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Diffstat (limited to '')
| -rw-r--r-- | sql/session_tracker.cc | 1307 |
1 files changed, 1307 insertions, 0 deletions
diff --git a/sql/session_tracker.cc b/sql/session_tracker.cc new file mode 100644 index 00000000..de82d8be --- /dev/null +++ b/sql/session_tracker.cc @@ -0,0 +1,1307 @@ +/* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. + Copyright (c) 2016, 2020, MariaDB + + 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 St, Fifth Floor, Boston, MA 02110-1301 USA */ + + +#include "sql_plugin.h" +#include "table.h" +#include "rpl_gtid.h" +#include "sql_class.h" +#include "sql_show.h" +#include "sql_plugin.h" +#include "set_var.h" + +void State_tracker::set_changed(THD *thd) +{ + m_changed= true; + thd->lex->safe_to_cache_query= 0; + thd->server_status|= SERVER_SESSION_STATE_CHANGED; +} + + +/* To be used in expanding the buffer. */ +static const unsigned int EXTRA_ALLOC= 1024; + + +void Session_sysvars_tracker::vars_list::reinit() +{ + track_all= 0; + if (m_registered_sysvars.records) + my_hash_reset(&m_registered_sysvars); +} + +/** + Copy the given list. + + @param from Source vars_list object. + @param thd THD handle to retrive the charset in use. + + @retval true there is something to track + @retval false nothing to track +*/ + +void Session_sysvars_tracker::vars_list::copy(vars_list* from, THD *thd) +{ + track_all= from->track_all; + free_hash(); + m_registered_sysvars= from->m_registered_sysvars; + from->init(); +} + +/** + Inserts the variable to be tracked into m_registered_sysvars hash. + + @param svar address of the system variable + + @retval false success + @retval true error +*/ + +bool Session_sysvars_tracker::vars_list::insert(const sys_var *svar) +{ + sysvar_node_st *node; + if (!(node= (sysvar_node_st *) my_malloc(PSI_INSTRUMENT_ME, + sizeof(sysvar_node_st), + MYF(MY_WME | + (mysqld_server_initialized ? + MY_THREAD_SPECIFIC : 0))))) + return true; + + node->m_svar= (sys_var *)svar; + node->test_load= node->m_svar->test_load; + node->m_changed= false; + if (my_hash_insert(&m_registered_sysvars, (uchar *) node)) + { + my_free(node); + if (!search((sys_var *)svar)) + { + //EOF (error is already reported) + return true; + } + } + return false; +} + +/** + Parse the specified system variables list. + + @Note In case of invalid entry a warning is raised per invalid entry. + This is done in order to handle 'potentially' valid system + variables from uninstalled plugins which might get installed in + future. + + + @param thd [IN] The thd handle. + @param var_list [IN] System variable list. + @param throw_error [IN] bool when set to true, returns an error + in case of invalid/duplicate values. + @param char_set [IN] charecter set information used for string + manipulations. + + @return + true Error + false Success +*/ +bool Session_sysvars_tracker::vars_list::parse_var_list(THD *thd, + LEX_STRING var_list, + bool throw_error, + CHARSET_INFO *char_set) +{ + const char separator= ','; + char *token, *lasts= NULL; + size_t rest= var_list.length; + + if (!var_list.str || var_list.length == 0) + return false; + + if(!strcmp(var_list.str, "*")) + { + track_all= true; + return false; + } + + token= var_list.str; + + track_all= false; + for (;;) + { + sys_var *svar; + LEX_CSTRING var; + + lasts= (char *) memchr(token, separator, rest); + + var.str= token; + if (lasts) + { + var.length= (lasts - token); + rest-= var.length + 1; + } + else + var.length= rest; + + /* Remove leading/trailing whitespace. */ + trim_whitespace(char_set, &var); + + if(!strcmp(var.str, "*")) + { + track_all= true; + } + else if ((svar= find_sys_var(thd, var.str, var.length, throw_error))) + { + if (insert(svar) == TRUE) + return true; + } + else if (throw_error && thd) + { + push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN, + ER_WRONG_VALUE_FOR_VAR, + "%.