├── .gitignore ├── LICENSE ├── README.md ├── scripts └── build_for.sh └── src ├── CMakeLists.txt ├── hack_context.h └── mdl_info.cc /.gitignore: -------------------------------------------------------------------------------- 1 | # Compiled Object files 2 | *.slo 3 | *.lo 4 | *.o 5 | 6 | # Compiled Dynamic libraries 7 | *.so 8 | *.dylib 9 | 10 | # Compiled Static libraries 11 | *.lai 12 | *.la 13 | *.a 14 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU LESSER GENERAL PUBLIC LICENSE 2 | Version 2.1, February 1999 3 | 4 | Copyright (C) 1991, 1999 Free Software Foundation, Inc. 5 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 6 | Everyone is permitted to copy and distribute verbatim copies 7 | of this license document, but changing it is not allowed. 8 | 9 | [This is the first released version of the Lesser GPL. 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Here is a sample; alter the names: 495 | 496 | Yoyodyne, Inc., hereby disclaims all copyright interest in the 497 | library `Frob' (a library for tweaking knobs) written by James Random Hacker. 498 | 499 | {signature of Ty Coon}, 1 April 1990 500 | Ty Coon, President of Vice 501 | 502 | That's all there is to it! 503 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | mysql-plugin-mdl-info 2 | ======================= 3 | 4 | This plugin is used to show all metadata locks (MDL) info of mysql 5.5+. 5 | The behavior of metadata locks has changed in mysql 5.5 . DDL statements may be blocked by MDL in some unobvious way like `begin; select * from some table;` and has no way to find out by whom the table is locked. This plugin used a trick way to fetch the MDL information and now, you can know who lock the tables through a information schema table. 6 | 7 | usage 8 | ----- 9 | 10 | first, compile the plugin and install in to plugin dir 11 | 12 | cp -r src /path/to/mysql-src/plugin/mdl_info 13 | cd /path/to/mysql-src 14 | cmake . -DBUILD_CONFIG=mysql_release 15 | cd plugin/mdl_info 16 | make 17 | make install 18 | 19 | CAUTION: mysql plugins MUST be built using the same version of the source code and the same build arguments. If mysqld is built as a debug version without cmake parameter -DBUILD_CONFIG, the parameter must not be added when compiling plugins. 20 | 21 | then, load the plugin into mysql 22 | 23 | mysql> INSTALL PLUGIN MDL_INFO SONAME 'mdl_info.so'; 24 | 25 | thus, you can found `MDL_INFO` table in `information_schema` database 26 | 27 | mysql> lock tables plugin read; 28 | Query OK, 0 rows affected (0.00 sec) 29 | 30 | mysql> select * from information_schema.MDL_INFO; 31 | +-----------+----------+-------------+-----------+----------+--------+ 32 | | THREAD_ID | DURATION | TYPE | NAMESPACE | DATABASE | NAME | 33 | +-----------+----------+-------------+-----------+----------+--------+ 34 | | 4 | EXPLICIT | SHARED_READ | TABLE | mysql | plugin | 35 | +-----------+----------+-------------+-----------+----------+--------+ 36 | 1 row in set (0.00 sec) 37 | 38 | mysql> unlock tables; 39 | Query OK, 0 rows affected (0.00 sec) 40 | 41 | mysql> lock tables plugin write; 42 | Query OK, 0 rows