Use Kotlin DSL for benchmark workflow (#221)

Use
[github-workflows-kt](https://github.com/typesafegithub/github-workflows-kt)
to implement the workflow in Kotlin, increasing maintainability and
readability.

Note: proper, type-safe matrix strategy support is yet to be
implemented, it's tracked in
typesafegithub/github-workflows-kt#368.

# Testing done
1. Compared what's logged in the "Store benchmark result" step as
"Data", and there are no differences.
* version from `main` branch:
https://github.com/krzema12/snakeyaml-engine-kmp/actions/runs/10187305280/job/28181268567
* version from this branch:
https://github.com/krzema12/snakeyaml-engine-kmp/actions/runs/10244555647/job/28338076917?pr=221
2. Compared with https://www.yamldiff.com/. Most important differences:
* the new version has a consistency check which is required to ensure
that the YAML reflects what's described in Kotlin
* the new version doesn't have the reports preprocessing step
implemented directly, and instead delegates it to the Kotlin script
itself
* instead of using step outputs or env vars (so effectively to not
repeat ourselves with the file paths), I just used Kotlin's constants
* github-workflows-kt proactively adds step IDs to be able to refer to
them whenever needed

![SemanticDiff](https://github.com/user-attachments/assets/d77eb0fc-9129-4121-92a7-e3bc822a1318)