*s is not a valid system variable and will" + "be ignored.", (int)var.length, token); + } + else + return true; + + if (lasts) + token= lasts + 1; + else + break; + } + return false; +} + + +bool sysvartrack_validate_value(THD *thd, const char *str, size_t len) +{ + LEX_STRING var_list= { (char *) str, len }; + const char separator= ','; + char *token, *lasts= NULL; + size_t rest= var_list.length; + + if (!var_list.str) + { + my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), + "session_track_system_variables", "NULL"); + return false; + } + if (var_list.length == 0 || + !strcmp(var_list.str, "*")) + { + return false; + } + + token= var_list.str; + + for (;;) + { + LEX_CSTRING var; + + lasts= (char *) memchr(token, separator, rest); + + var.str= token; + if (lasts) + { + var.length= (lasts - token); + rest-= var.length + 1; + } + else + var.length= rest; + + /* Remove leading/trailing whitespace. */ + trim_whitespace(system_charset_info, &var); + + if (!strcmp(var.str, "*") && !find_sys_var(thd, var.str, var.length)) + return true; + + if (lasts) + token= lasts + 1; + else + break; + } + return false; +} + + +/* Sorts variable references array */ +static int name_array_sorter(const void *a, const void *b) +{ + LEX_CSTRING **an= (LEX_CSTRING **)a, **bn=(LEX_CSTRING **)b; + size_t min= MY_MIN((*an)->length, (*bn)->length); + int res= strncmp((*an)->str, (*bn)->str, min); + if (res == 0) + res= ((int)(*bn)->length)- ((int)(*an)->length); + return res; +} + +/** + Construct variable list by internal hash with references +*/ + +bool Session_sysvars_tracker::vars_list::construct_var_list(char *buf, + size_t buf_len) +{ + LEX_CSTRING **names; + uint idx; + size_t left= buf_len; + size_t names_size= m_registered_sysvars.records * sizeof(LEX_CSTRING *); + const char separator= ','; + + if (unlikely(buf_len < 1)) + return true; + + if (unlikely(track_all)) + { + if (buf_len < 2) + return true; + buf[0]= '*'; + buf[1]= '\0'; + return false; + } + + if (m_registered_sysvars.records == 0) + { + buf[0]= '\0'; + return false; + } + + if (unlikely(!(names= (LEX_CSTRING**) my_safe_alloca(names_size)))) + return true; + + idx= 0; + + mysql_mutex_lock(&LOCK_plugin); + for (ulong i= 0; i < m_registered_sysvars.records; i++) + { + sysvar_node_st *node= at(i); + if (*node->test_load) + names[idx++]= &node->m_svar->name; + } + DBUG_ASSERT(idx <= m_registered_sysvars.records); + + /* + We check number of records again here because number of variables + could be reduced in case of plugin unload. + */ + if (m_registered_sysvars.records == 0) + { + mysql_mutex_unlock(&LOCK_plugin); + buf[0]= '\0'; + return false; + } + + my_qsort(names, idx, sizeof(LEX_CSTRING*), &name_array_sorter); + + for(uint i= 0; i < idx; i++) + { + LEX_CSTRING *nm= names[i]; + size_t ln= nm->length + 1; + if (ln > left) + { + mysql_mutex_unlock(&LOCK_plugin); + my_safe_afree(names, names_size); + return true; + } + memcpy(buf, nm->str, nm->length); + buf[nm->length]= separator; + buf+= ln; + left-= ln; + } + mysql_mutex_unlock(&LOCK_plugin); + + buf--; buf[0]= '\0'; + my_safe_afree(names, names_size); + + return false; +} + + +void Session_sysvars_tracker::init(THD *thd) +{ + mysql_mutex_assert_owner(&LOCK_global_system_variables); + DBUG_ASSERT(thd->variables.session_track_system_variables == + global_system_variables.session_track_system_variables); + DBUG_ASSERT(global_system_variables.session_track_system_variables); + thd->variables.session_track_system_variables= + my_strdup(PSI_INSTRUMENT_ME, + global_system_variables.session_track_system_variables, + MYF(MY_WME | MY_THREAD_SPECIFIC)); +} + + +void Session_sysvars_tracker::deinit(THD *thd) +{ + my_free(thd->variables.session_track_system_variables); + thd->variables.session_track_system_variables= 0; +} + + +/** + Enable session tracker by parsing global value of tracked variables. + + @param thd [IN] The thd handle. + + @retval true Error + @retval false Success +*/ + +bool Session_sysvars_tracker::enable(THD *thd) +{ + orig_list.reinit(); + m_parsed= false; + m_enabled= thd->variables.session_track_system_variables && + *thd->variables.session_track_system_variables; + reset_changed(); + return false; +} + + +/** + Once the value of the @@session_track_system_variables has been + successfully updated, this function calls + Session_sysvars_tracker::vars_list::copy updating the hash in orig_list + which represents the system variables to be tracked. + + We are doing via tool list because there possible errors with memory + in this case