tag.go

/*
Copyright 2018 Turbine Labs, 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 stats

const (
	StatusCodeTag        = "status_code"
	StatusClassTag       = "status_class"
	StatusClassSuccess   = "success"
	StatusClassRedirect  = "redirect"
	StatusClassClientErr = "client_error"
	StatusClassServerErr = "server_error"

	NodeTag         = "node"
	ProxyTag        = "proxy"
	ProxyVersionTag = "proxy-version"
	SourceTag       = "source"
	TimestampTag    = "timestamp"
	ZoneTag         = "zone"
)

// Tag is an optional piece of metadata to be added to one or more stat points
type Tag struct {
	K string
	V string
}

// NewTag produces a new tag from a string
func NewTag(tag string) Tag {
	return Tag{K: tag}
}

// NewKVTag produces a new tag from a key/value pair
func NewKVTag(k, v string) Tag {
	return Tag{k, v}
}

func statusCodeClassifier(tags []Tag) []Tag {
	for _, tag := range tags {
		if tag.K == StatusCodeTag {
			if statusClass, ok := statusClassFromValue(tag.V); ok {
				return append(tags, NewKVTag(StatusClassTag, statusClass))
			}
			return tags
		}
	}

	return tags
}

func statusClassFromValue(v string) (string, bool) {
	if v == "" {
		return "", false
	}

	// validate numeric
	for _, r := range v {
		if r < '0' || r > '9' {
			return "", false
		}
	}

	if len(v) != 3 {
		return StatusClassServerErr, true
	}

	switch v[0] {
	case '1', '2':
		return StatusClassSuccess, true
	case '3':
		return StatusClassRedirect, true
	case '4':
		return StatusClassClientErr, true
	default:
		return StatusClassServerErr, true
	}
}