Package brave.http

Class HttpClientHandler<Req,Resp>

java.lang.Object

brave.http.HttpClientHandler<Req,Resp>

Type Parameters:

Req - the native http request type of the client.

Resp - the native http response type of the client.

public final class HttpClientHandler<Req,Resp>
extends Object

This standardizes a way to instrument http clients, particularly in a way that encourages use of portable customizations via HttpRequestParser and HttpResponseParser.

Synchronous interception is the most straight forward instrumentation.

You generally need to:

1. Start the span and add trace headers to the request
2. Put the span in scope so things like log integration works
3. Invoke the request
4. If there was a Throwable, add it to the span
5. Complete the span

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

Since:

4.3

Method Summary

Modifier and Type	Method	Description
static HttpClientHandler<HttpClientRequest,HttpClientResponse>	create(HttpTracing httpTracing)
void	handleReceive(HttpClientResponse response, brave.Span span)	Finishes the client span after assigning it tags according to the response or error.
brave.Span	handleSend(HttpClientRequest request)	Starts the client span after assigning it a name and tags.
brave.Span	handleSend(HttpClientRequest request, brave.Span span)	Like handleSend(HttpClientRequest), except explicitly controls the span representing the request.
brave.Span	handleSendWithParent(HttpClientRequest request, brave.propagation.TraceContext parent)	Like handleSend(HttpClientRequest), except explicitly controls the parent of the client span.

Methods inherited from class java.lang.Object

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

Method Detail

create

public static HttpClientHandler<HttpClientRequest,HttpClientResponse> create(HttpTracing httpTracing)

Since:

5.7

handleSend

public brave.Span handleSend(HttpClientRequest request)

Starts the client span after assigning it a name and tags. This injects the trace context onto the request before returning.

Call this before sending the request on the wire.

Since:

5.7

See Also:

handleSendWithParent(HttpClientRequest, TraceContext), HttpTracing.clientRequestSampler(), HttpTracing.clientRequestParser()

handleSendWithParent

public brave.Span handleSendWithParent(HttpClientRequest request,
                                       @Nullable
                                       brave.propagation.TraceContext parent)

Like handleSend(HttpClientRequest), except explicitly controls the parent of the client span.

Parameters:

parent - the parent of the client span representing this request, or null for a new trace.

Since:

5.10

See Also:

Tracer.nextSpanWithParent(SamplerFunction, Object, TraceContext)

handleSend

public brave.Span handleSend(HttpClientRequest request,
                             brave.Span span)

Like handleSend(HttpClientRequest), except explicitly controls the span representing the request.

Since:

5.7

handleReceive

public void handleReceive(HttpClientResponse response,
                          brave.Span span)

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

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

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

Since:

5.12

See Also:

HttpResponseParser.parse(HttpResponse, TraceContext, SpanCustomizer)