value will be unchanged. + + @note This function is called from the ON_UPDATE() function of the + session_track_system_variables' sys_var class. + + @param thd [IN] The thd handle. + + @retval true Error + @retval false Success +*/ + +bool Session_sysvars_tracker::update(THD *thd, set_var *var) +{ + vars_list tool_list; + size_t length= 1; + + void *copy= var->save_result.string_value.str ? + my_memdup(PSI_INSTRUMENT_ME, var->save_result.string_value.str, + (length= var->save_result.string_value.length + 1), + MYF(MY_WME | MY_THREAD_SPECIFIC)) : + my_strdup(PSI_INSTRUMENT_ME, "", + MYF(MY_WME | MY_THREAD_SPECIFIC)); + if (!copy) + return true; + + if (tool_list.parse_var_list(thd, var->save_result.string_value, true, + thd->charset())) + { + my_free(copy); + return true; + } + + my_free(thd->variables.session_track_system_variables); + thd->variables.session_track_system_variables= static_cast<char*>(copy); + + m_parsed= true; + orig_list.copy(&tool_list, thd); + orig_list.construct_var_list(thd->variables.session_track_system_variables, + length); + return false; +} + + +bool Session_sysvars_tracker::vars_list::store(THD *thd, String *buf) +{ + for (ulong i= 0; i < m_registered_sysvars.records; i++) + { + sysvar_node_st *node= at(i); + + if (!node->m_changed) + continue; + + char val_buf[SHOW_VAR_FUNC_BUFF_SIZE]; + SHOW_VAR show; + CHARSET_INFO *charset; + size_t val_length, length; + mysql_mutex_lock(&LOCK_plugin); + if (!*node->test_load) + { + mysql_mutex_unlock(&LOCK_plugin); + continue; + } + sys_var *svar= node->m_svar; + bool is_plugin= svar->cast_pluginvar(); + if (!is_plugin) + mysql_mutex_unlock(&LOCK_plugin); + + /* As its always system variable. */ + show.type= SHOW_SYS; + show.name= svar->name.str; + show.value= (char *) svar; + + mysql_mutex_lock(&LOCK_global_system_variables); + const char *value= get_one_variable(thd, &show, OPT_SESSION, SHOW_SYS, NULL, + &charset, val_buf, &val_length); + mysql_mutex_unlock(&LOCK_global_system_variables); + + if (is_plugin) + mysql_mutex_unlock(&LOCK_plugin); + + length= net_length_size(svar->name.length) + + svar->name.length + + net_length_size(val_length) + + val_length; + + compile_time_assert(SESSION_TRACK_SYSTEM_VARIABLES < 251); + if (unlikely((1 + net_length_size(length) + length + buf->length() >= + MAX_PACKET_LENGTH) || + buf->reserve(1 + net_length_size(length) + length, + EXTRA_ALLOC))) + return true; + + + /* Session state type (SESSION_TRACK_SYSTEM_VARIABLES) */ + buf->q_append((char)SESSION_TRACK_SYSTEM_VARIABLES); + + /* Length of the overall entity. */ + buf->q_net_store_length((ulonglong)length); + + /* System variable's name (length-encoded string). */ + buf->q_net_store_data((const uchar*)svar->name.str, svar->name.length); + + /* System variable's value (length-encoded string). */ + buf->q_net_store_data((const uchar*)value, val_length); + } + return false; +} + + +/** + Store the data for changed system variables in the specified buffer. + Once the data is stored, we reset the flags related to state-change + (see reset()). + + @param thd [IN] The thd handle. + @paran buf [INOUT] Buffer to store the information to. + + @retval true Error + @retval false Success +*/ + +bool Session_sysvars_tracker::store(THD *thd, String *buf) +{ + if (!orig_list.is_enabled()) + return false; + + if (orig_list.store(thd, buf)) + return true; + + orig_list.reset(); + + return false; +} + + +/** + Mark the system variable as changed. + + @param [IN] pointer on a variable +*/ + +void Session_sysvars_tracker::mark_as_changed(THD *thd, const sys_var *var) +{ + sysvar_node_st *node; + + if (!is_enabled()) + return; + + if (!m_parsed) + { + DBUG_ASSERT(thd->variables.session_track_system_variables); + LEX_STRING tmp= { thd->variables.session_track_system_variables, + strlen(thd->variables.session_track_system_variables) }; + if (orig_list.parse_var_list(thd, tmp, true, thd->charset())) + { + orig_list.reinit(); + return; + } + m_parsed= true; + } + + /* + Check if the specified system variable is being tracked, if so + mark it as changed and also set the class's m_changed flag. + */ + if (orig_list.is_enabled() && (node= orig_list.insert_or_search(var))) + { + node->m_changed= true; + set_changed(thd); + } +} + + +/** + Supply