add metadata_lock_info

plugin/metadata_lock_info/CMakeLists.txt

+SET(METADATA_LOCK_INFO_SOURCES metadata_lock_info.cc)
+MYSQL_ADD_PLUGIN(metadata_lock_info ${METADATA_LOCK_INFO_SOURCES} MODULE_OUTPUT_NAME "metadata_lock_info")

plugin/metadata_lock_info/metadata_lock_info.cc

+/* Copyright (C) 2013 Kentoku Shiba
+
+  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+#define MYSQL_SERVER 1
+#include "mysql_version.h"
+#include "mysql/plugin.h"
+#include "sql_class.h"
+#include "sql_show.h"
+
+static const LEX_STRING metadata_lock_info_lock_name[] = {
+  { C_STRING_WITH_LEN("Global read lock") },
+  { C_STRING_WITH_LEN("Schema metadata lock") },
+  { C_STRING_WITH_LEN("Table metadata lock") },
+  { C_STRING_WITH_LEN("Stored function metadata lock") },
+  { C_STRING_WITH_LEN("Stored procedure metadata lock") },
+  { C_STRING_WITH_LEN("Trigger metadata lock") },
+  { C_STRING_WITH_LEN("Event metadata lock") },
+  { C_STRING_WITH_LEN("Commit lock") },
+  { C_STRING_WITH_LEN("User lock") },
+};
+
+static const LEX_STRING metadata_lock_info_lock_mode[] = {
+  { C_STRING_WITH_LEN("MDL_INTENTION_EXCLUSIVE") },
+  { C_STRING_WITH_LEN("MDL_SHARED") },
+  { C_STRING_WITH_LEN("MDL_SHARED_HIGH_PRIO") },
+  { C_STRING_WITH_LEN("MDL_SHARED_READ") },
+  { C_STRING_WITH_LEN("MDL_SHARED_WRITE") },
+  { C_STRING_WITH_LEN("MDL_SHARED_NO_WRITE") },
+  { C_STRING_WITH_LEN("MDL_SHARED_NO_READ_WRITE") },
+  { C_STRING_WITH_LEN("MDL_EXCLUSIVE") },
+};
+
+static const LEX_STRING metadata_lock_info_duration[] = {
+  { C_STRING_WITH_LEN("MDL_STATEMENT") },
+  { C_STRING_WITH_LEN("MDL_TRANSACTION") },
+  { C_STRING_WITH_LEN("MDL_EXPLICIT") },
+};
+
+static ST_FIELD_INFO i_s_metadata_lock_info_fields_info[] =
+{
+  {"THREAD_ID", 20, MYSQL_TYPE_LONGLONG, 0,
+    MY_I_S_UNSIGNED, "thread_id", SKIP_OPEN_TABLE},
+  {"LOCK_MODE", 24, MYSQL_TYPE_STRING, 0,
+    MY_I_S_MAYBE_NULL, "lock_mode", SKIP_OPEN_TABLE},
+  {"LOCK_DURATION", 30, MYSQL_TYPE_STRING, 0,
+    MY_I_S_MAYBE_NULL, "lock_duration", SKIP_OPEN_TABLE},
+  {"LOCK_TYPE", 30, MYSQL_TYPE_STRING, 0,
+    MY_I_S_MAYBE_NULL, "lock_type", SKIP_OPEN_TABLE},
+  {"TABLE_SCHEMA", 64, MYSQL_TYPE_STRING, 0,
+    MY_I_S_MAYBE_NULL, "table_schema", SKIP_OPEN_TABLE},
+  {"TABLE_NAME", 64, MYSQL_TYPE_STRING, 0,
+    MY_I_S_MAYBE_NULL, "table_name", SKIP_OPEN_TABLE},
+  {NULL, 0,  MYSQL_TYPE_STRING, 0, 0, NULL, 0}
+};
+
+struct st_i_s_metadata_param
+{
+  THD   *thd;
+  TABLE *table;
+};
+
+int i_s_metadata_lock_info_fill_row(
+  MDL_ticket *mdl_ticket,
+  void *arg
+) {
+  st_i_s_metadata_param *param = (st_i_s_metadata_param *) arg;
+  THD *thd = param->thd;
+  TABLE *table = param->table;
+  DBUG_ENTER("i_s_metadata_lock_info_fill_row");
+  MDL_request mdl_request;
+  enum_mdl_duration mdl_duration;
+  MDL_context *mdl_ctx = mdl_ticket->get_ctx();
+  enum_mdl_type mdl_ticket_type = mdl_ticket->get_type();
+  MDL_key *mdl_key = mdl_ticket->get_key();
