@opentelemetry/core
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OpenTelemetry Core provides constants and utilities shared by all OpenTelemetry SDK packages.
99 lines • 3.76 kB
JavaScript
/*
* 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
*
* https://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.
*/
import { validateKey, validateValue } from '../internal/validators';
const MAX_TRACE_STATE_ITEMS = 32;
const MAX_TRACE_STATE_LEN = 512;
const LIST_MEMBERS_SEPARATOR = ',';
const LIST_MEMBER_KEY_VALUE_SPLITTER = '=';
/**
* TraceState must be a class and not a simple object type because of the spec
* requirement (https://www.w3.org/TR/trace-context/#tracestate-field).
*
* Here is the list of allowed mutations:
* - New key-value pair should be added into the beginning of the list
* - The value of any key can be updated. Modified keys MUST be moved to the
* beginning of the list.
*/
export class TraceState {
_internalState = new Map();
constructor(rawTraceState) {
if (rawTraceState)
this._parse(rawTraceState);
}
set(key, value) {
// TODO: Benchmark the different approaches(map vs list) and
// use the faster one.
const traceState = this._clone();
if (traceState._internalState.has(key)) {
traceState._internalState.delete(key);
}
traceState._internalState.set(key, value);
return traceState;
}
unset(key) {
const traceState = this._clone();
traceState._internalState.delete(key);
return traceState;
}
get(key) {
return this._internalState.get(key);
}
serialize() {
return this._keys()
.reduce((agg, key) => {
agg.push(key + LIST_MEMBER_KEY_VALUE_SPLITTER + this.get(key));
return agg;
}, [])
.join(LIST_MEMBERS_SEPARATOR);
}
_parse(rawTraceState) {
if (rawTraceState.length > MAX_TRACE_STATE_LEN)
return;
this._internalState = rawTraceState
.split(LIST_MEMBERS_SEPARATOR)
.reverse() // Store in reverse so new keys (.set(...)) will be placed at the beginning
.reduce((agg, part) => {
const listMember = part.trim(); // Optional Whitespace (OWS) handling
const i = listMember.indexOf(LIST_MEMBER_KEY_VALUE_SPLITTER);
if (i !== -1) {
const key = listMember.slice(0, i);
const value = listMember.slice(i + 1, part.length);
if (validateKey(key) && validateValue(value)) {
agg.set(key, value);
}
else {
// TODO: Consider to add warning log
}
}
return agg;
}, new Map());
// Because of the reverse() requirement, trunc must be done after map is created
if (this._internalState.size > MAX_TRACE_STATE_ITEMS) {
this._internalState = new Map(Array.from(this._internalState.entries())
.reverse() // Use reverse same as original tracestate parse chain
.slice(0, MAX_TRACE_STATE_ITEMS));
}
}
_keys() {
return Array.from(this._internalState.keys()).reverse();
}
_clone() {
const traceState = new TraceState();
traceState._internalState = new Map(this._internalState);
return traceState;
}
}
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