| 1 | /* |
| 2 | * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: GPL-2.0-only |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #include "sessiond-trace-chunks.hpp" |
| 9 | |
| 10 | #include <common/defaults.hpp> |
| 11 | #include <common/error.hpp> |
| 12 | #include <common/hashtable/hashtable.hpp> |
| 13 | #include <common/hashtable/utils.hpp> |
| 14 | #include <common/macros.hpp> |
| 15 | #include <common/string-utils/format.hpp> |
| 16 | #include <common/trace-chunk-registry.hpp> |
| 17 | #include <common/urcu.hpp> |
| 18 | |
| 19 | #include <inttypes.h> |
| 20 | #include <stdio.h> |
| 21 | #include <urcu.h> |
| 22 | #include <urcu/rculfhash.h> |
| 23 | #include <urcu/ref.h> |
| 24 | |
| 25 | /* |
| 26 | * Lifetime of trace chunks within the relay daemon. |
| 27 | * |
| 28 | * Trace chunks are shared accross connections initiated from a given |
| 29 | * session daemon. When a session is created by a consumer daemon, the |
| 30 | * UUID of its associated session daemon is transmitted (in the case of |
| 31 | * 2.11+ consumer daemons). |
| 32 | * |
| 33 | * The sessiond_trace_chunk_registry_new_session() and |
| 34 | * sessiond_trace_chunk_registry_session_closed() methods create and |
| 35 | * manage the reference count of lttng_trace_chunk_registry objects |
| 36 | * associated to the various sessiond instances served by the relay daemon. |
| 37 | * |
| 38 | * When all sessions associated with a given sessiond instance are |
| 39 | * destroyed, its registry is destroyed. |
| 40 | * |
| 41 | * lttng_trace_chunk objects are uniquely identified by the |
| 42 | * (sessiond_uuid, sessiond_session_id, chunk_id) tuple. If a trace chunk |
| 43 | * matching that tuple already exists, a new reference to the trace chunk |
| 44 | * is acquired and it is returned to the caller. Otherwise, a new trace |
| 45 | * chunk is created. This is how trace chunks are de-duplicated across |
| 46 | * multiple consumer daemons managed by the same session daemon. |
| 47 | * |
| 48 | * Note that trace chunks are always added to their matching |
| 49 | * lttng_trace_chunk_registry. They are automatically removed from the |
| 50 | * trace chunk registry when their reference count reaches zero. |
| 51 | */ |
| 52 | |
| 53 | /* |
| 54 | * It is assumed that the sessiond_trace_chunk_registry is created and |
| 55 | * destroyed by the same thread. |
| 56 | */ |
| 57 | struct sessiond_trace_chunk_registry { |
| 58 | /* Maps an lttng_uuid to an lttng_trace_chunk_registry. */ |
| 59 | struct cds_lfht *ht; |
| 60 | }; |
| 61 | |
| 62 | namespace { |
| 63 | struct trace_chunk_registry_ht_key { |
| 64 | lttng_uuid sessiond_uuid; |
| 65 | }; |
| 66 | |
| 67 | struct trace_chunk_registry_ht_element { |
| 68 | struct trace_chunk_registry_ht_key key; |
| 69 | struct urcu_ref ref; |
| 70 | /* Node into the sessiond_trace_chunk_registry's hash table. */ |
| 71 | struct cds_lfht_node ht_node; |
| 72 | /* Used for defered call_rcu reclaim. */ |
| 73 | struct rcu_head rcu_node; |
| 74 | struct lttng_trace_chunk_registry *trace_chunk_registry; |
| 75 | struct sessiond_trace_chunk_registry *sessiond_trace_chunk_registry; |
| 76 | }; |
| 77 | } /* namespace */ |
| 78 | |
| 79 | static unsigned long trace_chunk_registry_ht_key_hash(const struct trace_chunk_registry_ht_key *key) |
| 80 | { |
