igalshilman commented on a change in pull request #2: URL: https://github.com/apache/flink-statefun-playground/pull/2#discussion_r596898147
########## File path: java/shopping-cart/src/main/java/org/apache/flink/statefun/examples/shoppingcart/InventoryFn.java ########## @@ -0,0 +1,70 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.flink.statefun.examples.shoppingcart; + +import static org.apache.flink.statefun.examples.shoppingcart.Messages.*; +import static org.apache.flink.statefun.examples.shoppingcart.Messages.ItemAvailability.*; + +import java.util.concurrent.CompletableFuture; +import org.apache.flink.statefun.sdk.java.AddressScopedStorage; +import org.apache.flink.statefun.sdk.java.Context; +import org.apache.flink.statefun.sdk.java.StatefulFunction; +import org.apache.flink.statefun.sdk.java.TypeName; +import org.apache.flink.statefun.sdk.java.ValueSpec; +import org.apache.flink.statefun.sdk.java.message.Message; +import org.apache.flink.statefun.sdk.java.message.MessageBuilder; + +final class InventoryFn implements StatefulFunction { + + static final TypeName TYPE = TypeName.typeNameFromString("com.example.fns/inventory"); + + static final ValueSpec<Integer> INVENTORY = ValueSpec.named("inventory").withIntType(); + + @Override + public CompletableFuture<Void> apply(Context context, Message message) { + AddressScopedStorage storage = context.storage(); + int quantity = storage.get(INVENTORY).orElse(0); + if (message.is(RESTOCK_ITEM_TYPE)) { + RestockItem restock = message.as(RESTOCK_ITEM_TYPE); + int newQuantity = quantity + restock.getQuantity(); + storage.set(INVENTORY, newQuantity); + } else if (message.is(REQUEST_ITEM_TYPE)) { + RequestItem request = message.as(REQUEST_ITEM_TYPE); + int requestQuantity = request.getQuantity(); + + ItemAvailability itemAvailability; + + if (quantity >= requestQuantity) { + storage.set(INVENTORY, quantity - requestQuantity); + itemAvailability = new ItemAvailability(Status.INSTOCK, requestQuantity); + } else { + itemAvailability = new ItemAvailability(Status.OUTOFSTOCK, requestQuantity); + } + + context + .caller() + .ifPresent( Review comment: I think that the `ifPresent` might be a bit confusing to folks. If you known that there is a caller in this case, how about calling `.get()` or `.getOrElse( () -> throw new IllegalStateException("There should always be a caller in this example")).` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
