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[github/fretlink/terraform-provider-statuscake.git] / vendor / go.opencensus.io / tag / map.go

// Copyright 2017, OpenCensus 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 tag

import (
        "bytes"
        "context"
        "fmt"
        "sort"
)

// Tag is a key value pair that can be propagated on wire.
type Tag struct {
        Key   Key
        Value string
}

// Map is a map of tags. Use New to create a context containing
// a new Map.
type Map struct {
        m map[Key]string
}

// Value returns the value for the key if a value for the key exists.
func (m *Map) Value(k Key) (string, bool) {
        if m == nil {
                return "", false
        }
        v, ok := m.m[k]
        return v, ok
}

func (m *Map) String() string {
        if m == nil {
                return "nil"
        }
        keys := make([]Key, 0, len(m.m))
        for k := range m.m {
                keys = append(keys, k)
        }
        sort.Slice(keys, func(i, j int) bool { return keys[i].Name() < keys[j].Name() })

        var buffer bytes.Buffer
        buffer.WriteString("{ ")
        for _, k := range keys {
                buffer.WriteString(fmt.Sprintf("{%v %v}", k.name, m.m[k]))
        }
        buffer.WriteString(" }")
        return buffer.String()
}

func (m *Map) insert(k Key, v string) {
        if _, ok := m.m[k]; ok {
                return
        }
        m.m[k] = v
}

func (m *Map) update(k Key, v string) {
        if _, ok := m.m[k]; ok {
                m.m[k] = v
        }
}

func (m *Map) upsert(k Key, v string) {
        m.m[k] = v
}

func (m *Map) delete(k Key) {
        delete(m.m, k)
}

func newMap() *Map {
        return &Map{m: make(map[Key]string)}
}

// Mutator modifies a tag map.
type Mutator interface {
        Mutate(t *Map) (*Map, error)
}

// Insert returns a mutator that inserts a
// value associated with k. If k already exists in the tag map,
// mutator doesn't update the value.
func Insert(k Key, v string) Mutator {
        return &mutator{
                fn: func(m *Map) (*Map, error) {
                        if !checkValue(v) {
                                return nil, errInvalidValue
                        }
                        m.insert(k, v)
                        return m, nil
                },
        }
}

// Update returns a mutator that updates the
// value of the tag associated with k with v. If k doesn't
// exists in the tag map, the mutator doesn't insert the value.
func Update(k Key, v string) Mutator {
        return &mutator{
                fn: func(m *Map) (*Map, error) {
                        if !checkValue(v) {
                                return nil, errInvalidValue
                        }
                        m.update(k, v)
                        return m, nil
                },
        }
}

// Upsert returns a mutator that upserts the
// value of the tag associated with k with v. It inserts the
// value if k doesn't exist already. It mutates the value
// if k already exists.
func Upsert(k Key, v string) Mutator {
        return &mutator{
                fn: func(m *Map) (*Map, error) {
                        if !checkValue(v) {
                                return nil, errInvalidValue
                        }
                        m.upsert(k, v)
                        return m, nil
                },
        }
}

// Delete returns a mutator that deletes
// the value associated with k.
func Delete(k Key) Mutator {
        return &mutator{
                fn: func(m *Map) (*Map, error) {
                        m.delete(k)
                        return m, nil
                },
        }
}

// New returns a new context that contains a tag map
// originated from the incoming context and modified
// with the provided mutators.
func New(ctx context.Context, mutator ...Mutator) (context.Context, error) {
        m := newMap()
        orig := FromContext(ctx)
        if orig != nil {
                for k, v := range orig.m {
                        if !checkKeyName(k.Name()) {
                                return ctx, fmt.Errorf("key:%q: %v", k, errInvalidKeyName)
                        }
                        if !checkValue(v) {
                                return ctx, fmt.Errorf("key:%q value:%q: %v", k.Name(), v, errInvalidValue)
                        }
                        m.insert(k, v)
                }
        }
        var err error
        for _, mod := range mutator {
                m, err = mod.Mutate(m)
                if err != nil {
                        return ctx, err
                }
        }
        return NewContext(ctx, m), nil
}

// Do is similar to pprof.Do: a convenience for installing the tags
// from the context as Go profiler labels. This allows you to
// correlated runtime profiling with stats.
//
// It converts the key/values from the given map to Go profiler labels
// and calls pprof.Do.
//
// Do is going to do nothing if your Go version is below 1.9.
func Do(ctx context.Context, f func(ctx context.Context)) {
        do(ctx, f)
}

type mutator struct {
        fn func(t *Map) (*Map, error)
}

func (m *mutator) Mutate(t *Map) (*Map, error) {
        return m.fn(t)
}