/***************************************************************************** Copyright (c) 2007, 2015, Oracle and/or its affiliates. All Rights Reserved. Copyright (c) 2017, 2021, MariaDB Corporation. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA *****************************************************************************/ /**************************************************//** @file trx/trx0i_s.cc INFORMATION SCHEMA innodb_trx, innodb_locks and innodb_lock_waits tables fetch code. The code below fetches information needed to fill those 3 dynamic tables and uploads it into a "transactions table cache" for later retrieval. Created July 17, 2007 Vasil Dimov *******************************************************/ #include "trx0i_s.h" #include "buf0buf.h" #include "dict0dict.h" #include "ha0storage.h" #include "hash0hash.h" #include "lock0iter.h" #include "lock0lock.h" #include "mem0mem.h" #include "page0page.h" #include "rem0rec.h" #include "row0row.h" #include "srv0srv.h" #include "sync0rw.h" #include "sync0sync.h" #include "trx0sys.h" #include "que0que.h" #include "trx0purge.h" #include "sql_class.h" /** Initial number of rows in the table cache */ #define TABLE_CACHE_INITIAL_ROWSNUM 1024 /** @brief The maximum number of chunks to allocate for a table cache. The rows of a table cache are stored in a set of chunks. When a new row is added a new chunk is allocated if necessary. Assuming that the first one is 1024 rows (TABLE_CACHE_INITIAL_ROWSNUM) and each subsequent is N/2 where N is the number of rows we have allocated till now, then 39th chunk would accommodate 1677416425 rows and all chunks would accommodate 3354832851 rows. */ #define MEM_CHUNKS_IN_TABLE_CACHE 39 /** The following are some testing auxiliary macros. Do not enable them in a production environment. */ /* @{ */ #if 0 /** If this is enabled then lock folds will always be different resulting in equal rows being put in a different cells of the hash table. Checking for duplicates will be flawed because different fold will be calculated when a row is searched in the hash table. */ #define TEST_LOCK_FOLD_ALWAYS_DIFFERENT #endif #if 0 /** This effectively kills the search-for-duplicate-before-adding-a-row function, but searching in the hash is still performed. It will always be assumed that lock is not present and insertion will be performed in the hash table. */ #define TEST_NO_LOCKS_ROW_IS_EVER_EQUAL_TO_LOCK_T #endif #if 0 /** This aggressively repeats adding each row many times. Depending on the above settings this may be noop or may result in lots of rows being added. */ #define TEST_ADD_EACH_LOCKS_ROW_MANY_TIMES #endif #if 0 /** Very similar to TEST_NO_LOCKS_ROW_IS_EVER_EQUAL_TO_LOCK_T but hash table search is not performed at all. */ #define TEST_DO_NOT_CHECK_FOR_DUPLICATE_ROWS #endif #if 0 /** Do not insert each row into the hash table, duplicates may appear if this is enabled, also if this is enabled searching into the hash is noop because it will be empty. */ #define TEST_DO_NOT_INSERT_INTO_THE_HASH_TABLE #endif /* @} */ /** Memory limit passed to ha_storage_put_memlim(). @param cache hash storage @return maximum allowed allocation size */ #define MAX_ALLOWED_FOR_STORAGE(cache) \ (TRX_I_S_MEM_LIMIT \ - (cache)->mem_allocd) /** Memory limit in table_cache_create_empty_row(). @param cache hash storage @return maximum allowed allocation size */ #define MAX_ALLOWED_FOR_ALLOC(cache) \ (TRX_I_S_MEM_LIMIT \ - (cache)->mem_allocd \ - ha_storage_get_size((cache)->storage)) /** Memory for each table in the intermediate buffer is allocated in separate chunks. These chunks are considered to be concatenated to represent one flat array of rows. */ struct i_s_mem_chunk_t { ulint offset; /*!< offset, in number of rows */ ulint rows_allocd; /*!< the size of this chunk, in number of rows */ void* base; /*!< start of the chunk */ }; /** This represents one table's cache. */ struct i_s_table_cache_t { ulint rows_used; /*!< number of used rows */ ulint rows_allocd; /*!< number of allocated rows */ ulint row_size; /*!< size of a single row */ i_s_mem_chunk_t chunks[MEM_CHUNKS_IN_TABLE_CACHE]; /*!< array of memory chunks that stores the rows */ }; /** This structure describes the intermediate buffer */ struct trx_i_s_cache_t { rw_lock_t rw_lock; /*!< read-write lock protecting the rest of this structure */ Atomic_relaxed last_read; /*!< last time the cache was read; measured in nanoseconds */ i_s_table_cache_t innodb_trx; /*!< innodb_trx table */ i_s_table_cache_t innodb_locks; /*!< innodb_locks table */ i_s_table_cache_t innodb_lock_waits;/*!