.github/workflows/benchmark.main.kts

@@ -0,0 +1,161 @@
+#!/usr/bin/env kotlin
+@file:Repository("https://repo1.maven.org/maven2/")
+@file:DependsOn("io.github.typesafegithub:github-workflows-kt:2.3.0")
+@file:DependsOn("org.jetbrains.kotlinx:kotlinx-serialization-json:1.7.1")
+
+@file:Repository("https://bindings.krzeminski.it/")
+@file:DependsOn("actions:checkout:v4")
+@file:DependsOn("actions:download-artifact:v4")
+@file:DependsOn("actions:upload-artifact:v4")
+@file:DependsOn("actions:setup-java:v4")
+@file:DependsOn("gradle:actions__wrapper-validation:v4")
+@file:DependsOn("gradle:actions__setup-gradle:v4")
+@file:DependsOn("benchmark-action:github-action-benchmark:v1")
+
+import io.github.typesafegithub.workflows.actions.actions.Checkout
+import io.github.typesafegithub.workflows.actions.actions.DownloadArtifact
+import io.github.typesafegithub.workflows.actions.actions.UploadArtifact
+import io.github.typesafegithub.workflows.actions.actions.SetupJava
+import io.github.typesafegithub.workflows.actions.benchmarkaction.GithubActionBenchmark
+import io.github.typesafegithub.workflows.actions.gradle.ActionsSetupGradle
+import io.github.typesafegithub.workflows.actions.gradle.ActionsWrapperValidation
+import io.github.typesafegithub.workflows.annotations.ExperimentalKotlinLogicStep
+import io.github.typesafegithub.workflows.domain.Concurrency
+import io.github.typesafegithub.workflows.domain.RunnerType
+import io.github.typesafegithub.workflows.domain.triggers.PullRequest
+import io.github.typesafegithub.workflows.domain.triggers.Push
+import io.github.typesafegithub.workflows.dsl.expressions.Contexts
+import io.github.typesafegithub.workflows.dsl.expressions.expr
+import io.github.typesafegithub.workflows.dsl.workflow
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonArray
+import kotlinx.serialization.json.jsonArray
+import java.io.File
+
+val BENCHMARK_RESULTS = "snake-kmp-benchmarks/build/reports/benchmarks"
+val RESULTS_DIR = "bench-results"
+val AGGREGATED_REPORT = "aggregated.json"
+val PUBLISH_BENCHMARK_RESULTS by Contexts.secrets
+
+workflow(
+    name = "Run Benchmarks",
+    sourceFile = __FILE__,
+    on = listOf(
+        Push(branches = listOf("main")),
+        PullRequest()
+    ),
+    concurrency = Concurrency(
+        group = "${expr { github.workflow }} @ ${expr { "${github.eventPullRequest.pull_request.head.label} || ${github.head_ref} || ${github.ref}" }}",
+        cancelInProgress = true,
+    )
+) {
+    val runBenchmark = job(
+        id = "run-benchmark",
+        name = "Performance regression check on ${'$'}{{ matrix.os }} runner",
+        runsOn = RunnerType.Custom("${'$'}{{ matrix.os }}"),
+        _customArguments = mapOf(
+            "strategy" to mapOf(
+                "fail-fast" to true,
+                "matrix" to mapOf(
+                    "include" to listOf(
+                        mapOf("os" to "ubuntu-latest"),
+                        mapOf(
+                            "os" to "macos-latest",
+                            "additional-args" to "-x jvmBenchmark -x jsBenchmark",
+                        ),
+                        mapOf(
+                            "os" to "macos-13", // for macosX64
+                            "additional-args" to "-x jvmBenchmark -x jsBenchmark",
+                        ),
+                        mapOf(
+                            "os" to "windows-latest",
+                            "additional-args" to "-x jvmBenchmark -x jsBenchmark",
+                        ),
+                    )
+                )
+            )
+        )
+    ) {
+        uses(action = Checkout())
+        uses(
+            name = "Set up JDK",
+            action = SetupJava(
+                javaVersion = "11",
+                distribution = SetupJava.Distribution.Zulu,
+                cache = SetupJava.BuildPlatform.Gradle,
+            ),
+        )
+        uses(
+            name = "Validate Gradle Wrapper",
+            action = ActionsWrapperValidation(),
+        )
+        uses(
+            name = "Setup Gradle",
+            action = ActionsSetupGradle(
+                gradleVersion = "wrapper",
+            ),
+        )
+        run(
+            name = "Run benchmarks",
+            command = "./gradlew -p snake-kmp-benchmarks benchmark --no-parallel ${ expr{ "matrix.additional-args" }}",
+        )
+        uses(
+            action = UploadArtifact(
+                name = "bench-results-${ expr { "matrix.os" } }",
+                path = listOf("$BENCHMARK_RESULTS/main/**/*.json"),
+            )
+        )
+    }
+
+    job(
+        id = "collect-benchmarks-results",
+        runsOn = RunnerType.UbuntuLatest,
+        needs = listOf(runBenchmark),
+    ) {
+        // without checkout step 'benchmark-action/github-action-benchmark' action won't work
+        uses(action = Checkout())
+        uses(
+            name = "Download benchmark results",
+            action = DownloadArtifact(
+                pattern = "bench-results-*",
+                path = RESULTS_DIR,
+                mergeMultiple = true,
+            )
+        )
+        @OptIn(ExperimentalKotlinLogicStep::class)
+        run(
+            name = "Prepare and join benchmark reports",
+        ) {
+            val mergedReports = File(RESULTS_DIR).walk()
+                .filter { it.extension == "json" }
+                .flatMap {
+                    val reportForPlatform = it.readText()
+                        // Trim lengthy Kotlin package and data file path to make benchmark name more readable
+                        .replace("it.krzeminski.snakeyaml.engine.kmp.benchmark", it.nameWithoutExtension)
+                        .replace(Regex("\"[^\"]+data"), "\"data")
+                    Json.parseToJsonElement(reportForPlatform).jsonArray
+                }
+                .toList()
+            val mergedReport = JsonArray(mergedReports).toString()
+            File(AGGREGATED_REPORT).writeText(mergedReport)
+        }
+        uses(
+            name = "Store benchmark result",
+            action = GithubActionBenchmark(
+                name = "SnakeKMP benchmarks",
+                tool = GithubActionBenchmark.Tool.Jmh,
+                commentOnAlert = true,
+                summaryAlways = true,
+                alertThreshold = "150%",
+                failThreshold = "200%",
+                ghRepository = "github.com/krzema12/snakeyaml-engine-kmp-benchmarks",
+                outputFilePath = AGGREGATED_REPORT,
+                _customInputs = mapOf(
+                    "github-token" to expr { PUBLISH_BENCHMARK_RESULTS },
+                    // Push and deploy GitHub pages branch automatically only if run in main repo and not in PR
+                    "auto-push" to expr { "${github.repository} == 'krzema12/snakeyaml-engine-kmp' && ${github.event_name} != 'pull_request'" },
+                )
+            ),
+        )
+    }
+}

