error.go

/*
Copyright 2013 CoreOS Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package error

import (
	"encoding/json"
	"fmt"
	"net/http"
)

var errors map[int]string

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
	EcodeValueOrTTLRequired = 204

	EcodeRaftInternal = 300
	EcodeLeaderElect  = 301

	EcodeWatcherCleared    = 400
	EcodeEventIndexCleared = 401
)

func init() {
	errors = make(map[int]string)

	// command related errors
	errors[EcodeKeyNotFound] = "Key not found"
	errors[EcodeTestFailed] = "Compare failed" //test and set
	errors[EcodeNotFile] = "Not a file"
	errors[EcodeNoMorePeer] = "Reached the max number of peers in the cluster"
	errors[EcodeNotDir] = "Not a directory"
	errors[EcodeNodeExist] = "Key already exists" // create
	errors[EcodeRootROnly] = "Root is read only"
	errors[EcodeKeyIsPreserved] = "The prefix of given key is a keyword in etcd"
	errors[EcodeDirNotEmpty] = "Directory not empty"

	// Post form related errors
	errors[EcodeValueRequired] = "Value is Required in POST form"
	errors[EcodePrevValueRequired] = "PrevValue is Required in POST form"
	errors[EcodeTTLNaN] = "The given TTL in POST form is not a number"
	errors[EcodeIndexNaN] = "The given index in POST form is not a number"
	errors[EcodeValueOrTTLRequired] = "Value or TTL is required in POST form"

	// raft related errors
	errors[EcodeRaftInternal] = "Raft Internal Error"
	errors[EcodeLeaderElect] = "During Leader Election"

	// etcd related errors
	errors[EcodeWatcherCleared] = "watcher is cleared due to etcd recovery"
	errors[EcodeEventIndexCleared] = "The event in requested index is outdated and cleared"

}

type Error struct {
	ErrorCode int    `json:"errorCode"`
	Message   string `json:"message"`
	Cause     string `json:"cause,omitempty"`
	Index     uint64 `json:"index"`
}

func NewError(errorCode int, cause string, index uint64) *Error {
	return &Error{
		ErrorCode: errorCode,
		Message:   errors[errorCode],
		Cause:     cause,
		Index:     index,
	}
}

func Message(code int) string {
	return errors[code]
}

// Only for error interface
func (e Error) Error() string {
	return e.Message
}

func (e Error) toJsonString() string {
	b, _ := json.Marshal(e)
	return string(b)
}

func (e Error) Write(w http.ResponseWriter) {
	w.Header().Add("X-Etcd-Index", fmt.Sprint(e.Index))
	// 3xx is raft internal error
	status := http.StatusBadRequest
	switch e.ErrorCode {
	case EcodeKeyNotFound:
		status = http.StatusNotFound
	case EcodeNotFile, EcodeDirNotEmpty:
		status = http.StatusForbidden
	case EcodeTestFailed, EcodeNodeExist:
		status = http.StatusPreconditionFailed
	default:
		if e.ErrorCode/100 == 3 {
			status = http.StatusInternalServerError
		}
	}
	http.Error(w, e.toJsonString(), status)
}