buildscript: read jmh include class from project property (#4215)

The project property can be set form the CLI, so that it is simple to
run JMH on a single class.

1 files changed, 5 insertions, 0 deletions

diff --git a/build.gradle b/build.gradle
index 157b23ef9..f34da55d9 100644
--- a/build.gradle
+++ b/build.gradle
@@ -288,6 +288,8 @@ subprojects {
         source = fileTree(dir: "src/test", include: "**/*.java")
     }
 
+    // invoke jmh on a single benchmark class like so:
+    //   ./gradlew -PjmhIncludeSingleClass=StatsTraceContextBenchmark clean :grpc-core:jmh
     jmh {
         warmupIterations = 10
         iterations = 10
@@ -296,6 +298,9 @@ subprojects {
         // dependencies that break when including them. (context's testCompile
         // depends on core; core's testCompile depends on testing)
         includeTests = false
+        if (project.hasProperty('jmhIncludeSingleClass')) {
+          include = [project.property('jmhIncludeSingleClass')]
+        }
     }
 
     task javadocJar(type: Jar) {