chore: object constructor for sampler

Author: abhishekg999

examples/simple_chat/instrumentation.ts

@@ -1,17 +1,23 @@
 import { OpenAIInstrumentation } from "@opentelemetry/instrumentation-openai";
 import { SamplingDecision } from "@opentelemetry/sdk-trace-base";
-import { Judgeval, ExperimentalSpanFilterSampler, type NodeTracer } from "judgeval";
+import {
+  ExperimentalSpanFilterSampler,
+  Judgeval,
+  type NodeTracer,
+} from "judgeval";
 
 export const client = Judgeval.create();
 
 const initPromise = client.nodeTracer.create({
   projectName: "auto_instrumentation_example",
   instrumentations: [new OpenAIInstrumentation()],
-  sampler: new ExperimentalSpanFilterSampler((span) => {
-    console.log(span);
-    return span.resource.attributes["service.name"] === "judgeval"
-      ? SamplingDecision.RECORD_AND_SAMPLED
-      : SamplingDecision.NOT_RECORD;
+  sampler: new ExperimentalSpanFilterSampler({
+    filter: (span) => {
+      console.log(span);
+      return span.resource.attributes["service.name"] === "judgeval"
+        ? SamplingDecision.RECORD_AND_SAMPLED
+        : SamplingDecision.NOT_RECORD;
+    },
   }),
 });
 

src/tracer/samplers/ExperimentalSpanFilterSampler.ts

@@ -15,18 +15,19 @@ import { Logger } from "../../utils";
 // @ref https://github.com/open-telemetry/opentelemetry-js/blob/main/api/src/trace/context-utils.ts
 const SPAN_KEY_NAME = "OpenTelemetry Context Key SPAN" as const;
 
+export interface ExperimentalSpanFilterSamplerConfig {
+  filter: (span: ReadableSpan) => SamplingDecision;
+}
 export class ExperimentalSpanFilterSampler implements Sampler {
-  constructor(
-    private readonly filterFn: (span: ReadableSpan) => SamplingDecision,
-  ) {}
+  constructor(private readonly config: ExperimentalSpanFilterSamplerConfig) {}
 
   shouldSample(
     context: Context,
     _traceId: string,
     _spanName: string,
     _spanKind: SpanKind,
     _attributes: Attributes,
-    _links: Link[],
+    _links: Link[]
   ): SamplingResult {
     // @ts-expect-error - not intended to be public API but exists
     const currentContext = context._currentContext as Map<symbol, unknown>;
@@ -37,22 +38,22 @@ export class ExperimentalSpanFilterSampler implements Sampler {
     }
 
     const spanKey = Array.from(currentContext.keys()).find(
-      (key) => key.description === SPAN_KEY_NAME,
+      (key) => key.description === SPAN_KEY_NAME
     );
 
     // // @ref https://github.com/open-telemetry/opentelemetry-js/blob/main/api/src/context/context.ts
     const span = spanKey ? currentContext.get(spanKey) : undefined;
     try {
-      const decision = this.filterFn(span as ReadableSpan);
+      const decision = this.config.filter(span as ReadableSpan);
       if (decision === SamplingDecision.NOT_RECORD) {
         Logger.info(
-          `[ExperimentalSpanFilterSampler] Dropping span because it does not match the filter function.`,
+          `[ExperimentalSpanFilterSampler] Dropping span because it does not match the filter function.`
         );
       }
       return { decision };
     } catch (error) {
       Logger.error(
-        `[ExperimentalSpanFilterSampler] Error filtering span: ${error}`,
+        `[ExperimentalSpanFilterSampler] Error filtering span: ${error}`
       );
       return { decision: SamplingDecision.RECORD_AND_SAMPLED };
     }