Fix: protect the channel's metadata stream using the metadata cache lock
[lttng-tools.git] / src / common / consumer / consumer-metadata-cache.c
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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
6c1c0768 19#define _LGPL_SOURCE
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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>
c8fea79c 32#include <common/consumer/consumer.h>
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33
34#include "consumer-metadata-cache.h"
35
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36extern struct lttng_consumer_global_data consumer_data;
37
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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 */
44static int extend_metadata_cache(struct lttng_consumer_channel *channel,
45 unsigned int size)
46{
47 int ret = 0;
48 char *tmp_data_ptr;
53efb85a 49 unsigned int new_size, old_size;
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50
51 assert(channel);
52 assert(channel->metadata_cache);
53
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54 old_size = channel->metadata_cache->cache_alloc_size;
55 new_size = max_t(unsigned int, old_size + size, old_size << 1);
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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 }
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64 /* Zero newly allocated memory */
65 memset(tmp_data_ptr + old_size, 0, new_size - old_size);
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66 channel->metadata_cache->data = tmp_data_ptr;
67 channel->metadata_cache->cache_alloc_size = new_size;
68
69end:
70 return ret;
71}
72
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73/*
74 * Reset the metadata cache.
75 */
76static
77void 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 */
90static
91int 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
104end:
105 return ret;
106}
107
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108/*
109 * Write metadata to the cache, extend the cache if necessary. We support
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110 * overlapping updates, but they need to be contiguous. Send the
111 * contiguous metadata in cache to the ring buffer. The metadata cache
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112 * lock MUST be acquired to write in the cache.
113 *
114 * Return 0 on success, a negative value on error.
115 */
116int consumer_metadata_cache_write(struct lttng_consumer_channel *channel,
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117 unsigned int offset, unsigned int len, uint64_t version,
118 char *data)
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119{
120 int ret = 0;
6cd525e8 121 int size_ret;
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122 struct consumer_metadata_cache *cache;
123
124 assert(channel);
125 assert(channel->metadata_cache);
126
127 cache = channel->metadata_cache;
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128
129 ret = metadata_cache_check_version(cache, channel, version);
130 if (ret < 0) {
131 goto end;
132 }
133
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134 DBG("Writing %u bytes from offset %u in metadata cache", len, offset);
135
136 if (offset + len > cache->cache_alloc_size) {
137 ret = extend_metadata_cache(channel,
138 len - cache->cache_alloc_size + offset);
139 if (ret < 0) {
140 ERR("Extending metadata cache");
141 goto end;
142 }
143 }
144
145 memcpy(cache->data + offset, data, len);
331744e3 146 if (offset + len > cache->max_offset) {
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147 char dummy = 'c';
148
c585821b 149 cache->max_offset = offset + len;
5feafd41 150 if (channel->monitor && channel->metadata_stream) {
6cd525e8 151 size_ret = lttng_write(channel->metadata_stream->ust_metadata_poll_pipe[1],
04ef1097 152 &dummy, 1);
6cd525e8 153 if (size_ret < 1) {
04ef1097 154 ERR("Wakeup UST metadata pipe");
6cd525e8 155 ret = -1;
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156 goto end;
157 }
331744e3 158 }
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159 }
160
161end:
162 return ret;
163}
164
165/*
166 * Create the metadata cache, original allocated size: max_sb_size
167 *
168 * Return 0 on success, a negative value on error.
169 */
170int consumer_metadata_cache_allocate(struct lttng_consumer_channel *channel)
171{
172 int ret;
173
174 assert(channel);
175
176 channel->metadata_cache = zmalloc(
177 sizeof(struct consumer_metadata_cache));
178 if (!channel->metadata_cache) {
179 PERROR("zmalloc metadata cache struct");
180 ret = -1;
181 goto end;
182 }
183 ret = pthread_mutex_init(&channel->metadata_cache->lock, NULL);
184 if (ret != 0) {
185 PERROR("mutex init");
186 goto end_free_cache;
187 }
188
189 channel->metadata_cache->cache_alloc_size = DEFAULT_METADATA_CACHE_SIZE;
190 channel->metadata_cache->data = zmalloc(
191 channel->metadata_cache->cache_alloc_size * sizeof(char));
192 if (!channel->metadata_cache->data) {
193 PERROR("zmalloc metadata cache data");
194 ret = -1;
195 goto end_free_mutex;
196 }
197 DBG("Allocated metadata cache of %" PRIu64 " bytes",
198 channel->metadata_cache->cache_alloc_size);
199
200 ret = 0;
201 goto end;
202
203end_free_mutex:
204 pthread_mutex_destroy(&channel->metadata_cache->lock);
205end_free_cache:
206 free(channel->metadata_cache);
207end:
208 return ret;
209}
210
211/*
212 * Destroy and free the metadata cache
213 */
214void consumer_metadata_cache_destroy(struct lttng_consumer_channel *channel)
215{
216 if (!channel || !channel->metadata_cache) {
217 return;
218 }
219
220 DBG("Destroying metadata cache");
221
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222 pthread_mutex_destroy(&channel->metadata_cache->lock);
223 free(channel->metadata_cache->data);
224 free(channel->metadata_cache);
225}
226
227/*
228 * Check if the cache is flushed up to the offset passed in parameter.
229 *
230 * Return 0 if everything has been flushed, 1 if there is data not flushed.
231 */
232int consumer_metadata_cache_flushed(struct lttng_consumer_channel *channel,
5e41ebe1 233 uint64_t offset, int timer)
331744e3 234{
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235 int ret = 0;
236 struct lttng_consumer_stream *metadata_stream;
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237
238 assert(channel);
239 assert(channel->metadata_cache);
240
7f725ec5 241 /*
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242 * If not called from a timer handler, we have to take the
243 * channel lock to be mutually exclusive with channel teardown.
244 * Timer handler does not need to take this lock because it is
245 * already synchronized by timer stop (and, more importantly,
246 * taking this lock in a timer handler would cause a deadlock).
7f725ec5 247 */
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248 if (!timer) {
249 pthread_mutex_lock(&channel->lock);
250 }
ec6ea7d0 251 pthread_mutex_lock(&channel->timer_lock);
331744e3 252 pthread_mutex_lock(&channel->metadata_cache->lock);
fe81e5c9 253
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254 metadata_stream = channel->metadata_stream;
255
256 if (!metadata_stream) {
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257 /*
258 * Having no metadata stream means the channel is being destroyed so there
259 * is no cache to flush anymore.
260 */
261 ret = 0;
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262 } else if (metadata_stream->ust_metadata_pushed >= offset) {
263 ret = 0;
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264 } else if (channel->metadata_stream->endpoint_status !=
265 CONSUMER_ENDPOINT_ACTIVE) {
266 /* An inactive endpoint means we don't have to flush anymore. */
267 ret = 0;
331744e3 268 } else {
fe81e5c9 269 /* Still not completely flushed. */
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270 ret = 1;
271 }
fe81e5c9 272
331744e3 273 pthread_mutex_unlock(&channel->metadata_cache->lock);
ec6ea7d0 274 pthread_mutex_unlock(&channel->timer_lock);
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275 if (!timer) {
276 pthread_mutex_unlock(&channel->lock);
277 }
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278
279 return ret;
280}
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