error.go

// Copyright 2014, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package etcdtopo

import (
	"errors"

	"golang.org/x/net/context"

	"github.com/coreos/go-etcd/etcd"
	"github.com/youtube/vitess/go/vt/topo"
)

// Errors specific to this package.
var (
	// ErrBadResponse is returned from this package if the response from the etcd
	// server does not contain the data that the API promises. The etcd client
	// unmarshals JSON from the server into a Response struct that uses pointers,
	// so we need to check for nil pointers, or else a misbehaving etcd could
	// cause us to panic.
	ErrBadResponse = errors.New("etcd request returned success, but response is missing required data")
)

// Error codes returned by etcd:
// https://github.com/coreos/etcd/blob/v0.4.6/Documentation/errorcode.md
const (
	EcodeKeyNotFound    = 100
	EcodeTestFailed     = 101
	EcodeNotFile        = 102
	EcodeNoMorePeer     = 103
	EcodeNotDir         = 104
	EcodeNodeExist      = 105
	EcodeKeyIsPreserved = 106
	EcodeRootROnly      = 107
	EcodeDirNotEmpty    = 108

	EcodeValueRequired     = 200
	EcodePrevValueRequired = 201
	EcodeTTLNaN            = 202
	EcodeIndexNaN          = 203

	EcodeRaftInternal = 300
	EcodeLeaderElect  = 301

	EcodeWatcherCleared    = 400
	EcodeEventIndexCleared = 401
)

// convertError converts etcd-specific errors to corresponding topo errors, if
// they exist, and passes others through. It also converts context errors to
// topo package equivalents.
func convertError(err error) error {
	switch typeErr := err.(type) {
	case *etcd.EtcdError:
		switch typeErr.ErrorCode {
		case EcodeTestFailed:
			return topo.ErrBadVersion
		case EcodeKeyNotFound:
			return topo.ErrNoNode
		case EcodeNodeExist:
			return topo.ErrNodeExists
		case EcodeDirNotEmpty:
			return topo.ErrNotEmpty
		}
	default:
		switch err {
		case context.Canceled:
			return topo.ErrInterrupted
		case context.DeadlineExceeded:
			return topo.ErrTimeout
		}
	}
	return err
}