sdk-api-kotlin-gen (#240)

* Factor out common codegen module in sdk-api-gen-common
* Implement sdk-api-kotlin-gen and test it
* Rewrite the kotlin example with sdk-api-kotlin-gen

Author: slinkydeveloper

examples/README.md

@@ -7,7 +7,7 @@ For a sample project configuration and more elaborated examples, check out the [
 Available examples:
 
 * [`Counter`](src/main/java/my/restate/sdk/examples/Counter.java): Shows a simple virtual object using state primitives.
-* [`Counter`](src/main/kotlin/my/restate/sdk/examples/Counter.kt): Same as `Counter` but using Kotlin.
+* [`CounterKt`](src/main/kotlin/my/restate/sdk/examples/CounterKt.kt): Same as `Counter` but using Kotlin.
 * [`LoanWorkflow`](src/main/java/my/restate/sdk/examples/LoanWorkflow.java): Shows a simple workflow example using the Workflow API.
 
 ## Package the examples for Lambda
@@ -35,7 +35,7 @@ You can run the Java Counter example via:
 You can modify the class to run setting `-PmainClass=<FQCN>`, for example, in order to run the Kotlin implementation:
 
 ```shell
-./gradlew :examples:run -PmainClass=my.restate.sdk.examples.CounterKt
+./gradlew :examples:run -PmainClass=my.restate.sdk.examples.CounterKtKt
 ```
 
 ## Invoking the counter bindableComponent

examples/build.gradle.kts

@@ -1,12 +1,17 @@
+import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar
+import com.github.jengelman.gradle.plugins.shadow.transformers.ServiceFileTransformer
+
 plugins {
   java
   kotlin("jvm")
   kotlin("plugin.serialization")
   application
-  id("com.github.johnrengelman.shadow").version("7.1.2")
+  alias(kotlinLibs.plugins.ksp)
+  id("com.github.johnrengelman.shadow").version("8.1.1")
 }
 
 dependencies {
+  ksp(project(":sdk-api-kotlin-gen"))
   annotationProcessor(project(":sdk-api-gen"))
 
   implementation(project(":sdk-api"))
@@ -19,13 +24,6 @@ dependencies {
   implementation(platform(jacksonLibs.jackson.bom))
   implementation(jacksonLibs.jackson.jsr310)
 
-  implementation(coreLibs.protobuf.java)
-  implementation(coreLibs.protobuf.kotlin)
-
-  implementation(platform(vertxLibs.vertx.bom))
-  implementation(vertxLibs.vertx.core)
-  implementation(vertxLibs.vertx.kotlin.coroutines)
-
   implementation(kotlinLibs.kotlinx.coroutines)
   implementation(kotlinLibs.kotlinx.serialization.core)
   implementation(kotlinLibs.kotlinx.serialization.json)
@@ -38,3 +36,7 @@ application {
       project.findProperty("mainClass")?.toString() ?: "my.restate.sdk.examples.Counter"
   mainClass.set(mainClassValue)
 }
+
+tasks.withType<Jar> { this.enabled = false }
+
+tasks.withType<ShadowJar> { transform(ServiceFileTransformer::class.java) }

examples/src/main/java/my/restate/sdk/examples/LambdaHandler.java

@@ -24,7 +24,7 @@ public void register(RestateLambdaEndpointBuilder builder) {
       if (Counter.class.getCanonicalName().equals(serviceClass)) {
         builder.with(new Counter());
       } else if (CounterKt.class.getCanonicalName().equals(serviceClass)) {
-        builder.with(CounterKt.getCounter());
+        builder.with(new CounterKt());
       } else {
         throw new IllegalArgumentException(
             "Bad \"LAMBDA_FACTORY_SERVICE_CLASS\" env: " + serviceClass);

examples/src/main/kotlin/my/restate/sdk/examples/Counter.kt

@@ -0,0 +1,56 @@
+// Copyright (c) 2023 - Restate Software, Inc., Restate GmbH
+//
+// This file is part of the Restate Java SDK,
+// which is released under the MIT license.
+//
+// You can find a copy of the license in file LICENSE in the root
+// directory of this repository or package, or at
+// https://github.com/restatedev/sdk-java/blob/main/LICENSE
+package my.restate.sdk.examples
+
+import dev.restate.sdk.annotation.Handler
+import dev.restate.sdk.annotation.VirtualObject
+import dev.restate.sdk.common.StateKey
+import dev.restate.sdk.http.vertx.RestateHttpEndpointBuilder
+import dev.restate.sdk.kotlin.KtSerdes
+import dev.restate.sdk.kotlin.ObjectContext
+import kotlinx.serialization.Serializable
+
+@Serializable data class CounterUpdate(var oldValue: Long, val newValue: Long)
+
+@VirtualObject
+class CounterKt {
+
+  companion object {
+    private val TOTAL = StateKey.of<Long>("total", KtSerdes.json())
+  }
+
+  @Handler
+  suspend fun reset(ctx: ObjectContext) {
+    ctx.clear(TOTAL)
+  }
+
+  @Handler
+  suspend fun add(ctx: ObjectContext, value: Long) {
+    val currentValue = ctx.get(TOTAL) ?: 0L
+    val newValue = currentValue + value
+    ctx.set(TOTAL, newValue)
+  }
+
+  @Handler
+  suspend fun get(ctx: ObjectContext): Long {
+    return ctx.get(TOTAL) ?: 0L
+  }
+
+  @Handler
+  suspend fun getAndAdd(ctx: ObjectContext, value: Long): CounterUpdate {
+    val currentValue = ctx.get(TOTAL) ?: 0L
+    val newValue = currentValue + value
+    ctx.set(TOTAL, newValue)
+    return CounterUpdate(currentValue, newValue)
+  }
+}
+
+fun main() {
+  RestateHttpEndpointBuilder.builder().with(CounterKt()).buildAndListen()
+}

