// Copyright 2016 Documize Inc. <legal@documize.com>. All rights reserved.
//
// This software (Documize Community Edition) is licensed under
// GNU AGPL v3 http://www.gnu.org/licenses/agpl-3.0.en.html
//
// You can operate outside the AGPL restrictions by purchasing
// Documize Enterprise Edition and obtaining a commercial license
// by contacting <sales@documize.com>.
//
// https://documize.com

package database

// import (
// 	"crypto/rand"
// 	"time"

// 	"github.com/documize/community/core/env"
// 	"github.com/jmoiron/sqlx"
// )

// // Lock will try to lock the database instance to the running process.
// // Uses a "random" delay as a por man's database cluster-aware process.
// // We skip delay if there are no scripts to process.
// func Lock(runtime *env.Runtime, scriptsToProcess int) (bool, error) {
// 	// Wait for random period of time.
// 	b := make([]byte, 2)
// 	_, err := rand.Read(b)
// 	if err != nil {
// 		return false, err
// 	}
// 	wait := ((time.Duration(b[0]) << 8) | time.Duration(b[1])) * time.Millisecond / 10 // up to 6.5 secs wait

// 	// Why delay if nothing to process?
// 	if scriptsToProcess > 0 {
// 		time.Sleep(wait)
// 	}

// 	// Start transaction fotr lock process.
// 	tx, err := runtime.Db.Beginx()
// 	if err != nil {
// 		runtime.Log.Error("Database: unable to start transaction", err)
// 		return false, err
// 	}

// 	// Lock the database.
// 	_, err = tx.Exec(runtime.StoreProvider.QueryStartLock())
// 	if err != nil {
// 		runtime.Log.Error("Database: unable to lock tables", err)
// 		return false, err
// 	}

// 	// Unlock the database at the end of this function.
// 	defer func() {
// 		_, err = tx.Exec(runtime.StoreProvider.QueryFinishLock())
// 		if err != nil {
// 			runtime.Log.Error("Database: unable to unlock tables", err)
// 		}
// 		tx.Commit()
// 	}()

// 	// Try to record this process as leader of database migration process.
// 	_, err = tx.Exec(runtime.StoreProvider.QueryInsertProcessID())
// 	if err != nil {
// 		runtime.Log.Info("Database: marked as slave process awaiting upgrade")
// 		return false, nil
// 	}

// 	// We are the leader!
// 	runtime.Log.Info("Database: marked as database upgrade process leader")
// 	return true, err
// }

// // Unlock completes process that was started with Lock().
// func Unlock(runtime *env.Runtime, tx *sqlx.Tx, err error, amLeader bool) error {
// 	if amLeader {
// 		defer func() {
// 			doUnlock(runtime)
// 		}()

// 		if tx != nil {
// 			if err == nil {
// 				tx.Commit()
// 				runtime.Log.Info("Database: is ready")
// 				return nil
// 			}
// 			tx.Rollback()
// 		}

// 		runtime.Log.Error("Database: install/upgrade failed", err)

// 		return err
// 	}

// 	return nil // not the leader, so ignore errors
// }

// // Helper method for defer function called from Unlock().
// func doUnlock(runtime *env.Runtime) error {
// 	tx, err := runtime.Db.Beginx()
// 	if err != nil {
// 		return err
// 	}
// 	_, err = tx.Exec(runtime.StoreProvider.QueryDeleteProcessID())
// 	if err != nil {
// 		return err
// 	}

// 	return tx.Commit()
// }