< innodb_lock_waits table */ /** the hash table size is LOCKS_HASH_CELLS_NUM * sizeof(void*) bytes */ #define LOCKS_HASH_CELLS_NUM 10000 hash_table_t locks_hash; /*!< hash table used to eliminate duplicate entries in the innodb_locks table */ /** Initial size of the cache storage */ #define CACHE_STORAGE_INITIAL_SIZE 1024 /** Number of hash cells in the cache storage */ #define CACHE_STORAGE_HASH_CELLS 2048 ha_storage_t* storage; /*!< storage for external volatile data that may become unavailable when we release lock_sys.mutex */ ulint mem_allocd; /*!< the amount of memory allocated with mem_alloc*() */ bool is_truncated; /*!< this is true if the memory limit was hit and thus the data in the cache is truncated */ }; /** This is the intermediate buffer where data needed to fill the INFORMATION SCHEMA tables is fetched and later retrieved by the C++ code in handler/i_s.cc. */ static trx_i_s_cache_t trx_i_s_cache_static; /** This is the intermediate buffer where data needed to fill the INFORMATION SCHEMA tables is fetched and later retrieved by the C++ code in handler/i_s.cc. */ trx_i_s_cache_t* trx_i_s_cache = &trx_i_s_cache_static; /** @return the heap number of a record lock @retval 0xFFFF for table locks */ static uint16_t wait_lock_get_heap_no(const lock_t *lock) { return lock_get_type(lock) == LOCK_REC ? static_cast(lock_rec_find_set_bit(lock)) : uint16_t{0xFFFF}; } /*******************************************************************//** Initializes the members of a table cache. */ static void table_cache_init( /*=============*/ i_s_table_cache_t* table_cache, /*!< out: table cache */ size_t row_size) /*!< in: the size of a row */ { ulint i; table_cache->rows_used = 0; table_cache->rows_allocd = 0; table_cache->row_size = row_size; for (i = 0; i < MEM_CHUNKS_IN_TABLE_CACHE; i++) { /* the memory is actually allocated in table_cache_create_empty_row() */ table_cache->chunks[i].base = NULL; } } /*******************************************************************//** Frees a table cache. */ static void table_cache_free( /*=============*/ i_s_table_cache_t* table_cache) /*!< in/out: table cache */ { ulint i; for (i = 0; i < MEM_CHUNKS_IN_TABLE_CACHE; i++) { /* the memory is actually allocated in table_cache_create_empty_row() */ if (table_cache->chunks[i].base) { ut_free(table_cache->chunks[i].base); table_cache->chunks[i].base = NULL; } } } /*******************************************************************//** Returns an empty row from a table cache. The row is allocated if no more empty rows are available. The number of used rows is incremented. If the memory limit is hit then NULL is returned and nothing is allocated. @return empty row, or NULL if out of memory */ static void* table_cache_create_empty_row( /*=========================*/ i_s_table_cache_t* table_cache, /*!< in/out: table cache */ trx_i_s_cache_t* cache) /*!< in/out: cache to record how many bytes are allocated */ { ulint i; void* row; ut_a(table_cache->rows_used <= table_cache->rows_allocd); if (table_cache->rows_used == table_cache->rows_allocd) { /* rows_used == rows_allocd means that new chunk needs to be allocated: either no more empty rows in the last allocated chunk or nothing has been allocated yet (rows_num == rows_allocd == 0); */ i_s_mem_chunk_t* chunk; ulint req_bytes; ulint got_bytes; ulint req_rows; ulint got_rows; /* find the first not allocated chunk */ for (i = 0; i < MEM_CHUNKS_IN_TABLE_CACHE; i++) { if (table_cache->chunks[i].base == NULL) { break; } } /* i == MEM_CHUNKS_IN_TABLE_CACHE means that all chunks have been allocated :-X */ ut_a(i < MEM_CHUNKS_IN_TABLE_CACHE); /* allocate the chunk we just found */ if (i == 0) { /* first chunk, nothing is allocated yet */ req_rows = TABLE_CACHE_INITIAL_ROWSNUM; } else { /* Memory is increased by the formula new = old + old / 2; We are trying not to be aggressive here (= using the common new = old * 2) because the allocated memory will not be freed until InnoDB exit (it is reused). So it is better to once allocate the memory in more steps, but have less unused/wasted memory than to use less steps in allocation (which is done once in a lifetime) but end up with lots of unused/wasted memory. */ req_rows = table_cache->rows_allocd / 2; } req_bytes = req_rows * table_cache->row_size; if (req_bytes > MAX_ALLOWED_FOR_ALLOC(cache)) { return(NULL); } chunk = &table_cache->chunks[i]; got_bytes = req_bytes; chunk->base = ut_malloc_nokey(req_bytes); got_rows = got_bytes / table_cache->row_size; cache->mem_allocd += got_bytes; #if 0 printf("allocating chunk %d req bytes=%lu, got bytes=%lu," " row size=%lu," " req rows=%lu, got rows=%lu\n", i, req_bytes, got_bytes, table_cache->row_size, req_rows, got_rows); #endif chunk->rows_allocd = got_rows; table_cache->rows_allocd += got_rows; /* adjust the offset of the next chunk */ if (i < MEM_CHUNKS_IN_TABLE_CACHE - 1) { table_cache->chunks[i + 1].offset = chunk->offset + chunk->rows_allocd; } /* return the first empty row in the newly allocated chunk */ row = chunk->base; } else { char* chunk_start; ulint offset; /* there is an empty row, no need to allocate new chunks */ /* find the first chunk that contains allocated but empty/unused rows */ for (i = 0; i < MEM_CHUNKS_IN_TABLE_CACHE; i++) { if (table_cache->chunks[i].offset + table_cache->chunks[i].rows_allocd > table_cache->rows_used) { break; } } /* i == MEM_CHUNKS_IN_TABLE_CACHE means that all chunks are full, but table_cache->rows_used != table_cache->rows_allocd means exactly the opposite - there are allocated but empty/unused rows :-X */ ut_a(i < MEM_CHUNKS_IN_TABLE_CACHE); chunk_start = (char*) table_cache->chunks[i].base; offset = table_cache->rows_used - table_cache->chunks[i].offset; row = chunk_start + offset * table_cache->row_size; } table_cache->rows_used++; return(row); } #ifdef UNIV_DEBUG /*******************************************************************//** Validates a row in the locks cache. @return TRUE if valid */ static ibool i_s_locks_row_validate( /*===================*/ const i_s_locks_row_t* row) /*!< in: row to validate */ { ut_ad(row->lock_mode); ut_ad(row->lock_table != NULL); ut_ad(row->lock_table_id != 0); if (!row->lock_index) { /* table lock */ ut_ad(!row->lock_data); ut_ad(row->lock_page == page_id_t(0, 0)); ut_ad(!row->lock_rec); } else { /* record lock */ /* row->lock_data == NULL if buf_page_try_get() == NULL */ } return(TRUE); } #endif /* UNIV_DEBUG */ /*******************************************************************//** Fills i_s_trx_row_t object. If memory can not be allocated then FALSE is returned. @return FALSE if allocation fails */ static ibool fill_trx_row( /*=========*/ i_s_trx_row_t* row, /*!< out: result object that's filled */ const trx_t* trx, /*!< in: transaction to get data from */ const i_s_locks_row_t* requested_lock_row,/*!< in: pointer to the corresponding row in innodb_locks if trx is waiting or NULL if trx is not waiting */ trx_i_s_cache_t* cache) /*!< in/out: cache into which to copy volatile strings */ { const char* s; ut_ad(lock_mutex_own()); row->trx_id = trx_get_id_for_print(trx); row->trx_started = trx->start_time; row->trx_state = trx_get_que_state_str(trx); row->requested_lock_row = requested_lock_row; ut_ad(requested_lock_row == NULL || i_s_locks_row_validate(requested_lock_row)); if (trx->lock.wait_lock != NULL) { ut_a(requested_lock_row != NULL); row->trx_wait_started = trx->lock.wait_started; } else { ut_a(requested_lock_row == NULL); row->trx_wait_started = 0; } row->trx_weight = static_cast(TRX_WEIGHT(trx)); if (trx->mysql_thd == NULL) { /* For internal transactions e.g., purge and transactions being recovered at startup there is no associated MySQL thread data structure. */ row->trx_mysql_thread_id = 0; row->trx_query = NULL; goto thd_done; } row->trx_mysql_thread_id = thd_get_thread_id(trx->mysql_thd); char query[TRX_I_S_TRX_QUERY_MAX_LEN + 1]; if (size_t stmt_len = thd_query_safe(trx->mysql_thd, query, sizeof query)) { row->trx_query = static_cast( ha_storage_put_memlim( cache->storage, query, stmt_len + 1, MAX_ALLOWED_FOR_STORAGE(cache))); row->trx_query_cs = thd_charset(trx->mysql_thd); if (row->trx_query == NULL) { return(FALSE); } } else { row->trx_query = NULL; } thd_done: row->trx_operation_state = trx->op_info; row->trx_tables_in_use = trx->n_mysql_tables_in_use; row->trx_tables_locked = lock_number_of_tables_locked(&trx->lock); /* These are protected by both trx->mutex or lock_sys.mutex, or just lock_sys.mutex. For reading, it suffices to hold lock_sys.mutex. */ row->trx_lock_structs = UT_LIST_GET_LEN(trx->lock.trx_locks); row->trx_lock_memory_bytes = mem_heap_get_size(trx->lock.lock_heap); row->trx_rows_locked = lock_number_of_rows_locked(&trx->lock); row->trx_rows_modified = trx->undo_no; row->trx_isolation_level = trx->isolation_level; row->trx_unique_checks = (ibool) trx->check_unique_secondary; row->trx_foreign_key_checks = (ibool) trx->check_foreigns; s = trx->detailed_error; if (s != NULL && s[0] != '\0') { TRX_I_S_STRING_COPY(s, row->trx_foreign_key_error, TRX_I_S_TRX_FK_ERROR_MAX_LEN, cache); if (row->trx_foreign_key_error == NULL) { return(FALSE); } } else { row->trx_foreign_key_error = NULL; } row->trx_is_read_only = trx->read_only; row->trx_is_autocommit_non_locking = trx->is_autocommit_non_locking(); return(TRUE); } /*******************************************************************//** Format the nth field of "rec" and put it in "buf". The result is always NUL-terminated. Returns the number of bytes that were written to "buf" (including the terminating NUL). @return end of the result */ static ulint put_nth_field( /*==========*/ char* buf, /*!