1 /* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements. See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License. You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "apr.h"
18
19 #if APR_HAVE_STDIO_H
20 #include <stdio.h>
21 #endif
22 #if APR_HAVE_STDLIB_H
23 #include <stdlib.h>
24 #endif
25 #if APR_HAVE_UNISTD_H
26 #include <unistd.h>
27 #endif
28
29 #include "apu.h"
30 #include "apr_portable.h"
31 #include "apr_thread_mutex.h"
32 #include "apr_thread_cond.h"
33 #include "apr_errno.h"
34 #include "apr_queue.h"
35
36 #if APR_HAS_THREADS
37 /*
38 * define this to get debug messages
39 *
40 #define QUEUE_DEBUG
41 */
42
43 struct apr_queue_t {
44 void **data;
45 unsigned int nelts; /**< # elements */
46 unsigned int in; /**< next empty location */
47 unsigned int out; /**< next filled location */
48 unsigned int bounds;/**< max size of queue */
49 unsigned int full_waiters;
50 unsigned int empty_waiters;
51 apr_thread_mutex_t *one_big_mutex;
52 apr_thread_cond_t *not_empty;
53 apr_thread_cond_t *not_full;
54 int terminated;
55 };
56
57 #ifdef QUEUE_DEBUG
Q_DBG(char * msg,apr_queue_t * q)58 static void Q_DBG(char*msg, apr_queue_t *q) {
59 fprintf(stderr, "%ld\t#%d in %d out %d\t%s\n",
60 apr_os_thread_current(),
61 q->nelts, q->in, q->out,
62 msg
63 );
64 }
65 #else
66 #define Q_DBG(x,y)
67 #endif
68
69 /**
70 * Detects when the apr_queue_t is full. This utility function is expected
71 * to be called from within critical sections, and is not threadsafe.
72 */
73 #define apr_queue_full(queue) ((queue)->nelts == (queue)->bounds)
74
75 /**
76 * Detects when the apr_queue_t is empty. This utility function is expected
77 * to be called from within critical sections, and is not threadsafe.
78 */
79 #define apr_queue_empty(queue) ((queue)->nelts == 0)
80
81 /**
82 * Callback routine that is called to destroy this
83 * apr_queue_t when its pool is destroyed.
84 */
queue_destroy(void * data)85 static apr_status_t queue_destroy(void *data)
86 {
87 apr_queue_t *queue = data;
88
89 /* Ignore errors here, we can't do anything about them anyway. */
90
91 apr_thread_cond_destroy(queue->not_empty);
92 apr_thread_cond_destroy(queue->not_full);
93 apr_thread_mutex_destroy(queue->one_big_mutex);
94
95 return APR_SUCCESS;
96 }
97
98 /**
99 * Initialize the apr_queue_t.
100 */
apr_queue_create(apr_queue_t ** q,unsigned int queue_capacity,apr_pool_t * a)101 APU_DECLARE(apr_status_t) apr_queue_create(apr_queue_t **q,
102 unsigned int queue_capacity,
103 apr_pool_t *a)
104 {
105 apr_status_t rv;
106 apr_queue_t *queue;
107 queue = apr_palloc(a, sizeof(apr_queue_t));
108 *q = queue;
109
110 /* nested doesn't work ;( */
111 rv = apr_thread_mutex_create(&queue->one_big_mutex,
112 APR_THREAD_MUTEX_UNNESTED,
113 a);
114 if (rv != APR_SUCCESS) {
115 return rv;
116 }
117
118 rv = apr_thread_cond_create(&queue->not_empty, a);
119 if (rv != APR_SUCCESS) {
120 return rv;
121 }
122
123 rv = apr_thread_cond_create(&queue->not_full, a);
124 if (rv != APR_SUCCESS) {
125 return rv;
126 }
127
128 /* Set all the data in the queue to NULL */
129 queue->data = apr_pcalloc(a, queue_capacity * sizeof(void*));
130 queue->bounds = queue_capacity;
131 queue->nelts = 0;
132 queue->in = 0;
133 queue->out = 0;
134 queue->terminated = 0;
135 queue->full_waiters = 0;
136 queue->empty_waiters = 0;
137
138 apr_pool_cleanup_register(a, queue, queue_destroy, apr_pool_cleanup_null);
139
140 return APR_SUCCESS;
141 }
142
143 /**
144 * Push new data onto the queue. Blocks if the queue is full. Once
145 * the push operation has completed, it signals other threads waiting
146 * in apr_queue_pop() that they may continue consuming sockets.
