Do not add MDL changes to sql_class.h

thd_innodb_lock_wait_timeout(): Renamed from thd_lock_wait_timeout()
to avoid confusion.

thd_lock_wait_timeout(), thd_mdl_context(): New interfaces, to be used
for acquiring or releasing MDL.

11 files changed, 149 insertions, 96 deletions

diff --git a/include/mysql/service_thd_mdl.h b/include/mysql/service_thd_mdl.h
new file mode 100644
index 00000000000..86d5d1ef3dc
--- /dev/null
+++ b/include/mysql/service_thd_mdl.h
@@ -0,0 +1,55 @@
+/* Copyright (c) 2019, 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 St, Fifth Floor, Boston, MA 02110-1335  USA */
+
+#pragma once
+
+/**
+  @file include/mysql/service_thd_mdl.h
+  This service provides functions for plugins and storage engines to access
+  metadata locks.
+*/
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+extern struct thd_mdl_service_st {
+  ulong (*thd_lock_wait_timeout_func)(MYSQL_THD);
+  void *(*thd_mdl_context)(MYSQL_THD);
+} *thd_mdl_service;
+
+#ifdef MYSQL_DYNAMIC_PLUGIN
+# define thd_lock_wait_timeout(_THD) \
+  thd_mdl_service->thd_lock_wait_timeout_func(_THD)
+# define thd_mdl_context(_THD) thd_mdl_service->thd_mdl_context(_THD)
+#else
+/**
+  Read the value of lock_wait_timeout.
+  @param thd   the session, or NULL to read the global value
+  @return the value of lock_wait_timeout
+*/
+ulong thd_lock_wait_timeout(MYSQL_THD thd);
+/**
+  MDL_context accessor
+  @param thd   the current session
+  @return pointer to thd->mdl_context
+*/
+void *thd_mdl_context(MYSQL_THD thd);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/include/service_versions.h b/include/service_versions.h
index 16d21ac40d3..66451ee3ea5 100644
--- a/include/service_versions.h
+++ b/include/service_versions.h
@@ -1,5 +1,5 @@
 /* Copyright (c) 2009, 2010, Oracle and/or its affiliates.
-   Copyright (c) 2012, 2017, MariaDB
+   Copyright (c) 2012, 2019, 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
@@ -43,3 +43,4 @@
 #define VERSION_thd_wait                0x0100
 #define VERSION_wsrep                   0x0202
 #define VERSION_json                    0x0100
+#define VERSION_thd_mdl                 0x0100
diff --git a/sql/mdl.cc b/sql/mdl.cc
index 78520393fb7..e7c0d699d76 100644
--- a/sql/mdl.cc
+++ b/sql/mdl.cc
@@ -3210,46 +3210,6 @@ bool MDL_context::has_explicit_locks()
   return false;
 }
 
-template
-bool acquire_shared_table_mdl<true>(THD *thd, const char *db_name,
-			            const char *tbl_name,
-			            MDL_ticket **out_mdl_ticket);
-template
-bool acquire_shared_table_mdl<false>(THD *thd, const char *db_name,
-			             const char *tbl_name,
-			             MDL_ticket **out_mdl_ticket);
-template<bool no_wait>
-bool acquire_shared_table_mdl(THD *thd, const char *db_name,
-			      const char *tbl_name,
-			      MDL_ticket **out_mdl_ticket)
-{
-  MDL_request mdl_request;
-  mdl_request.init(MDL_key::TABLE, db_name, tbl_name,
-                   MDL_SHARED, MDL_EXPLICIT);
-  if (no_wait)
-  {
-    if (thd->mdl_context.try_acquire_lock(&mdl_request)
-        || !mdl_request.ticket)
-      return true;
-  }
-  else
-  {
-    if (thd->mdl_context.acquire_lock(&mdl_request,
-                                      thd->variables.lock_wait_timeout))
-      return true;
-  }
-
-  if (out_mdl_ticket)
-    *out_mdl_ticket= mdl_request.ticket;
-
-  return false;
-}
-
-void release_mdl(THD *thd, MDL_ticket *mdl_ticket)
-{
-  thd->mdl_context.release_lock(mdl_ticket);
-}
-
 #ifdef WITH_WSREP
 static
 const char *wsrep_get_mdl_namespace_name(MDL_key::enum_mdl_namespace ns)
diff --git a/sql/mdl.h b/sql/mdl.h
index c4243f9f5d5..b084670e5c6 100644
--- a/sql/mdl.h
+++ b/sql/mdl.h
@@ -1106,28 +1106,4 @@ void mdl_dbug_print_locks();
 #else
   static inline void mdl_dbug_print_locks() {}
 #endif /* DBUG_OFF */
-
-/**
-  Acquire shared metadata lock on the given table name with
-  explicit duration.
-
-  @param thd		thread to which mdl lock belongs to
-  @param db_name	database name
-  @param tbl_name	table name
-  @param out_mdl_ticket	pointer to MDL_ticket upon successful lock
-			attempt
-*/
-template<bool no_wait=false>
-bool acquire_shared_table_mdl(THD *thd, const char *db_name,
-                              const char *tbl_name,
-                              MDL_ticket **out_mdl_ticket);
-
-/**
-  Release MDL_EXPLICIT lock held by a ticket
-
-  @param thd		thread to which lock belongs to
-  @param mdl_ticket	lock ticket
-*/
-void release_mdl(THD *thd, MDL_ticket *mdl_ticket);
-
 #endif /* MDL_H */
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 022403a95a0..a4582b6b678 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -5310,6 +5310,31 @@ extern "C" void thd_wait_end(MYSQL_THD thd)
 
