@azure/monitor-opentelemetry
Version:
Azure Monitor OpenTelemetry (Node.js)
90 lines • 3.63 kB
JavaScript
import { diag } from "@opentelemetry/api";
import { SamplingDecision } from "@opentelemetry/sdk-trace-base";
import { AzureMonitorSampleRate } from "../types.js";
/**
* ApplicationInsightsSampler is responsible for the following:
* Implements same trace id hashing algorithm so that traces are sampled the same across multiple nodes
* Adds item count to span attribute if span is sampled (needed for ingestion service)
* @param samplingRatio - 0 to 1 value.
*/
export class ApplicationInsightsSampler {
/**
* Initializes a new instance of the ApplicationInsightsSampler class.
* @param samplingRatio - Value in the range [0,1], 1 meaning all data will sampled and 0 all Tracing data will be sampled out.
*/
constructor(samplingRatio = 1) {
this._samplingRatio = samplingRatio;
if (this._samplingRatio > 1 ||
this._samplingRatio < 0 ||
!Number.isFinite(this._samplingRatio)) {
diag.warn("Invalid sampling rate, sampling rate must be a value in the range [0,1].");
}
this._sampleRate = Math.round(this._samplingRatio * 100);
}
/**
* Checks whether span needs to be created and tracked.
*
* @param context - Parent Context which may contain a span.
* @param traceId - of the span to be created. It can be different from the
* traceId in the {@link SpanContext}. Typically in situations when the
* span to be created starts a new trace.
* @param spanName - of the span to be created.
* @param spanKind - of the span to be created.
* @param attributes - Initial set of SpanAttributes for the Span being constructed.
* @param links - Collection of links that will be associated with the Span to
* be created. Typically useful for batch operations.
* @returns a {@link SamplingResult}.
*/
shouldSample(
// @ts-expect-error unused var
context, traceId,
// @ts-expect-error unused var
spanName,
// @ts-expect-error unused var
spanKind, attributes,
// @ts-expect-error unused var
links) {
let isSampledIn = false;
if (this._sampleRate === 100) {
isSampledIn = true;
}
else if (this._sampleRate === 0) {
isSampledIn = false;
}
else {
isSampledIn = this._getSamplingHashCode(traceId) < this._sampleRate;
}
// Add sample rate as span attribute if it is not 100
attributes = attributes || {};
if (this._sampleRate !== 100) {
attributes[AzureMonitorSampleRate] = this._sampleRate;
}
return isSampledIn
? { decision: SamplingDecision.RECORD_AND_SAMPLED, attributes: attributes }
: { decision: SamplingDecision.RECORD, attributes: attributes };
}
/**
* Return Sampler description
*/
toString() {
return `ApplicationInsightsSampler{${this._samplingRatio}}`;
}
_getSamplingHashCode(input) {
const csharpMin = -2147483648;
const csharpMax = 2147483647;
let hash = 5381;
if (!input) {
return 0;
}
while (input.length < 8) {
input = input + input;
}
for (let i = 0; i < input.length; i++) {
// JS doesn't respond to integer overflow by wrapping around. Simulate it with bitwise operators ( | 0)
hash = ((((hash << 5) + hash) | 0) + input.charCodeAt(i)) | 0;
}
hash = hash <= csharpMin ? csharpMax : Math.abs(hash);
return (hash / csharpMax) * 100;
}
}
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