| 81 | const uint64_t uuid_h1 = reinterpret_cast<const uint64_t *>(key->sessiond_uuid.data())[0]; |
| 82 | const uint64_t uuid_h2 = reinterpret_cast<const uint64_t *>(key->sessiond_uuid.data())[1]; |
| 83 | |
| 84 | return hash_key_u64(&uuid_h1, lttng_ht_seed) ^ hash_key_u64(&uuid_h2, lttng_ht_seed); |
| 85 | } |
| 86 | |
| 87 | /* cds_lfht match function */ |
| 88 | static int trace_chunk_registry_ht_key_match(struct cds_lfht_node *node, const void *_key) |
| 89 | { |
| 90 | const struct trace_chunk_registry_ht_key *key = (struct trace_chunk_registry_ht_key *) _key; |
| 91 | struct trace_chunk_registry_ht_element *registry; |
| 92 | |
| 93 | registry = lttng::utils::container_of(node, &trace_chunk_registry_ht_element::ht_node); |
| 94 | return key->sessiond_uuid == registry->key.sessiond_uuid; |
| 95 | } |
| 96 | |
| 97 | static void trace_chunk_registry_ht_element_free(struct rcu_head *node) |
| 98 | { |
| 99 | struct trace_chunk_registry_ht_element *element = |
| 100 | lttng::utils::container_of(node, &trace_chunk_registry_ht_element::rcu_node); |
| 101 | |
| 102 | free(element); |
| 103 | } |
| 104 | |
| 105 | static void trace_chunk_registry_ht_element_release(struct urcu_ref *ref) |
| 106 | { |
| 107 | struct trace_chunk_registry_ht_element *element = |
| 108 | lttng::utils::container_of(ref, &trace_chunk_registry_ht_element::ref); |
| 109 | char uuid_str[LTTNG_UUID_STR_LEN]; |
| 110 | |
| 111 | lttng_uuid_to_str(element->key.sessiond_uuid, uuid_str); |
| 112 | |
| 113 | DBG("Destroying trace chunk registry associated to sessiond {%s}", uuid_str); |
| 114 | if (element->sessiond_trace_chunk_registry) { |
| 115 | /* Unpublish. */ |
| 116 | lttng::urcu::read_lock_guard read_lock; |
| 117 | cds_lfht_del(element->sessiond_trace_chunk_registry->ht, &element->ht_node); |
| 118 | element->sessiond_trace_chunk_registry = nullptr; |
| 119 | } |
| 120 | |
| 121 | lttng_trace_chunk_registry_destroy(element->trace_chunk_registry); |
| 122 | /* Defered reclaim of the object */ |
| 123 | call_rcu(&element->rcu_node, trace_chunk_registry_ht_element_free); |
| 124 | } |
| 125 | |
| 126 | static bool trace_chunk_registry_ht_element_get(struct trace_chunk_registry_ht_element *element) |
| 127 | { |
| 128 | return urcu_ref_get_unless_zero(&element->ref); |
| 129 | } |
| 130 | |
| 131 | static void trace_chunk_registry_ht_element_put(struct trace_chunk_registry_ht_element *element) |
| 132 | { |
| 133 | if (!element) { |
| 134 | return; |
| 135 | } |
| 136 | |
| 137 | urcu_ref_put(&element->ref, trace_chunk_registry_ht_element_release); |
| 138 | } |
| 139 | |
| 140 | /* Acquires a reference to the returned element on behalf of the caller. */ |
| 141 | static struct trace_chunk_registry_ht_element * |
| 142 | trace_chunk_registry_ht_element_find(struct sessiond_trace_chunk_registry *sessiond_registry, |
| 143 | const struct trace_chunk_registry_ht_key *key) |
| 144 | { |
| 145 | struct trace_chunk_registry_ht_element *element = nullptr; |
| 146 | struct cds_lfht_node *node; |
| 147 | struct cds_lfht_iter iter; |
| 148 | |
| 149 | lttng::urcu::read_lock_guard read_lock; |
| 150 | cds_lfht_lookup(sessiond_registry->ht, |
| 151 | trace_chunk_registry_ht_key_hash(key), |
| 152 | trace_chunk_registry_ht_key_match, |
| 153 | key, |
| 154 | &iter); |
| 155 | node = cds_lfht_iter_get_node(&iter); |
| 156 | if (node) { |
| 157 | element = |