examples/src/main/kotlin/my/restate/sdk/examples/CounterKt.kt

@@ -0,0 +1,13 @@
+plugins {
+  `java-library`
+  `library-publishing-conventions`
+}
+
+description = "Restate SDK API Gen Common"
+
+dependencies {
+  compileOnly(coreLibs.jspecify)
+
+  api("com.github.jknack:handlebars:4.3.1")
+  api(project(":sdk-common"))
+}

sdk-api-gen-common/build.gradle.kts

@@ -0,0 +1,140 @@
+// Copyright (c) 2023 - Restate Software, Inc., Restate GmbH
+//
+// This file is part of the Restate Java SDK,
+// which is released under the MIT license.
+//
+// You can find a copy of the license in file LICENSE in the root
+// directory of this repository or package, or at
+// https://github.com/restatedev/sdk-java/blob/main/LICENSE
+package dev.restate.sdk.gen.model;
+
+import dev.restate.sdk.common.ComponentType;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Objects;
+
+public class Component {
+
+  private final CharSequence targetPkg;
+  private final CharSequence targetFqcn;
+  private final String componentName;
+  private final ComponentType componentType;
+  private final List<Handler> handlers;
+
+  public Component(
+      CharSequence targetPkg,
+      CharSequence targetFqcn,
+      String componentName,
+      ComponentType componentType,
+      List<Handler> handlers) {
+    this.targetPkg = targetPkg;
+    this.targetFqcn = targetFqcn;
+    this.componentName = componentName;
+
+    this.componentType = componentType;
+    this.handlers = handlers;
+  }
+
+  public CharSequence getTargetPkg() {
+    return this.targetPkg;
+  }
+
+  public CharSequence getTargetFqcn() {
+    return this.targetFqcn;
+  }
+
+  public String getFullyQualifiedComponentName() {
+    return this.componentName;
+  }
+
+  public String getSimpleComponentName() {
+    return this.componentName.substring(this.componentName.lastIndexOf('.') + 1);
+  }
+
+  public CharSequence getGeneratedClassFqcnPrefix() {
+    if (this.targetPkg == null || this.targetPkg.length() == 0) {
+      return getSimpleComponentName();
+    }
+    return this.targetPkg + "." + getSimpleComponentName();
+  }
+
+  public ComponentType getComponentType() {
+    return componentType;
+  }
+
+  public List<Handler> getMethods() {
+    return handlers;
+  }
+
+  public static Builder builder() {
+    return new Builder();
+  }
+
+  public static class Builder {
+    private CharSequence targetPkg;
+    private CharSequence targetFqcn;
+    private String componentName;
+    private ComponentType componentType;
+    private final List<Handler> handlers = new ArrayList<>();
+
+    public Builder withTargetPkg(CharSequence targetPkg) {
+      this.targetPkg = targetPkg;
+      return this;
+    }
+
+    public Builder withTargetFqcn(CharSequence targetFqcn) {
+      this.targetFqcn = targetFqcn;
+      return this;
+    }
+
+    public Builder withComponentName(String componentName) {
+      this.componentName = componentName;
+      return this;
+    }
+
+    public Builder withComponentType(ComponentType componentType) {
+      this.componentType = componentType;
+      return this;
+    }
+
+    public Builder withHandlers(Collection<Handler> handlers) {
+      this.handlers.addAll(handlers);
+      return this;
+    }
+
+    public Builder withHandler(Handler handler) {
+      this.handlers.add(handler);
+      return this;
+    }
+
+    public CharSequence getTargetPkg() {
+      return targetPkg;
+    }
+
+    public CharSequence getTargetFqcn() {
+      return targetFqcn;
+    }
+
+    public String getComponentName() {
+      return componentName;
+    }
+
+    public ComponentType getComponentType() {
+      return componentType;
+    }
+
+    public List<Handler> getHandlers() {
+      return handlers;
+    }
+
+    public Component build() {
+      return new Component(
+          Objects.requireNonNull(targetPkg),
+          Objects.requireNonNull(targetFqcn),
+          Objects.requireNonNull(componentName),
+          Objects.requireNonNull(componentType),
+          handlers);
+    }
+  }
+}