[BT] Implement classpath snapshotting in the Build Tools API

#KT-57565 In Progress

compiler/build-tools/kotlin-build-tools-api/api/kotlin-build-tools-api.api

@@ -9,7 +9,7 @@ public final class org/jetbrains/kotlin/buildtools/api/CompilationResult : java/
 
 public abstract interface class org/jetbrains/kotlin/buildtools/api/CompilationService {
 	public static final field Companion Lorg/jetbrains/kotlin/buildtools/api/CompilationService$Companion;
-	public abstract fun calculateClasspathSnapshot (Ljava/io/File;)Lorg/jetbrains/kotlin/buildtools/api/jvm/ClasspathEntrySnapshot;
+	public abstract fun calculateClasspathSnapshot (Ljava/io/File;Lorg/jetbrains/kotlin/buildtools/api/jvm/ClassSnapshotGranularity;)Lorg/jetbrains/kotlin/buildtools/api/jvm/ClasspathEntrySnapshot;
 	public abstract fun compileJvm (Lorg/jetbrains/kotlin/buildtools/api/ProjectId;Lorg/jetbrains/kotlin/buildtools/api/CompilerExecutionStrategyConfiguration;Lorg/jetbrains/kotlin/buildtools/api/jvm/JvmCompilationConfiguration;Ljava/util/List;Ljava/util/List;)Lorg/jetbrains/kotlin/buildtools/api/CompilationResult;
 	public abstract fun finishProjectCompilation (Lorg/jetbrains/kotlin/buildtools/api/ProjectId;)V
 	public static fun loadImplementation (Ljava/lang/ClassLoader;)Lorg/jetbrains/kotlin/buildtools/api/CompilationService;
@@ -82,6 +82,10 @@ public final class org/jetbrains/kotlin/buildtools/api/SourcesChanges$Unknown :
 	public static final field INSTANCE Lorg/jetbrains/kotlin/buildtools/api/SourcesChanges$Unknown;
 }
 
+public abstract interface class org/jetbrains/kotlin/buildtools/api/jvm/AccessibleClassSnapshot : org/jetbrains/kotlin/buildtools/api/jvm/ClassSnapshot {
+	public abstract fun getClassAbiHash ()J
+}
+
 public abstract interface class org/jetbrains/kotlin/buildtools/api/jvm/ClassSnapshot {
 }
 
@@ -93,7 +97,7 @@ public final class org/jetbrains/kotlin/buildtools/api/jvm/ClassSnapshotGranular
 }
 
 public abstract interface class org/jetbrains/kotlin/buildtools/api/jvm/ClasspathEntrySnapshot {
-	public abstract fun getClassSnapshots ()Ljava/util/LinkedHashMap;
+	public abstract fun getClassSnapshots ()Ljava/util/Map;
 	public abstract fun saveSnapshot (Ljava/io/File;)V
 }
 
@@ -115,6 +119,9 @@ public abstract interface class org/jetbrains/kotlin/buildtools/api/jvm/Classpat
 	public abstract fun useProjectDir (Ljava/io/File;)Lorg/jetbrains/kotlin/buildtools/api/jvm/ClasspathSnapshotBasedIncrementalJvmCompilationConfiguration;
 }
 
+public abstract interface class org/jetbrains/kotlin/buildtools/api/jvm/InaccessibleClassSnapshot : org/jetbrains/kotlin/buildtools/api/jvm/ClassSnapshot {
+}
+
 public abstract interface class org/jetbrains/kotlin/buildtools/api/jvm/IncrementalCompilationApproachParameters {
 }
 

compiler/build-tools/kotlin-build-tools-api/src/main/kotlin/org/jetbrains/kotlin/buildtools/api/CompilationService.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.buildtools.api
 
+import org.jetbrains.kotlin.buildtools.api.jvm.ClassSnapshotGranularity
 import org.jetbrains.kotlin.buildtools.api.jvm.ClasspathEntrySnapshot
 import org.jetbrains.kotlin.buildtools.api.jvm.JvmCompilationConfiguration
 import java.io.File
@@ -28,7 +29,7 @@ public interface CompilationService {
     /**
      * TODO KT-57565
      */
-    public fun calculateClasspathSnapshot(classpathEntry: File): ClasspathEntrySnapshot
+    public fun calculateClasspathSnapshot(classpathEntry: File, granularity: ClassSnapshotGranularity): ClasspathEntrySnapshot
 
     /**
      * Provides a default [CompilerExecutionStrategyConfiguration] allowing to use it as is or customizing for specific requirements.

compiler/build-tools/kotlin-build-tools-api/src/main/kotlin/org/jetbrains/kotlin/buildtools/api/jvm/ClasspathEntrySnapshot.kt

