MDEV-6181 EITS could eat all tmpdir space and hang

Don't ignore errors from Count_distinct_field::add(),
pass them to the caller, so that it could abort the data
collection loop.

mysql-test/r/stat_tables-enospc.result

+call mtr.add_suppression("No space left on device");
+create table t1 (a varchar(255), b varchar(255), c varchar(255));
+set use_stat_tables=PREFERABLY, optimizer_use_condition_selectivity=3;
+set debug_dbug='+d,simulate_file_write_error';
+analyze table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	Error	Error writing file 'tmp-file' (Errcode: 28 "No space left on device")
+test.t1	analyze	status	Operation failed
+set debug_dbug='';
+drop table t1;

mysql-test/t/stat_tables-enospc.test

+#
+# MDEV-6181 EITS could eat all tmpdir space and hang
+#
+# test that ANALYZE TABLE is immediately aborted when going out of disk space
+--source include/have_debug.inc
+call mtr.add_suppression("No space left on device");
+create table t1 (a varchar(255), b varchar(255), c varchar(255));
+--disable_query_log
+let $i=10000;
+while ($i) {
+  insert t1 values (repeat(format(rand(),10), 20),
+                    repeat(format(rand(),10), 20),
+                    repeat(format(rand(),10), 20));
+  dec $i;
+}
+--enable_query_log
+set use_stat_tables=PREFERABLY, optimizer_use_condition_selectivity=3;
+set debug_dbug='+d,simulate_file_write_error';
+--replace_regex /'.*'/'tmp-file'/
+analyze table t1;
+set debug_dbug='';
+drop table t1;
+

sql/sql_statistics.cc

@@ -184,7 +184,7 @@ class Column_statistics_collected :public Column_statistics
 public:
 
   inline void init(THD *thd, Field * table_field);
-  inline void add(ha_rows rowno);
+  inline bool add(ha_rows rowno);
   inline void finish(ha_rows rows); 
   inline void cleanup();
 };
@@ -2219,9 +2219,10 @@ void Column_statistics_collected::init(THD *thd, Field *table_field)
 */
 
 inline
-void Column_statistics_collected::add(ha_rows rowno)
+bool Column_statistics_collected::add(ha_rows rowno)
 {
 
+  bool err= 0;
   if (column->is_null())
     nulls++;
   else
@@ -2232,8 +2233,9 @@ void Column_statistics_collected::add(ha_rows rowno)
     if (max_value && column->update_max(max_value, rowno == nulls))
       set_not_null(COLUMN_STAT_MAX_VALUE);
     if (count_distinct) 
-      count_distinct->add();
+      err= count_distinct->add();
   } 
+  return err;
 }
 
 
@@ -2487,8 +2489,11 @@ int collect_statistics_for_table(THD *thd, TABLE *table)
         table_field= *field_ptr;
         if (!bitmap_is_set(table->read_set, table_field->field_index))
           continue;  
-        table_field->collected_stats->add(rows);
+        if ((rc= table_field->collected_stats->add(rows)))
+          break;
       }
+      if (rc)
+        break;
       rows++;
     }
     file->ha_rnd_end();
@@ -2518,7 +2523,7 @@ int collect_statistics_for_table(THD *thd, TABLE *table)
     else
       table_field->collected_stats->cleanup();
   }
-bitmap_clear_all(table->write_set);
+  bitmap_clear_all(table->write_set);
 
   if (!rc)
   {