Added backup handler calls

Part of MDEV-5336 Implement LOCK FOR BACKUP

Added support for backup calls in Aria to protect
removal of redo logs.

sql/handler.cc

@@ -822,6 +822,43 @@ void ha_kill_query(THD* thd, enum thd_kill_levels level)
 }
 
 
+/*****************************************************************************
+  Backup functions
+******************************************************************************/
+
+static my_bool plugin_prepare_for_backup(THD *unused1, plugin_ref plugin,
+                                         void *not_used)
+{
+  handlerton *hton= plugin_hton(plugin);
+  if (hton->state == SHOW_OPTION_YES && hton->prepare_for_backup)
+    hton->prepare_for_backup();
+  return FALSE;
+}
+
+void ha_prepare_for_backup()
+{
+  plugin_foreach_with_mask(0, plugin_prepare_for_backup,
+                           MYSQL_STORAGE_ENGINE_PLUGIN,
+                           PLUGIN_IS_DELETED|PLUGIN_IS_READY, 0);
+}
+
+static my_bool plugin_end_backup(THD *unused1, plugin_ref plugin,
+                                 void *not_used)
+{
+  handlerton *hton= plugin_hton(plugin);
+  if (hton->state == SHOW_OPTION_YES && hton->end_backup)
+    hton->end_backup();
+  return FALSE;
+}
+
+void ha_end_backup()
+{
+  plugin_foreach_with_mask(0, plugin_end_backup,
+                           MYSQL_STORAGE_ENGINE_PLUGIN,
+                           PLUGIN_IS_DELETED|PLUGIN_IS_READY, 0);
+}
+
+
 /* ========================================================================
  ======================= TRANSACTIONS ===================================*/
 

sql/handler.h

@@ -1613,6 +1613,10 @@ struct handlerton
    @return transaction commit ID
    @retval 0 if no system-versioned data was affected by the transaction */
    ulonglong (*prepare_commit_versioned)(THD *thd, ulonglong *trx_id);
+
+  /* backup */
+  void (*prepare_for_backup)(void);
+  void (*end_backup)(void);
 };
 
 
@@ -4676,6 +4680,7 @@ public:
   { DBUG_ASSERT(ht); return partition_ht()->flags & HTON_NATIVE_SYS_VERSIONING; }
   virtual void update_partition(uint	part_id)
   {}
+
 protected:
   Handler_share *get_ha_share_ptr();
   void set_ha_share_ptr(Handler_share *arg_ha_share);
@@ -4754,6 +4759,8 @@ int ha_create_table(THD *thd, const char *path,
                     HA_CREATE_INFO *create_info, LEX_CUSTRING *frm);
 int ha_delete_table(THD *thd, handlerton *db_type, const char *path,
                     const LEX_CSTRING *db, const LEX_CSTRING *alias, bool generate_warning);
+void ha_prepare_for_backup();
+void ha_end_backup();
 
 /* statistics and info */
 bool ha_show_status(THD *thd, handlerton *db_type, enum ha_stat_type stat);

storage/maria/ha_maria.cc

@@ -3443,6 +3443,21 @@ int maria_checkpoint_state(handlerton *hton, bool disabled)
 }
 
 
+/*
+  Handle backup calls
+*/
+
+void maria_prepare_for_backup()
+{
+  translog_disable_purge();
+}
+
+void maria_end_backup()
+{
+  translog_enable_purge();
+}
+
+
 
 #define SHOW_MSG_LEN (FN_REFLEN + 20)
 /**
@@ -3643,6 +3658,9 @@ static int ha_maria_init(void *p)
 #endif
   maria_hton->flush_logs= maria_flush_logs;
   maria_hton->show_status= maria_show_status;
+  maria_hton->prepare_for_backup= maria_prepare_for_backup;
+  maria_hton->end_backup= maria_end_backup;
+
   /* TODO: decide if we support Maria being used for log tables */
   maria_hton->flags= HTON_CAN_RECREATE | HTON_SUPPORT_LOG_TABLES;
   bzero(maria_log_pagecache, sizeof(*maria_log_pagecache));

storage/maria/ma_loghandler.c

@@ -56,6 +56,8 @@ static mysql_cond_t  COND_soft_sync;
 static MA_SERVICE_THREAD_CONTROL soft_sync_control=
   {0, FALSE, FALSE, &LOCK_soft_sync, &COND_soft_sync};
 
+uint log_purge_disabled= 0;
+
 
 /* transaction log file descriptor */
 typedef struct st_translog_file
@@ -3620,6 +3622,7 @@ my_bool translog_init_with_table(const char *directory,
   translog_syncs= 0;
   flush_start= 0;
   id_to_share= NULL;
+  log_purge_disabled= 0;
 
   log_descriptor.directory_fd= -1;
   log_descriptor.is_everything_flushed= 1;
@@ -8668,7 +8671,7 @@ my_bool translog_purge(TRANSLOG_ADDRESS low)
         mysql_rwlock_unlock(&log_descriptor.open_files_lock);
         translog_close_log_file(file);
       }
-      if (log_purge_type == TRANSLOG_PURGE_IMMIDIATE)
+      if (log_purge_type == TRANSLOG_PURGE_IMMIDIATE && ! log_purge_disabled)
       {
         char path[FN_REFLEN], *file_name;
         file_name= translog_filename_by_fileno(i, path);
@@ -8721,7 +8724,7 @@ my_bool translog_purge_at_flush()
 
   mysql_mutex_lock(&log_descriptor.purger_lock);
 
-  if (unlikely(log_descriptor.min_need_file == 0))
+  if (unlikely(log_descriptor.min_need_file == 0 || log_purge_disabled))
   {
     DBUG_PRINT("info", ("No info about min need file => exit"));
     mysql_mutex_unlock(&log_descriptor.purger_lock);
@@ -9285,3 +9288,22 @@ void dump_page(uchar *buffer, File handler)
   }
   dump_datapage(buffer, handler);
 }
+
+
+/*
+  Handle backup calls
+*/
+
+void translog_disable_purge()
+{
+  mysql_mutex_lock(&log_descriptor.purger_lock);
+  log_purge_disabled++;
+  mysql_mutex_unlock(&log_descriptor.purger_lock);
+}
+
+void translog_enable_purge()
+{
+  mysql_mutex_lock(&log_descriptor.purger_lock);
+  log_purge_disabled--;
+  mysql_mutex_unlock(&log_descriptor.purger_lock);
+}

storage/maria/ma_loghandler.h

@@ -367,6 +367,8 @@ extern void dump_page(uchar *buffer, File handler);
 extern my_bool translog_log_debug_info(TRN *trn,
                                        enum translog_debug_info_type type,
                                        uchar *info, size_t length);
+extern void translog_disable_purge(void);
+extern void translog_enable_purge(void);
 
 enum enum_translog_status
 {
@@ -520,6 +522,7 @@ typedef enum
 } enum_maria_translog_purge_type;
 extern ulong log_purge_type;
 extern ulong log_file_size;
+extern uint  log_purge_disabled;                /* For backup */
 
 typedef enum
 {