ci: add a benchmark workflow #7

	name: Benchstat

	on:
	pull_request:
	branches: [ master ]

	permissions: # added using https://github.com/step-security/secure-workflows
	contents: read

	jobs:

	bench:
	name: Performance regression check
	runs-on: ubuntu-latest
	steps:
	- name: Checkout (new)
	uses: actions/checkout@v3

	- name: Set up Go
	uses: actions/setup-go@v4
	with:
	go-version-file: '${{ github.workspace }}/go.mod'

	- name: Get dependencies
	run: go mod download

	- name: Benchmark against GITHUB_BASE_REF
	run: \|
	go install golang.org/x/perf/cmd/benchstat@latest
	echo "New Commit:"
	git log -1 --format="%H"
	go test -bench=. -benchmem -benchtime=100ms -count=10 > /tmp/new.txt
	git reset --hard HEAD
	git checkout $GITHUB_BASE_REF
	echo "Base Commit:"
	git log -1 --format="%H"
	go test -bench=. -benchmem -benchtime=100ms -count=10 > /tmp/old.txt
	$GOBIN/benchstat /tmp/old.txt /tmp/new.txt

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