< out: buffer */ ulint buf_size,/*!< in: buffer size in bytes */ ulint n, /*!< in: number of field */ const dict_index_t* index, /*!< in: index */ const rec_t* rec, /*!< in: record */ const rec_offs* offsets)/*!< in: record offsets, returned by rec_get_offsets() */ { const byte* data; ulint data_len; dict_field_t* dict_field; ulint ret; ut_ad(rec_offs_validate(rec, NULL, offsets)); if (buf_size == 0) { return(0); } ret = 0; if (n > 0) { /* we must append ", " before the actual data */ if (buf_size < 3) { buf[0] = '\0'; return(1); } memcpy(buf, ", ", 3); buf += 2; buf_size -= 2; ret += 2; } /* now buf_size >= 1 */ data = rec_get_nth_field(rec, offsets, n, &data_len); dict_field = dict_index_get_nth_field(index, n); ret += row_raw_format((const char*) data, data_len, dict_field, buf, buf_size); return(ret); } /*******************************************************************//** Fills the "lock_data" member of i_s_locks_row_t object. If memory can not be allocated then FALSE is returned. @return FALSE if allocation fails */ static ibool fill_lock_data( /*===========*/ const char** lock_data,/*!< out: "lock_data" to fill */ const lock_t* lock, /*!< in: lock used to find the data */ ulint heap_no,/*!< in: rec num used to find the data */ trx_i_s_cache_t* cache) /*!< in/out: cache where to store volatile data */ { ut_a(lock_get_type(lock) == LOCK_REC); switch (heap_no) { case PAGE_HEAP_NO_INFIMUM: case PAGE_HEAP_NO_SUPREMUM: *lock_data = ha_storage_put_str_memlim( cache->storage, heap_no == PAGE_HEAP_NO_INFIMUM ? "infimum pseudo-record" : "supremum pseudo-record", MAX_ALLOWED_FOR_STORAGE(cache)); return(*lock_data != NULL); } mtr_t mtr; const buf_block_t* block; const page_t* page; const rec_t* rec; const dict_index_t* index; ulint n_fields; mem_heap_t* heap; rec_offs offsets_onstack[REC_OFFS_NORMAL_SIZE]; rec_offs* offsets; char buf[TRX_I_S_LOCK_DATA_MAX_LEN]; ulint buf_used; ulint i; mtr_start(&mtr); block = buf_page_try_get(lock->un_member.rec_lock.page_id, &mtr); if (block == NULL) { *lock_data = NULL; mtr_commit(&mtr); return(TRUE); } page = reinterpret_cast(buf_block_get_frame(block)); rec_offs_init(offsets_onstack); offsets = offsets_onstack; rec = page_find_rec_with_heap_no(page, heap_no); index = lock_rec_get_index(lock); n_fields = dict_index_get_n_unique(index); ut_a(n_fields > 0); heap = NULL; offsets = rec_get_offsets(rec, index, offsets, index->n_core_fields, n_fields, &heap); /* format and store the data */ buf_used = 0; for (i = 0; i < n_fields; i++) { buf_used += put_nth_field( buf + buf_used, sizeof(buf) - buf_used, i, index, rec, offsets) - 1; } *lock_data = (const char*) ha_storage_put_memlim( cache->storage, buf, buf_used + 1, MAX_ALLOWED_FOR_STORAGE(cache)); if (heap != NULL) { /* this means that rec_get_offsets() has created a new heap and has stored offsets in it; check that this is really the case and free the heap */ ut_a(offsets != offsets_onstack); mem_heap_free(heap); } mtr_commit(&mtr); if (*lock_data == NULL) { return(FALSE); } return(TRUE); } /*******************************************************************//** Fills i_s_locks_row_t object. Returns its first argument. If memory can not be allocated then FALSE is returned. @return false if allocation fails */ static bool fill_locks_row( i_s_locks_row_t* row, /*!< out: result object that's filled */ const lock_t* lock, /*!< in: lock to get data from */ uint16_t heap_no,/*!< in: lock's record number or 0 if the lock is a table lock */ trx_i_s_cache_t* cache) /*!< in/out: cache into which to copy volatile strings */ { row->lock_trx_id = lock->trx->id; const auto lock_type = lock_get_type(lock); ut_ad(lock_type == LOCK_REC || lock_type == LOCK_TABLE); const bool is_gap_lock = lock_type == LOCK_REC && (lock->type_mode & LOCK_GAP); switch (lock->type_mode & LOCK_MODE_MASK) { case LOCK_S: row->lock_mode = uint8_t(1 + is_gap_lock); break; case LOCK_X: row->lock_mode = uint8_t(3 + is_gap_lock); break; case LOCK_IS: row->lock_mode = uint8_t(5 + is_gap_lock); break; case LOCK_IX: row->lock_mode = uint8_t(7 + is_gap_lock); break; case LOCK_AUTO_INC: row->lock_mode = 9; break; default: ut_ad("unknown lock mode" == 0); row->lock_mode = 0; } row->lock_table = ha_storage_put_str_memlim( cache->storage, lock_get_table_name(lock).m_name, MAX_ALLOWED_FOR_STORAGE(cache)); /* memory could not be allocated */ if (row->lock_table == NULL) { return false; } if (lock_type == LOCK_REC) { row->lock_index = ha_storage_put_str_memlim( cache->storage, lock_rec_get_index_name(lock), MAX_ALLOWED_FOR_STORAGE(cache)); /* memory could not be allocated */ if (row->lock_index == NULL) { return false; } row->lock_page = lock->un_member.rec_lock.page_id; row->lock_rec = heap_no; if (!fill_lock_data(&row->lock_data, lock, heap_no, cache)) { /* memory could not be allocated */ return false; } } else { row->lock_index = NULL; row->lock_page = page_id_t(0, 0); row->lock_rec = 0; row->lock_data = NULL; } row->lock_table_id = lock_get_table_id(lock); row->hash_chain.value = row; ut_ad(i_s_locks_row_validate(row)); return true; } /*******************************************************************//** Fills i_s_lock_waits_row_t object. Returns its first argument. @return result object that's filled */ static i_s_lock_waits_row_t* fill_lock_waits_row( /*================*/ i_s_lock_waits_row_t* row, /*!< out: result object that's filled */ const i_s_locks_row_t* requested_lock_row,/*!< in: pointer to the relevant requested lock row in innodb_locks */ const i_s_locks_row_t* blocking_lock_row)/*!< in: pointer to the relevant blocking lock row in innodb_locks */ { ut_ad(i_s_locks_row_validate(requested_lock_row)); ut_ad(i_s_locks_row_validate(blocking_lock_row)); row->requested_lock_row = requested_lock_row; row->blocking_lock_row = blocking_lock_row; return(row); } /*******************************************************************//** Calculates a hash fold for a lock. For a record lock the fold is calculated from 4 elements, which uniquely identify a lock at a given point in time: transaction id, space id, page number, record number. For a table lock the fold is table's id. @return fold */ static ulint fold_lock( /*======*/ const lock_t* lock, /*!< in: lock object to fold */ ulint heap_no)/*!< in: lock's record number or 0xFFFF if the lock is a table lock */ { #ifdef TEST_LOCK_FOLD_ALWAYS_DIFFERENT static ulint fold = 0; return(fold++); #else ulint ret; switch (lock_get_type(lock)) { case LOCK_REC: ut_a(heap_no != 0xFFFF); ret = ut_fold_ulint_pair((ulint) lock->trx->id, lock->un_member.rec_lock.page_id. fold()); ret = ut_fold_ulint_pair(ret, heap_no); break; case LOCK_TABLE: /* this check is actually not necessary for continuing correct operation, but something must have gone wrong if it fails. */ ut_a(heap_no == 0xFFFF); ret = (ulint) lock_get_table_id(lock); break; default: ut_error; } return(ret); #endif } /*******************************************************************//** Checks whether i_s_locks_row_t object represents a lock_t object. @return TRUE if they match */ static ibool locks_row_eq_lock( /*==============*/ const i_s_locks_row_t* row, /*!< in: innodb_locks row */ const lock_t* lock, /*!< in: lock object */ ulint heap_no)/*!< in: lock's record number or 0xFFFF if the lock is a table lock */ { ut_ad(i_s_locks_row_validate(row)); #ifdef TEST_NO_LOCKS_ROW_IS_EVER_EQUAL_TO_LOCK_T return(0); #else switch (lock_get_type(lock)) { case LOCK_REC: ut_a(heap_no != 0xFFFF); return(row->lock_trx_id == lock->trx->id && row->lock_page == lock->un_member.rec_lock.page_id && row->lock_rec == heap_no); case LOCK_TABLE: /* this check is actually not necessary for continuing correct operation, but something must have gone wrong if it fails. */ ut_a(heap_no == 0xFFFF); return(row->lock_trx_id == lock->trx->id && row->lock_table_id == lock_get_table_id(lock)); default: ut_error; return(FALSE); } #endif } /*******************************************************************//** Searches for a row in the innodb_locks cache that has a specified id. This happens in O(1) time since a hash table is used. Returns pointer to the row or NULL if none is found. @return row or NULL */ static i_s_locks_row_t* search_innodb_locks( /*================*/ trx_i_s_cache_t* cache, /*!< in: cache */ const lock_t* lock, /*!< in: lock to search for */ uint16_t heap_no)/*!< in: lock's record number or 0xFFFF if the lock is a table lock */ { i_s_hash_chain_t* hash_chain; HASH_SEARCH( /* hash_chain->"next" */ next, /* the hash table */ &cache->locks_hash, /* fold */ fold_lock(lock, heap_no), /* the type of the next variable */ i_s_hash_chain_t*, /* auxiliary variable */ hash_chain, /* assertion on every traversed item */ ut_ad(i_s_locks_row_validate(hash_chain->value)), /* this determines if we have found the lock */ locks_row_eq_lock(hash_chain->value, lock, heap_no)); if (hash_chain == NULL) { return(NULL); } /* else */ return(hash_chain->value); } /*******************************************************************//** Adds new element to the locks cache, enlarging it if necessary. Returns a pointer to the added row. If the row is already present then no row is added and a pointer to the existing row is returned. If row can not be allocated then NULL is returned. @return row */ static i_s_locks_row_t* add_lock_to_cache( /*==============*/ trx_i_s_cache_t* cache, /*!