Golang pgx.ConnPool類代碼示例

// OpenFromConnPool takes the existing *pgx.ConnPool pool and returns a *sql.DB
// with pool as the backend. This enables full control over the connection
// process and configuration while maintaining compatibility with the
// database/sql interface. In addition, by calling Driver() on the returned
// *sql.DB and typecasting to *stdlib.Driver a reference to the pgx.ConnPool can
// be reaquired later. This allows fast paths targeting pgx to be used while
// still maintaining compatibility with other databases and drivers.
//
// pool connection size must be at least 2.
func OpenFromConnPool(pool *pgx.ConnPool) (*sql.DB, error) {
	d := &Driver{Pool: pool}
	name := fmt.Sprintf("pgx-%d", openFromConnPoolCount)
	openFromConnPoolCount++
	sql.Register(name, d)
	db, err := sql.Open(name, "")
	if err != nil {
		return nil, err
	}

	// Presumably OpenFromConnPool is being used because the user wants to use
	// database/sql most of the time, but fast path with pgx some of the time.
	// Allow database/sql to use all the connections, but release 2 idle ones.
	// Don't have database/sql immediately release all idle connections because
	// that would mean that prepared statements would be lost (which kills
	// performance if the prepared statements constantly have to be reprepared)
	stat := pool.Stat()

	if stat.MaxConnections <= 2 {
		return nil, errors.New("pool connection size must be at least 2")
	}
	db.SetMaxIdleConns(stat.MaxConnections - 2)
	db.SetMaxOpenConns(stat.MaxConnections)

	return db, nil
}

func unlistenAndRelease(pool *pgx.ConnPool, conn *pgx.Conn, channel string) {
	_, err := conn.Exec(fmt.Sprintf(sqlUnlisten, channel))
	if err != nil {
		conn.Close()
		return
	}
	pool.Release(conn)
}

func setupStressDB(t *testing.T, pool *pgx.ConnPool) {
	_, err := pool.Exec(`
		drop table if exists widgets;
		create table widgets(
			id serial primary key,
			name varchar not null,
			description text,
			creation_time timestamptz
		);
`)
	if err != nil {
		t.Fatal(err)
	}
}

func txInsertRollback(pool *pgx.ConnPool, actionNum int) error {
	tx, err := pool.Begin()
	if err != nil {
		return err
	}

	sql := `
		insert into widgets(name, description, creation_time)
		values($1, $2, $3)`

	_, err = tx.Exec(sql, fake.ProductName(), fake.Sentences(), time.Now())
	if err != nil {
		return err
	}

	return tx.Rollback()
}

func listenAndPoolUnlistens(pool *pgx.ConnPool, actionNum int) error {
	conn, err := pool.Acquire()
	if err != nil {
		return err
	}
	defer pool.Release(conn)

	err = conn.Listen("stress")
	if err != nil {
		return err
	}

	_, err = conn.WaitForNotification(100 * time.Millisecond)
	if err == pgx.ErrNotificationTimeout {
		return nil
	}
	return err
}

func txMultipleQueries(pool *pgx.ConnPool, actionNum int) error {
	tx, err := pool.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	errExpectedTxDeath := errors.New("Expected tx death")

	actions := []struct {
		name string
		fn   func() error
	}{
		{"insertUnprepared", func() error { return insertUnprepared(tx, actionNum) }},
		{"queryRowWithoutParams", func() error { return queryRowWithoutParams(tx, actionNum) }},
		{"query", func() error { return query(tx, actionNum) }},
		{"queryCloseEarly", func() error { return queryCloseEarly(tx, actionNum) }},
		{"queryErrorWhileReturningRows", func() error {
			err := queryErrorWhileReturningRows(tx, actionNum)
			if err != nil {
				return err
			}
			return errExpectedTxDeath
		}},
	}

	for i := 0; i < 20; i++ {
		action := actions[rand.Intn(len(actions))]
		err := action.fn()
		if err == errExpectedTxDeath {
			return nil
		} else if err != nil {
			return err
		}
	}

	return tx.Commit()
}

func truncateAndClose(pool *pgx.ConnPool) {
	if _, err := pool.Exec("TRUNCATE TABLE que_jobs"); err != nil {
		panic(err)
	}
	pool.Close()
}

func notify(pool *pgx.ConnPool, actionNum int) error {
	_, err := pool.Exec("notify stress")
	return err
}