Merge.

3 files changed, 215 insertions, 42 deletions

diff --git a/mysql-test/r/merge.result b/mysql-test/r/merge.result
index 3af152672ab..a4f1c79dff4 100644
--- a/mysql-test/r/merge.result
+++ b/mysql-test/r/merge.result
@@ -2341,4 +2341,33 @@ REPAIR TABLE m1;
 Table	Op	Msg_type	Msg_text
 test.m1	repair	note	The storage engine for the table doesn't support repair
 DROP TABLE m1, t1;
+#
+# BUG#11763712 - 56458: KILLING A FLUSH TABLE FOR A MERGE/CHILD
+#                       CRASHES SERVER
+#
+CREATE TABLE t1(a INT);
+CREATE TABLE t2(a INT);
+CREATE TABLE t3(a INT, b INT);
+CREATE TABLE m1(a INT) ENGINE=MERGE UNION=(t1, t2);
+# Test reopen merge parent failure
+LOCK TABLES m1 READ;
+# Remove 'm1' table using file operations.
+FLUSH TABLES;
+ERROR 42S02: Table 'test.m1' doesn't exist
+UNLOCK TABLES;
+CREATE TABLE m1(a INT) ENGINE=MERGE UNION=(t1, t2);
+# Test reopen merge child failure
+LOCK TABLES m1 READ;
+# Remove 't1' table using file operations.
+FLUSH TABLES;
+ERROR 42S02: Table 'test.t1' doesn't exist
+UNLOCK TABLES;
+CREATE TABLE t1(a INT);
+# Test reattach merge failure
+LOCK TABLES m1 READ;
+# Replace 't1' with 't3' table using file operations.
+FLUSH TABLES;
+ERROR HY000: Can't reopen table: 'm1'
+UNLOCK TABLES;
+DROP TABLE t1, t2, t3, m1;
 End of 5.1 tests
diff --git a/mysql-test/t/merge.test b/mysql-test/t/merge.test
index f290803bbd2..a6affbb0540 100644
--- a/mysql-test/t/merge.test
+++ b/mysql-test/t/merge.test
@@ -1783,4 +1783,49 @@ REPAIR TABLE m1;
 #
 DROP TABLE m1, t1;
 
+
+--echo #
+--echo # BUG#11763712 - 56458: KILLING A FLUSH TABLE FOR A MERGE/CHILD
+--echo #                       CRASHES SERVER
+--echo #
+CREATE TABLE t1(a INT);
+CREATE TABLE t2(a INT);
+CREATE TABLE t3(a INT, b INT);
+CREATE TABLE m1(a INT) ENGINE=MERGE UNION=(t1, t2);
+
+--echo # Test reopen merge parent failure
+LOCK TABLES m1 READ;
+--echo # Remove 'm1' table using file operations.
+remove_file $MYSQLD_DATADIR/test/m1.MRG;
+remove_file $MYSQLD_DATADIR/test/m1.frm;
+--error ER_NO_SUCH_TABLE
+FLUSH TABLES;
+UNLOCK TABLES;
+CREATE TABLE m1(a INT) ENGINE=MERGE UNION=(t1, t2);
+
+--echo # Test reopen merge child failure
+LOCK TABLES m1 READ;
+--echo # Remove 't1' table using file operations.
+remove_file $MYSQLD_DATADIR/test/t1.frm;
+remove_file $MYSQLD_DATADIR/test/t1.MYI;
+remove_file $MYSQLD_DATADIR/test/t1.MYD;
+--error ER_NO_SUCH_TABLE
+FLUSH TABLES;
+UNLOCK TABLES;
+CREATE TABLE t1(a INT);
+
+--echo # Test reattach merge failure
+LOCK TABLES m1 READ;
+--echo # Replace 't1' with 't3' table using file operations.
+remove_file $MYSQLD_DATADIR/test/t1.frm;
+remove_file $MYSQLD_DATADIR/test/t1.MYI;
+remove_file $MYSQLD_DATADIR/test/t1.MYD;
+copy_file $MYSQLD_DATADIR/test/t3.frm $MYSQLD_DATADIR/test/t1.frm;
+copy_file $MYSQLD_DATADIR/test/t3.MYI $MYSQLD_DATADIR/test/t1.MYI;
+copy_file $MYSQLD_DATADIR/test/t3.MYD $MYSQLD_DATADIR/test/t1.MYD;
+--error ER_CANT_REOPEN_TABLE
+FLUSH TABLES;
+UNLOCK TABLES;
+DROP TABLE t1, t2, t3, m1;
+
 --echo End of 5.1 tests
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index ab1ba156905..ace78947054 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -96,6 +96,13 @@ static TABLE_SHARE *oldest_unused_share, end_of_unused_share;
 static pthread_mutex_t LOCK_table_share;
 static bool table_def_inited= 0;
 