| 158 | lttng::utils::container_of(node, &trace_chunk_registry_ht_element::ht_node); |
| 159 | /* |
| 160 | * Only consider the look-up as successful if a reference |
| 161 | * could be acquired. |
| 162 | */ |
| 163 | if (!trace_chunk_registry_ht_element_get(element)) { |
| 164 | element = nullptr; |
| 165 | } |
| 166 | } |
| 167 | return element; |
| 168 | } |
| 169 | |
| 170 | static int |
| 171 | trace_chunk_registry_ht_element_create(struct sessiond_trace_chunk_registry *sessiond_registry, |
| 172 | const struct trace_chunk_registry_ht_key *key) |
| 173 | { |
| 174 | int ret = 0; |
| 175 | struct trace_chunk_registry_ht_element *new_element; |
| 176 | struct lttng_trace_chunk_registry *trace_chunk_registry; |
| 177 | char uuid_str[LTTNG_UUID_STR_LEN]; |
| 178 | |
| 179 | lttng_uuid_to_str(key->sessiond_uuid, uuid_str); |
| 180 | |
| 181 | trace_chunk_registry = lttng_trace_chunk_registry_create(); |
| 182 | if (!trace_chunk_registry) { |
| 183 | ret = -1; |
| 184 | goto end; |
| 185 | } |
| 186 | |
| 187 | new_element = zmalloc<trace_chunk_registry_ht_element>(); |
| 188 | if (!new_element) { |
| 189 | ret = -1; |
| 190 | goto end; |
| 191 | } |
| 192 | |
| 193 | memcpy(&new_element->key, key, sizeof(new_element->key)); |
| 194 | urcu_ref_init(&new_element->ref); |
| 195 | cds_lfht_node_init(&new_element->ht_node); |
| 196 | new_element->trace_chunk_registry = trace_chunk_registry; |
| 197 | trace_chunk_registry = nullptr; |
| 198 | |
| 199 | /* Attempt to publish the new element. */ |
| 200 | { |
| 201 | /* |
| 202 | * Keep the rcu read lock is held accross all attempts |
| 203 | * purely for efficiency reasons. |
| 204 | */ |
| 205 | lttng::urcu::read_lock_guard read_lock; |
| 206 | while (true) { |
| 207 | struct cds_lfht_node *published_node; |
| 208 | struct trace_chunk_registry_ht_element *published_element; |
| 209 | |
| 210 | published_node = cds_lfht_add_unique( |
| 211 | sessiond_registry->ht, |
| 212 | trace_chunk_registry_ht_key_hash(&new_element->key), |
| 213 | trace_chunk_registry_ht_key_match, |
| 214 | &new_element->key, |
| 215 | &new_element->ht_node); |
| 216 | if (published_node == &new_element->ht_node) { |
| 217 | /* New element published successfully. */ |
| 218 | DBG("Created trace chunk registry for sessiond {%s}", uuid_str); |
| 219 | new_element->sessiond_trace_chunk_registry = sessiond_registry; |
| 220 | break; |
| 221 | } |
| 222 | |
| 223 | /* |
| 224 | * An equivalent element was published during the creation of |
| 225 | * this element. Attempt to acquire a reference to the one that |
| 226 | * was already published and release the reference to the copy |
| 227 | * we created if successful. |
| 228 | */ |
| 229 | published_element = lttng::utils::container_of( |
| 230 | published_node, &trace_chunk_registry_ht_element::ht_node); |
| 231 | if (trace_chunk_registry_ht_element_get(published_element)) { |
| 232 | DBG("Acquired reference to trace chunk registry of sessiond {%s}", |
| 233 | uuid_str); |
| 234 | trace_chunk_registry_ht_element_put(new_element); |
| 235 | new_element = nullptr; |
| 236 | break; |
| 237 | } |
| 238 | /* |
| 239 | * A reference to the previously published element could not |
| 240 | * be acquired. Hence, retry to publish our copy of the |
| 241 | * element. |
| 242 | */ |
| 243 | } |
| 244 | } |
| 245 | end: |
| 246 | if (ret < 0) { |
