Pre freeze flush proposal

[artkhod]

If lambda instrumentation is not configured create a hook to flush before timeout.

export async function createInstrumentations(
  providers: Parameters<typeof createRequestHook>[0],
) {
  return [
    new AwsInstrumentation({
      suppressInternalInstrumentation: true,
    }),
    new AwsLambdaInstrumentation({
      requestHook: createRequestHook(providers),
    }),
    ...(await defaultConfigureInstrumentations()),
  ];
}

The only problem is that flush may take unknown amount of time, so the decision on the buffer should be delegated to the user with an ENV var with a fallback to some default value (potentially dependent on duration - the longer the timeout is, more signals to slush, therefore longer buffer)

function createRequestHook(
  providers: Array<
    { forceFlush: () => Promise<void> }
  >,
) {
  const requestHook: RequestHook = (span, hookInfo) => {
    setTimeout(async () => {
      if (span.isRecording()) {
        await Promise.allSettled(
          providers.map((provider) => provider?.forceFlush()),
        );
      }
    }, calculateTimeoutBuffer(hookInfo.context.getRemainingTimeInMillis())).unref();
  }
}