.github/workflows/benchmark.yaml

@@ -1,94 +1,103 @@
-name: Run Benchmarks
+# This file was generated using Kotlin DSL (.github/workflows/benchmark.main.kts).
+# If you want to modify the workflow, please change the Kotlin file and regenerate this YAML file.
+# Generated with https://github.com/typesafegithub/github-workflows-kt
+
+name: 'Run Benchmarks'
 on:
   push:
     branches:
-      - main
-  pull_request:
-
-env:
-  BENCHMARK_RESULTS: snake-kmp-benchmarks/build/reports/benchmarks
-
+    - 'main'
+  pull_request: {}
 concurrency:
-  group: ${{ github.workflow }} @ ${{ github.event.pull_request.head.label || github.head_ref || github.ref }}
+  group: '${{ github.workflow }} @ ${{ github.event.pull_request.head.label || github.head_ref || github.ref }}'
   cancel-in-progress: true
-
 jobs:
+  check_yaml_consistency:
+    name: 'Check YAML consistency'
+    runs-on: 'ubuntu-latest'
+    steps:
+    - id: 'step-0'
+      name: 'Check out'
+      uses: 'actions/checkout@v4'
+    - id: 'step-1'
+      name: 'Execute script'
+      run: 'rm ''.github/workflows/benchmark.yaml'' && ''.github/workflows/benchmark.main.kts'''
+    - id: 'step-2'
+      name: 'Consistency check'
+      run: 'git diff --exit-code ''.github/workflows/benchmark.yaml'''
   run-benchmark:
+    name: 'Performance regression check on ${{ matrix.os }} runner'
+    runs-on: '${{ matrix.os }}'
+    needs:
+    - 'check_yaml_consistency'
     strategy:
       fail-fast: true
       matrix:
         include:
-          - os: ubuntu-latest
-          - os: macos-latest
-            additional-args: '-x jvmBenchmark -x jsBenchmark'
-          - os: macos-13 # for macosX64
-            additional-args: '-x jvmBenchmark -x jsBenchmark'
-          - os: windows-latest
-            additional-args: '-x jvmBenchmark -x jsBenchmark'
-    name: Performance regression check on ${{ matrix.os }} runner
-    runs-on: ${{ matrix.os }}
+        - os: 'ubuntu-latest'
+        - os: 'macos-latest'
+          additional-args: '-x jvmBenchmark -x jsBenchmark'
+        - os: 'macos-13'
+          additional-args: '-x jvmBenchmark -x jsBenchmark'
+        - os: 'windows-latest'
+          additional-args: '-x jvmBenchmark -x jsBenchmark'
     steps:
-    - uses: actions/checkout@v4
-    - name: 'Set up JDK'
+    - id: 'step-0'
+      uses: 'actions/checkout@v4'
+    - id: 'step-1'
+      name: 'Set up JDK'
       uses: 'actions/setup-java@v4'
       with:
         java-version: '11'
         distribution: 'zulu'
         cache: 'gradle'
-    - name: Validate Gradle Wrapper
-      uses: gradle/actions/wrapper-validation@v4
-    - name: Setup Gradle
-      uses: gradle/actions/setup-gradle@v4
+    - id: 'step-2'
+      name: 'Validate Gradle Wrapper'
+      uses: 'gradle/actions/wrapper-validation@v4'
+    - id: 'step-3'
+      name: 'Setup Gradle'
+      uses: 'gradle/actions/setup-gradle@v4'
       with:
-        gradle-version: wrapper
-    - name: Run benchmarks
-      run: ./gradlew -p snake-kmp-benchmarks benchmark --no-parallel ${{ matrix.additional-args }}
-    - uses: actions/upload-artifact@v4
+        gradle-version: 'wrapper'
+    - id: 'step-4'
+      name: 'Run benchmarks'
+      run: './gradlew -p snake-kmp-benchmarks benchmark --no-parallel ${{ matrix.additional-args }}'
+    - id: 'step-5'
+      uses: 'actions/upload-artifact@v4'
       with:
-        name: bench-results-${{ matrix.os }}