 #endif // INNODB_COMPATIBILITY_HOOKS */
 
+
+/**
+  Read the value of lock_wait_timeout.
+  @param thd   the session, or NULL to read the global value
+  @return the value of lock_wait_timeout
+*/
+extern "C" ulong thd_lock_wait_timeout(MYSQL_THD thd)
+{
+  return thd
+    ? thd->variables.lock_wait_timeout
+    : global_system_variables.lock_wait_timeout;
+}
+
+
+/**
+  MDL_context accessor
+  @param thd   the current session
+  @return pointer to thd->mdl_context
+*/
+extern "C" void *thd_mdl_context(MYSQL_THD thd)
+{
+  return &thd->mdl_context;
+}
+
+
 /****************************************************************************
   Handling of statement states in functions and triggers.
 
diff --git a/sql/sql_plugin_services.ic b/sql/sql_plugin_services.ic
index c3b0088c9bd..2677a38bf59 100644
--- a/sql/sql_plugin_services.ic
+++ b/sql/sql_plugin_services.ic
@@ -1,5 +1,5 @@
 /* Copyright (c) 2009, 2010, Oracle and/or its affiliates.
-   Copyright (c) 2012, 2014, Monty Program Ab
+   Copyright (c) 2012, 2019, 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
@@ -17,6 +17,7 @@
 /* support for Services */
 #include <service_versions.h>
 #include <mysql/service_wsrep.h>
+#include <mysql/service_thd_mdl.h>
 
 struct st_service_ref {
   const char *name;
@@ -220,6 +221,12 @@ struct json_service_st json_handler=
   json_unescape_json
 };
 
+static struct thd_mdl_service_st thd_mdl_handler=
+{
+  thd_lock_wait_timeout,
+  thd_mdl_context
+};
+
 static struct st_service_ref list_of_services[]=
 {
   { "base64_service",              VERSION_base64,              &base64_handler },
@@ -243,6 +250,7 @@ static struct st_service_ref list_of_services[]=
   { "thd_timezone_service",        VERSION_thd_timezone,        &thd_timezone_handler },
   { "thd_wait_service",            VERSION_thd_wait,            &thd_wait_handler },
   { "wsrep_service",               VERSION_wsrep,               &wsrep_handler },
-  { "json_service",                VERSION_json,                &json_handler }
+  { "json_service",                VERSION_json,                &json_handler },
+  { "thd_mdl_service",             VERSION_thd_mdl,             &thd_mdl_handler }
 };
 
diff --git a/storage/innobase/dict/dict0dict.cc b/storage/innobase/dict/dict0dict.cc
index 72112ffc42b..7a9c5ef6a3a 100644
--- a/storage/innobase/dict/dict0dict.cc
+++ b/storage/innobase/dict/dict0dict.cc
@@ -37,6 +37,7 @@ Created 1/8/1996 Heikki Tuuri
 #include "fil0fil.h"
 #include <algorithm>
 #include "sql_table.h"
+#include <mysql/service_thd_mdl.h>
 
 /** dummy index for ROW_FORMAT=REDUNDANT supremum and infimum records */
 dict_index_t*	dict_ind_redundant;
@@ -165,6 +166,47 @@ dict_lru_validate(void);
 /*===================*/
 #endif /* UNIV_DEBUG */
 
+
+/**
+  Acquire shared metadata lock with explicit duration on a table name.
+  @param thd     current thread
+  @param db      database name
+  @param t       table name
+  @param trylock whether to fail if the request would block
+  @return granted MDL_ticket
+  @retval nullptr       on failure
+*/
+static MY_ATTRIBUTE((nonnull))
+MDL_ticket *acquire_mdl(THD *thd, const char *db, const char *t, bool trylock)
+{
+  MDL_context *mdlc= static_cast<MDL_context*>(thd_mdl_context(thd));
+  ut_ad(mdlc);
+  if (!mdlc)
+    return nullptr;
+
+  MDL_request request;
+  request.init(MDL_key::TABLE, db, t, MDL_SHARED, MDL_EXPLICIT);
+  if (trylock
+      ? mdlc->try_acquire_lock(&request)
+      : mdlc->acquire_lock(&request, thd_lock_wait_timeout(thd)))
+    return nullptr;
+
+  return request.ticket;
+}
+
+
+/**
+  Release a metadata lock.
+  @param thd  session
+  @param mdl  metadata lock
+*/
+static MY_ATTRIBUTE((nonnull)) void release_mdl(THD *thd, MDL_ticket *mdl)
+{
+  if (MDL_context *mdlc= static_cast<MDL_context*>(thd_mdl_context(thd)))
+    mdlc->release_lock(mdl);
+}
+
+
 /* Stream for storing detailed information about the latest foreign key
 and unique key errors. Only created if !srv_read_only_mode */
 FILE*	dict_foreign_err_file		= NULL;
@@ -767,7 +809,6 @@ bool dict_parse_tbl_name(const char* tbl_name,
   return true;
 }
 
