From f79e21040743183c867e9fd4bf7e33694fa6dac4 Mon Sep 17 00:00:00 2001
From: Denis Arh <denis.arh@gmail.com>
Date: Fri, 19 Jun 2020 19:31:05 +0200
Subject: [PATCH] Improve transaction handling in github.com/titpetric/factory

This is an ugly/temp update of vendored github.com/titpetric/factory.

It fixes:
 - invalid savepoint rollback SQL syntax
 - err handling on rollback calls
 - inc. number of tries in case of a (dead)lock (from 3 to 64)
 - better backoff algo for sleep between retries
---
 .../github.com/titpetric/factory/database.go  | 27 +++++++++++++++----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/vendor/github.com/titpetric/factory/database.go b/vendor/github.com/titpetric/factory/database.go
index 95f0d5de1..3b4e35f83 100644
--- a/vendor/github.com/titpetric/factory/database.go
+++ b/vendor/github.com/titpetric/factory/database.go
@@ -235,6 +235,10 @@ func (r *DB) Begin() (err error) {
 
 // Transaction will create a transaction and invoke a callback
 func (r *DB) Transaction(callback func() error) (err error) {
+	// Max tries in case of a (dead)lock
+	// @todo should be configurable
+	const MAX_TRIES = 64
+
 	var try int
 
 	// Perform transaction statements
@@ -250,7 +254,8 @@ func (r *DB) Transaction(callback func() error) (err error) {
 		}
 
 		try++
-		if try > 3 {
+		//
+		if try > MAX_TRIES {
 			r.logger.Log(r.ctx, fmt.Sprintf("Retried transaction %d times, aborting", try-1))
 			break
 		}
@@ -267,8 +272,15 @@ func (r *DB) Transaction(callback func() error) (err error) {
 		//   - 1213: deadlock found
 		if cause.Number == 1205 || cause.Number == 1213 {
 			r.logger.Log(r.ctx, "Retrying transaction", logger.NewField("try", try), logger.NewField("cause", cause))
-			r.Rollback()
-			time.Sleep(50 * time.Millisecond)
+
+			err = r.Rollback()
+			if err != nil {
+				r.logger.Log(r.ctx, "failed to rollback transaction", logger.NewField("err", err))
+				return err
+			}
+
+			// raise time to sleep on each try
+			time.Sleep(time.Millisecond * time.Duration(try * 50))
 			continue
 		}
 
@@ -277,7 +289,12 @@ func (r *DB) Transaction(callback func() error) (err error) {
 	}
 
 	if err != nil {
-		r.Rollback()
+		rerr := r.Rollback()
+		if rerr != nil {
+			r.logger.Log(r.ctx, "failed to rollback transaction", logger.NewField("err", rerr))
+			return rerr
+		}
+
 		return err
 	}
 	return r.Commit()
@@ -318,7 +335,7 @@ func (r *DB) Rollback() (err error) {
 			r.inTx = 0
 			return nil
 		}
-		if _, err = r.Exec(fmt.Sprintf("ROLLBACK SAVEPOINT sp_%d", r.inTx-1)); err != nil {
+		if _, err = r.Exec(fmt.Sprintf("ROLLBACK TO SAVEPOINT sp_%d", r.inTx-1)); err != nil {
 			return errors.WithStack(err)
 		}
 		r.inTx--