Add benchmark tooling

This adds a way to compare benchmarks that we use in kube-state-metrics
already, hopefully allowing for better comparisons when applying
changes.

Signed-off-by: Manuel Rüger <[email protected]>

Makefile

@@ -1,5 +1,6 @@
 BRANCH=`git rev-parse --abbrev-ref HEAD`
 COMMIT=`git rev-parse --short HEAD`
+LATEST_RELEASE_BRANCH := release-$(shell grep -ohE "[0-9]+.[0-9]+" version/version.go)
 GOLDFLAGS="-X main.branch $(BRANCH) -X main.commit $(COMMIT)"
 GOFILES = $(shell find . -name \*.go)
 
@@ -94,3 +95,11 @@ test-failpoint:
 test-robustness: gofail-enable build
 	sudo env PATH=$$PATH go test -v ${TESTFLAGS} ./tests/dmflakey -test.root
 	sudo env PATH=$(PWD)/bin:$$PATH go test -v ${TESTFLAGS} ${ROBUSTNESS_TESTFLAGS} ./tests/robustness -test.root
+
+.PHONY: test-benchmark-compare
+# Runs benchmark tests on the current git ref and the last release and compares
+# the two.
+test-benchmark-compare:
+	@git fetch
+	./tests/compare_benchmarks.sh main
+	./tests/compare_benchmarks.sh ${LATEST_RELEASE_BRANCH}

tests/compare_benchmarks.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# exit immediately when a command fails
+set -e
+# only exit with zero if all commands of the pipeline exit successfully
+set -o pipefail
+# error on unset variables
+set -u
+
+[[ "$#" -eq 1 ]] || echo "One argument required, $# provided."
+
+REF_CURRENT="$(git rev-parse --abbrev-ref HEAD)"
+REF_TO_COMPARE=$1
+
+RESULT_CURRENT="$(mktemp)-${REF_CURRENT}"
+RESULT_TO_COMPARE="$(mktemp)-${REF_TO_COMPARE}"
+
+echo ""
+echo "### Testing ${REF_CURRENT}"
+
+go test -benchmem -run=NONE -bench=. ./... | tee "${RESULT_CURRENT}"
+
+echo ""
+echo "### Done testing ${REF_CURRENT}"
+
+echo ""
+echo "### Testing ${REF_TO_COMPARE}"
+
+git checkout "${REF_TO_COMPARE}"
+
+go test -benchmem -run=NONE -bench=. ./... | tee "${RESULT_TO_COMPARE}"
+
+echo ""
+echo "### Done testing ${REF_TO_COMPARE}"
+
+git checkout -
+
+echo ""
+echo "### Result"
+echo "old=${REF_TO_COMPARE} new=${REF_CURRENT}"
+
+benchstat "${RESULT_TO_COMPARE}" "${RESULT_CURRENT}"