error.go

// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package lad

import (
	"github.com/tnngo/lad/internal/pool"
	"github.com/tnngo/lad/ladcore"
)

var _errArrayElemPool = pool.New(func() *errArrayElem {
	return &errArrayElem{}
})

// Error is shorthand for the common idiom NamedError("error", err).
func Error(err error) Field {
	return NamedError("error", err)
}

// NamedError constructs a field that lazily stores err.Error() under the
// provided key. Errors which also implement fmt.Formatter (like those produced
// by github.com/pkg/errors) will also have their verbose representation stored
// under key+"Verbose". If passed a nil error, the field is a no-op.
//
// For the common case in which the key is simply "error", the Error function
// is shorter and less repetitive.
func NamedError(key string, err error) Field {
	if err == nil {
		return Skip()
	}
	return Field{Key: key, Type: ladcore.ErrorType, Interface: err}
}

type errArray []error

func (errs errArray) MarshalLogArray(arr ladcore.ArrayEncoder) error {
	for i := range errs {
		if errs[i] == nil {
			continue
		}
		// To represent each error as an object with an "error" attribute and
		// potentially an "errorVerbose" attribute, we need to wrap it in a
		// type that implements LogObjectMarshaler. To prevent this from
		// allocating, pool the wrapper type.
		elem := _errArrayElemPool.Get()
		elem.error = errs[i]
		err := arr.AppendObject(elem)
		elem.error = nil
		_errArrayElemPool.Put(elem)
		if err != nil {
			return err
		}
	}
	return nil
}

type errArrayElem struct {
	error
}

func (e *errArrayElem) MarshalLogObject(enc ladcore.ObjectEncoder) error {
	// Re-use the error field's logic, which supports non-standard error types.
	Error(e.error).AddTo(enc)
	return nil
}