affected (0.00 sec) 43 | 44 | mysql> select * from information_schema.MDL_INFO; 45 | +-----------+----------+----------------------+-----------+----------+--------+ 46 | | THREAD_ID | DURATION | TYPE | NAMESPACE | DATABASE | NAME | 47 | +-----------+----------+----------------------+-----------+----------+--------+ 48 | | 4 | EXPLICIT | INTENTION_EXCLUSIVE | GLOBAL | | | 49 | | 4 | EXPLICIT | SHARED_NO_READ_WRITE | TABLE | mysql | plugin | 50 | | 4 | EXPLICIT | INTENTION_EXCLUSIVE | SCHEMA | mysql | | 51 | +-----------+----------+----------------------+-----------+----------+--------+ 52 | 3 rows in set (0.00 sec) 53 | 54 | mysql> unlock tables; 55 | Query OK, 0 rows affected (0.00 sec) 56 | 57 | mysql> begin; 58 | Query OK, 0 rows affected (0.00 sec) 59 | 60 | mysql> select * from plugin; 61 | +-----------+--------------+ 62 | | name | dl | 63 | +-----------+--------------+ 64 | | MDL_INFO | mdl_info.so | 65 | +-----------+--------------+ 66 | 1 row in set (0.01 sec) 67 | 68 | mysql> select * from information_schema.MDL_INFO; 69 | +-----------+-------------+-------------+-----------+----------+--------+ 70 | | THREAD_ID | DURATION | TYPE | NAMESPACE | DATABASE | NAME | 71 | +-----------+-------------+-------------+-----------+----------+--------+ 72 | | 4 | TRANSACTION | SHARED_READ | TABLE | mysql | plugin | 73 | +-----------+-------------+-------------+-----------+----------+--------+ 74 | 1 row in set (0.01 sec) 75 | 76 | mysql> rollback; 77 | Query OK, 0 rows affected (0.00 sec) 78 | 79 | mysql> flush tables with read lock; 80 | Query OK, 0 rows affected (0.00 sec) 81 | 82 | mysql> select * from information_schema.MDL_INFO; 83 | +-----------+----------+--------+-----------+----------+------+ 84 | | THREAD_ID | DURATION | TYPE | NAMESPACE | DATABASE | NAME | 85 | +-----------+----------+--------+-----------+----------+------+ 86 | | 4 | EXPLICIT | SHARED | COMMIT | | | 87 | | 4 | EXPLICIT | SHARED | GLOBAL | | | 88 | +-----------+----------+--------+-----------+----------+------+ 89 | 2 rows in set (0.00 sec) 90 | 91 | mysql> unlock tables; 92 | Query OK, 0 rows affected (0.00 sec) 93 | 94 | 95 | 96 | 97 | -------------------------------------------------------------------------------- /scripts/build_for.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | 3 | ver="$1" 4 | target="${2:-.}" 5 | target="$(readlink -e "$target")" 6 | cwd="$(dirname `readlink -e "$0"`)" 7 | BUILD_CONFIG="${BUILD_CONFIG:-mysql_release}" 8 | 9 | if [[ -z "$ver" ]]; then 10 | echo "usage: ./build_for.sh " >&2 11 | exit 1 12 | fi 13 | 14 | name='mdl_info' 15 | 16 | cd "$target" 17 | if [[ ! -e "mysql-$ver" ]]; then 18 | file="mysql-$ver.tar.gz" 19 | if [[ ! -e "$file" ]]; then 20 | wget "http://downloads.mysql.com/archives/get/file/$file" 21 | fi 22 | tar -xzvf "$file" 23 | fi 24 | if [[ ! -e "mysql-$ver/plugin/${name}" ]]; then 25 | cp -r "$cwd/../src" "mysql-$ver/plugin/${name}" 26 | fi 27 | cd "mysql-$ver" 28 | if [[ ! -e plugin/${name}/${name}.so ]]; then 29 | cmake . -DBUILD_CONFIG="${BUILD_CONFIG}" 30 | ncpu=$( grep "processor" /proc/cpuinfo | wc -l ) 31 | (( nproc=$ncpu*2 )) 