Dedicated function to wakeup the consumer metadata pipe
[lttng-tools.git] / src / common / consumer / consumer-metadata-cache.c
1 /*
2 * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
3 * David Goulet <dgoulet@efficios.com>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License, version 2 only,
7 * as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 *
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
17 */
18
19 #define _LGPL_SOURCE
20 #include <assert.h>
21 #include <pthread.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <sys/types.h>
25 #include <unistd.h>
26 #include <inttypes.h>
27
28 #include <common/common.h>
29 #include <common/utils.h>
30 #include <common/sessiond-comm/sessiond-comm.h>
31 #include <common/ust-consumer/ust-consumer.h>
32 #include <common/consumer/consumer.h>
33
34 #include "consumer-metadata-cache.h"
35
36 extern struct lttng_consumer_global_data consumer_data;
37
38 /*
39 * Extend the allocated size of the metadata cache. Called only from
40 * lttng_ustconsumer_write_metadata_cache.
41 *
42 * Return 0 on success, a negative value on error.
43 */
44 static int extend_metadata_cache(struct lttng_consumer_channel *channel,
45 unsigned int size)
46 {
47 int ret = 0;
48 char *tmp_data_ptr;
49 unsigned int new_size, old_size;
50
51 assert(channel);
52 assert(channel->metadata_cache);
53
54 old_size = channel->metadata_cache->cache_alloc_size;
55 new_size = max_t(unsigned int, old_size + size, old_size << 1);
56 DBG("Extending metadata cache to %u", new_size);
57 tmp_data_ptr = realloc(channel->metadata_cache->data, new_size);
58 if (!tmp_data_ptr) {
59 ERR("Reallocating metadata cache");
60 free(channel->metadata_cache->data);
61 ret = -1;
62 goto end;
63 }
64 /* Zero newly allocated memory */
65 memset(tmp_data_ptr + old_size, 0, new_size - old_size);
66 channel->metadata_cache->data = tmp_data_ptr;
67 channel->metadata_cache->cache_alloc_size = new_size;
68
69 end:
70 return ret;
71 }
72
73 /*
74 * Reset the metadata cache.
75 */
76 static
77 void metadata_cache_reset(struct consumer_metadata_cache *cache)
78 {
79 memset(cache->data, 0, cache->cache_alloc_size);
80 cache->max_offset = 0;
81 }
82
83 /*
84 * Check if the metadata cache version changed.
85 * If it did, reset the metadata cache.
86 * The metadata cache lock MUST be held.
87 *
88 * Returns 0 on success, a negative value on error.
89 */
90 static
91 int metadata_cache_check_version(struct consumer_metadata_cache *cache,
92 struct lttng_consumer_channel *channel, uint64_t version)
93 {
94 int ret = 0;
95
96 if (cache->version == version) {
97 goto end;
98 }
99
100 DBG("Metadata cache version update to %" PRIu64, version);
101 metadata_cache_reset(cache);
102 cache->version = version;
103
104 end:
105 return ret;
106 }
107
108 /*
109 * Write a character on the metadata poll pipe to wake the metadata thread.
110 * Returns 0 on success, -1 on error.
111 */
112 int consumer_metadata_wakeup_pipe(const struct lttng_consumer_channel *channel)
113 {
114 int ret = 0;
115 const char dummy = 'c';
116
117 if (channel->monitor && channel->metadata_stream) {
118 ssize_t write_ret;
119
120 write_ret = lttng_write(channel->metadata_stream->ust_metadata_poll_pipe[1],
121 &dummy, 1);
122 if (write_ret < 1) {
123 PERROR("Wake-up UST metadata pipe");
124 ret = -1;
125 goto end;
126 }
127 }
128
129 end:
130 return ret;
131 }
132
133 /*
134 * Write metadata to the cache, extend the cache if necessary. We support
135 * overlapping updates, but they need to be contiguous. Send the
136 * contiguous metadata in cache to the ring buffer. The metadata cache
137 * lock MUST be acquired to write in the cache.
138 *
139 * Return 0 on success, a negative value on error.