+/**
+  Dummy TABLE instance which is used in reopen_tables() and reattach_merge()
+  functions to mark MERGE tables and their children with which there is some
+  kind of problem and which therefore we need to close.
+*/
+static TABLE bad_merge_marker;
+
 static int open_unireg_entry(THD *thd, TABLE *entry, TABLE_LIST *table_list,
 			     const char *alias,
                              char *cache_key, uint cache_key_length,
@@ -3215,46 +3222,65 @@ void close_data_files_and_morph_locks(THD *thd, const char *db,
 
 
 /**
+  @brief Mark merge parent and children with bad_merge_marker
+
+  @param[in,out]  parent       the TABLE object of the parent
+*/
+
+static void mark_merge_parent_and_children_as_bad(TABLE *parent)
+{
+  TABLE_LIST *child_l;
+  DBUG_ENTER("mark_merge_parent_and_children_as_bad");
+  parent->parent= &bad_merge_marker;
+  for (child_l= parent->child_l; ; child_l= child_l->next_global)
+  {
+    child_l->table->parent= &bad_merge_marker;
+    child_l->table= NULL;
+    if (&child_l->next_global == parent->child_last_l)
+      break;
+  }
+  DBUG_VOID_RETURN;
+}
+
+
+/**
   Reattach MERGE children after reopen.
 
   @param[in]     thd            thread context
-  @param[in,out] err_tables_p   pointer to pointer of tables in error
+
+  @note If reattach failed for certain MERGE table, the table (and all
+        it's children) are marked with bad_merge_marker.
 
   @return       status
-    @retval     FALSE           OK, err_tables_p unchanged
-    @retval     TRUE            Error, err_tables_p contains table(s)
+    @retval     FALSE           OK
+    @retval     TRUE            Error
 */
 
-static bool reattach_merge(THD *thd, TABLE **err_tables_p)
+static bool reattach_merge(THD *thd)
 {
   TABLE *table;
-  TABLE *next;
-  TABLE **prv_p= &thd->open_tables;
   bool error= FALSE;
   DBUG_ENTER("reattach_merge");
 