< in/out: cache */ const lock_t* lock, /*!< in: the element to add */ uint16_t heap_no)/*!< in: lock's record number or 0 if the lock is a table lock */ { i_s_locks_row_t* dst_row; #ifdef TEST_ADD_EACH_LOCKS_ROW_MANY_TIMES ulint i; for (i = 0; i < 10000; i++) { #endif #ifndef TEST_DO_NOT_CHECK_FOR_DUPLICATE_ROWS /* quit if this lock is already present */ dst_row = search_innodb_locks(cache, lock, heap_no); if (dst_row != NULL) { ut_ad(i_s_locks_row_validate(dst_row)); return(dst_row); } #endif dst_row = (i_s_locks_row_t*) table_cache_create_empty_row(&cache->innodb_locks, cache); /* memory could not be allocated */ if (dst_row == NULL) { return(NULL); } if (!fill_locks_row(dst_row, lock, heap_no, cache)) { /* memory could not be allocated */ cache->innodb_locks.rows_used--; return(NULL); } #ifndef TEST_DO_NOT_INSERT_INTO_THE_HASH_TABLE HASH_INSERT( /* the type used in the hash chain */ i_s_hash_chain_t, /* hash_chain->"next" */ next, /* the hash table */ &cache->locks_hash, /* fold */ fold_lock(lock, heap_no), /* add this data to the hash */ &dst_row->hash_chain); #endif #ifdef TEST_ADD_EACH_LOCKS_ROW_MANY_TIMES } /* for()-loop */ #endif ut_ad(i_s_locks_row_validate(dst_row)); return(dst_row); } /*******************************************************************//** Adds new pair of locks to the lock waits cache. If memory can not be allocated then FALSE is returned. @return FALSE if allocation fails */ static ibool add_lock_wait_to_cache( /*===================*/ trx_i_s_cache_t* cache, /*!< in/out: cache */ const i_s_locks_row_t* requested_lock_row,/*!< in: pointer to the relevant requested lock row in innodb_locks */ const i_s_locks_row_t* blocking_lock_row)/*!< in: pointer to the relevant blocking lock row in innodb_locks */ { i_s_lock_waits_row_t* dst_row; dst_row = (i_s_lock_waits_row_t*) table_cache_create_empty_row(&cache->innodb_lock_waits, cache); /* memory could not be allocated */ if (dst_row == NULL) { return(FALSE); } fill_lock_waits_row(dst_row, requested_lock_row, blocking_lock_row); return(TRUE); } /*******************************************************************//** Adds transaction's relevant (important) locks to cache. If the transaction is waiting, then the wait lock is added to innodb_locks and a pointer to the added row is returned in requested_lock_row, otherwise requested_lock_row is set to NULL. If rows can not be allocated then FALSE is returned and the value of requested_lock_row is undefined. @return FALSE if allocation fails */ static ibool add_trx_relevant_locks_to_cache( /*============================*/ trx_i_s_cache_t* cache, /*!< in/out: cache */ const trx_t* trx, /*!< in: transaction */ i_s_locks_row_t** requested_lock_row)/*!< out: pointer to the requested lock row, or NULL or undefined */ { ut_ad(lock_mutex_own()); /* If transaction is waiting we add the wait lock and all locks from another transactions that are blocking the wait lock. */ if (trx->lock.que_state == TRX_QUE_LOCK_WAIT) { const lock_t* curr_lock; i_s_locks_row_t* blocking_lock_row; lock_queue_iterator_t iter; ut_a(trx->lock.wait_lock != NULL); uint16_t wait_lock_heap_no = wait_lock_get_heap_no(trx->lock.wait_lock); /* add the requested lock */ *requested_lock_row = add_lock_to_cache(cache, trx->lock.wait_lock, wait_lock_heap_no); /* memory could not be allocated */ if (*requested_lock_row == NULL) { return(FALSE); } /* then iterate over the locks before the wait lock and add the ones that are blocking it */ lock_queue_iterator_reset(&iter, trx->lock.wait_lock, ULINT_UNDEFINED); for (curr_lock = lock_queue_iterator_get_prev(&iter); curr_lock != NULL; curr_lock = lock_queue_iterator_get_prev(&iter)) { if (lock_has_to_wait(trx->lock.wait_lock, curr_lock)) { /* add the lock that is blocking trx->lock.wait_lock */ blocking_lock_row = add_lock_to_cache( cache, curr_lock, /* heap_no is the same for the wait and waited locks */ wait_lock_heap_no); /* memory could not be allocated */ if (blocking_lock_row == NULL) { return(FALSE); } /* add the relation between both locks to innodb_lock_waits */ if (!add_lock_wait_to_cache( cache, *requested_lock_row, blocking_lock_row)) { /* memory could not be allocated */ return(FALSE); } } } } else { *requested_lock_row = NULL; } return(TRUE); } /** The minimum time that a cache must not be updated after it has been read for the last time; measured in nanoseconds. We use this