distributed tracing for armeria

[synk]

Introduces distributed tracing capability to armeria clients/servers. This enables us to watch timing data among the whole armeria rpc chain.

This feature depends on brave distributed tracing library compatible with zipkin.

Decorate HTTP client

// Create a brave instance with service name, span collector, and sampling rate.
Brave brave = new Brave.Builder("FibClientMain")
        .spanCollector(new ScribeSpanCollector("127.0.0.1", 9410))
        .traceSampler(Sampler.create(0.01f))
        .build();

FibService.Iface fibClient =
        new ClientBuilder("tbinary+http://127.0.0.1:8080/thrift/fib")
                .decorator(HttpTracingClient.decorator(brave))
                .build(FibService.Iface.class);

Decorate HTTP server

// Create a brave instance with service name, span collector, and sampling rate.
Brave brave = new Brave.Builder("FibServerMain")
        .spanCollector(new ScribeSpanCollector("127.0.0.1", 9410))
        .traceSampler(Sampler.create(0.01f))
        .build();

ServerBuilder builder = new ServerBuilder();

builder.port(8080, SessionProtocol.HTTP);

VirtualHost vh = new VirtualHostBuilder()
        .serviceAt("/thrift/fib",
                ThriftService.of(new FibServiceHandler(brave))
                             .decorate(HttpTracingService.decorator(brave))
        )
        .build();

Add custom annotations using brave's API

// Add custom attribute to the span in service handler
brave.serverTracer().submitBinaryAnnotation("foo", "bar");

// Add custom timing tag in server handler
brave.serverTracer().submitAnnotation("somethinghappen");

[trustin]

w00t!

[synk]

@trustin Please take a look

[trustin]

Could we add a property instead of duplicating version numbers?

[trustin]

@synk First pass done. Please ping me for another pass.

[synk]

@trustin Thanks. I'll ping when I finished

[synk]

@trustin I think I handled your comments. Please take a look again.

[trustin]

How about renaming this method to newDecorator() for consistency with MetricCollectingClient.new...Decorator()?

[trustin]

Please fix the Javadoc errors:

[ERROR] Exit code: 1 - /home/travis/build/line/armeria/src/main/java/com/linecorp/armeria/client/tracing/HttpTracingClient.java:28: error: self-closing element not allowed
[ERROR] * <p/>
[ERROR] ^
[ERROR] /home/travis/build/line/armeria/src/main/java/com/linecorp/armeria/client/tracing/TracingRemoteInvoker.java:44: error: self-closing element not allowed
[ERROR] * <p/>
[ERROR] ^
[ERROR] /home/travis/build/line/armeria/src/main/java/com/linecorp/armeria/server/tracing/TracingServiceInvocationHandler.java:41: error: self-closing element not allowed
[ERROR] * <p/>
[ERROR] ^

It seems like Javadoc does not like <p/> and </p>. (only <p> is allowed for P tags)

[trustin]

@synk Looks good to me except for a few nits. Please squash for a merge.

[synk]

@trustin I've squashed. Please merge if it's OK.

[synk]

I forgot setting capacity here.

[trustin]

BOOM!