SpringCloud 使用顯式父級創(chuàng)建Span

您可能要開始一個新的跨度并提供該跨度的顯式父項。假定范圍的父級在一個線程中，而您想在另一個線程中開始一個新的范圍。在Brave中，每當您調(diào)用nextSpan()時，它都會參照當前范圍的跨度創(chuàng)建一個跨度。您可以將范圍放入范圍中，然后調(diào)用nextSpan()，如以下示例所示：

// let's assume that we're in a thread Y and we've received
// the `initialSpan` from thread X. `initialSpan` will be the parent
// of the `newSpan`
Span newSpan = null;
try (Tracer.SpanInScope ws = this.tracer.withSpanInScope(initialSpan)) {
	newSpan = this.tracer.nextSpan().name("calculateCommission");
	// ...
	// You can tag a span
	newSpan.tag("commissionValue", commissionValue);
	// ...
	// You can log an event on a span
	newSpan.annotate("commissionCalculated");
}
finally {
	// Once done remember to finish the span. This will allow collecting
	// the span to send it to Zipkin. The tags and events set on the
	// newSpan will not be present on the parent
	if (newSpan != null) {
		newSpan.finish();
	}
}

創(chuàng)建這樣的跨度后，必須完成它。否則，不會報告該錯誤（例如，報告到Zipkin）。