Reintroduce clients generation (#482)

* Reintroduce clients generation

* Add option to disable client generation

Author: slinkydeveloper

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

@@ -8,7 +8,6 @@
 // https://github.com/restatedev/sdk-java/blob/main/LICENSE
 package my.restate.sdk.examples;
 
-import dev.restate.client.Client;
 import dev.restate.sdk.Context;
 import dev.restate.sdk.SharedWorkflowContext;
 import dev.restate.sdk.WorkflowContext;
@@ -80,12 +79,13 @@ public String run(WorkflowContext ctx, LoanRequest loanRequest) {
     ctx.set(STATUS, Status.APPROVED);
 
     // 4. Request money transaction to the bank
+    var bankClient = LoanWorkflowMockBankClient.fromContext(ctx);
     Instant executionTime;
     try {
       executionTime =
-          ctx.call(
-                  LoanWorkflowMockBankHandlers.transfer(
-                      new TransferRequest(loanRequest.customerBankAccount(), loanRequest.amount())))
+          bankClient
+              .transfer(
+                  new TransferRequest(loanRequest.customerBankAccount(), loanRequest.amount()))
               .await(Duration.ofDays(7));
     } catch (TerminalException e) {
       LOG.warn("Transaction failed", e);
@@ -135,14 +135,13 @@ public static void main(String[] args) {
     }
 
     // To invoke the workflow:
-    Client client = Client.connect("http://127.0.0.1:8080");
+    LoanWorkflowClient.IngressClient client =
+        LoanWorkflowClient.connect("http://127.0.0.1:8080", "my-loan");
 
     var state =
         client.submit(
-            LoanWorkflowHandlers.run(
-                "my-loan",
-                new LoanRequest(
-                    "Francesco", "slinkydeveloper", "DE1234", new BigDecimal("1000000000"))));
+            new LoanRequest(
+                "Francesco", "slinkydeveloper", "DE1234", new BigDecimal("1000000000")));
 
     LOG.info("Started loan workflow");
 
@@ -156,14 +155,12 @@ public static void main(String[] args) {
     LOG.info("We took the decision to approve your loan! You can now achieve your dreams!");
 
     // Now approve it
-    client.call(LoanWorkflowHandlers.approveLoan("my-loan"));
+    client.approveLoan();
 
     // Wait for output
-    state.response().invocationHandle().attach();
+    client.workflowHandle().attach();
 
-    LOG.info(
-        "Loan workflow completed, now in status {}",
-        client.call(LoanWorkflowHandlers.getStatus("my-loan")));
+    LOG.info("Loan workflow completed, now in status {}", client.getStatus());
   }
 
   // -- Some mocks

sdk-api-gen-common/src/main/java/dev/restate/sdk/gen/model/AnnotationProcessingOptions.java

@@ -0,0 +1,44 @@
+// 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 java.util.*;
+
+public class AnnotationProcessingOptions {
+
+  private static final String DISABLED_CLIENT_GENERATION =
+      "dev.restate.codegen.disabledClientGeneration";
+
+  private final Set<String> disabledClientGenFQCN;
+
+  public AnnotationProcessingOptions(Map<String, String> options) {
+    this.disabledClientGenFQCN =
+        new HashSet<>(List.of(options.getOrDefault(DISABLED_CLIENT_GENERATION, "").split("[,|]")));
+  }
+
+  public boolean isClientGenDisabled(String fqcn) {
+    return this.disabledClientGenFQCN.contains(fqcn);
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (!(o instanceof AnnotationProcessingOptions that)) return false;
+    return Objects.equals(disabledClientGenFQCN, that.disabledClientGenFQCN);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hashCode(disabledClientGenFQCN);
+  }
+
+  @Override
+  public String toString() {
+    return "AnnotationProcessingOptions{" + "disabledClientGenFQCN=" + disabledClientGenFQCN + '}';
+  }
+}

sdk-api-gen-common/src/main/java/dev/restate/sdk/gen/template/HandlebarsTemplateEngine.java

@@ -109,6 +109,7 @@ static class ServiceTemplateModel {
     public final String documentation;
 
     public final String metadataClass;
+    public final String handlersClass;
 
     public final String serdeFactoryDecl;
     public final String serdeFactoryRef;
@@ -128,7 +129,8 @@ private ServiceTemplateModel(
       this.generatedClassSimpleName = this.generatedClassSimpleNamePrefix + baseTemplateName;
       this.restateServiceName = inner.getRestateServiceName();
 
-      this.metadataClass = this.generatedClassSimpleNamePrefix + "Handlers.Metadata";
+      this.handlersClass = this.generatedClassSimpleNamePrefix + "Handlers";
+      this.metadataClass = this.handlersClass + ".Metadata";
 
       this.serdeFactoryDecl = inner.getSerdeFactoryDecl();
       this.serdeFactoryRef = metadataClass + ".SERDE_FACTORY";

sdk-api-gen/src/main/java/dev/restate/sdk/gen/ServiceProcessor.java

@@ -11,6 +11,7 @@
 import dev.restate.common.function.ThrowingFunction;
 import dev.restate.sdk.endpoint.definition.ServiceDefinitionFactory;
 import dev.restate.sdk.endpoint.definition.ServiceType;
+import dev.restate.sdk.gen.model.AnnotationProcessingOptions;
 import dev.restate.sdk.gen.model.Service;
 import dev.restate.sdk.gen.template.HandlebarsTemplateEngine;
 import java.io.*;
@@ -32,7 +33,9 @@
 public class ServiceProcessor extends AbstractProcessor {
 
   private HandlebarsTemplateEngine serviceDefinitionFactoryCodegen;
+  private HandlebarsTemplateEngine clientCodegen;
   private HandlebarsTemplateEngine handlersCodegen;
+  private AnnotationProcessingOptions options;
 
   private static final Set<String> RESERVED_METHOD_NAMES =
       Set.of("send", "submit", "workflowHandle");
@@ -55,6 +58,18 @@ public synchronized void init(ProcessingEnvironment processingEnv) {
                 ServiceType.VIRTUAL_OBJECT,
                 "templates/ServiceDefinitionFactory.hbs"),
             RESERVED_METHOD_NAMES);
+    this.clientCodegen =
+        new HandlebarsTemplateEngine(
+            "Client",
+            filerTemplateLoader,
+            Map.of(
+                ServiceType.WORKFLOW,
+                "templates/Client.hbs",
+                ServiceType.SERVICE,
+                "templates/Client.hbs",
+                ServiceType.VIRTUAL_OBJECT,
+                "templates/Client.hbs"),
+            RESERVED_METHOD_NAMES);
     this.handlersCodegen =
         new HandlebarsTemplateEngine(
             "Handlers",
@@ -67,6 +82,7 @@ public synchronized void init(ProcessingEnvironment processingEnv) {
                 ServiceType.VIRTUAL_OBJECT,
                 "templates/Handlers.hbs"),
             RESERVED_METHOD_NAMES);
+    this.options = new AnnotationProcessingOptions(processingEnv.getOptions());
   }
 
   @Override
@@ -104,6 +120,9 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
             name -> filer.createSourceFile(name, e.getKey()).openWriter();
         this.serviceDefinitionFactoryCodegen.generate(fileCreator, e.getValue());
         this.handlersCodegen.generate(fileCreator, e.getValue());
+        if (!this.options.isClientGenDisabled(e.getValue().getTargetFqcn().toString())) {
+          this.clientCodegen.generate(fileCreator, e.getValue());
+        }
       } catch (Throwable ex) {
         throw new RuntimeException(ex);
       }