MDEV-16294: INSTALL PLUGIN IF NOT EXISTS / UNINSTALL PLUGIN IF EXISTS

Add INSTALL SONAME IF NOT EXISTS; syntax only, installing
duplicate SONAMES doesn't currently cause any errors or warnings.

UNINSTALL SONAME IF EXISTS was added.

Allow the installation / uninstallation of plugins without
doing checks for existence first.

mysql-test/main/plugin.result

@@ -331,3 +331,34 @@ UNINSTALL PLUGIN example;
 RENAME TABLE t1 TO t2;
 ERROR 42S02: Table 'test.t1' doesn't exist
 DROP TABLE t1;
+#
+# INSTALL IF NOT EXISTS [PLUGIN name] SONAME library /
+# UNINSTALL IF EXISTS PLUGIN|SONAME name
+#
+#
+select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
+plugin_name
+INSTALL PLUGIN IF NOT EXISTS example SONAME 'ha_example';
+select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
+plugin_name
+EXAMPLE
+INSTALL PLUGIN IF NOT EXISTS EXAMPLE SONAME 'ha_example';
+SHOW WARNINGS;
+Level	Code	Message
+Note	1968	Plugin 'EXAMPLE' already installed
+INSTALL SONAME IF NOT EXISTS 'ha_example';
+SHOW WARNINGS;
+Level	Code	Message
+Note	1968	Plugin 'EXAMPLE' already installed
+UNINSTALL PLUGIN IF EXISTS example;
+select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
+plugin_name
+UNUSABLE
+UNINSTALL SONAME IF EXISTS 'ha_example';
+Warnings:
+Note	1305	PLUGIN EXAMPLE does not exist
+SHOW WARNINGS;
+Level	Code	Message
+Note	1305	PLUGIN EXAMPLE does not exist
+select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
+plugin_name

mysql-test/main/plugin.test

@@ -265,3 +265,22 @@ UNINSTALL PLUGIN example;
 --error ER_NO_SUCH_TABLE
 RENAME TABLE t1 TO t2;
 DROP TABLE t1;
+
+--echo #
+--echo # INSTALL IF NOT EXISTS [PLUGIN name] SONAME library /
+--echo # UNINSTALL IF EXISTS PLUGIN|SONAME name
+--echo #
+--echo #
+
+select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
+INSTALL PLUGIN IF NOT EXISTS example SONAME 'ha_example';
+select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
+INSTALL PLUGIN IF NOT EXISTS EXAMPLE SONAME 'ha_example';
+SHOW WARNINGS;
+INSTALL SONAME IF NOT EXISTS 'ha_example';
+SHOW WARNINGS;
+UNINSTALL PLUGIN IF EXISTS example;
+select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';
+UNINSTALL SONAME IF EXISTS 'ha_example';
+SHOW WARNINGS;
+select plugin_name from information_schema.plugins where plugin_library like 'ha_example%';

sql/sql_plugin.cc

@@ -1077,7 +1077,7 @@ static st_plugin_int *plugin_insert_or_reuse(struct st_plugin_int *plugin)
   NOTE
     Requires that a write-lock is held on LOCK_system_variables_hash
 */
-static bool plugin_add(MEM_ROOT *tmp_root,
+static bool plugin_add(MEM_ROOT *tmp_root, THD *thd,
                        const LEX_CSTRING *name, LEX_CSTRING *dl, myf MyFlags)
 {
   struct st_plugin_int tmp, *maybe_dupe;
@@ -1088,7 +1088,14 @@ static bool plugin_add(MEM_ROOT *tmp_root,
 