32 | make -j $nproc "${name}" 33 | fi 34 | my_ver=$(gawk -F'[()" ]+' '$1=="SET"&&$2=="CPACK_PACKAGE_FILE_NAME"{print $3}' "CPackConfig.cmake") 35 | ver="${my_ver#*-}" 36 | cp plugin/${name}/${name}.so "$target/${name}_${ver}.so" 37 | 38 | -------------------------------------------------------------------------------- /src/CMakeLists.txt: -------------------------------------------------------------------------------- 1 | cmake_minimum_required(VERSION 2.6) 2 | 3 | MYSQL_ADD_PLUGIN(mdl_info mdl_info.cc 4 | MODULE_ONLY MODULE_OUTPUT_NAME "mdl_info") 5 | 6 | -------------------------------------------------------------------------------- /src/hack_context.h: -------------------------------------------------------------------------------- 1 | #if MYSQL_VERSION_ID >= 50600 2 | class Hack_MDL_context { 3 | public: 4 | MDL_wait m_wait; 5 | MDL_context::Ticket_list m_tickets[MDL_DURATION_END]; 6 | MDL_context_owner *m_owner; 7 | bool m_needs_thr_lock_abort; 8 | mysql_prlock_t m_LOCK_waiting_for; 9 | MDL_wait_for_subgraph *m_waiting_for; 10 | }; 11 | #else 12 | class Hack_MDL_context { 13 | public: 14 | MDL_wait m_wait; 15 | MDL_context::Ticket_list m_tickets[MDL_DURATION_END]; 16 | THD *m_thd; 17 | bool m_needs_thr_lock_abort; 18 | mysql_prlock_t m_LOCK_waiting_for; 19 | MDL_wait_for_subgraph *m_waiting_for; 20 | }; 21 | #endif 22 | -------------------------------------------------------------------------------- /src/mdl_info.cc: -------------------------------------------------------------------------------- 1 | #define MYSQL_SERVER 2 | 3 | #include "sql_class.h" 4 | #include "table.h" 5 | #include "set_var.h" 6 | #if MYSQL_VERSION_ID >= 50600 7 | #include "global_threads.h" 8 | #endif 9 | #include "hack_context.h" 10 | #include "mdl.cc" 11 | 12 | static struct st_mysql_information_schema is_mdl_info = 13 | { MYSQL_INFORMATION_SCHEMA_INTERFACE_VERSION }; 14 | 15 | static ST_FIELD_INFO mdl_info_table_fields[] = 16 | { 17 | {"THREAD_ID", 11, MYSQL_TYPE_LONG, 0, MY_I_S_UNSIGNED, 0, 0}, 18 | {"DURATION", 30, MYSQL_TYPE_STRING, 0, 0, 0, 0}, 19 | {"TYPE", 255, MYSQL_TYPE_STRING, 0, 0, 0, 0}, 20 | {"NAMESPACE", 30, MYSQL_TYPE_STRING, 0, 0, 0, 0}, 21 | {"DATABASE", 255, MYSQL_TYPE_STRING, 0, 0, 0, 0}, 22 | {"NAME", 255, MYSQL_TYPE_STRING, 0, 0, 0, 0}, 23 | {0, 0, MYSQL_TYPE_NULL, 0, 0, 0, 0} 24 | }; 25 | 26 | static const char *type_desc[] = 27 | { 28 | "INTENTION_EXCLUSIVE", 29 | "SHARED", 30 | "SHARED_HIGH_PRIO", 31 | "SHARED_READ", 32 | "SHARED_WRITE", 33 | "SHARED_NO_WRITE", 34 | "SHARED_NO_READ_WRITE", 35 | "EXCLUSIVE", 36 | "NULL" //MDL_TYPE_END 37 | }; 38 | 39 | static const char *ns_desc[] = 40 | { 41 | "GLOBAL", 42 | "SCHEMA", 43 | "TABLE", 44 | "FUNCTION", 45 | "PROCEDURE", 46 | "TRIGGER", 47 | "EVENT", 48 | "COMMIT", 49 | "NULL" //NAMESPACE_END 50 | }; 51 | 52 | struct MDL_lock; 53 | typedef MDL_context::Ticket_iterator Ticket_iterator; 54 | bool schema_table_store_record(THD *thd, TABLE *table); 55 | static int mdl_info_init(void *ptr); 56 | static int mdl_info_fill_table(THD *thd, TABLE_LIST *tables, Item *cond); 57 | static void ticket_fill_table(THD *thd, THD *cur_thd, TABLE *table, Item *cond, Ticket_iterator itr, const char *duration); 58 | 59 | static int mdl_info_fill_table(THD *thd, TABLE_LIST *tables, Item *cond) 60 | { 61 | TABLE *table = tables->table; 62 | if (thd->killed != 0) { 63 | return 1; 64 | } 65 | 66 | mysql_mutex_lock(&LOCK_thread_count); 67 | THD *cur_thd; 68 | #if MYSQL_VERSION_ID < 50600 69 | I_List_iterator it(threads); 70 | while ((cur_thd= it++)) 71 | { 72 | #else 73 | Thread_iterator it= global_thread_list_begin(); 74 | Thread_iterator end= global_thread_list_end(); 75 | for (; it != end; ++it) 76 | { 77 | cur_thd = *it; 78 | #endif 79 | if (cur_thd == NULL) 80 | { 81 | continue; 82 | } 83 | if (! cur_thd->mdl_context.has_locks()) { 84 | continue; 85 | } 86 | Hack_MDL_context *hmc; 87 | hmc = (Hack_MDL_context *)(&(cur_thd->mdl_context)); 88 | Ticket_iterator stmt_tks = MDL_context::Ticket_iterator(hmc->m_tickets[MDL_STATEMENT]); 89 | ticket_fill_table(thd, cur_thd, table, cond, stmt_tks, "STATEMENT"); 90 | Ticket_iterator tran_tks = MDL_context::Ticket_iterator(hmc->m_tickets[MDL_TRANSACTION]); 91 | ticket_fill_table(thd, cur_thd, table, cond, tran_tks, "TRANSACTION"); 92 | Ticket_iterator expl_tks = MDL_context::Ticket_iterator(hmc->m_tickets[MDL_EXPLICIT]); 93 | ticket_fill_table(thd, cur_thd, table, cond, expl_tks, "EXPLICIT"); 94 | } 95 | mysql_mutex_unlock(&LOCK_thread_count); 96 | return 0; 97 | } 98 | 99 | static void ticket_fill_table(THD *thd, THD *cur_thd, TABLE *table, Item *cond, Ticket_iterator itr, const char *duration) 100 | { 101 | MDL_key *key; 102 | MDL_lock *lock; 103 | MDL_ticket *ticket; 104 | const char *type; 105 | const char *ns; 106 | 107 | while ((ticket = itr++)) { 108 | type = type_desc[(int) ticket->get_type()]; 109 | lock = ticket->get_lock(); 110 | if (!lock) { 111 | continue; 112 | } 113 | key = &(lock->key); 114 | if (!key) { 115 | continue; 116 | } 117 | ns = ns_desc[(int) key->mdl_namespace()]; 118 | table->field[0]->store(cur_thd->thread_id); 119 | table->field[1]->store(duration, strlen(duration), system_charset_info); 120 | table->field[2]->store(type, strlen(type), system_charset_info); 121 | table->field[3]->store(ns, strlen(ns), system_charset_info); 122 | table->field[4]->store(key->db_name(), key->db_name_length(), system_charset_info); 123 | table->field[5]->store(key->name(), key->name_length(), system_charset_info); 124 | schema_table_store_record(thd, table); 125 | } 126 | return; 127 | } 128 | 129 | static int mdl_info_init(void *ptr) 130 | { 131 | ST_SCHEMA_TABLE *schema_table = (ST_SCHEMA_TABLE *)ptr; 132 | schema_table->fields_info = mdl_info_table_fields; 133 | schema_table->fill_table = mdl_info_fill_table; 134 | return 0; 135 | } 136 | 137 | mysql_declare_plugin(mdl_info) 138 | { 139 | MYSQL_INFORMATION_SCHEMA_PLUGIN, 140 | &is_mdl_info, 141 | "MDL_INFO", 142 | "Xie Zhenye", 143 | "MDL Locks", 144 | PLUGIN_LICENSE_GPL, 145 | mdl_info_init, 146 | NULL, 147 | 0x0100, 148 | NULL, 149 | NULL, 150 | NULL, 151 | 0 152 | } 153 | mysql_declare_plugin_end; 154 | 155 | --------------------------------------------------------------------------------