Add task to put jmh benchmarks results to teamcity statistics (#1568)

Author: sandwwraith

build.gradle

@@ -173,3 +173,4 @@ subprojects {
 
 apply from: rootProject.file('gradle/compiler-version.gradle')
 apply from: rootProject.file("gradle/dokka.gradle")
+apply from: rootProject.file("gradle/benchmark-parsing.gradle")

gradle/benchmark-parsing.gradle

@@ -0,0 +1,26 @@
+import groovy.json.JsonSlurper
+import org.gradle.api.*
+
+/**
+ * Utility for printing benchmark results.
+ * Results can be obtained with JMH flags
+ * -rf json -rff serialization-benchmark-results.json
+ */
+class PrintBenchmarksTask extends DefaultTask {
+    private String fileName = "serialization-benchmark-results.json"
+
+    @TaskAction
+    def printBenchmarkJsonAsTeamcityStats() {
+        File jsonFile = project.file(fileName)
+        if (!jsonFile.exists()) throw new TaskExecutionException(this, new FileNotFoundException("File $fileName not found"))
+        def parsedJson = new JsonSlurper().parseText(jsonFile.text)
+
+        parsedJson.each { v ->
+            def name = (v.benchmark - "kotlinx.benchmarks.")
+            def score = v.primaryMetric.score
+            println("##teamcity[buildStatisticValue key='" + name + "' value='" + score + "']")
+        }
+    }
+}
+
+rootProject.tasks.register("printBenchmarksJsonAsTeamcityStats", PrintBenchmarksTask)