Add versioning to perf SQL database

perf/go/migratedb/main.go

+package main
+
+// Executes database migrations to the latest target version. In production this
+// requires the root password for MySQL. The user will be prompted for that so
+// it is not entered via the command line.
+
+import (
+        "bufio"
+        "flag"
+        "fmt"
+        "os"
+        "strings"
+
+        "github.com/golang/glog"
+        "skia.googlesource.com/buildbot.git/perf/go/db"
+)
+
+// flags
+var (
+        dbConnString = flag.String("db_conn_string", "root:%s@tcp(173.194.104.24:3306)/skia?parseTime=true", "\n\tDatabase string to open connect to the MySQL database. "+
+                "\n\tNeeds to follow the format of the golang-mysql driver (https://github.com/go-sql-driver/mysql."+
+                "\n\tIf the string contains %s the user will be prompted to enter a password which will then be used for subtitution.")
+)
+
+func main() {
+        flag.Parse()
+
+        var connectionStr = *dbConnString
+
+        // if it contains formatting information read the password from stdin.
+        if strings.Contains(connectionStr, "%s") {
+                glog.Infof("Using connection string: %s", connectionStr)
+                reader := bufio.NewReader(os.Stdin)
+                fmt.Print("Enter password for MySQL: ")
+                password, err := reader.ReadString('\n')
+                if err != nil {
+                        glog.Fatalf("Unable to read password. Error: %s", err.Error())
+                }
+                connectionStr = fmt.Sprintf(connectionStr, strings.TrimRight(password, "\n"))
+        }
+
+        // Initialize the database.
+        db.Init(connectionStr)
+
+        // Get the current database version
+        maxDBVersion := db.MaxDBVersion()
+        glog.Infof("Latest database version: %d", maxDBVersion)
+
+        dbVersion, err := db.DBVersion()
+        if err != nil {
+                glog.Fatalf("Unable to retrieve database version. Error: %s", err.Error())
+        }
+        glog.Infof("Current database version: %d", dbVersion)
+
+        if dbVersion < maxDBVersion {
+                glog.Infof("Migrating to version: %d", maxDBVersion)
+                err = db.Migrate(maxDBVersion)
+                if err != nil {
+                        glog.Fatalf("Unable to retrieve database version. Error: %s", err.Error())
+                }
+        }
+
+        glog.Infoln("Database migration finished.")
+}