| 247 | ERR("Failed to create trace chunk registry for session daemon {%s}", uuid_str); |
| 248 | } |
| 249 | lttng_trace_chunk_registry_destroy(trace_chunk_registry); |
| 250 | return ret; |
| 251 | } |
| 252 | |
| 253 | struct sessiond_trace_chunk_registry *sessiond_trace_chunk_registry_create() |
| 254 | { |
| 255 | struct sessiond_trace_chunk_registry *sessiond_registry = |
| 256 | zmalloc<sessiond_trace_chunk_registry>(); |
| 257 | |
| 258 | if (!sessiond_registry) { |
| 259 | goto end; |
| 260 | } |
| 261 | |
| 262 | sessiond_registry->ht = cds_lfht_new( |
| 263 | DEFAULT_HT_SIZE, 1, 0, CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, nullptr); |
| 264 | if (!sessiond_registry->ht) { |
| 265 | goto error; |
| 266 | } |
| 267 | |
| 268 | end: |
| 269 | return sessiond_registry; |
| 270 | error: |
| 271 | sessiond_trace_chunk_registry_destroy(sessiond_registry); |
| 272 | return nullptr; |
| 273 | } |
| 274 | |
| 275 | void sessiond_trace_chunk_registry_destroy(struct sessiond_trace_chunk_registry *sessiond_registry) |
| 276 | { |
| 277 | int ret = cds_lfht_destroy(sessiond_registry->ht, nullptr); |
| 278 | |
| 279 | LTTNG_ASSERT(!ret); |
| 280 | free(sessiond_registry); |
| 281 | } |
| 282 | |
| 283 | int sessiond_trace_chunk_registry_session_created( |
| 284 | struct sessiond_trace_chunk_registry *sessiond_registry, const lttng_uuid& sessiond_uuid) |
| 285 | { |
| 286 | int ret = 0; |
| 287 | struct trace_chunk_registry_ht_key key; |
| 288 | struct trace_chunk_registry_ht_element *element; |
| 289 | |
| 290 | key.sessiond_uuid = sessiond_uuid; |
| 291 | |
| 292 | element = trace_chunk_registry_ht_element_find(sessiond_registry, &key); |
| 293 | if (element) { |
| 294 | char uuid_str[LTTNG_UUID_STR_LEN]; |
| 295 | |
| 296 | lttng_uuid_to_str(sessiond_uuid, uuid_str); |
| 297 | DBG("Acquired reference to trace chunk registry of sessiond {%s}", uuid_str); |
| 298 | goto end; |
| 299 | } else { |
| 300 | ret = trace_chunk_registry_ht_element_create(sessiond_registry, &key); |
| 301 | } |
| 302 | end: |
| 303 | return ret; |
| 304 | } |
| 305 | |
| 306 | int sessiond_trace_chunk_registry_session_destroyed( |
| 307 | struct sessiond_trace_chunk_registry *sessiond_registry, const lttng_uuid& sessiond_uuid) |
| 308 | { |
| 309 | int ret = 0; |
| 310 | struct trace_chunk_registry_ht_key key; |
| 311 | struct trace_chunk_registry_ht_element *element; |
| 312 | char uuid_str[LTTNG_UUID_STR_LEN]; |
| 313 | |
| 314 | lttng_uuid_to_str(sessiond_uuid, uuid_str); |
| 315 | key.sessiond_uuid = sessiond_uuid; |
| 316 | |
| 317 | element = trace_chunk_registry_ht_element_find(sessiond_registry, &key); |
| 318 | if (element) { |
| 319 | DBG("Releasing reference to trace chunk registry of sessiond {%s}", uuid_str); |
| 320 | /* |
| 321 | * Release the reference held by the session and the reference |
| 322 | * acquired through the "find" operation. |
| 323 | */ |
| 324 | trace_chunk_registry_ht_element_put(element); |
| 325 | trace_chunk_registry_ht_element_put(element); |
| 326 | } else { |
| 327 | ERR("Failed to find trace chunk registry of sessiond {%s}", uuid_str); |
| 328 | ret = -1; |
| 329 | } |
| 330 | return ret; |
| 331 | } |
| 332 | |
| 333 | struct lttng_trace_chunk * |
| 334 | sessiond_trace_chunk_registry_publish_chunk(struct sessiond_trace_chunk_registry *sessiond_registry, |