-        path: ${{ env.BENCHMARK_RESULTS }}/main/**/*.json
+        name: 'bench-results-${{ matrix.os }}'
+        path: 'snake-kmp-benchmarks/build/reports/benchmarks/main/**/*.json'
   collect-benchmarks-results:
-    runs-on: ubuntu-latest
+    runs-on: 'ubuntu-latest'
     needs:
-      - run-benchmark
-    env:
-      RESULTS_DIR: bench-results
+    - 'run-benchmark'
+    - 'check_yaml_consistency'
     steps:
-    # without checkout step 'benchmark-action/github-action-benchmark' action won't work
-    - uses: actions/checkout@v4
-    - name: Download benchmark results
-      uses: actions/download-artifact@v4
+    - id: 'step-0'
+      uses: 'actions/checkout@v4'
+    - id: 'step-1'
+      name: 'Download benchmark results'
+      uses: 'actions/download-artifact@v4'
       with:
-        pattern: bench-results-*
-        path: ${{ env.RESULTS_DIR }}
-        merge-multiple: true
-    - name: Prepare and join benchmark reports
-      id: prep
-      run: |
-        for report in $(find ./${{ env.RESULTS_DIR }} -type f -name "*.json")
-        do
-          file_name=$(basename "$report")
-          platform="${file_name%.*}"
-          # Trim 'it.krzeminski.snakeyaml.engine.kmp.benchmark.' to make benchmark name more readable
-          jq "[ .[] | .benchmark |= \"${platform}.\" + ltrimstr(\"it.krzeminski.snakeyaml.engine.kmp.benchmark.\") | .params |= map_values(. |= match(\"data.+\"; \"g\").string) ]" $report > ${{ env.RESULTS_DIR }}/$platform.json
-        done
-        AGGREGATED_REPORT=aggregated.json
-        # Joined reports looks like this: [[{},{}], [{},{}]]
-        # We need to transform them into this: [{},{}]
-        ls ${{ env.RESULTS_DIR }}/*.json
-        jq -s '[ .[] | .[] ]' ${{ env.RESULTS_DIR }}/*.json > $AGGREGATED_REPORT
-        echo "report=$AGGREGATED_REPORT" >> $GITHUB_OUTPUT
-    - name: Store benchmark result
-      uses: benchmark-action/github-action-benchmark@v1
+        path: 'bench-results'
+        pattern: 'bench-results-*'
+        merge-multiple: 'true'
+    - id: 'step-2'
+      name: 'Prepare and join benchmark reports'
+      env:
+        GHWKT_GITHUB_CONTEXT_JSON: '${{ toJSON(github) }}'
+      run: 'GHWKT_RUN_STEP=''collect-benchmarks-results:step-2'' ''.github/workflows/benchmark.main.kts'''
+    - id: 'step-3'
+      name: 'Store benchmark result'
+      uses: 'benchmark-action/github-action-benchmark@v1'
       with:
-        name: SnakeKMP benchmarks
+        name: 'SnakeKMP benchmarks'
         tool: 'jmh'
-        output-file-path: ${{ steps.prep.outputs.report }}
-        comment-on-alert: true
-        summary-always: true
+        output-file-path: 'aggregated.json'
+        gh-repository: 'github.com/krzema12/snakeyaml-engine-kmp-benchmarks'
+        summary-always: 'true'
+        comment-on-alert: 'true'
         alert-threshold: '150%'
         fail-threshold: '200%'
-        gh-repository: github.com/krzema12/snakeyaml-engine-kmp-benchmarks
-        github-token: ${{ secrets.PUBLISH_BENCHMARK_RESULTS }}
-        # Push and deploy GitHub pages branch automatically only if run in main repo and not in PR
-        auto-push: ${{ github.repository == 'krzema12/snakeyaml-engine-kmp' && github.event_name != 'pull_request' }}
+        github-token: '${{ secrets.PUBLISH_BENCHMARK_RESULTS }}'
+        auto-push: '${{ github.repository == ''krzema12/snakeyaml-engine-kmp'' && github.event_name != ''pull_request'' }}'