Unverified Commit d9aea3f7 authored by Hong Minhee's avatar Hong Minhee
Browse files

Fix race condition in #updateTraceSummary with CAS 

Use compare-and-swap operation when available to ensure atomic updates
to trace summaries in concurrent/distributed environments.

https://github.com/fedify-dev/fedify/pull/502#discussion_r2642988002
https://github.com/fedify-dev/fedify/pull/502#discussion_r2642993304
parent 31edf2a9

packages/fedify/src/otel/exporter.ts

+32 −10
Original line number Diff line number Diff line
@@ -445,20 +445,42 @@ export class FedifySpanExporter implements SpanExporter { 
      record.traceId,

    ] as KvKey;



    const existing = await this.#kv.get<TraceSummary>(summaryKey);



    const summary: TraceSummary = existing ?? {

    const createOrUpdateSummary = (

      existing: TraceSummary | undefined,

    ): TraceSummary => {

      const summary: TraceSummary = existing != null

        ? {

          traceId: existing.traceId,

          timestamp: existing.timestamp,

          activityCount: existing.activityCount,

          activityTypes: [...existing.activityTypes],

        }

        : {

          traceId: record.traceId,

          timestamp: record.timestamp,

          activityCount: 0,

          activityTypes: [],

        };



      summary.activityCount += 1;

      if (!summary.activityTypes.includes(record.activityType)) {

        summary.activityTypes.push(record.activityType);

      }

      return summary;

    };



    if (this.#kv.cas != null) {

      for (let attempt = 0; attempt < 3; attempt++) {

        const existing = await this.#kv.get<TraceSummary>(summaryKey);

        const summary = createOrUpdateSummary(existing);

        if (await this.#kv.cas(summaryKey, existing, summary, options)) {

          return;

        }

      }

    }



    // Fallback to non-atomic set if CAS is not available or fails

    const existing = await this.#kv.get<TraceSummary>(summaryKey);

    const summary = createOrUpdateSummary(existing);

    await this.#kv.set(summaryKey, summary, options);

  }