-  for (table= thd->open_tables; table; table= next)
+  for (table= thd->open_tables; table; table= table->next)
   {
-    next= table->next;
-    DBUG_PRINT("tcache", ("check table: '%s'.'%s' 0x%lx  next: 0x%lx",
+    DBUG_PRINT("tcache", ("check table: '%s'.'%s' 0x%lx",
                           table->s->db.str, table->s->table_name.str,
-                          (long) table, (long) next));
-    /* Reattach children for MERGE tables with "closed data files" only. */
-    if (table->child_l && !table->children_attached)
+                          (long) table));
+    /*
+      Reattach children only for MERGE tables that had children or parent
+      with "closed data files" and were reopen. For extra safety skip MERGE
+      tables which we failed to reopen (should not happen with current code).
+    */
+    if (table->child_l && table->parent != &bad_merge_marker &&
+        !table->children_attached)
     {
       DBUG_PRINT("tcache", ("MERGE parent, attach children"));
-      if(table->file->extra(HA_EXTRA_ATTACH_CHILDREN))
+      if (table->file->extra(HA_EXTRA_ATTACH_CHILDREN))
       {
         my_error(ER_CANT_REOPEN_TABLE, MYF(0), table->alias);
         error= TRUE;
-        /* Remove table from open_tables. */
-        *prv_p= next;
-        if (next)
-          prv_p= &next->next;
-        /* Stack table on error list. */
-        table->next= *err_tables_p;
-        *err_tables_p= table;
-        continue;
+        mark_merge_parent_and_children_as_bad(table);
       }
       else
       {
@@ -3264,7 +3290,6 @@ static bool reattach_merge(THD *thd, TABLE **err_tables_p)
                             table->s->table_name.str, (long) table));
       }
     }
-    prv_p= &table->next;
   }
   DBUG_RETURN(error);
 }
@@ -3294,7 +3319,6 @@ bool reopen_tables(THD *thd, bool get_locks, bool mark_share_as_old)
 {
   TABLE *table,*next,**prev;
   TABLE **tables,**tables_ptr;			// For locks
-  TABLE *err_tables= NULL;
   bool error=0, not_used;
   bool merge_table_found= FALSE;
   const uint flags= MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN |
@@ -3328,29 +3352,69 @@ bool reopen_tables(THD *thd, bool get_locks, bool mark_share_as_old)
   for (table=thd->open_tables; table ; table=next)
   {
     uint db_stat=table->db_stat;
+    TABLE *parent= table->child_l ? table : table->parent;
     next=table->next;
     DBUG_PRINT("tcache", ("open table: '%s'.'%s' 0x%lx  "
                           "parent: 0x%lx  db_stat: %u",
                           table->s->db.str, table->s->table_name.str,
                           (long) table, (long) table->parent, db_stat));
-    if (table->child_l && !db_stat)
+    /*
+      If we need to reopen child or parent table in a MERGE table, then
+      children in this MERGE table has to be already detached at this
+      point.
+    */
+    DBUG_ASSERT(db_stat || !parent || !parent->children_attached);
+    /*
+      Thanks to the above assumption the below condition will guarantee that
+      merge_table_found is TRUE when we need to reopen child or parent table.
+      Note that it works even in situation when it is only a child and not a
+      parent that needs reopen (this can happen when get_locks == FALSE).
+    */
+    if (table->child_l && !table->children_attached)
       merge_table_found= TRUE;
-    if (!tables || (!db_stat && reopen_table(table)))
+
+    if (!tables)
     {
-      my_error(ER_CANT_REOPEN_TABLE, MYF(0), table->alias);
       /*
-        If we could not allocate 'tables', we may close open tables
-        here. If a MERGE table is affected, detach the children first.
-        It is not necessary to clear the child or parent table reference
-        of this table because the TABLE is freed. But we need to clear
-        the child or parent references of the other belonging tables so
-        that they cannot be moved into the unused_tables chain with
-        these pointers set.
+        If we could not allocate 'tables' we close ALL open tables here.
+        Before closing MERGE child or parent we need to detach children
+        and/or clear references in/to them.
       */
-      if (table->child_l || table->parent)
+      if (parent)
         detach_merge_children(table, TRUE);
-      VOID(hash_delete(&open_cache,(uchar*) table));
-      error=1;
+    }
+    else if (table->parent == &bad_merge_marker)
+    {
+      /*
+        This is either a child or a parent of a MERGE table for which
+        we already decided that we are unable to reopen it. Close it.
+
+        Reset parent reference, it may be used while freeing the table.
+      */
+      table->parent= NULL;
+    }
+    else if (!db_stat && reopen_table(table))
+    {
+      /*
+        If we fail to reopen a child or a parent in a MERGE table and the
+        MERGE table is affected for the first time, mark all relevant tables
+        invalid. Otherwise handle it as usual.
+
+        All in all we must end up with:
+        - child tables are detached from parent. This was done earlier,
+          but child<->parent references were kept valid for reopen.
+        - parent is not in the to-be-locked tables
+        - all child tables and parent are not in the THD::open_tables.
+        - all child tables and parent are not in the open_cache.
+
+        Please note that below we do additional pass through THD::open_tables
+        list to achieve the last three points.
+      */
+      if (parent)
+      {
+        mark_merge_parent_and_children_as_bad(parent);
+        table->parent= NULL;
+      }
     }
     else
     {
@@ -3366,21 +3430,56 @@ bool reopen_tables(THD *thd, bool get_locks, bool mark_share_as_old)
 	table->s->version=0;
 	table->open_placeholder= 0;
       }
+      continue;
     }
+    my_error(ER_CANT_REOPEN_TABLE, MYF(0), table->alias);
+    VOID(hash_delete(&open_cache, (uchar *) table));
+    error= 1;
   }
   *prev=0;
   /*
     When all tables are open again, we can re-attach MERGE children to
-    their parents. All TABLE objects are still present.
+    their parents.
+
+    If there was an error while reopening a child or a parent of a MERGE
+    table, or while reattaching child tables to their parents, some tables
+    may have been kept open but marked for close with bad_merge_marker.
+    Close these tables now.
   */
-  DBUG_PRINT("tcache", ("re-attaching MERGE tables: %d", merge_table_found));
-  if (!error && merge_table_found && reattach_merge(thd, &err_tables))
+  if (tables && merge_table_found && (error|= reattach_merge(thd)))
   {
-    while (err_tables)
+    prev= &thd->open_tables;
+    for (table= thd->open_tables; table; table= next)
     {
-      VOID(hash_delete(&open_cache, (uchar*) err_tables));
-      err_tables= err_tables->next;
+      next= table->next;
+      if (table->parent == &bad_merge_marker)
+      {
+        /* Remove merge parent from to-be-locked tables array. */
+        if (get_locks && table->child_l)
+        {
+          TABLE **t;
+          for (t= tables; t < tables_ptr; t++)
+          {
+            if (*t == table)
+            {
+              tables_ptr--;
+              memmove(t, t + 1, (tables_ptr - t) * sizeof(TABLE *));
+              break;
+            }
+          }
+        }
+        /* Reset parent reference, it may be used while freeing the table. */
+        table->parent= NULL;
+        /* Free table. */
+        VOID(hash_delete(&open_cache, (uchar *) table));
+      }
+      else
+      {
+        *prev= table;
+        prev= &table->next;
+      }
     }
+    *prev= 0;
   }
   DBUG_PRINT("tcache", ("open tables to lock: %u",
                         (uint) (tables_ptr - tables)));