Merge pull request #695 from github/named-panic

Adding --force-named-panic option

Author: Shlomi Noach

doc/command-line-flags.md

@@ -111,6 +111,14 @@ While the ongoing estimated number of rows is still heuristic, it's almost exact
 
 Without this parameter, migration is a _noop_: testing table creation and validity of migration, but not touching data.
 
+### force-named-cut-over
+
+If given, a `cut-over` command must name the migrated table, or else ignored.
+
+### force-named-panic
+
+If given, a `panic` command must name the migrated table, or else ignored.
+
 ### force-table-names
 
 Table name prefix to be used on the temporary tables.

go/base/context.go

@@ -128,6 +128,7 @@ type MigrationContext struct {
 	CutOverExponentialBackoff           bool
 	ExponentialBackoffMaxInterval       int64
 	ForceNamedCutOverCommand            bool
+	ForceNamedPanicCommand              bool
 	PanicFlagFile                       string
 	HooksPath                           string
 	HooksHintMessage                    string

go/cmd/gh-ost/main.go

@@ -88,6 +88,7 @@ func main() {
 	flag.BoolVar(&migrationContext.TimestampOldTable, "timestamp-old-table", false, "Use a timestamp in old table name. This makes old table names unique and non conflicting cross migrations")
 	cutOver := flag.String("cut-over", "atomic", "choose cut-over type (default|atomic, two-step)")
 	flag.BoolVar(&migrationContext.ForceNamedCutOverCommand, "force-named-cut-over", false, "When true, the 'unpostpone|cut-over' interactive command must name the migrated table")
+	flag.BoolVar(&migrationContext.ForceNamedPanicCommand, "force-named-panic", false, "When true, the 'panic' interactive command must name the migrated table")
 
 	flag.BoolVar(&migrationContext.SwitchToRowBinlogFormat, "switch-to-rbr", false, "let this tool automatically switch binary log format to 'ROW' on the replica, if needed. The format will NOT be switched back. I'm too scared to do that, and wish to protect you if you happen to execute another migration while this one is running")
 	flag.BoolVar(&migrationContext.AssumeRBR, "assume-rbr", false, "set to 'true' when you know for certain your server uses 'ROW' binlog_format. gh-ost is unable to tell, event after reading binlog_format, whether the replication process does indeed use 'ROW', and restarts replication to be certain RBR setting is applied. Such operation requires SUPER privileges which you might not have. Setting this flag avoids restarting replication and you can proceed to use gh-ost without SUPER privileges")

go/logic/server.go

@@ -292,12 +292,22 @@ help                                 # This message
 		}
 	case "throttle", "pause", "suspend":
 		{
+			if arg != "" && arg != this.migrationContext.OriginalTableName {
+				// User explicitly provided table name. This is a courtesy protection mechanism
+				err := fmt.Errorf("User commanded 'throttle' on %s, but migrated table is %s; ignoring request.", arg, this.migrationContext.OriginalTableName)
+				return NoPrintStatusRule, err
+			}
 			atomic.StoreInt64(&this.migrationContext.ThrottleCommandedByUser, 1)
 			fmt.Fprintf(writer, throttleHint)
 			return ForcePrintStatusAndHintRule, nil
 		}
 	case "no-throttle", "unthrottle", "resume", "continue":
 		{
+			if arg != "" && arg != this.migrationContext.OriginalTableName {
+				// User explicitly provided table name. This is a courtesy protection mechanism
+				err := fmt.Errorf("User commanded 'no-throttle' on %s, but migrated table is %s; ignoring request.", arg, this.migrationContext.OriginalTableName)
+				return NoPrintStatusRule, err
+			}
 			atomic.StoreInt64(&this.migrationContext.ThrottleCommandedByUser, 0)
 			return ForcePrintStatusAndHintRule, nil
 		}
@@ -322,6 +332,15 @@ help                                 # This message
 		}
 	case "panic":
 		{
+			if arg == "" && this.migrationContext.ForceNamedPanicCommand {
+				err := fmt.Errorf("User commanded 'panic' without specifying table name, but --force-named-panic is set")
+				return NoPrintStatusRule, err
+			}
+			if arg != "" && arg != this.migrationContext.OriginalTableName {
+				// User explicitly provided table name. This is a courtesy protection mechanism
+				err := fmt.Errorf("User commanded 'panic' on %s, but migrated table is %s; ignoring request.", arg, this.migrationContext.OriginalTableName)
+				return NoPrintStatusRule, err
+			}
 			err := fmt.Errorf("User commanded 'panic'. I will now panic, without cleanup. PANIC!")
 			this.migrationContext.PanicAbort <- err
 			return NoPrintStatusRule, err