+  MDL_key::enum_mdl_namespace mdl_namespace = mdl_key->mdl_namespace();
+  mdl_request.init(mdl_key, mdl_ticket_type, MDL_STATEMENT);
+  mdl_ctx->find_ticket(&mdl_request, &mdl_duration);
+  table->field[0]->store((longlong) mdl_ctx->get_thread_id(), TRUE);
+  table->field[1]->set_notnull();
+  table->field[1]->store(
+    metadata_lock_info_lock_mode[(int) mdl_ticket_type].str,
+    metadata_lock_info_lock_mode[(int) mdl_ticket_type].length,
+    system_charset_info);
+  table->field[2]->set_notnull();
+  table->field[2]->store(
+    metadata_lock_info_duration[(int) mdl_duration].str,
+    metadata_lock_info_duration[(int) mdl_duration].length,
+    system_charset_info);
+  table->field[3]->set_notnull();
+  table->field[3]->store(
+    metadata_lock_info_lock_name[(int) mdl_namespace].str,
+    metadata_lock_info_lock_name[(int) mdl_namespace].length,
+    system_charset_info);
+  table->field[4]->set_notnull();
+  table->field[4]->store(mdl_key->db_name(),
+    mdl_key->db_name_length(), system_charset_info);
+  table->field[5]->set_notnull();
+  table->field[5]->store(mdl_key->name(),
+    mdl_key->name_length(), system_charset_info);
+  if (schema_table_store_record(thd, table))
+    DBUG_RETURN(1);
+  DBUG_RETURN(0);
+}
+
+int i_s_metadata_lock_info_fill_table(
+  THD *thd,
+  TABLE_LIST *tables,
+  COND *cond
+) {
+  st_i_s_metadata_param param;
+  DBUG_ENTER("i_s_metadata_lock_info_fill_table");
+  param.table = tables->table;
+  param.thd = thd;
+  DBUG_RETURN(mdl_iterate(i_s_metadata_lock_info_fill_row, &param));
+}
+
+static int i_s_metadata_lock_info_init(
+  void *p
+) {
+  ST_SCHEMA_TABLE *schema = (ST_SCHEMA_TABLE *) p;
+  DBUG_ENTER("i_s_metadata_lock_info_init");
+  schema->fields_info = i_s_metadata_lock_info_fields_info;
+  schema->fill_table = i_s_metadata_lock_info_fill_table;
+  schema->idx_field1 = 0;
+  DBUG_RETURN(0);
+}
+
+static int i_s_metadata_lock_info_deinit(
+  void *p
+) {
+  DBUG_ENTER("i_s_metadata_lock_info_deinit");
+  DBUG_RETURN(0);
+}
+
+static struct st_mysql_information_schema i_s_metadata_lock_info_plugin =
+{ MYSQL_INFORMATION_SCHEMA_INTERFACE_VERSION };
+
+#ifdef MARIADB_BASE_VERSION
+maria_declare_plugin(metadata_lock_info)
+{
+  MYSQL_INFORMATION_SCHEMA_PLUGIN,
+  &i_s_metadata_lock_info_plugin,
+  "METADATA_LOCK_INFO",
+  "Kentoku Shiba",
+  "Metadata locking viewer",
+  PLUGIN_LICENSE_GPL,
+  i_s_metadata_lock_info_init,
+  i_s_metadata_lock_info_deinit,
+  0x0001,
+  NULL,
+  NULL,
+  NULL,
+  MariaDB_PLUGIN_MATURITY_ALPHA,
+}
+maria_declare_plugin_end;
+#else
+mysql_declare_plugin(metadata_lock_info)
+{
+  MYSQL_INFORMATION_SCHEMA_PLUGIN,
+  &i_s_metadata_lock_info_plugin,
+  "METADATA_LOCK_INFO",
+  "Kentoku Shiba",
+  "Metadata locking viewer",
+  PLUGIN_LICENSE_GPL,
+  i_s_metadata_lock_info_init,
+  i_s_metadata_lock_info_deinit,
+  0x0001,
+  NULL,
+  NULL,
+  NULL,
+#if MYSQL_VERSION_ID >= 50600
+  0,
+#endif
+}
+mysql_declare_plugin_end;
+#endif

