Method TryUpdateIfStale

data/shared_state_variable.go:390–469

(ctx context.Context, staleness time.Duration, executeNewValueFn func(ctx context.Context) (int64, error))

}

func (c *counterInt64) TryUpdateIfStale(ctx context.Context, staleness time.Duration, executeNewValueFn func(ctx context.Context) (int64, error)) (int64, error) {
	ctx, span := common.StartSpan(ctx, "CounterInt64.TryUpdateIfStale",
		trace.WithAttributes(
			attribute.String("key", c.key),
			attribute.Int64("staleness_ms", staleness.Milliseconds()),
		),
	)
	defer span.End()

	if !c.IsStale(staleness) {
		span.SetAttributes(attribute.Bool("skipped_not_stale", true))
		return c.value.Load(), nil
	}

	// Track time waiting for mutex
	_, mutexSpan := common.StartSpan(ctx, "CounterInt64.TryUpdateIfStale.AcquireMutex")
	c.updateMu.Lock()
	mutexSpan.End()
	defer c.updateMu.Unlock()

	// Double-check staleness after acquiring mutex
	if !c.IsStale(staleness) {
		span.SetAttributes(attribute.Bool("skipped_not_stale_after_mutex", true))
		return c.value.Load(), nil
	}

	initialVal := c.value.Load()
	span.SetAttributes(attribute.Int64("initial_value", initialVal))
	// IMPORTANT: Foreground path MUST be local-only and bounded by updateMaxWait.
	// Do NOT acquire distributed locks or do any remote I/O here, otherwise degraded shared state
	// (e.g. Redis lock acquisition) can block normal request flow.
	span.SetAttributes(attribute.Bool("foreground_remote_io_disabled", true))

	// Execute the refresh function (e.g., RPC call to get latest block) in background
	resultCh := make(chan refreshResult, 1)
	go func() {
		fnCtx, fnCancel := context.WithTimeout(c.registry.appCtx, c.registry.fallbackTimeout)
		defer fnCancel()

		// Create a span for the actual RPC/refresh call - this is usually what takes time
		_, fnSpan := common.StartSpan(ctx, "CounterInt64.TryUpdateIfStale.ExecuteRefresh",
			trace.WithAttributes(
				attribute.String("key", c.key),
				attribute.Int64("timeout_ms", c.registry.fallbackTimeout.Milliseconds()),
			),
		)
		value, err := executeNewValueFn(fnCtx)
		if err != nil {
			fnSpan.SetAttributes(attribute.String("error", err.Error()))
		} else {
			fnSpan.SetAttributes(attribute.Int64("result_value", value))
		}
		fnSpan.End()

		resultCh <- refreshResult{val: value, err: err}
	}()

	timer := time.NewTimer(c.registry.updateMaxWait)