Add pure Kotlin EventSourcedEntityFactory, EntityHandler and ResolvedEntityFactory implementations

cloudstate-kotlin-support/pom.xml

@@ -16,7 +16,6 @@
         <grpc.version>1.22.1</grpc.version>
         <akka.version>2.6.0-M7</akka.version>
         <akka.grpc.version>0.7.1</akka.grpc.version>
-
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 
@@ -39,6 +38,7 @@
             <version>0.4.3</version>
         </dependency>
 
+        <!-- Remove Bytebuddy when issue https://github.com/cloudstateio/kotlin-support/issues/6 is fixed -->
         <dependency>
             <groupId>net.bytebuddy</groupId>
             <artifactId>byte-buddy</artifactId>

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/annotations/EntityId.java

@@ -0,0 +1,18 @@
+package io.cloudstate.kotlinsupport.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation used to indicate that the annotated parameter accepts an entity id.
+ *
+ * <p>This parameter may appear on handler methods and constructors for any class that provides
+ * behavior for stateful service entity.
+ *
+ * <p>The type of the parameter must be {@link String}.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.PARAMETER, ElementType.FIELD})
+public @interface EntityId {}

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/annotations/crdt/CommandHandler.java

@@ -0,0 +1,39 @@
+package io.cloudstate.kotlinsupport.annotations.crdt;
+
+import io.cloudstate.javasupport.crdt.CommandContext;
+import io.cloudstate.javasupport.impl.CloudStateAnnotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a method as a command handler.
+ *
+ * <p>This method will be invoked whenever the service call with name that matches this command
+ * handlers name is invoked.
+ *
+ * <p>The method may take the command object as a parameter, its type must match the gRPC service
+ * input type.
+ *
+ * <p>The return type of the method must match the gRPC services output type.
+ *
+ * <p>The method may also take a {@link CommandContext}, and/or a {@link
+ * io.cloudstate.javasupport.EntityId} annotated {@link String} parameter.
+ */
+@CloudStateAnnotation
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface CommandHandler {
+
+  /**
+   * The name of the command to handle.
+   *
+   * <p>If not specified, the name of the method will be used as the command name, with the first
+   * letter capitalized to match the gRPC convention of capitalizing rpc method names.
+   *
+   * @return The command name.
+   */
+  String name() default "";
+}

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/annotations/crdt/CrdtEntity.java

@@ -0,0 +1,31 @@
+package io.cloudstate.kotlinsupport.annotations.crdt;
+
+import io.cloudstate.javasupport.crdt.CommandHandler;
+import io.cloudstate.javasupport.crdt.Crdt;
+import io.cloudstate.javasupport.crdt.CrdtContext;
+import io.cloudstate.javasupport.crdt.CrdtFactory;
+import io.cloudstate.javasupport.impl.CloudStateAnnotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * A CRDT backed entity.
+ *
+ * <p>CRDT entities store their state in a subclass {@link Crdt}. These may be created using a
+ * {@link CrdtFactory}, which can be injected into the constructor or as a parameter to any {@link
+ * CommandHandler} annotated method.
+ *
+ * <p>Only one CRDT may be created, it is important that before creating a CRDT, the entity should
+ * check whether the CRDT has already been created, for example, it may have been created on another
+ * node and replicated to this node. To check, either use the {@link CrdtContext#state(Class)}
+ * method, which can be injected into the constructor or any {@link CommandHandler} method, or have
+ * an instance of the CRDT wrapped in {@link java.util.Optional} injected into the constructor or
+ * command handler methods.
+ */
+@CloudStateAnnotation
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface CrdtEntity {}

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/annotations/eventsourced/CommandHandler.java

@@ -0,0 +1,37 @@
+package io.cloudstate.kotlinsupport.annotations.eventsourced;
+
+import io.cloudstate.javasupport.eventsourced.CommandContext;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a method as a command handler.
+ *
+ * <p>This method will be invoked whenever the service call with name that matches this command
+ * handlers name is invoked.
+ *
+ * <p>The method may take the command object as a parameter, its type must match the gRPC service
+ * input type.
+ *
+ * <p>The return type of the method must match the gRPC services output type.
+ *
+ * <p>The method may also take a {@link CommandContext}, and/or a {@link
+ * io.cloudstate.javasupport.EntityId} annotated {@link String} parameter.
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface CommandHandler {
+
+  /**
+   * The name of the command to handle.
+   *
+   * <p>If not specified, the name of the method will be used as the command name, with the first
+   * letter capitalized to match the gRPC convention of capitalizing rpc method names.
+   *
+   * @return The command name.
+   */
+  String name() default "";
+}