key to a hash. + + @param entry [IN] A single entry. + @param length [OUT] Length of the key. + @param not_used Unused. + + @return Pointer to the key buffer. +*/ + +uchar *Session_sysvars_tracker::sysvars_get_key(const char *entry, + size_t *length, + my_bool not_used __attribute__((unused))) +{ + *length= sizeof(sys_var *); + return (uchar *) &(((sysvar_node_st *) entry)->m_svar); +} + + +void Session_sysvars_tracker::vars_list::reset() +{ + for (ulong i= 0; i < m_registered_sysvars.records; i++) + at(i)->m_changed= false; +} + + +bool sysvartrack_global_update(THD *thd, char *str, size_t len) +{ + LEX_STRING tmp= { str, len }; + Session_sysvars_tracker::vars_list dummy; + if (!dummy.parse_var_list(thd, tmp, false, system_charset_info)) + { + dummy.construct_var_list(str, len + 1); + return false; + } + return true; +} + + +int session_tracker_init() +{ + DBUG_ASSERT(global_system_variables.session_track_system_variables); + if (sysvartrack_validate_value(0, + global_system_variables.session_track_system_variables, + strlen(global_system_variables.session_track_system_variables))) + { + sql_print_error("The variable session_track_system_variables has " + "invalid values."); + return 1; + } + return 0; +} + + +/////////////////////////////////////////////////////////////////////////////// + +/** + Enable/disable the tracker based on @@session_track_schema's value. + + @param thd [IN] The thd handle. + + @return + false (always) +*/ + +bool Current_schema_tracker::update(THD *thd, set_var *) +{ + m_enabled= thd->variables.session_track_schema; + return false; +} + + +/** + Store the schema name as length-encoded string in the specified buffer. + + @param thd [IN] The thd handle. + @paran buf [INOUT] Buffer to store the information to. + + @reval false Success + @retval true Error +*/ + +bool Current_schema_tracker::store(THD *thd, String *buf) +{ + size_t db_length, length; + + /* + Protocol made (by unknown reasons) redundant: + It saves length of database name and name of database name + + length of saved length of database length. + */ + length= db_length= thd->db.length; + length += net_length_size(length); + + compile_time_assert(SESSION_TRACK_SCHEMA < 251); + compile_time_assert(NAME_LEN < 251); + DBUG_ASSERT(length < 251); + if (unlikely((1 + 1 + length + buf->length() >= MAX_PACKET_LENGTH) || + buf->reserve(1 + 1 + length, EXTRA_ALLOC))) + return true; + + /* Session state type (SESSION_TRACK_SCHEMA) */ + buf->q_append((char)SESSION_TRACK_SCHEMA); + + /* Length of the overall entity. */ + buf->q_net_store_length(length); + + /* Length and current schema name */ + buf->q_net_store_data((const uchar *)thd->db.str, thd->db.length); + + return false; +} + + +/////////////////////////////////////////////////////////////////////////////// + +/** + Enable/disable the tracker based on @@session_track_transaction_info. + + @param thd [IN] The thd handle. + + @retval true if updating the tracking level failed + @retval false otherwise +*/ + +bool Transaction_state_tracker::update(THD *thd, set_var *) +{ + if (thd->variables.session_track_transaction_info != TX_TRACK_NONE) + { + /* + If we only just turned reporting on (rather than changing between + state and characteristics reporting), start from a defined state. + */ + if (!m_enabled) + { + tx_curr_state = + tx_reported_state = TX_EMPTY; + tx_changed |= TX_CHG_STATE; + m_enabled= true; + } + if (thd->variables.session_track_transaction_info == TX_TRACK_CHISTICS) + tx_changed |= TX_CHG_CHISTICS; + set_changed(thd); + } + else + m_enabled= false; + + return false; +} + + +/** + Store the transaction state (and, optionally, characteristics) + as length-encoded string in the specified buffer. Once the data + is stored, we reset the flags related to state-change (see reset()). + + + @param thd [IN] The thd handle. + @paran buf [INOUT] Buffer to store the information to. + + @retval false Success + @retval true Error +*/ + +static LEX_CSTRING isol[]= { + { STRING_WITH_LEN("READ UNCOMMITTED") }, + { STRING_WITH_LEN("READ COMMITTED") }, + { STRING_WITH_LEN("REPEATABLE READ") }, + { STRING_WITH_LEN("SERIALIZABLE") } +}; + +bool Transaction_state_tracker::store(THD *thd, String *buf) +{ + /* STATE */ + if (tx_changed & TX_CHG_STATE) + { + if (unlikely((11 + buf->length() >= MAX_PACKET_LENGTH) || + buf->reserve(11, EXTRA_ALLOC))) + return true; + + buf->q_append((char)SESSION_TRACK_TRANSACTION_STATE); + + buf->q_append((char)9); // whole packet length + buf->q_append((char)8); // results length + + buf->q_append((char)((tx_curr_state & TX_EXPLICIT) ? 