plugin/metadata_lock_info/mysql-test/metadata_lock_info/r/global_read_lock.result

+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name
+FLUSH TABLES WITH READ LOCK;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name
+MDL_SHARED	MDL_EXPLICIT	Global read lock		
+MDL_SHARED	MDL_EXPLICIT	Commit lock		
+UNLOCK TABLES;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name

plugin/metadata_lock_info/mysql-test/metadata_lock_info/r/table_metadata_lock.result

+CREATE TABLE IF NOT EXISTS t1(a int);
+BEGIN;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name
+SELECT * FROM t1;
+a
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name
+MDL_SHARED_READ	MDL_TRANSACTION	Table metadata lock	test	t1
+ROLLBACK;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name
+DROP TABLE t1;

plugin/metadata_lock_info/mysql-test/metadata_lock_info/r/user_lock.result

+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name
+SELECT GET_LOCK('LOCK1',0);
+GET_LOCK('LOCK1',0)
+1
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name
+MDL_SHARED_NO_READ_WRITE	MDL_EXPLICIT	User lock	LOCK1	
+SELECT RELEASE_LOCK('LOCK1');
+RELEASE_LOCK('LOCK1')
+1
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+lock_mode	lock_duration	lock_type	table_schema	table_name

plugin/metadata_lock_info/mysql-test/metadata_lock_info/suite.opt

+--loose-metadata_lock_info
+--plugin-load=$METADATA_LOCK_INFO_SO

plugin/metadata_lock_info/mysql-test/metadata_lock_info/suite.pm

+package My::Suite::Metadata_lock_info;
+
+@ISA = qw(My::Suite);
+
+return "No Metadata_lock_info plugin" unless $ENV{METADATA_LOCK_INFO_SO};
+
+bless { };
+

plugin/metadata_lock_info/mysql-test/metadata_lock_info/t/global_read_lock.test

+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+FLUSH TABLES WITH READ LOCK;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+UNLOCK TABLES;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;

plugin/metadata_lock_info/mysql-test/metadata_lock_info/t/table_metadata_lock.test

+CREATE TABLE IF NOT EXISTS t1(a int);
+BEGIN;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+SELECT * FROM t1;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+ROLLBACK;
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+DROP TABLE t1;

plugin/metadata_lock_info/mysql-test/metadata_lock_info/t/user_lock.test

+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+SELECT GET_LOCK('LOCK1',0);
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;
+SELECT RELEASE_LOCK('LOCK1');
+SELECT lock_mode, lock_duration, lock_type, table_schema, table_name FROM information_schema.metadata_lock_info;

sql/mdl.cc

@@ -158,6 +158,7 @@ class MDL_map_partition
                    I_P_List_counter>
           Lock_cache;
   Lock_cache m_unused_locks_cache;
+  friend int mdl_iterate(int (*)(MDL_ticket *, void *), void *);
 };
 
 
@@ -187,6 +188,7 @@ class MDL_map
   MDL_lock *m_global_lock;
   /** Pre-allocated MDL_lock object for COMMIT namespace. */
   MDL_lock *m_commit_lock;
+  friend int mdl_iterate(int (*)(MDL_ticket *, void *), void *);
 };
 
 
@@ -706,6 +708,46 @@ void mdl_destroy()
 }
 
 
+static inline int mdl_iterate_lock(MDL_lock *lock,
+                                   int (*callback)(MDL_ticket *ticket, void *arg),
+                                   void *arg)
+{
+  MDL_lock::Ticket_iterator ticket_it(lock->m_granted);
+  MDL_ticket *ticket;
+  int res= 0;
+  mysql_prlock_rdlock(&lock->m_rwlock);
+  while ((ticket= ticket_it++) && !(res= callback(ticket, arg))) /* no-op */;
+  mysql_prlock_unlock(&lock->m_rwlock);
+  return res;
+}
+
+
+int mdl_iterate(int (*callback)(MDL_ticket *ticket, void *arg), void *arg)
+{
+  uint i, j;
+  int res;
+  DBUG_ENTER("mdl_iterate");
+
+  if ((res= mdl_iterate_lock(mdl_locks.m_global_lock, callback, arg)) ||
+      (res= mdl_iterate_lock(mdl_locks.m_commit_lock, callback, arg)))
+    DBUG_RETURN(res);
+
+  for (i= 0; i < mdl_locks.m_partitions.elements(); i++)
+  {
+    MDL_map_partition *part= mdl_locks.m_partitions.at(i);
+    mysql_mutex_lock(&part->m_mutex);
+    for (j= 0; j < part->m_locks.records; j++)
+    {
+      if ((res= mdl_iterate_lock((MDL_lock*) my_hash_element(&part->m_locks, j),
+                                 callback, arg)))
+        break;
+    }
+    mysql_mutex_unlock(&part->m_mutex);
+  }
+  DBUG_RETURN(res);
+}
+
+
 /** Initialize the container for all MDL locks. */
 
 void MDL_map::init()

sql/mdl.h

@@ -904,14 +904,14 @@ class MDL_context
   MDL_wait_for_subgraph *m_waiting_for;
 private:
   THD *get_thd() const { return m_owner->get_thd(); }
-  MDL_ticket *find_ticket(MDL_request *mdl_req,
-                          enum_mdl_duration *duration);
   void release_locks_stored_before(enum_mdl_duration duration, MDL_ticket *sentinel);
   void release_lock(enum_mdl_duration duration, MDL_ticket *ticket);
   bool try_acquire_lock_impl(MDL_request *mdl_request,
                              MDL_ticket **out_ticket);
 
 public:
+  MDL_ticket *find_ticket(MDL_request *mdl_req,
+                          enum_mdl_duration *duration);
   void find_deadlock();
 
   ulong get_thread_id() const { return thd_get_thread_id(get_thd()); }
@@ -988,4 +988,7 @@ static const ulong MDL_LOCKS_HASH_PARTITIONS_DEFAULT = 8;
   to avoid starving out weak, low-prio locks.
 */
 extern "C" ulong max_write_lock_count;
+
+extern MYSQL_PLUGIN_IMPORT
+int mdl_iterate(int (*callback)(MDL_ticket *ticket, void *arg), void *arg);
 #endif