async post()

in glean/src/platform/browser/fetch_uploader.ts [16:69]
36 lines of code
5 McCabe index (conditional complexity)

  async post(
    url: string,
    pingRequest: PingRequest<string | Uint8Array>,
    keepalive = true
  ): Promise<UploadResult> {
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), this.timeoutMs);

    // We expect to have a gzipped payload.
    const gzipRequest = pingRequest.asCompressedPayload();

    let response;
    try {
      response = await fetch(url.toString(), {
        headers: gzipRequest.headers,
        method: "POST",
        body: gzipRequest.payload,
        keepalive,
        // Strips any cookies or authorization headers from the request.
        credentials: "omit",
        signal: controller.signal,
        redirect: "error",
      });
    } catch(e) {
      // If we time out and call controller.abort,
      // the fetch API will throw a DOMException with name "AbortError".
      if (e instanceof DOMException) {
        log(LOG_TAG, ["Timeout while attempting to upload ping.\n", e], LoggingLevel.Error);
      } else if (e instanceof TypeError) {
        if (keepalive) {
          // Try again without `keepalive`, because that may be the issue.
          // This problem was observed in chromium versions below v81.
          // See: https://chromium.googlesource.com/chromium/src/+/26d70b36dd1c18244fb17b91d275332c8b73eab3
          return this.post(url, gzipRequest, false);
        }

        // From MDN: "A fetch() promise will reject with a TypeError
        // when a network error is encountered or CORS is misconfigured on the server-side,
        // although this usually means permission issues or similar"
        // See: https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#checking_that_the_fetch_was_successful
        //
        // We will treat this as we treat server / network errors in this case.
        log(LOG_TAG, ["Network error while attempting to upload ping.\n", e], LoggingLevel.Error);
      } else {
        log(LOG_TAG, ["Unknown error while attempting to upload ping.\n", e], LoggingLevel.Error);
      }

      clearTimeout(timeout);
      return new UploadResult(UploadResultStatus.RecoverableFailure);
    }

    clearTimeout(timeout);
    return new UploadResult(UploadResultStatus.Success, response.status);
  }