Custom instrumentation

You can implement custom instrumentation in two ways: manual instrumentation and annotation-based instrumentation.

Manual instrumentation

Manual instrumentation follows the OpenTracing specification. In SOFATracer, the beforeInvoke and afterInvoke functions encapsulate the span lifecycle.

The following code provides an example:

     // Inject the tracer
    @Autowired
    Tracer tracer;

    private void testManual() {
        try {
            // Start with beforeInvoke
            SofaTracerSpan sofaTracerSpan = ((FlexibleTracer) tracer).beforeInvoke("testManual");
            sofaTracerSpan.setTag("manualKey", "glmapper");
            // do your biz

        } catch (Throwable t) {
            // End upon an exception
            ((FlexibleTracer) tracer).afterInvoke(t.getMessage());
        } finally {
            // End normally
            ((FlexibleTracer) tracer).afterInvoke();
        }
    }

This method is less convenient than using annotations, but it provides a clear view of the span lifecycle. Manual instrumentation also complements annotation-based instrumentation.

Annotation-based instrumentation

SOFATracer provides the @Tracer annotation, which applies at the method level.

The following code provides an example:

// Use the @Tracer annotation on the hello method for instrumentation
    @Tracer
    public String hello(String word) {
        // Custom tag data
        SpanTags.putTags("author", "glmapper");

        // Ineffective
        helloInner(word);

        return "glmapper : hello " + word;
    }

    // Use the @Tracer annotation on the hello method for instrumentation
    @Tracer
    private String helloInner(String word) {
        return "glmapper : hello " + word;
    }

@Tracer is implemented based on Spring AOP and therefore relies on the proxy mechanism in Spring. As shown in the code snippet, the annotation-based instrumentation for the helloInner method fails. This happens because the method is executed using this instead of a proxy object. In this case, you can use manual instrumentation as a workaround.

SpanTags is a utility class that SOFATracer provides. When using annotation-based or manual instrumentation, you can use the static methods in this class to set tags.

Log format

• JSON format

  {"time":"2019-09-05 10:23:53.549","local.app":"flexible-sample","traceId":"0a0fe9291567650233504100130712","spanId":"0.2","span.kind":"client","result.code":"","current.thread.name":"http-nio-8080-exec-1","time.cost.milliseconds":"4ms","method":"hello","param.types":"java.lang.String","author":"glmapper","sys.baggage":"","biz.baggage":""}

• Non-JSON format

  2019-09-0510:25:50.992,flexible-sample,0a0fe9291567650350953100130778,0.2,client,,http-nio-8080-exec-1,4ms,hello,param.types=java.lang.String&author=glmapper&,,