140 */
141 int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
142 unsigned int offset, unsigned int len, uint64_t version,
143 char *data)
144 {
145 int ret = 0;
146 struct consumer_metadata_cache *cache;
147
148 assert(channel);
149 assert(channel->metadata_cache);
150
151 cache = channel->metadata_cache;
152
153 ret = metadata_cache_check_version(cache, channel, version);
154 if (ret < 0) {
155 goto end;
156 }
157
158 DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
159
160 if (offset + len > cache->cache_alloc_size) {
161 ret = extend_metadata_cache(channel,
162 len - cache->cache_alloc_size + offset);
163 if (ret < 0) {
164 ERR("Extending metadata cache");
165 goto end;
166 }
167 }
168
169 memcpy(cache->data + offset, data, len);
170 if (offset + len > cache->max_offset) {
171 cache->max_offset = offset + len;
172 ret = consumer_metadata_wakeup_pipe(channel);
173 }
174
175 end:
176 return ret;
177 }
178
179 /*
180 * Create the metadata cache, original allocated size: max_sb_size
181 *
182 * Return 0 on success, a negative value on error.
183 */
184 int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
185 {
186 int ret;
187
188 assert(channel);
189
190 channel->metadata_cache = zmalloc(
191 sizeof(struct consumer_metadata_cache));
192 if (!channel->metadata_cache) {
193 PERROR("zmalloc metadata cache struct");
194 ret = -1;
195 goto end;
196 }
197 ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
198 if (ret != 0) {
199 PERROR("mutex init");
200 goto end_free_cache;
201 }
202
203 channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
204 channel->metadata_cache->data = zmalloc(
205 channel->metadata_cache->cache_alloc_size * sizeof(char));
206 if (!channel->metadata_cache->data) {
207 PERROR("zmalloc metadata cache data");
208 ret = -1;
209 goto end_free_mutex;
210 }
211 DBG("Allocated metadata cache of %" PRIu64 " bytes",
212 channel->metadata_cache->cache_alloc_size);
213
214 ret = 0;
215 goto end;
216
217 end_free_mutex:
218 pthread_mutex_destroy(&channel->metadata_cache->lock);
219 end_free_cache:
220 free(channel->metadata_cache);
221 end:
222 return ret;
223 }
224
225 /*
226 * Destroy and free the metadata cache
227 */
228 void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
229 {
230 if (!channel || !channel->metadata_cache) {
231 return;
232 }
233
234 DBG("Destroying metadata cache");
235
236 pthread_mutex_destroy(&channel->metadata_cache->lock);
237 free(channel->metadata_cache->data);
238 free(channel->metadata_cache);
239 }
240
241 /*
242 * Check if the cache is flushed up to the offset passed in parameter.
243 *
244 * Return 0 if everything has been flushed, 1 if there is data not flushed.
245 */
246 int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
247 uint64_t offset, int timer)
248 {
249 int ret = 0;
250 struct lttng_consumer_stream *metadata_stream;
251
252 assert(channel);
253 assert(channel->metadata_cache);
254
255 /*
256 * If not called from a timer handler, we have to take the
257 * channel lock to be mutually exclusive with channel teardown.
258 * Timer handler does not need to take this lock because it is
259 * already synchronized by timer stop (and, more importantly,
260 * taking this lock in a timer handler would cause a deadlock).
261 */
262 if (!timer) {
263 pthread_mutex_lock(&channel->lock);
264 }
265 pthread_mutex_lock(&channel->timer_lock);
266 pthread_mutex_lock(&channel->metadata_cache->lock);
267
268 metadata_stream = channel->metadata_stream;
269
270 if (!metadata_stream) {
271 /*
272 * Having no metadata stream means the channel is being destroyed so there
273 * is no cache to flush anymore.
274 */
275 ret = 0;
276 } else if (metadata_stream->ust_metadata_pushed >= offset) {
277 ret = 0;
278 } else if (channel->metadata_stream->endpoint_status !=
279 CONSUMER_ENDPOINT_ACTIVE) {
280 /* An inactive endpoint means we don't have to flush anymore. */
281 ret = 0;
282 } else {
283 /* Still not completely flushed. */
284 ret = 1;
285 }
286
287 pthread_mutex_unlock(&channel->metadata_cache->lock);
288 pthread_mutex_unlock(&channel->timer_lock);
289 if (!timer) {
290 pthread_mutex_unlock(&channel->lock);
291 }
292
293 return ret;
294 }
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