| 335 | const lttng_uuid& sessiond_uuid, |
| 336 | uint64_t session_id, |
| 337 | struct lttng_trace_chunk *new_chunk) |
| 338 | { |
| 339 | enum lttng_trace_chunk_status status; |
| 340 | uint64_t chunk_id; |
| 341 | bool is_anonymous_chunk; |
| 342 | struct trace_chunk_registry_ht_key key; |
| 343 | struct trace_chunk_registry_ht_element *element = nullptr; |
| 344 | char uuid_str[LTTNG_UUID_STR_LEN]; |
| 345 | char chunk_id_str[MAX_INT_DEC_LEN(typeof(chunk_id))] = "-1"; |
| 346 | struct lttng_trace_chunk *published_chunk = nullptr; |
| 347 | bool trace_chunk_already_published; |
| 348 | |
| 349 | lttng_uuid_to_str(sessiond_uuid, uuid_str); |
| 350 | key.sessiond_uuid = sessiond_uuid; |
| 351 | |
| 352 | status = lttng_trace_chunk_get_id(new_chunk, &chunk_id); |
| 353 | if (status == LTTNG_TRACE_CHUNK_STATUS_OK) { |
| 354 | int ret; |
| 355 | |
| 356 | ret = snprintf(chunk_id_str, sizeof(chunk_id_str), "%" PRIu64, chunk_id); |
| 357 | if (ret < 0) { |
| 358 | lttng_strncpy(chunk_id_str, "-1", sizeof(chunk_id_str)); |
| 359 | WARN("Failed to format trace chunk id"); |
| 360 | } |
| 361 | is_anonymous_chunk = false; |
| 362 | } else if (status == LTTNG_TRACE_CHUNK_STATUS_NONE) { |
| 363 | is_anonymous_chunk = true; |
| 364 | } else { |
| 365 | ERR("Failed to get trace chunk id"); |
| 366 | goto end; |
| 367 | } |
| 368 | |
| 369 | DBG("Attempting to publish trace chunk: sessiond {%s}, session_id = " |
| 370 | "%" PRIu64 ", chunk_id = %s", |
| 371 | uuid_str, |
| 372 | session_id, |
| 373 | is_anonymous_chunk ? "anonymous" : chunk_id_str); |
| 374 | |
| 375 | element = trace_chunk_registry_ht_element_find(sessiond_registry, &key); |
| 376 | if (!element) { |
| 377 | ERR("Failed to find registry of sessiond {%s}", uuid_str); |
| 378 | goto end; |
| 379 | } |
| 380 | |
| 381 | published_chunk = lttng_trace_chunk_registry_publish_chunk(element->trace_chunk_registry, |
| 382 | session_id, |
| 383 | new_chunk, |
| 384 | &trace_chunk_already_published); |
| 385 | /* |
| 386 | * When the trace chunk is first published, two references to the |
| 387 | * published chunks exist. One is taken by the registry while the other |
| 388 | * is being returned to the caller. In the use case of the relay daemon, |
| 389 | * the reference held by the registry itself is undesirable. |
| 390 | * |
| 391 | * We want the trace chunk to be removed from the registry as soon |
| 392 | * as it is not being used by the relay daemon (through a session |
| 393 | * or a stream). This differs from the behaviour of the consumer |
| 394 | * daemon which relies on an explicit command from the session |
| 395 | * daemon to release the registry's reference. |
| 396 | * |
| 397 | * In cases where the trace chunk had already been published, |
| 398 | * the reference belonging to the sessiond trace chunk |
| 399 | * registry instance has already been 'put'. We simply return |
| 400 | * the published trace chunk with a reference taken on behalf of the |
| 401 | * caller. |
| 402 | */ |
| 403 | if (!trace_chunk_already_published) { |
| 404 | lttng_trace_chunk_put(published_chunk); |
| 405 | } |
| 406 | end: |
| 407 | trace_chunk_registry_ht_element_put(element); |
| 408 | return published_chunk; |
| 409 | } |
| 410 | |
| 411 | struct lttng_trace_chunk *sessiond_trace_chunk_registry_get_anonymous_chunk( |