147 */
apr_queue_push(apr_queue_t * queue,void * data)148 APU_DECLARE(apr_status_t) apr_queue_push(apr_queue_t *queue, void *data)
149 {
150 apr_status_t rv;
151
152 if (queue->terminated) {
153 return APR_EOF; /* no more elements ever again */
154 }
155
156 rv = apr_thread_mutex_lock(queue->one_big_mutex);
157 if (rv != APR_SUCCESS) {
158 return rv;
159 }
160
161 if (apr_queue_full(queue)) {
162 if (!queue->terminated) {
163 queue->full_waiters++;
164 rv = apr_thread_cond_wait(queue->not_full, queue->one_big_mutex);
165 queue->full_waiters--;
166 if (rv != APR_SUCCESS) {
167 apr_thread_mutex_unlock(queue->one_big_mutex);
168 return rv;
169 }
170 }
171 /* If we wake up and it's still empty, then we were interrupted */
172 if (apr_queue_full(queue)) {
173 Q_DBG("queue full (intr)", queue);
174 rv = apr_thread_mutex_unlock(queue->one_big_mutex);
175 if (rv != APR_SUCCESS) {
176 return rv;
177 }
178 if (queue->terminated) {
179 return APR_EOF; /* no more elements ever again */
180 }
181 else {
182 return APR_EINTR;
183 }
184 }
185 }
186
187 queue->data[queue->in] = data;
188 queue->in++;
189 if (queue->in >= queue->bounds)
190 queue->in -= queue->bounds;
191 queue->nelts++;
192
193 if (queue->empty_waiters) {
194 Q_DBG("sig !empty", queue);
195 rv = apr_thread_cond_signal(queue->not_empty);
196 if (rv != APR_SUCCESS) {
197 apr_thread_mutex_unlock(queue->one_big_mutex);
198 return rv;
199 }
200 }
201
202 rv = apr_thread_mutex_unlock(queue->one_big_mutex);
203 return rv;
204 }
205
206 /**
207 * Push new data onto the queue. If the queue is full, return APR_EAGAIN. If
208 * the push operation completes successfully, it signals other threads
209 * waiting in apr_queue_pop() that they may continue consuming sockets.
210 */
apr_queue_trypush(apr_queue_t * queue,void * data)211 APU_DECLARE(apr_status_t) apr_queue_trypush(apr_queue_t *queue, void *data)
212 {
213 apr_status_t rv;
214
215 if (queue->terminated) {
216 return APR_EOF; /* no more elements ever again */
217 }
218
219 rv = apr_thread_mutex_lock(queue->one_big_mutex);
220 if (rv != APR_SUCCESS) {
221 return rv;
222 }
223
224 if (apr_queue_full(queue)) {
225 rv = apr_thread_mutex_unlock(queue->one_big_mutex);
226 return APR_EAGAIN;
227 }
228
229 queue->data[queue->in] = data;
230 queue->in++;
231 if (queue->in >= queue->bounds)
232 queue->in -= queue->bounds;
233 queue->nelts++;
234
235 if (queue->empty_waiters) {
236 Q_DBG("sig !empty", queue);
237 rv = apr_thread_cond_signal(queue->not_empty);
238 if (rv != APR_SUCCESS) {
239 apr_thread_mutex_unlock(queue->one_big_mutex);
240 return rv;
241 }
242 }
243
244 rv = apr_thread_mutex_unlock(queue->one_big_mutex);
245 return rv;
246 }
247
248 /**
249 * not thread safe
250 */
apr_queue_size(apr_queue_t * queue)251 APU_DECLARE(unsigned int) apr_queue_size(apr_queue_t *queue) {
252 return queue->nelts;
253 }
254
255 /**
256 * Retrieves the next item from the queue. If there are no
257 * items available, it will block until one becomes available.
258 * Once retrieved, the item is placed into the address specified by
259 * 'data'.