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/annotations/eventsourced/EventHandler.java

@@ -0,0 +1,30 @@
+package io.cloudstate.kotlinsupport.annotations.eventsourced;
+
+import io.cloudstate.javasupport.eventsourced.EventContext;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a method as an event handler.
+ *
+ * <p>This method will be invoked whenever an event matching this event handlers event class is
+ * either replayed on entity recovery, by a command handler.
+ *
+ * <p>The method may take the event object as a parameter.
+ *
+ * <p>Methods annotated with this may take an {@link EventContext}.
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface EventHandler {
+  /**
+   * The event class. Generally, this will be determined by looking at the parameter of the event
+   * handler method, however if the event doesn't need to be passed to the method (for example,
+   * perhaps it contains no data), then this can be used to indicate which event this handler
+   * handles.
+   */
+  Class<?> eventClass() default Object.class;
+}

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/annotations/eventsourced/EventSourcedEntity.java

@@ -0,0 +1,26 @@
+package io.cloudstate.kotlinsupport.annotations.eventsourced;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/** An event sourced entity. */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface EventSourcedEntity {
+  /**
+   * The name of the persistence id.
+   *
+   * <p>If not specifed, defaults to the entities unqualified classname. It's strongly recommended
+   * that you specify it explicitly.
+   */
+  String persistenceId() default "";
+
+  /**
+   * Specifies how snapshots of the entity state should be made: Zero means use default from
+   * configuration file. (Default) Any negative value means never snapshot. Any positive value means
+   * snapshot at-or-after that number of events.
+   */
+  int snapshotEvery() default 0;
+}

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/annotations/eventsourced/Snapshot.java

@@ -0,0 +1,23 @@
+package io.cloudstate.kotlinsupport.annotations.eventsourced;
+
+import io.cloudstate.javasupport.eventsourced.SnapshotContext;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a method as a snapshot method.
+ *
+ * <p>An event sourced behavior may have at most one of these. When provided, it will be
+ * periodically (every <em>n</em> events emitted) be invoked to retrieve a snapshot of the current
+ * state, to be persisted, so that the event log can be loaded without replaying the entire history.
+ *
+ * <p>The method must return the current state of the entity.
+ *
+ * <p>The method may accept a {@link SnapshotContext} parameter.
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Snapshot {}

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/annotations/eventsourced/SnapshotHandler.java

@@ -0,0 +1,25 @@
+package io.cloudstate.kotlinsupport.annotations.eventsourced;
+
+import io.cloudstate.javasupport.eventsourced.SnapshotContext;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a method as a snapshot handler.
+ *
+ * <p>If, when recovering an entity, that entity has a snapshot, the snapshot will be passed to a
+ * corresponding snapshot handler method whose argument matches its type. The entity must set its
+ * current state to that snapshot.
+ *
+ * <p>An entity may declare more than one snapshot handler if it wants different handling for
+ * different types.
+ *
+ * <p>The snapshot handler method may additionally accept a {@link SnapshotContext} parameter,
+ * allowing it to access context for the snapshot, if required.
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface SnapshotHandler {}

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/transcoding/crdt/CommandHandlerImpl.java

@@ -4,7 +4,7 @@
 
 import java.lang.annotation.Annotation;
 
-public final class CommandHandlerImpl implements CommandHandler {
+public class CommandHandlerImpl implements CommandHandler {
 
     private final String name;
 

cloudstate-kotlin-support/src/main/java/io/cloudstate/kotlinsupport/transcoding/crdt/CrdtEntityImpl.java

@@ -4,7 +4,7 @@
 
 import java.lang.annotation.Annotation;
 
-public final class CrdtEntityImpl implements CrdtEntity {
+public class CrdtEntityImpl implements CrdtEntity {
     public Class<? extends Annotation> annotationType() {
         return CrdtEntity.class;
     }