   if (name->str && plugin_find_internal(name, MYSQL_ANY_PLUGIN))
   {
-    my_error(ER_PLUGIN_INSTALLED, MyFlags, name->str);
+    if (thd && thd->lex->create_info.if_not_exists())
+    {
+      my_error(ER_PLUGIN_INSTALLED, MyFlags & ME_WARNING, name->str);
+    }
+    else
+    {
+      my_error(ER_PLUGIN_INSTALLED, MyFlags, name->str);
+    }
     DBUG_RETURN(TRUE);
   }
   /* Clear the whole struct to catch future extensions. */
@@ -1847,7 +1854,7 @@ static void plugin_load(MEM_ROOT *tmp_root)
       the mutex here to satisfy the assert
     */
     mysql_mutex_lock(&LOCK_plugin);
-    plugin_add(tmp_root, &name, &dl, MYF(ME_ERROR_LOG));
+    plugin_add(tmp_root, NULL, &name, &dl, MYF(ME_ERROR_LOG));
     free_root(tmp_root, MYF(MY_MARK_BLOCKS_FREE));
     mysql_mutex_unlock(&LOCK_plugin);
   }
@@ -1902,7 +1909,7 @@ static bool plugin_load_list(MEM_ROOT *tmp_root, const char *list)
         mysql_mutex_lock(&LOCK_plugin);
         free_root(tmp_root, MYF(MY_MARK_BLOCKS_FREE));
         name.str= 0; // load everything
-        if (plugin_add(tmp_root, (LEX_CSTRING*) &name, (LEX_CSTRING*) &dl,
+        if (plugin_add(tmp_root, NULL, (LEX_CSTRING*) &name, (LEX_CSTRING*) &dl,
                        MYF(ME_ERROR_LOG)))
           goto error;
       }
@@ -1910,7 +1917,7 @@ static bool plugin_load_list(MEM_ROOT *tmp_root, const char *list)
       {
         free_root(tmp_root, MYF(MY_MARK_BLOCKS_FREE));
         mysql_mutex_lock(&LOCK_plugin);
-        if (plugin_add(tmp_root, (LEX_CSTRING*) &name, (LEX_CSTRING*) &dl,
+        if (plugin_add(tmp_root, NULL, (LEX_CSTRING*) &name, (LEX_CSTRING*) &dl,
                        MYF(ME_ERROR_LOG)))
           goto error;
       }
@@ -2194,7 +2201,7 @@ bool mysql_install_plugin(THD *thd, const LEX_CSTRING *name,
     mysql_audit_acquire_plugins(thd, event_class_mask);
 
   mysql_mutex_lock(&LOCK_plugin);
-  error= plugin_add(thd->mem_root, name, &dl, MYF(0));
+  error= plugin_add(thd->mem_root, thd, name, &dl, MYF(0));
   if (unlikely(error))
     goto err;
 
@@ -2236,8 +2243,17 @@ static bool do_uninstall(THD *thd, TABLE *table, const LEX_CSTRING *name)
   if (!(plugin= plugin_find_internal(name, MYSQL_ANY_PLUGIN)) ||
       plugin->state & (PLUGIN_IS_UNINITIALIZED | PLUGIN_IS_DYING))
   {
-    my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "PLUGIN", name->str);
-    return 1;
+    if (thd->lex->if_exists())
+    {
+      push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE, ER_SP_DOES_NOT_EXIST,
+                          ER_THD(thd, ER_SP_DOES_NOT_EXIST), "PLUGIN", name->str);
+      return 0;
+    }
+    else
+    {
+      my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "PLUGIN", name->str);
+      return 1;
+    }
   }
   if (!plugin->plugin_dl)
   {

sql/sql_yacc.yy

@@ -17490,35 +17490,45 @@ opt_migrate:
         ;
 
 install:
-          INSTALL_SYM PLUGIN_SYM ident SONAME_SYM TEXT_STRING_sys
+          INSTALL_SYM PLUGIN_SYM opt_if_not_exists ident SONAME_SYM TEXT_STRING_sys
           {
             LEX *lex= Lex;
+            lex->create_info.init();
+            if (lex->add_create_options_with_check($3))
+              MYSQL_YYABORT;
             lex->sql_command= SQLCOM_INSTALL_PLUGIN;
-            lex->comment= $3;
-            lex->ident= $5;
+            lex->comment= $4;
+            lex->ident= $6;
           }
-        | INSTALL_SYM SONAME_SYM TEXT_STRING_sys
+        | INSTALL_SYM SONAME_SYM opt_if_not_exists TEXT_STRING_sys
           {
             LEX *lex= Lex;
+            lex->create_info.init();
+            if (lex->add_create_options_with_check($3))
+              MYSQL_YYABORT;
             lex->sql_command= SQLCOM_INSTALL_PLUGIN;
             lex->comment= null_clex_str;
-            lex->ident= $3;
+            lex->ident= $4;
           }
         ;
 
 uninstall:
-          UNINSTALL_SYM PLUGIN_SYM ident
+          UNINSTALL_SYM PLUGIN_SYM opt_if_exists ident
           {
             LEX *lex= Lex;
+            if (lex->add_create_options_with_check($3))
+              MYSQL_YYABORT;
             lex->sql_command= SQLCOM_UNINSTALL_PLUGIN;
-            lex->comment= $3;
+            lex->comment= $4;
           }
-        | UNINSTALL_SYM SONAME_SYM TEXT_STRING_sys
+        | UNINSTALL_SYM SONAME_SYM opt_if_exists TEXT_STRING_sys
           {
             LEX *lex= Lex;
+            if (lex->add_create_options_with_check($3))
+              MYSQL_YYABORT;
             lex->sql_command= SQLCOM_UNINSTALL_PLUGIN;
             lex->comment= null_clex_str;
-            lex->ident= $3;
+            lex->ident= $4;
           }
         ;