technique to ensure that SELECTs which join several INFORMATION SCHEMA tables read the same version of the cache. */ #define CACHE_MIN_IDLE_TIME_NS 100000000 /* 0.1 sec */ /*******************************************************************//** Checks if the cache can safely be updated. @return whether the cache can be updated */ static bool can_cache_be_updated(trx_i_s_cache_t* cache) { /* cache->last_read is only updated when a shared rw lock on the whole cache is being held (see trx_i_s_cache_end_read()) and we are currently holding an exclusive rw lock on the cache. So it is not possible for last_read to be updated while we are reading it. */ ut_ad(rw_lock_own(&cache->rw_lock, RW_LOCK_X)); return my_interval_timer() - cache->last_read > CACHE_MIN_IDLE_TIME_NS; } /*******************************************************************//** Declare a cache empty, preparing it to be filled up. Not all resources are freed because they can be reused. */ static void trx_i_s_cache_clear( /*================*/ trx_i_s_cache_t* cache) /*!< out: cache to clear */ { cache->innodb_trx.rows_used = 0; cache->innodb_locks.rows_used = 0; cache->innodb_lock_waits.rows_used = 0; cache->locks_hash.clear(); ha_storage_empty(&cache->storage); } /** Add transactions to innodb_trx's cache. We also add all locks that are relevant to each transaction into innodb_locks' and innodb_lock_waits' caches. */ static void fetch_data_into_cache_low(trx_i_s_cache_t *cache, const trx_t *trx) { i_s_locks_row_t *requested_lock_row; #ifdef UNIV_DEBUG { const auto state= trx->state; if (trx->is_autocommit_non_locking()) { ut_ad(trx->read_only); ut_ad(!trx->is_recovered); ut_ad(trx->mysql_thd); ut_ad(state == TRX_STATE_NOT_STARTED || state == TRX_STATE_ACTIVE); } else ut_ad(state == TRX_STATE_ACTIVE || state == TRX_STATE_PREPARED || state == TRX_STATE_PREPARED_RECOVERED || state == TRX_STATE_COMMITTED_IN_MEMORY); } #endif /* UNIV_DEBUG */ if (add_trx_relevant_locks_to_cache(cache, trx, &requested_lock_row)) { if (i_s_trx_row_t *trx_row= reinterpret_cast( table_cache_create_empty_row(&cache->innodb_trx, cache))) { if (fill_trx_row(trx_row, trx, requested_lock_row, cache)) return; --cache->innodb_trx.rows_used; } } /* memory could not be allocated */ cache->is_truncated= true; } /** Fetches the data needed to fill the 3 INFORMATION SCHEMA tables into the table cache buffer. Cache must be locked for write. */ static void fetch_data_into_cache(trx_i_s_cache_t *cache) { ut_ad(lock_mutex_own()); trx_i_s_cache_clear(cache); /* Capture the state of transactions */ trx_sys.trx_list.for_each([cache](trx_t &trx) { if (!cache->is_truncated && trx.state != TRX_STATE_NOT_STARTED && &trx != (purge_sys.query ? purge_sys.query->trx : nullptr)) { mutex_enter(&trx.mutex); if (trx.state != TRX_STATE_NOT_STARTED) fetch_data_into_cache_low(cache, &trx); mutex_exit(&trx.mutex); } }); cache->is_truncated= false; } /*******************************************************************//** Update the transactions cache if it has not been read for some time. Called from handler/i_s.cc. @return 0 - fetched, 1 - not */ int trx_i_s_possibly_fetch_data_into_cache( /*===================================*/ trx_i_s_cache_t* cache) /*!< in/out: cache */ { if (!can_cache_be_updated(cache)) { return(1); } /* We need to read trx_sys and record/table lock queues */ lock_mutex_enter(); fetch_data_into_cache(cache); lock_mutex_exit(); /* update cache last read time */ cache->last_read = my_interval_timer(); return(0); } /*******************************************************************//** Returns TRUE if the data in the cache is truncated due to the memory limit posed by TRX_I_S_MEM_LIMIT. @return TRUE if truncated */ bool trx_i_s_cache_is_truncated( /*=======================*/ trx_i_s_cache_t* cache) /*!< in: cache */ { return(cache->is_truncated); } /*******************************************************************//** Initialize INFORMATION SCHEMA trx related cache. */ void trx_i_s_cache_init( /*===============*/ trx_i_s_cache_t* cache) /*!< out: cache to init */ { /* The latching is done in the following order: acquire trx_i_s_cache_t::rw_lock, X acquire lock mutex release lock mutex release trx_i_s_cache_t::rw_lock acquire trx_i_s_cache_t::rw_lock, S release trx_i_s_cache_t::rw_lock */ rw_lock_create(trx_i_s_cache_lock_key, &cache->rw_lock, SYNC_TRX_I_S_RWLOCK); cache->last_read = 0; table_cache_init(&cache->innodb_trx, sizeof(i_s_trx_row_t)); table_cache_init(&cache->innodb_locks, sizeof(i_s_locks_row_t)); table_cache_init(&cache->innodb_lock_waits, sizeof(i_s_lock_waits_row_t)); cache->locks_hash.create(LOCKS_HASH_CELLS_NUM); cache->storage = ha_storage_create(CACHE_STORAGE_INITIAL_SIZE, CACHE_STORAGE_HASH_CELLS); cache->mem_allocd = 0; cache->is_truncated = false; } /*******************************************************************//** Free the INFORMATION SCHEMA trx related cache. */ void trx_i_s_cache_free( /*===============*/ trx_i_s_cache_t* cache) /*!