Reduce DB connections leaks

Attempt to fix the MaxConnection test bug.
Relates to #68.

db/database.go

@@ -179,6 +179,7 @@ func RepeatDeadlocked(ctx context.Context, opts *sql.TxOptions, fct func(tx *sql
 				if !ok || !errors.As(err, &mySqlError) || mySqlError.Number != 1213 {
 					panic(exc)
 				}
+				log.Println("SQL error 1213. Restarting transaction.")
 			}()
 
 			fct(tx)

main/create_test.go

@@ -140,6 +140,7 @@ func (self *createPollChecker) Check(t *testing.T, response *http.Response, requ
 
 	// Check Alternatives
 	rows, err := db.DB.Query(qCheckAlternative, pollSegment.Id)
+	defer rows.Close()
 	mustt(t, err)
 	for id, alt := range query.Alternatives {
 		if !rows.Next() {

main/delete.go

@@ -57,6 +57,7 @@ func DeleteHandler(ctx context.Context, response server.Response, request *serve
 	)
 
 	rows, err := db.DB.QueryContext(ctx, qTitle, segment.Id, request.User.Id)
+	defer rows.Close()
 	must(err)
 	if !rows.Next() {
 		panic(server.NewHttpError(ImpossibleStatus, ImpossibleMessage, ""))
@@ -66,9 +67,9 @@ func DeleteHandler(ctx context.Context, response server.Response, request *serve
 		panic(server.NewHttpError(http.StatusInternalServerError, server.InternalHttpErrorMsg,
 			"Two polls witht the same Id"))
 	}
-	rows.Close()
 
 	rows, err = db.DB.QueryContext(ctx, qParticipants, segment.Id)
+	defer rows.Close()
 	must(err)
 	for rows.Next() {
 		var uid uint32

main/poll_test.go

@@ -18,7 +18,9 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"net/http"
+	"runtime"
 	"strconv"
 	"testing"
 
@@ -336,7 +338,15 @@ func (self *pollTest) GetName() string {
 	return self.Name
 }
 
+func stats(ctx string) {
+	stats := db.DB.Stats()
+	fmt.Printf("%s -- open %d, use %d, idle %d, goroutines %d\n", ctx,
+		stats.OpenConnections, stats.InUse, stats.Idle, runtime.NumGoroutine())
+}
+
 func (self *pollTest) Prepare(t *testing.T) {
+	stats("Before Prepare")
+
 	if !self.Sequential {
 		t.Parallel()
 	}
@@ -419,6 +429,7 @@ func (self *pollTest) Prepare(t *testing.T) {
 	if checker, ok := self.Checker.(interface { Before(*testing.T) }); ok {
 		checker.Before(t)
 	}
+	stats("After Prepare")
 }
 
 func (self *pollTest) GetRequest(t *testing.T) *srvt.Request {
@@ -450,6 +461,7 @@ func (self *pollTest) Check(t *testing.T, response *http.Response, request *serv
 	} else {
 		t.Errorf("Checker is not an srvt.Checker")
 	}
+	stats("After Check")
 }
 
 func (self *pollTest) Close() {

main/unlogged.go

@@ -64,6 +64,7 @@ func UnloggedFromHash(ctx context.Context, hash uint32) (user server.User, err e
 	if err != nil {
 		return
 	}
+	rows.Close()
 
 	user.Hash = hash
 	user.Logged = false