'T' : + ((tx_curr_state & TX_IMPLICIT) ? 'I' : '_'))); + buf->q_append((char)((tx_curr_state & TX_READ_UNSAFE) ? 'r' : '_')); + buf->q_append((char)(((tx_curr_state & TX_READ_TRX) || + (tx_curr_state & TX_WITH_SNAPSHOT)) ? 'R' : '_')); + buf->q_append((char)((tx_curr_state & TX_WRITE_UNSAFE) ? 'w' : '_')); + buf->q_append((char)((tx_curr_state & TX_WRITE_TRX) ? 'W' : '_')); + buf->q_append((char)((tx_curr_state & TX_STMT_UNSAFE) ? 's' : '_')); + buf->q_append((char)((tx_curr_state & TX_RESULT_SET) ? 'S' : '_')); + buf->q_append((char)((tx_curr_state & TX_LOCKED_TABLES) ? 'L' : '_')); + } + + /* CHARACTERISTICS -- How to restart the transaction */ + + if ((thd->variables.session_track_transaction_info == TX_TRACK_CHISTICS) && + (tx_changed & TX_CHG_CHISTICS)) + { + bool is_xa= thd->transaction->xid_state.is_explicit_XA(); + size_t start; + + /* 2 length by 1 byte and code */ + if (unlikely((1 + 1 + 1 + 110 + buf->length() >= MAX_PACKET_LENGTH) || + buf->reserve(1 + 1 + 1, EXTRA_ALLOC))) + return true; + + compile_time_assert(SESSION_TRACK_TRANSACTION_CHARACTERISTICS < 251); + /* Session state type (SESSION_TRACK_TRANSACTION_CHARACTERISTICS) */ + buf->q_append((char)SESSION_TRACK_TRANSACTION_CHARACTERISTICS); + + /* placeholders for lengths. will be filled in at the end */ + buf->q_append('\0'); + buf->q_append('\0'); + + start= buf->length(); + + { + /* + We have four basic replay scenarios: + + a) SET TRANSACTION was used, but before an actual transaction + was started, the load balancer moves the connection elsewhere. + In that case, the same one-shots should be set up in the + target session. (read-only/read-write; isolation-level) + + b) The initial transaction has begun; the relevant characteristics + are the session defaults, possibly overridden by previous + SET TRANSACTION statements, possibly overridden or extended + by options passed to the START TRANSACTION statement. + If the load balancer wishes to move this transaction, + it needs to be replayed with the correct characteristics. + (read-only/read-write from SET or START; + isolation-level from SET only, snapshot from START only) + + c) A subsequent transaction started with START TRANSACTION + (which is legal syntax in lieu of COMMIT AND CHAIN in MySQL) + may add/modify the current one-shots: + + - It may set up a read-only/read-write one-shot. + This one-shot will override the value used in the previous + transaction (whether that came from the default or a one-shot), + and, like all one-shots currently do, it will carry over into + any subsequent transactions that don't explicitly override them + in turn. This behavior is not guaranteed in the docs and may + change in the future, but the tracker item should correctly + reflect whatever behavior a given version of mysqld implements. + + - It may also set up a WITH CONSISTENT SNAPSHOT one-shot. + This one-shot does not currently carry over into subsequent + transactions (meaning that with "traditional syntax", WITH + CONSISTENT SNAPSHOT can only be requested for the first part + of a transaction chain). Again, the tracker item should reflect + mysqld behavior. + + d) A subsequent transaction started using COMMIT AND CHAIN + (or, for that matter, BEGIN WORK, which is currently + legal and equivalent syntax in MySQL, or START TRANSACTION + sans options) will re-use any one-shots set up so far + (with SET before the first transaction started, and with + all subsequent STARTs), except for WITH CONSISTANT SNAPSHOT, + which will never be chained and only applies when explicitly + given. + + It bears noting that if we switch sessions in a follow-up + transaction, SET TRANSACTION would be illegal in the old + session (as a transaction is active), whereas in the target + session which is being prepared, it should