< in, own: cache to free */ { rw_lock_free(&cache->rw_lock); cache->locks_hash.free(); ha_storage_free(cache->storage); table_cache_free(&cache->innodb_trx); table_cache_free(&cache->innodb_locks); table_cache_free(&cache->innodb_lock_waits); } /*******************************************************************//** Issue a shared/read lock on the tables cache. */ void trx_i_s_cache_start_read( /*=====================*/ trx_i_s_cache_t* cache) /*!< in: cache */ { rw_lock_s_lock(&cache->rw_lock); } /*******************************************************************//** Release a shared/read lock on the tables cache. */ void trx_i_s_cache_end_read( /*===================*/ trx_i_s_cache_t* cache) /*!< in: cache */ { cache->last_read = my_interval_timer(); rw_lock_s_unlock(&cache->rw_lock); } /*******************************************************************//** Issue an exclusive/write lock on the tables cache. */ void trx_i_s_cache_start_write( /*======================*/ trx_i_s_cache_t* cache) /*!< in: cache */ { rw_lock_x_lock(&cache->rw_lock); } /*******************************************************************//** Release an exclusive/write lock on the tables cache. */ void trx_i_s_cache_end_write( /*====================*/ trx_i_s_cache_t* cache) /*!< in: cache */ { ut_ad(rw_lock_own(&cache->rw_lock, RW_LOCK_X)); rw_lock_x_unlock(&cache->rw_lock); } /*******************************************************************//** Selects a INFORMATION SCHEMA table cache from the whole cache. @return table cache */ static i_s_table_cache_t* cache_select_table( /*===============*/ trx_i_s_cache_t* cache, /*!< in: whole cache */ enum i_s_table table) /*!< in: which table */ { ut_ad(rw_lock_own_flagged(&cache->rw_lock, RW_LOCK_FLAG_X | RW_LOCK_FLAG_S)); switch (table) { case I_S_INNODB_TRX: return &cache->innodb_trx; case I_S_INNODB_LOCKS: return &cache->innodb_locks; case I_S_INNODB_LOCK_WAITS: return &cache->innodb_lock_waits; } ut_error; return NULL; } /*******************************************************************//** Retrieves the number of used rows in the cache for a given INFORMATION SCHEMA table. @return number of rows */ ulint trx_i_s_cache_get_rows_used( /*========================*/ trx_i_s_cache_t* cache, /*!< in: cache */ enum i_s_table table) /*!< in: which table */ { i_s_table_cache_t* table_cache; table_cache = cache_select_table(cache, table); return(table_cache->rows_used); } /*******************************************************************//** Retrieves the nth row (zero-based) in the cache for a given INFORMATION SCHEMA table. @return row */ void* trx_i_s_cache_get_nth_row( /*======================*/ trx_i_s_cache_t* cache, /*!< in: cache */ enum i_s_table table, /*!< in: which table */ ulint n) /*!< in: row number */ { i_s_table_cache_t* table_cache; ulint i; void* row; table_cache = cache_select_table(cache, table); ut_a(n < table_cache->rows_used); row = NULL; for (i = 0; i < MEM_CHUNKS_IN_TABLE_CACHE; i++) { if (table_cache->chunks[i].offset + table_cache->chunks[i].rows_allocd > n) { row = (char*) table_cache->chunks[i].base + (n - table_cache->chunks[i].offset) * table_cache->row_size; break; } } ut_a(row != NULL); return(row); } /*******************************************************************//** Crafts a lock id string from a i_s_locks_row_t object. Returns its second argument. This function aborts if there is not enough space in lock_id. Be sure to provide at least TRX_I_S_LOCK_ID_MAX_LEN + 1 if you want to be 100% sure that it will not abort. @return resulting lock id */ char* trx_i_s_create_lock_id( /*===================*/ const i_s_locks_row_t* row, /*!< in: innodb_locks row */ char* lock_id,/*!< out: resulting lock_id */ ulint lock_id_size)/*!< in: size of the lock id buffer */ { int res_len; /* please adjust TRX_I_S_LOCK_ID_MAX_LEN if you change this */ if (row->lock_index) { /* record lock */ res_len = snprintf(lock_id, lock_id_size, TRX_ID_FMT ":%u:%u:%u", row->lock_trx_id, row->lock_page.space(), row->lock_page.page_no(), row->lock_rec); } else { /* table lock */ res_len = snprintf(lock_id, lock_id_size, TRX_ID_FMT":" UINT64PF, row->lock_trx_id, row->lock_table_id); } /* the typecast is safe because snprintf(3) never returns negative result */ ut_a(res_len >= 0); ut_a((ulint) res_len < lock_id_size); return(lock_id); }