/error/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"
	"net/http"
)

var errors map[int]string

const ()

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

	// command related errors
	errors[100] = "Key Not Found"
	errors[101] = "The given PrevValue is not equal to the value of the key"
	errors[102] = "Not A File"
	errors[103] = "Reached the max number of machines in the cluster"

	// Post form related errors
	errors[200] = "Value is Required in POST form"
	errors[201] = "PrevValue is Required in POST form"
	errors[202] = "The given TTL in POST form is not a number"
	errors[203] = "The given index in POST form is not a number"

	// raft related errors
	errors[300] = "Raft Internal Error"
	errors[301] = "During Leader Election"

	// keyword
	errors[400] = "The prefix of the given key is a keyword in etcd"

	// etcd related errors
	errors[500] = "watcher is cleared due to etcd recovery"

}

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

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

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) {
	// 3xx is reft internal error
	if e.ErrorCode/100 == 3 {
		http.Error(w, e.toJsonString(), http.StatusInternalServerError)
	} else {
		http.Error(w, e.toJsonString(), http.StatusBadRequest)
	}
}