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opentelemetry-go/api/distributedcontext/context.go
rghetia 15bfc5bb12
Namespace import path under "/otel" (#274)
Also fixes example module paths so that they use the vanity URL instead
of the github URL.

[Closes #184]
2019-11-01 11:40:29 -07:00

57 lines
1.5 KiB
Go

// Copyright 2019, 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 distributedcontext
import (
"context"
"runtime/pprof"
"go.opentelemetry.io/otel/api/core"
)
type ctxEntriesType struct{}
var (
ctxEntriesKey = &ctxEntriesType{}
)
func WithMap(ctx context.Context, m Map) context.Context {
return context.WithValue(ctx, ctxEntriesKey, m)
}
func NewContext(ctx context.Context, keyvalues ...core.KeyValue) context.Context {
return WithMap(ctx, FromContext(ctx).Apply(MapUpdate{
MultiKV: keyvalues,
}))
}
func FromContext(ctx context.Context) Map {
if m, ok := ctx.Value(ctxEntriesKey).(Map); ok {
return m
}
return NewEmptyMap()
}
// Note: the golang pprof.Do API forces this memory allocation, we
// should file an issue about that. (There's a TODO in the source.)
func Do(ctx context.Context, f func(ctx context.Context)) {
m := FromContext(ctx)
keyvals := make([]string, 0, 2*len(m.m))
for k, v := range m.m {
keyvals = append(keyvals, string(k), v.value.Emit())
}
pprof.Do(ctx, pprof.Labels(keyvals...), f)
}