be legal, as no + transaction (chain) should have started yet. + + Therefore, we are free to generate SET TRANSACTION as a replay + statement even for a transaction that isn't the first in an + ongoing chain. Consider + + SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED; + START TRANSACTION READ ONLY, WITH CONSISTENT SNAPSHOT; + # work + COMMIT AND CHAIN; + + If we switch away at this point, the replay in the new session + needs to be + + SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED; + START TRANSACTION READ ONLY; + + When a transaction ends (COMMIT/ROLLBACK sans CHAIN), all + per-transaction characteristics are reset to the session's + defaults. + + This also holds for a transaction ended implicitly! (transaction.cc) + Once again, the aim is to have the tracker item reflect on a + given mysqld's actual behavior. + */ + + /* + "ISOLATION LEVEL" + Only legal in SET TRANSACTION, so will always be replayed as such. + */ + if (tx_isol_level != TX_ISOL_INHERIT) + { + /* + Unfortunately, we can't re-use tx_isolation_names / + tx_isolation_typelib as it hyphenates its items. + */ + buf->append(STRING_WITH_LEN("SET TRANSACTION ISOLATION LEVEL ")); + buf->append(&isol[tx_isol_level - 1]); + buf->append(STRING_WITH_LEN("; ")); + } + + /* + Start transaction will usually result in TX_EXPLICIT (transaction + started, but no data attached yet), except when WITH CONSISTENT + SNAPSHOT, in which case we may have data pending. + If it's an XA transaction, we don't go through here so we can + first print the trx access mode ("SET TRANSACTION READ ...") + separately before adding XA START (whereas with START TRANSACTION, + we can merge the access mode into the same statement). + */ + if ((tx_curr_state & TX_EXPLICIT) && !is_xa) + { + buf->append(STRING_WITH_LEN("START TRANSACTION")); + + /* + "WITH CONSISTENT SNAPSHOT" + Defaults to no, can only be enabled. + Only appears in START TRANSACTION. + */ + if (tx_curr_state & TX_WITH_SNAPSHOT) + { + buf->append(STRING_WITH_LEN(" WITH CONSISTENT SNAPSHOT")); + if (tx_read_flags != TX_READ_INHERIT) + buf->append(STRING_WITH_LEN(",")); + } + + /* + "READ WRITE / READ ONLY" can be set globally, per-session, + or just for one transaction. + + The latter case can take the form of + START TRANSACTION READ (WRITE|ONLY), or of + SET TRANSACTION READ (ONLY|WRITE). + (Both set thd->read_only for the upcoming transaction; + it will ultimately be re-set to the session default.) + + As the regular session-variable tracker does not monitor the one-shot, + we'll have to do it here. + + If READ is flagged as set explicitly (rather than just inherited + from the session's default), we'll get the actual bool from the THD. + */ + if (tx_read_flags != TX_READ_INHERIT) + { + if (tx_read_flags == TX_READ_ONLY) + buf->append(STRING_WITH_LEN(" READ ONLY")); + else + buf->append(STRING_WITH_LEN(" READ WRITE")); + } + buf->append(STRING_WITH_LEN("; ")); + } + else if (tx_read_flags != TX_READ_INHERIT) + { + /* + "READ ONLY" / "READ WRITE" + We could transform this to SET TRANSACTION even when it occurs + in START TRANSACTION, but for now, we'll resysynthesize the original + command as closely as possible. + */ + buf->append(STRING_WITH_LEN("SET TRANSACTION ")); + if (tx_read_flags == TX_READ_ONLY) + buf->append(STRING_WITH_LEN("READ ONLY; ")); + else + buf->append(STRING_WITH_LEN("READ WRITE; ")); + } + + if ((tx_curr_state & TX_EXPLICIT) && is_xa) + { + XID *xid= thd->transaction->xid_state.get_xid(); + long glen, blen; + + buf->append(STRING_WITH_LEN("XA START")); + + if ((glen= xid->gtrid_length) > 0) + { + buf->append(STRING_WITH_LEN(" '")); + buf->append(xid->data, glen); + + if ((blen= xid->bqual_length) > 0) + { + buf->append(STRING_WITH_LEN("','")); + buf->append(xid->data + glen, blen); + } + buf->append(STRING_WITH_LEN("'")); + + if (xid->formatID != 1) + { + buf->append(STRING_WITH_LEN(",")); + buf->append_ulonglong(xid->formatID); + } + } + + buf->append(STRING_WITH_LEN("; ")); + } + + // discard trailing space + if (buf->length() > start) + buf->length(buf->length() - 1); + } + + { + size_t length= buf->length() - start; + uchar *place= (uchar *)(buf->ptr() + (start - 2)); + DBUG_ASSERT(length < 