| 412 | struct sessiond_trace_chunk_registry *sessiond_registry, |
| 413 | const lttng_uuid& sessiond_uuid, |
| 414 | uint64_t session_id) |
| 415 | { |
| 416 | struct lttng_trace_chunk *chunk = nullptr; |
| 417 | struct trace_chunk_registry_ht_element *element; |
| 418 | struct trace_chunk_registry_ht_key key; |
| 419 | char uuid_str[LTTNG_UUID_STR_LEN]; |
| 420 | |
| 421 | lttng_uuid_to_str(sessiond_uuid, uuid_str); |
| 422 | |
| 423 | key.sessiond_uuid = sessiond_uuid; |
| 424 | element = trace_chunk_registry_ht_element_find(sessiond_registry, &key); |
| 425 | if (!element) { |
| 426 | ERR("Failed to find trace chunk registry of sessiond {%s}", uuid_str); |
| 427 | goto end; |
| 428 | } |
| 429 | |
| 430 | chunk = lttng_trace_chunk_registry_find_anonymous_chunk(element->trace_chunk_registry, |
| 431 | session_id); |
| 432 | trace_chunk_registry_ht_element_put(element); |
| 433 | end: |
| 434 | return chunk; |
| 435 | } |
| 436 | |
| 437 | struct lttng_trace_chunk * |
| 438 | sessiond_trace_chunk_registry_get_chunk(struct sessiond_trace_chunk_registry *sessiond_registry, |
| 439 | const lttng_uuid& sessiond_uuid, |
| 440 | uint64_t session_id, |
| 441 | uint64_t chunk_id) |
| 442 | { |
| 443 | struct lttng_trace_chunk *chunk = nullptr; |
| 444 | struct trace_chunk_registry_ht_element *element; |
| 445 | struct trace_chunk_registry_ht_key key; |
| 446 | char uuid_str[LTTNG_UUID_STR_LEN]; |
| 447 | |
| 448 | lttng_uuid_to_str(sessiond_uuid, uuid_str); |
| 449 | |
| 450 | key.sessiond_uuid = sessiond_uuid; |
| 451 | element = trace_chunk_registry_ht_element_find(sessiond_registry, &key); |
| 452 | if (!element) { |
| 453 | ERR("Failed to find trace chunk registry of sessiond {%s}", uuid_str); |
| 454 | goto end; |
| 455 | } |
| 456 | |
| 457 | chunk = lttng_trace_chunk_registry_find_chunk( |
| 458 | element->trace_chunk_registry, session_id, chunk_id); |
| 459 | trace_chunk_registry_ht_element_put(element); |
| 460 | end: |
| 461 | return chunk; |
| 462 | } |
| 463 | |
| 464 | int sessiond_trace_chunk_registry_chunk_exists( |
| 465 | struct sessiond_trace_chunk_registry *sessiond_registry, |
| 466 | const lttng_uuid& sessiond_uuid, |
| 467 | uint64_t session_id, |
| 468 | uint64_t chunk_id, |
| 469 | bool *chunk_exists) |
| 470 | { |
| 471 | int ret; |
| 472 | struct trace_chunk_registry_ht_element *element; |
| 473 | struct trace_chunk_registry_ht_key key; |
| 474 | |
| 475 | key.sessiond_uuid = sessiond_uuid; |
| 476 | element = trace_chunk_registry_ht_element_find(sessiond_registry, &key); |
| 477 | if (!element) { |
| 478 | char uuid_str[LTTNG_UUID_STR_LEN]; |
| 479 | |
| 480 | lttng_uuid_to_str(sessiond_uuid, uuid_str); |
| 481 | /* |
| 482 | * While this certainly means that the chunk does not exist, |
| 483 | * it is unexpected for a chunk existence query to target a |
| 484 | * session daemon that does not have an active |
| 485 | * connection/registry. This would indicate a protocol |
| 486 | * (or internal) error. |
| 487 | */ |
| 488 | ERR("Failed to find trace chunk registry of sessiond {%s}", uuid_str); |
| 489 | ret = -1; |
| 490 | goto end; |
| 491 | } |
| 492 | |
| 493 | ret = lttng_trace_chunk_registry_chunk_exists( |
| 494 | element->trace_chunk_registry, session_id, chunk_id, chunk_exists); |
| 495 | trace_chunk_registry_ht_element_put(element); |
| 496 | end: |
| 497 | return ret; |
| 498 | } |