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mirror of https://github.com/open-telemetry/opentelemetry-go.git synced 2024-12-12 10:04:29 +02:00
opentelemetry-go/api/correlation/map.go
Tyler Yahn c97b4f726c
Update project License headers and checking (#596)
Update license header to standard format for source files missed prior.

Add license header to new source files.

Add Makefile check to test all `*.go` and `*.sh` files have a copyright
notice (or comment about them being auto-generated) within the first few
lines.
2020-03-25 14:47:17 -07:00

179 lines
4.5 KiB
Go

// Copyright The OpenTelemetry Authors
//
// 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 correlation
import (
"go.opentelemetry.io/otel/api/core"
)
type rawMap map[core.Key]core.Value
type keySet map[core.Key]struct{}
// Map is an immutable storage for correlations.
type Map struct {
m rawMap
}
// MapUpdate contains information about correlation changes to be
// made.
type MapUpdate struct {
// DropSingleK contains a single key to be dropped from
// correlations. Use this to avoid an overhead of a slice
// allocation if there is only one key to drop.
DropSingleK core.Key
// DropMultiK contains all the keys to be dropped from
// correlations.
DropMultiK []core.Key
// SingleKV contains a single key-value pair to be added to
// correlations. Use this to avoid an overhead of a slice
// allocation if there is only one key-value pair to add.
SingleKV core.KeyValue
// MultiKV contains all the key-value pairs to be added to
// correlations.
MultiKV []core.KeyValue
}
func newMap(raw rawMap) Map {
return Map{
m: raw,
}
}
// NewEmptyMap creates an empty correlations map.
func NewEmptyMap() Map {
return newMap(nil)
}
// NewMap creates a map with the contents of the update applied. In
// this function, having an update with DropSingleK or DropMultiK
// makes no sense - those fields are effectively ignored.
func NewMap(update MapUpdate) Map {
return NewEmptyMap().Apply(update)
}
// Apply creates a copy of the map with the contents of the update
// applied. Apply will first drop the keys from DropSingleK and
// DropMultiK, then add key-value pairs from SingleKV and MultiKV.
func (m Map) Apply(update MapUpdate) Map {
delSet, addSet := getModificationSets(update)
mapSize := getNewMapSize(m.m, delSet, addSet)
r := make(rawMap, mapSize)
for k, v := range m.m {
// do not copy items we want to drop
if _, ok := delSet[k]; ok {
continue
}
// do not copy items we would overwrite
if _, ok := addSet[k]; ok {
continue
}
r[k] = v
}
if update.SingleKV.Key.Defined() {
r[update.SingleKV.Key] = update.SingleKV.Value
}
for _, kv := range update.MultiKV {
r[kv.Key] = kv.Value
}
if len(r) == 0 {
r = nil
}
return newMap(r)
}
func getModificationSets(update MapUpdate) (delSet, addSet keySet) {
deletionsCount := len(update.DropMultiK)
if update.DropSingleK.Defined() {
deletionsCount++
}
if deletionsCount > 0 {
delSet = make(map[core.Key]struct{}, deletionsCount)
for _, k := range update.DropMultiK {
delSet[k] = struct{}{}
}
if update.DropSingleK.Defined() {
delSet[update.DropSingleK] = struct{}{}
}
}
additionsCount := len(update.MultiKV)
if update.SingleKV.Key.Defined() {
additionsCount++
}
if additionsCount > 0 {
addSet = make(map[core.Key]struct{}, additionsCount)
for _, k := range update.MultiKV {
addSet[k.Key] = struct{}{}
}
if update.SingleKV.Key.Defined() {
addSet[update.SingleKV.Key] = struct{}{}
}
}
return
}
func getNewMapSize(m rawMap, delSet, addSet keySet) int {
mapSizeDiff := 0
for k := range addSet {
if _, ok := m[k]; !ok {
mapSizeDiff++
}
}
for k := range delSet {
if _, ok := m[k]; ok {
if _, inAddSet := addSet[k]; !inAddSet {
mapSizeDiff--
}
}
}
return len(m) + mapSizeDiff
}
// Value gets a value from correlations map and returns a boolean
// value indicating whether the key exist in the map.
func (m Map) Value(k core.Key) (core.Value, bool) {
value, ok := m.m[k]
return value, ok
}
// HasValue returns a boolean value indicating whether the key exist
// in the map.
func (m Map) HasValue(k core.Key) bool {
_, has := m.Value(k)
return has
}
// Len returns a length of the map.
func (m Map) Len() int {
return len(m.m)
}
// Foreach calls a passed callback once on each key-value pair until
// all the key-value pairs of the map were iterated or the callback
// returns false, whichever happens first.
func (m Map) Foreach(f func(kv core.KeyValue) bool) {
for k, v := range m.m {
if !f(core.KeyValue{
Key: k,
Value: v,
}) {
return
}
}
}