249); // in fact < 110 + DBUG_ASSERT(start >= 3); + + DBUG_ASSERT((place - 1)[0] == SESSION_TRACK_TRANSACTION_CHARACTERISTICS); + /* Length of the overall entity. */ + place[0]= (uchar)length + 1; + /* Transaction characteristics (length-encoded string). */ + place[1]= (uchar)length; + } + } + + tx_reported_state= tx_curr_state; + tx_changed= TX_CHG_NONE; + + return false; +} + + +/** + Helper function: turn table info into table access flag. + Accepts table lock type and engine type flag (transactional/ + non-transactional), and returns the corresponding access flag + out of TX_READ_TRX, TX_READ_UNSAFE, TX_WRITE_TRX, TX_WRITE_UNSAFE. + + @param thd [IN] The thd handle + @param set [IN] The table's access/lock type + @param set [IN] Whether the table's engine is transactional + + @return The table access flag +*/ + +enum_tx_state Transaction_state_tracker::calc_trx_state(THD *thd, + thr_lock_type l, + bool has_trx) +{ + enum_tx_state s; + bool read= (l <= TL_READ_NO_INSERT); + + if (read) + s= has_trx ? TX_READ_TRX : TX_READ_UNSAFE; + else + s= has_trx ? TX_WRITE_TRX : TX_WRITE_UNSAFE; + + return s; +} + + +/** + Register the end of an (implicit or explicit) transaction. + + @param thd [IN] The thd handle +*/ +void Transaction_state_tracker::end_trx(THD *thd) +{ + DBUG_ASSERT(thd->variables.session_track_transaction_info > TX_TRACK_NONE); + + if ((!m_enabled) || (thd->state_flags & Open_tables_state::BACKUPS_AVAIL)) + return; + + if (tx_curr_state != TX_EMPTY) + { + if (tx_curr_state & TX_EXPLICIT) + tx_changed |= TX_CHG_CHISTICS; + tx_curr_state &= TX_LOCKED_TABLES; + } + update_change_flags(thd); +} + + +/** + Clear flags pertaining to the current statement or transaction. + May be called repeatedly within the same execution cycle. + + @param thd [IN] The thd handle. + @param set [IN] The flags to clear +*/ + +void Transaction_state_tracker::clear_trx_state(THD *thd, uint clear) +{ + if ((!m_enabled) || (thd->state_flags & Open_tables_state::BACKUPS_AVAIL)) + return; + + tx_curr_state &= ~clear; + update_change_flags(thd); +} + + +/** + Add flags pertaining to the current statement or transaction. + May be called repeatedly within the same execution cycle, + e.g. to add access info for more tables. + + @param thd [IN] The thd handle. + @param set [IN] The flags to add +*/ + +void Transaction_state_tracker::add_trx_state(THD *thd, uint add) +{ + if ((!m_enabled) || (thd->state_flags & Open_tables_state::BACKUPS_AVAIL)) + return; + + if (add == TX_EXPLICIT) + { + /* Always send characteristic item (if tracked), always replace state. */ + tx_changed |= TX_CHG_CHISTICS; + tx_curr_state = TX_EXPLICIT; + } + + /* + If we're not in an implicit or explicit transaction, but + autocommit==0 and tables are accessed, we flag "implicit transaction." + */ + else if (!(tx_curr_state & (TX_EXPLICIT|TX_IMPLICIT)) && + (thd->variables.option_bits & OPTION_NOT_AUTOCOMMIT) && + (add & + (TX_READ_TRX | TX_READ_UNSAFE | TX_WRITE_TRX | TX_WRITE_UNSAFE))) + tx_curr_state |= TX_IMPLICIT; + + /* + Only flag state when in transaction or LOCK TABLES is added. + */ + if ((tx_curr_state & (TX_EXPLICIT | TX_IMPLICIT)) || + (add & TX_LOCKED_TABLES)) + tx_curr_state |= add; + + update_change_flags(thd); +} + + +/** + Add "unsafe statement" flag if applicable. + + @param thd [IN] The thd handle. + @param set [IN] The flags to add +*/ + +void Transaction_state_tracker::add_trx_state_from_thd(THD *thd) +{ + if (m_enabled) + { + if (thd->lex->is_stmt_unsafe()) + add_trx_state(thd, TX_STMT_UNSAFE); + } +} + + +/** + Set read flags (read only/read write) pertaining to the next + transaction. + + @param thd [IN] The thd handle. + @param set [IN] The flags to set +*/ + +void Transaction_state_tracker::set_read_flags(THD *thd, + enum enum_tx_read_flags flags) +{ + if (m_enabled && (tx_read_flags != flags)) + { + tx_read_flags = flags; + tx_changed |= TX_CHG_CHISTICS; + set_changed(thd); + } +} + + +/** + Set isolation level pertaining to the next transaction. + + @param thd [IN] The thd handle. + @param set [IN] The isolation level to set +*/ + +void Transaction_state_tracker::set_isol_level(THD *thd, + enum enum_tx_isol_level level) +{ + if (m_enabled && (tx_isol_level != level)) + { + tx_isol_level = level; + tx_changed |= TX_CHG_CHISTICS; + set_changed(thd); + } +} + + +/////////////////////////////////////////////////////////////////////////////// + +/** + @Enable/disable the tracker based on @@session_track_state_change value. + + @param thd [IN] The thd handle. + @return false (always) + +**/ + +bool Session_state_change_tracker::update(THD *thd, set_var *) +{ + m_enabled= thd->variables.session_track_state_change; + return false; +} + +/** + Store the '1' in the specified buffer when state is changed. + + @param thd [IN] The thd handle. + @paran buf [INOUT] Buffer to store the information to. + + @reval false Success + @retval true Error +**/ + +bool Session_state_change_tracker::store(THD *thd, String *buf) +{ + if (unlikely((1 + 1 + 1 + buf->length() >= MAX_PACKET_LENGTH) || + buf->reserve(1 + 1 + 1, EXTRA_ALLOC))) + return true; + + compile_time_assert(SESSION_TRACK_STATE_CHANGE < 251); + /* Session state type (SESSION_TRACK_STATE_CHANGE) */ + buf->q_append((char)SESSION_TRACK_STATE_CHANGE); + + /* Length of the overall entity (1 byte) */ + buf->q_append('\1'); + + DBUG_ASSERT(is_changed()); + buf->q_append('1'); + + return false; +} + +#ifdef USER_VAR_TRACKING + +bool User_variables_tracker::update(THD *thd, set_var *) +{ + m_enabled= thd->variables.session_track_user_variables; + return false; +} + + +bool User_variables_tracker::store(THD *thd, String *buf) +{ + for (ulong i= 0; i < m_changed_user_variables.size(); i++) + { + const user_var_entry *var= m_changed_user_variables.at(i); + String value_str; + bool null_value; + size_t length; + + var->val_str(&null_value, &value_str, DECIMAL_MAX_SCALE); + length= net_length_size(var->name.length) + var->name.length; + if (!null_value) + length+= net_length_size(value_str.length()) + value_str.length(); + else + length+= 1; + + if (buf->reserve(sizeof(char) + length + net_length_size(length))) + return true; + + // TODO: check max packet length MDEV-22709 + buf->q_append(static_cast<char>(SESSION_TRACK_USER_VARIABLES)); + buf->q_net_store_length(length); + buf->q_net_store_data(reinterpret_cast<const uchar*>(var->name.str), + var->name.length); + if (!null_value) + buf->q_net_store_data(reinterpret_cast<const uchar*>(value_str.ptr()), + value_str.length()); + else + { + char nullbuff[1]= { (char)251 }; + buf->q_append(nullbuff, sizeof(nullbuff)); + } + } + m_changed_user_variables.clear(); + return false; +} +#endif // USER_VAR_TRACKING + +/////////////////////////////////////////////////////////////////////////////// + +/** + @brief Store all change information in the specified buffer. + + @param thd [IN] The thd handle. + @param buf [OUT] Reference to the string buffer to which the state + change data needs to be written. +*/ + +void Session_tracker::store(THD *thd, String *buf) +{ + size_t start; + + /* track data ID fit into one byte in net coding */ + compile_time_assert(SESSION_TRACK_always_at_the_end < 251); + /* one tracker could serv several tracking data */ + compile_time_assert((uint) SESSION_TRACK_always_at_the_end >= + (uint) SESSION_TRACKER_END); + + /* + Probably most track result will fit in 251 byte so lets made it at + least efficient. We allocate 1 byte for length and then will move + string if there is more. + */ + buf->append('\0'); + start= buf->length(); + + /* Get total length. */ + for (int i= 0; i < SESSION_TRACKER_END; i++) + { + if (m_trackers[i]->is_changed()) + { + if (m_trackers[i]->store(thd, buf)) + { + // it is safer to have 0-length block in case of error + buf->length(start); + return; + } + m_trackers[i]->reset_changed(); + } + } + + size_t length= buf->length() - start; + uchar *data; + uint size; + + if ((size= net_length_size(length)) != 1) + { + if (buf->reserve(size - 1, 0)) + { + buf->length(start); // it is safer to have 0-length block in case of error + return; + } + + /* + The 'buf->reserve()' can change the buf->ptr() so we cannot + calculate the 'data' earlier. + */ + buf->length(buf->length() + (size - 1)); + data= (uchar *)(buf->ptr() + start); + memmove(data + (size - 1), data, length); + } + else + data= (uchar *)(buf->ptr() + start); + + net_store_length(data - 1, length); +} |