Add JMH tooling for dd-trace

dd-trace/dd-trace.gradle

@@ -1,6 +1,7 @@
 plugins {
   id 'groovy'
   id "com.github.johnrengelman.shadow" version "2.0.1"
+  id "me.champeau.gradle.jmh" version "0.4.4"
 }
 
 description = 'dd-trace'
@@ -32,6 +33,7 @@ dependencies {
   testCompile group: 'org.spockframework', name: 'spock-core', version: '1.0-groovy-2.4'
   testCompile group: 'org.codehaus.groovy', name: 'groovy-all', version: '2.4.4'
   testCompile group: 'io.ratpack', name: 'ratpack-groovy-test', version: '1.4.6'
+  jmh 'commons-io:commons-io:2.4'
 }
 
 shadowJar {
@@ -46,3 +48,29 @@ shadowJar {
   relocate 'org.reflections', 'dd.deps.org.reflections'
   relocate 'org.yaml', 'dd.deps.org.yaml'
 }
+
+jmh {
+  timeUnit = 'us' // Output time unit. Available time units are: [m, s, ms, us, ns].
+  benchmarkMode = ['thrpt', 'avgt']
+  timeOnIteration = '1s'
+  iterations = 1 // Number of measurement iterations to do.
+//  fork = 2 // How many times to forks a single benchmark. Use 0 to disable forking altogether
+  jvmArgs = []
+  failOnError = true // Should JMH fail immediately if any benchmark had experienced the unrecoverable error?
+  warmup = '2s' // Time to spend at each warmup iteration.
+  warmupIterations = 1 // Number of warmup iterations to do.
+//  warmupForks = 0 // How many warmup forks to make for a single benchmark. 0 to disable warmup forks.
+
+//  profilers = ['stack']
+  // Use profilers to collect additional data. Supported profilers: [cl, comp, gc, stack, perf, perfnorm, perfasm, xperf, xperfasm, hs_cl, hs_comp, hs_gc, hs_rt, hs_thr]
+
+//  humanOutputFile = project.file("${project.buildDir}/reports/jmh/human.txt") // human-readable output file
+//  operationsPerInvocation = 10 // Operations per invocation.
+//  synchronizeIterations = false // Synchronize iterations?
+//  timeout = '1s' // Timeout for benchmark iteration.
+//  includeTests = true
+  // Allows to include test sources into generate JMH jar, i.e. use it when benchmarks depend on the test classes.
+
+  duplicateClassesStrategy = 'fail'
+  jmhVersion = '1.19' // Specifies JMH version
+}

dd-trace/src/jmh/java/com/datadoghq/trace/DDTraceBenchmark.java

@@ -0,0 +1,59 @@
+package com.datadoghq.trace;
+
+import com.datadoghq.trace.writer.ListWriter;
+import io.opentracing.ActiveSpan;
+import io.opentracing.Span;
+import io.opentracing.Tracer;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+
+public class DDTraceBenchmark {
+  public static String SPAN_NAME = "span-benchmark";
+
+  @State(Scope.Thread)
+  public static class TraceState {
+    public ListWriter traceCollector = new ListWriter();
+    public Tracer tracer = new DDTracer(traceCollector);
+    public ActiveSpan activeSpan = tracer.buildSpan(SPAN_NAME).startActive();
+  }
+
+  @Benchmark
+  public Object testBuildSpan(final TraceState state) {
+    return state.tracer.buildSpan(SPAN_NAME);
+  }
+
+  @Benchmark
+  public Object testBuildStartSpan(final TraceState state) {
+    return state.tracer.buildSpan(SPAN_NAME).startManual();
+  }
+
+  @Benchmark
+  public Object testFullSpan(final TraceState state) {
+    final Span span = state.tracer.buildSpan(SPAN_NAME).startManual();
+    span.finish();
+    return span;
+  }
+
+  @Benchmark
+  public Object testBuildStartSpanActive(final TraceState state) {
+    return state.tracer.buildSpan(SPAN_NAME).startActive();
+  }
+
+  @Benchmark
+  public Object testFullActiveSpan(final TraceState state) {
+    final ActiveSpan activeSpan = state.tracer.buildSpan(SPAN_NAME).startActive();
+    activeSpan.deactivate();
+    return activeSpan;
+  }
+
+  @Benchmark
+  public Object testContinuationCapture(final TraceState state) {
+    return state.activeSpan.capture();
+  }
+
+  @Benchmark
+  public Object testContinuationActivate(final TraceState state) {
+    return state.activeSpan.capture().activate();
+  }
+}

dd-trace/src/jmh/reports/2017-07-18.using-array-copy.txt

@@ -0,0 +1,15 @@
+Benchmark                                   Mode  Cnt    Score    Error   Units
+DDTraceBenchmark.testBuildSpan             thrpt   10  124.480 ±  6.190  ops/us
+DDTraceBenchmark.testBuildStartSpan        thrpt   10    0.542 ±  0.210  ops/us
+DDTraceBenchmark.testBuildStartSpanActive  thrpt   10    0.433 ±  0.136  ops/us
+DDTraceBenchmark.testContinuationActivate  thrpt   10    1.408 ±  0.701  ops/us
+DDTraceBenchmark.testContinuationCapture   thrpt   10   77.598 ± 16.400  ops/us
+DDTraceBenchmark.testFullActiveSpan        thrpt   10    1.348 ±  0.935  ops/us
+DDTraceBenchmark.testFullSpan              thrpt   10    0.976 ±  1.515  ops/us
+DDTraceBenchmark.testBuildSpan              avgt   10    0.009 ±  0.003   us/op
+DDTraceBenchmark.testBuildStartSpan         avgt   10    2.287 ±  0.937   us/op
+DDTraceBenchmark.testBuildStartSpanActive   avgt   10    2.548 ±  1.400   us/op
+DDTraceBenchmark.testContinuationActivate   avgt   10    0.744 ±  0.192   us/op
+DDTraceBenchmark.testContinuationCapture    avgt   10    0.013 ±  0.003   us/op
+DDTraceBenchmark.testFullActiveSpan         avgt   10    1.039 ±  0.564   us/op
+DDTraceBenchmark.testFullSpan               avgt   10    1.789 ±  1.174   us/op