snapshot of https://github.com/mattermost/mattermost.git (master, 2026-09-16; blobs > 131072B omitted)

server/public/utils/sql/sql_utils.go

@@ -0,0 +1,76 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package sql
+
+import (
+	"context"
+	dbsql "database/sql"
+	"strings"
+	"time"
+
+	"github.com/mattermost/mattermost/server/public/model"
+	"github.com/mattermost/mattermost/server/public/shared/mlog"
+	"github.com/pkg/errors"
+)
+
+const (
+	DBPingTimeout    = 10 * time.Second
+	DBConnRetrySleep = 2 * time.Second
+
+	replicaLagPrefix = "replica-lag"
+)
+
+// SetupConnection sets up the connection to the database and pings it to make sure it's alive.
+// It also applies any database configuration settings that are required.
+func SetupConnection(logger mlog.LoggerIFace, connType string, dataSource string, settings *model.SqlSettings, attempts int) (*dbsql.DB, error) {
+	db, err := dbsql.Open(*settings.DriverName, dataSource)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to open SQL connection")
+	}
+
+	// At this point, we have passed sql.Open, so we deliberately ignore any errors.
+	sanitized, _ := model.SanitizeDataSource(*settings.DriverName, dataSource)
+
+	logger = logger.With(
+		mlog.String("database", connType),
+		mlog.String("dataSource", sanitized),
+	)
+
+	for attempt := 1; attempt <= attempts; attempt++ {
+		if attempt > 1 {
+			logger.Info("Pinging SQL", mlog.Int("attempt", attempt))
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), DBPingTimeout)
+		defer cancel()
+		err = db.PingContext(ctx)
+		if err != nil {
+			if attempt == attempts {
+				return nil, err
+			}
+			logger.Error("Failed to ping DB", mlog.Float("retrying in seconds", DBConnRetrySleep.Seconds()), mlog.Err(err))
+			time.Sleep(DBConnRetrySleep)
+			continue
+		}
+		break
+	}
+
+	if strings.HasPrefix(connType, replicaLagPrefix) {
+		// If this is a replica lag connection, we just open one connection.
+		//
+		// Arguably, if the query doesn't require a special credential, it does take up
+		// one extra connection from the replica DB. But falling back to the replica
+		// data source when the replica lag data source is null implies an ordering constraint
+		// which makes things brittle and is not a good design.
+		// If connections are an overhead, it is advised to use a connection pool.
+		db.SetMaxOpenConns(1)
+		db.SetMaxIdleConns(1)
+	} else {
+		db.SetMaxIdleConns(*settings.MaxIdleConns)
+		db.SetMaxOpenConns(*settings.MaxOpenConns)
+	}
+	db.SetConnMaxLifetime(time.Duration(*settings.ConnMaxLifetimeMilliseconds) * time.Millisecond)
+	db.SetConnMaxIdleTime(time.Duration(*settings.ConnMaxIdleTimeMilliseconds) * time.Millisecond)
+
+	return db, nil
+}