXT(fixup, f_link);
190 fixup_free(fixup);
191 fixup = fixup2;
192 }
193 if (f->cur != NULL)
194 fixup_free(f->cur);
195 pthread_cond_destroy(&f->cond);
196 pthread_mutex_destroy(&f->lock);
197 free(f);
198 }
199