@@ -15,7 +15,7 @@ import java.io.File
  */
 @ExperimentalBuildToolsApi
 public interface ClasspathEntrySnapshot {
-    public val classSnapshots: LinkedHashMap<String, ClassSnapshot>
+    public val classSnapshots: Map<String, ClassSnapshot>
 
     public fun saveSnapshot(path: File)
 }
@@ -26,6 +26,18 @@ public interface ClasspathEntrySnapshot {
  * This interface is not intended to be implemented by the API consumers.
  */
 @ExperimentalBuildToolsApi
-public interface ClassSnapshot {
-    // ... TODO: KT-57565, it will expose some part of org.jetbrains.kotlin.incremental.classpathDiff.ClassSnapshot hierarchy
+public sealed interface ClassSnapshot
+
+/**
+ * [ClassSnapshot] of an inaccessible class.
+ *
+ * A class is inaccessible if it can't be referenced from other source files (and therefore any changes in an inaccessible class will not
+ * require recompilation of other source files).
+ */
+@ExperimentalBuildToolsApi
+public interface InaccessibleClassSnapshot : ClassSnapshot
+
+@ExperimentalBuildToolsApi
+public interface AccessibleClassSnapshot : ClassSnapshot {
+    public val classAbiHash: Long
 }

compiler/build-tools/kotlin-build-tools-impl/build.gradle.kts

@@ -13,13 +13,18 @@ dependencies {
     compileOnly(project(":kotlin-daemon-client"))
     compileOnly(project(":compiler:incremental-compilation-impl"))
     compileOnly(project(":kotlin-compiler-runner-unshaded"))
+    compileOnly(intellijCore())
     runtimeOnly(project(":kotlin-compiler-embeddable"))
     runtimeOnly(project(":kotlin-compiler-runner"))
 }
 
 publish()
 
-standardPublicJars()
+runtimeJar(rewriteDefaultJarDepsToShadedCompiler {
+    from(mainSourceSet.output)
+})
+sourcesJar()
+javadocJar()
 
 kotlin {
     compilerOptions {

compiler/build-tools/kotlin-build-tools-impl/src/main/kotlin/org/jetbrains/kotlin/buildtools/internal/ClassSnapshotImpl.kt

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.buildtools.internal
+
+import org.jetbrains.kotlin.buildtools.api.jvm.AccessibleClassSnapshot
+import org.jetbrains.kotlin.buildtools.api.jvm.InaccessibleClassSnapshot
+
+class AccessibleClassSnapshotImpl(override val classAbiHash: Long) : AccessibleClassSnapshot
+
+object InaccessibleClassSnapshotImpl : InaccessibleClassSnapshot

compiler/build-tools/kotlin-build-tools-impl/src/main/kotlin/org/jetbrains/kotlin/buildtools/internal/ClasspathEntrySnapshotImpl.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.buildtools.internal
+
+import org.jetbrains.kotlin.buildtools.api.jvm.ClassSnapshot
+import org.jetbrains.kotlin.buildtools.api.jvm.ClasspathEntrySnapshot
+import org.jetbrains.kotlin.incremental.classpathDiff.AccessibleClassSnapshot
+import org.jetbrains.kotlin.incremental.classpathDiff.ClasspathEntrySnapshotExternalizer
+import org.jetbrains.kotlin.incremental.classpathDiff.InaccessibleClassSnapshot
+import org.jetbrains.kotlin.incremental.storage.saveToFile
+import java.io.File
+
+class ClasspathEntrySnapshotImpl(
+    private val origin: org.jetbrains.kotlin.incremental.classpathDiff.ClasspathEntrySnapshot,
+) :
+    ClasspathEntrySnapshot {
+    override val classSnapshots: Map<String, ClassSnapshot>
+        get() = origin.classSnapshots.mapValues {
+            when (val snapshot = it.value) {
+                is AccessibleClassSnapshot -> AccessibleClassSnapshotImpl(snapshot.classAbiHash)
+                is InaccessibleClassSnapshot -> InaccessibleClassSnapshotImpl
+            }
+        }
+
+    override fun saveSnapshot(path: File) {
+        ClasspathEntrySnapshotExternalizer.saveToFile(path, origin)
+    }
+}

compiler/build-tools/kotlin-build-tools-impl/src/main/kotlin/org/jetbrains/kotlin/buildtools/internal/CompilationServiceImpl.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.buildtools.internal
 
+import org.jetbrains.kotlin.build.report.metrics.DoNothingBuildMetricsReporter
 import org.jetbrains.kotlin.buildtools.api.*
 import org.jetbrains.kotlin.buildtools.api.jvm.*
 import org.jetbrains.kotlin.cli.common.ExitCode
@@ -18,6 +19,7 @@ import org.jetbrains.kotlin.daemon.client.BasicCompilerServicesWithResultsFacade
 import org.jetbrains.kotlin.daemon.common.CompilerId
 import org.jetbrains.kotlin.daemon.common.configureDaemonJVMOptions
 import org.jetbrains.kotlin.daemon.common.filterExtractProps
+import org.jetbrains.kotlin.incremental.classpathDiff.ClasspathEntrySnapshotter
 import java.io.File
 import java.net.URLClassLoader
 import java.util.concurrent.ConcurrentHashMap
@@ -36,9 +38,8 @@ private fun getCurrentClasspath() = (CompilationServiceImpl::class.java.classLoa
 internal object CompilationServiceImpl : CompilationService {
     private val buildIdToSessionFlagFile: MutableMap<ProjectId, File> = ConcurrentHashMap()
 
-    override fun calculateClasspathSnapshot(classpathEntry: File): ClasspathEntrySnapshot {
-        TODO("Calculating classpath snapshots via the Build Tools API is not yet implemented: KT-57565")
-    }
+    override fun calculateClasspathSnapshot(classpathEntry: File, granularity: ClassSnapshotGranularity) =
+        ClasspathEntrySnapshotImpl(ClasspathEntrySnapshotter.snapshot(classpathEntry, granularity, DoNothingBuildMetricsReporter))
 
     override fun makeCompilerExecutionStrategyConfiguration() = CompilerExecutionStrategyConfigurationImpl()