Deprecates SpanAdjuster for Brave's FirehoseHandler

Brave's `FirehoseHandler` has the features adjuster has, more
efficiently and also including the ability to prune spans.

See https://github.com/openzipkin/brave/pull/794

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/SpanAdjuster.java

@@ -19,16 +19,9 @@ package org.springframework.cloud.sleuth;
 import zipkin2.Span;
 
 /**
- * Adds ability to adjust a span before reporting it.
- *
- * <b>IMPORTANT</b> - if you override the default {@link brave.Tracing} implementation,
- * remember to ensure that you pass to it an adjusted version of the {@link zipkin2.reporter.Reporter<zipkin2.Span>}
- * bean. In other words you must reuse the list of available {@link SpanAdjuster}s and
- * wrap the provided {@link zipkin2.reporter.Reporter} interface with it.
- *
- * @author Marcin Grzejszczak
- * @since 1.1.4
+ * @deprecated use {@link brave.handler.FinishedSpanHandler}
  */
+@Deprecated
 public interface SpanAdjuster {
 	/**
 	 * You can adjust the {@link zipkin2.Span} by creating a new one using the {@link Span#toBuilder()}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/autoconfig/TraceAutoConfiguration.java

@@ -16,6 +16,7 @@
 
 package org.springframework.cloud.sleuth.autoconfig;
 
+import brave.handler.FinishedSpanHandler;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -58,6 +59,7 @@ public class TraceAutoConfiguration {
 	public static final String TRACER_BEAN_NAME = "tracer";
 
 	@Autowired(required = false) List<SpanAdjuster> spanAdjusters = new ArrayList<>();
+	@Autowired(required = false) List<FinishedSpanHandler> finishedSpanHandlers = new ArrayList<>();
 	@Autowired(required = false) List<CurrentTraceContext.ScopeDecorator> scopeDecorators = new ArrayList<>();
 
 	@Bean
@@ -71,7 +73,7 @@ public class TraceAutoConfiguration {
 			ErrorParser errorParser,
 			SleuthProperties sleuthProperties
 	) {
-		return Tracing.newBuilder()
+		Tracing.Builder builder = Tracing.newBuilder()
 				.sampler(sampler)
 				.errorParser(errorParser)
 				.localServiceName(serviceName)
@@ -79,8 +81,11 @@ public class TraceAutoConfiguration {
 				.currentTraceContext(currentTraceContext)
 				.spanReporter(adjustedReporter(reporter))
 				.traceId128Bit(sleuthProperties.isTraceId128())
-				.supportsJoin(sleuthProperties.isSupportsJoin())
-				.build();
+				.supportsJoin(sleuthProperties.isSupportsJoin());
+		for (FinishedSpanHandler finishedSpanHandlerFactory : this.finishedSpanHandlers) {
+			builder.addFinishedSpanHandler(finishedSpanHandlerFactory);
+		}
+		return builder.build();
 	}
 
 	private Reporter<zipkin2.Span> adjustedReporter(Reporter<zipkin2.Span> delegate) {

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/FinishedSpanHandlerTests.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2013-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.sleuth;
+
+import brave.Span;
+import brave.Tracer;
+import brave.handler.FinishedSpanHandler;
+import brave.handler.MutableSpan;
+import brave.propagation.TraceContext;
+import brave.sampler.Sampler;
+import org.assertj.core.api.BDDAssertions;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.sleuth.util.ArrayListSpanReporter;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.context.junit4.SpringRunner;
+import zipkin2.reporter.Reporter;
+
+/**
+ * @author Marcin Grzejszczak
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = FinishedSpanHandlerTests.FinishedSpanHandlerAspectTestsConfig.class,
+		webEnvironment = SpringBootTest.WebEnvironment.NONE)
+public class FinishedSpanHandlerTests {
+
+	@Autowired ArrayListSpanReporter reporter;
+	@Autowired Tracer tracer;
+
+	@Test
+	public void should_adjust_span_twice_before_reporting() {
+		Span hello = this.tracer.nextSpan().name("hello").start();
+
+		hello.finish();
+
+		BDDAssertions.then(this.reporter.getSpans()).hasSize(1);
+		BDDAssertions.then(this.reporter.getSpans().get(0).name()).isEqualTo("foo bar");
+	}
+
+	@Configuration
+	@EnableAutoConfiguration(exclude = IntegrationAutoConfiguration.class)
+	static class FinishedSpanHandlerAspectTestsConfig {
+		@Bean Sampler sampler() {
+			return Sampler.ALWAYS_SAMPLE;
+		}
+
+		@Bean Reporter<zipkin2.Span> reporter() {
+			return new ArrayListSpanReporter();
+		}
+
+		// tag::finishedSpanHandler[]
+		@Bean FinishedSpanHandler handlerOne() {
+			return new FinishedSpanHandler() {
+				@Override public boolean handle(TraceContext traceContext, MutableSpan span) {
+					span.name("foo");
+					return true; // keep this span
+				}
+			};
+		}
+
+		@Bean FinishedSpanHandler handlerTwo() {
+			return new FinishedSpanHandler() {
+				@Override public boolean handle(TraceContext traceContext, MutableSpan span) {
+					span.name(span.name() + " bar");
+					return true; // keep this span
+				}
+			};
+		}
+		// end::finishedSpanHandler[]
+	}
+}