Package brave.rpc

Class RpcServerHandler

java.lang.Object

brave.rpc.RpcServerHandler

public final class RpcServerHandler
extends Object

This standardizes a way to instrument RPC servers, particularly in a way that encourages use of portable customizations via RpcRequestParser and RpcResponseParser.

Synchronous interception is the most straight forward instrumentation.

You generally need to:

1. Extract any trace IDs from headers and start the span
2. Put the span in scope so things like log integration works
3. Process the request
4. If there was a Throwable, add it to the span
5. Complete the span

 RpcServerRequestWrapper requestWrapper = new RpcServerRequestWrapper(request);
 Span span = handler.handleReceive(requestWrapper); // 1.
 ServerResponse response = null;
 Throwable error = null;
 try (Scope scope = currentTraceContext.newScope(span.context())) { // 2.
   return response = process(request); // 3.
 } catch (Throwable e) {
   error = e; // 4.
   throw e;
 } finally {
   RpcServerResponseWrapper responseWrapper =
     new RpcServerResponseWrapper(requestWrapper, response, error);
   handler.handleSend(responseWrapper, span); // 5.
 }
 

Since:

5.12

Method Summary

Modifier and Type	Method	Description
static RpcServerHandler	create(RpcTracing rpcTracing)
brave.Span	handleReceive(RpcServerRequest request)	Conditionally joins a span, or starts a new trace, depending on if a trace context was extracted from the request.
void	handleSend(RpcServerResponse response, brave.Span span)	Finishes the server span after assigning it tags according to the response or error.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

create

public static RpcServerHandler create(RpcTracing rpcTracing)

Since:

5.12

handleReceive

public brave.Span handleReceive(RpcServerRequest request)

Conditionally joins a span, or starts a new trace, depending on if a trace context was extracted from the request. Tags are added before the span is started.

This is typically called before the request is processed by the actual library.

Since:

5.12

See Also:

RpcTracing.serverSampler(), RpcTracing.serverRequestParser()

handleSend

public void handleSend(RpcServerResponse response,
                       brave.Span span)

Finishes the server span after assigning it tags according to the response or error.

This is typically called once the response headers are sent, and after the span is no longer in scope.

Note: It is valid to have a RpcServerResponse that only includes an error. However, it is better to also include the request.

Since:

5.12

See Also:

RpcResponseParser.parse(RpcResponse, TraceContext, SpanCustomizer)