-
 /** Acquire MDL shared for the table name.
 @tparam trylock whether to use non-blocking operation
 @param[in,out]  table           table object
@@ -818,17 +859,11 @@ retry_mdl:
   if (unaccessible)
     return nullptr;
 
-  if (trylock)
-  {
-    if (acquire_shared_table_mdl<true>(thd, db_buf, tbl_buf, mdl))
-      return nullptr;
+  *mdl= acquire_mdl(thd, db_buf, tbl_buf, trylock);
+  if (*mdl)
     mdl_acquire= true;
-  }
-  else
-  {
-    if (!acquire_shared_table_mdl(thd, db_buf, tbl_buf, mdl))
-      mdl_acquire= true;
-  }
+  else if (trylock)
+    return nullptr;
 
   table= dict_table_open_on_id(table_id, dict_locked, table_op);
 
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 7268868e742..df9523b95d8 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -1704,14 +1704,10 @@ thd_is_select(
 	return(thd_sql_command(thd) == SQLCOM_SELECT);
 }
 
-/******************************************************************//**
-Returns the lock wait timeout for the current connection.
-@return the lock wait timeout, in seconds */
-ulong
-thd_lock_wait_timeout(
-/*==================*/
-	THD*	thd)	/*!< in: thread handle, or NULL to query
-			the global innodb_lock_wait_timeout */
+/**
+@param thd     session, or NULL to query the global value
+@return innodb_lock wait timeout */
+ulong thd_innodb_lock_wait_timeout(THD* thd)
 {
 	/* According to <mysql/plugin.h>, passing thd == NULL
 	returns the global value of the session variable. */
diff --git a/storage/innobase/include/ha_prototypes.h b/storage/innobase/include/ha_prototypes.h
index 443dce51ff5..22dc84ae241 100644
--- a/storage/innobase/include/ha_prototypes.h
+++ b/storage/innobase/include/ha_prototypes.h
@@ -297,14 +297,11 @@ const char*
 thd_innodb_tmpdir(
 	THD*	thd);
 
-/******************************************************************//**
-Returns the lock wait timeout for the current connection.
-@return the lock wait timeout, in seconds */
-ulong
-thd_lock_wait_timeout(
-/*==================*/
-	THD*	thd);	/*!< in: thread handle, or NULL to query
-			the global innodb_lock_wait_timeout */
+/**
+@param thd     session, or NULL to query the global value
+@return innodb_lock wait timeout */
+ulong thd_innodb_lock_wait_timeout(THD* thd);
+
 /** Get status of innodb_tmpdir.
 @param[in]	thd	thread handle, or NULL to query
 			the global innodb_tmpdir.
diff --git a/storage/innobase/include/trx0trx.h b/storage/innobase/include/trx0trx.h
index 2245168b169..e5c2c62a502 100644
--- a/storage/innobase/include/trx0trx.h
+++ b/storage/innobase/include/trx0trx.h
@@ -419,7 +419,7 @@ from innodb_lock_wait_timeout via trx_t::mysql_thd.
 @return lock wait timeout in seconds */
 #define trx_lock_wait_timeout_get(t)					\
 	((t)->mysql_thd != NULL						\
-	 ? thd_lock_wait_timeout((t)->mysql_thd)			\
+	 ? thd_innodb_lock_wait_timeout((t)->mysql_thd)			\
 	 : 0)
 
 /**
diff --git a/storage/innobase/lock/lock0lock.cc b/storage/innobase/lock/lock0lock.cc
index 77fee83aef2..056f31f7959 100644
--- a/storage/innobase/lock/lock0lock.cc
+++ b/storage/innobase/lock/lock0lock.cc
@@ -1704,7 +1704,7 @@ lock_rec_enqueue_waiting(
 		ut_ad(0);
 	}
 
-	if (trx->mysql_thd && thd_lock_wait_timeout(trx->mysql_thd) == 0) {
+	if (trx->mysql_thd && !thd_innodb_lock_wait_timeout(trx->mysql_thd)) {
 		trx->error_state = DB_LOCK_WAIT_TIMEOUT;
 		return DB_LOCK_WAIT_TIMEOUT;
 	}