Postgres advisory locks with Go

pglock.go

package database

import (
	"context"
	"errors"
	"fmt"
)
import "github.com/jackc/pgx/v4"

// mutex is an implementation of the Mutexer interface
type pgxMutex struct {
	conn *pgx.Conn
}

// newMutex returns a new Mutex
func NewPgxMutex(db *pgx.Conn) *pgxMutex {
	return &pgxMutex{conn: db}
}

// Lock set a mutex for database write
func (m *pgxMutex) Lock(ctx context.Context, lockID int) error {
	var result bool
	err := m.conn.QueryRow(ctx, fmt.Sprintf("SELECT pg_try_advisory_lock(%d)", lockID)).Scan(&result)
	if err != nil {
		return err
	}
	if !result {
		return errors.New("database mutex is already taken")
	}
	return nil
}

// Unlock remove the current database mutex
func (m *pgxMutex) Unlock(ctx context.Context, lockID int) error {
	var result bool
	err := m.conn.QueryRow(ctx, fmt.Sprintf("SELECT pg_advisory_unlock(%d)", lockID)).Scan(&result)
	if err != nil {
		return err
	}
	if !result {
		return errors.New("unable to release database mutex")
	}
	return nil
}