260 */
apr_queue_pop(apr_queue_t * queue,void ** data)261 APU_DECLARE(apr_status_t) apr_queue_pop(apr_queue_t *queue, void **data)
262 {
263 apr_status_t rv;
264
265 if (queue->terminated) {
266 return APR_EOF; /* no more elements ever again */
267 }
268
269 rv = apr_thread_mutex_lock(queue->one_big_mutex);
270 if (rv != APR_SUCCESS) {
271 return rv;
272 }
273
274 /* Keep waiting until we wake up and find that the queue is not empty. */
275 if (apr_queue_empty(queue)) {
276 if (!queue->terminated) {
277 queue->empty_waiters++;
278 rv = apr_thread_cond_wait(queue->not_empty, queue->one_big_mutex);
279 queue->empty_waiters--;
280 if (rv != APR_SUCCESS) {
281 apr_thread_mutex_unlock(queue->one_big_mutex);
282 return rv;
283 }
284 }
285 /* If we wake up and it's still empty, then we were interrupted */
286 if (apr_queue_empty(queue)) {
287 Q_DBG("queue empty (intr)", queue);
288 rv = apr_thread_mutex_unlock(queue->one_big_mutex);
289 if (rv != APR_SUCCESS) {
290 return rv;
291 }
292 if (queue->terminated) {
293 return APR_EOF; /* no more elements ever again */
294 }
295 else {
296 return APR_EINTR;
297 }
298 }
299 }
300
301 *data = queue->data[queue->out];
302 queue->nelts--;
303
304 queue->out++;
305 if (queue->out >= queue->bounds)
306 queue->out -= queue->bounds;
307 if (queue->full_waiters) {
308 Q_DBG("signal !full", queue);
309 rv = apr_thread_cond_signal(queue->not_full);
310 if (rv != APR_SUCCESS) {
311 apr_thread_mutex_unlock(queue->one_big_mutex);
312 return rv;
313 }
314 }
315
316 rv = apr_thread_mutex_unlock(queue->one_big_mutex);
317 return rv;
318 }
319
320 /**
321 * Retrieves the next item from the queue. If there are no
322 * items available, return APR_EAGAIN. Once retrieved,
323 * the item is placed into the address specified by 'data'.
324 */
apr_queue_trypop(apr_queue_t * queue,void ** data)325 APU_DECLARE(apr_status_t) apr_queue_trypop(apr_queue_t *queue, void **data)
326 {
327 apr_status_t rv;
328
329 if (queue->terminated) {
330 return APR_EOF; /* no more elements ever again */
331 }
332
333 rv = apr_thread_mutex_lock(queue->one_big_mutex);
334 if (rv != APR_SUCCESS) {
335 return rv;
336 }
337
338 if (apr_queue_empty(queue)) {
339 rv = apr_thread_mutex_unlock(queue->one_big_mutex);
340 return APR_EAGAIN;
341 }
342
343 *data = queue->data[queue->out];
344 queue->nelts--;
345
346 queue->out++;
347 if (queue->out >= queue->bounds)
348 queue->out -= queue->bounds;
349 if (queue->full_waiters) {
350 Q_DBG("signal !full", queue);
351 rv = apr_thread_cond_signal(queue->not_full);
352 if (rv != APR_SUCCESS) {
353 apr_thread_mutex_unlock(queue->one_big_mutex);
354 return rv;
355 }
356 }
357
358 rv = apr_thread_mutex_unlock(queue->one_big_mutex);
359 return rv;
360 }
361
apr_queue_interrupt_all(apr_queue_t * queue)362 APU_DECLARE(apr_status_t) apr_queue_interrupt_all(apr_queue_t *queue)
363 {
364 apr_status_t rv;
365 Q_DBG("intr all", queue);
366 if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
367 return rv;
368 }
369 apr_thread_cond_broadcast(queue->not_empty);
370 apr_thread_cond_broadcast(queue->not_full);
371
372 if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) {
373 return rv;
374 }
375
376 return APR_SUCCESS;
377 }
378
apr_queue_term(apr_queue_t * queue)379 APU_DECLARE(apr_status_t) apr_queue_term(apr_queue_t *queue)
380 {
381 apr_status_t rv;
382
383 if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
384 return rv;
385 }
386
387 /* we must hold one_big_mutex when setting this... otherwise,
388 * we could end up setting it and waking everybody up just after a
389 * would-be popper checks it but right before they block
390 */
391 queue->terminated = 1;
392 if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) {
393 return rv;
394 }
395 return apr_queue_interrupt_all(queue);
396 }
397
398 #endif /* APR_HAS_THREADS */
399