refactor: One stream -> using `flatMap` instead of an inner `subscribe`

[demos/kafka/chat] / src / main / java / de / juplo / kafka / chat / backend / implementation / StorageStrategy.java

diff --git a/src/main/java/de/juplo/kafka/chat/backend/implementation/StorageStrategy.java b/src/main/java/de/juplo/kafka/chat/backend/implementation/StorageStrategy.java
index 24fd15f..f9ce2b1 100644 (file)
--- a/src/main/java/de/juplo/kafka/chat/backend/implementation/StorageStrategy.java
+++ b/src/main/java/de/juplo/kafka/chat/backend/implementation/StorageStrategy.java
@@ -3,28 +3,39 @@ package de.juplo.kafka.chat.backend.implementation;
 import de.juplo.kafka.chat.backend.domain.ChatHomeService;
 import de.juplo.kafka.chat.backend.domain.ChatRoomInfo;
 import de.juplo.kafka.chat.backend.domain.Message;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
 
 import java.util.UUID;
 
 
 public interface StorageStrategy
 {
-  default void write(ChatHomeService chatHomeService)
+  Logger log = LoggerFactory.getLogger(StorageStrategy.class.getCanonicalName());
+
+  default Flux<ChatRoomInfo> write(ChatHomeService chatHomeService)
   {
-    writeChatRoomInfo(
+    return writeChatRoomInfo(
         chatHomeService
             .getChatRoomInfo()
-            .doOnNext(chatRoomInfo ->
+            .flatMap(chatRoomInfo ->
                 writeChatRoomData(
                     chatRoomInfo.getId(),
                     chatHomeService
                         .getChatRoomData(chatRoomInfo.getId())
-                        .flatMapMany(chatRoomData -> chatRoomData.getMessages()))));
+                        .flatMapMany(chatRoomData -> chatRoomData.getMessages())
+                        )
+                    .then(Mono.just(chatRoomInfo))
+                    .doOnSuccess(empty -> log.info("Stored {}", chatRoomInfo))
+                    .doOnError(throwable -> log.error("Could not store {}: {}", chatRoomInfo, throwable))))
+        .doOnComplete(() -> log.info("Stored {}", chatHomeService))
+        .doOnError(throwable -> log.error("Could not store {}: {}", chatHomeService, throwable));
   }
 
-  void writeChatRoomInfo(Flux<ChatRoomInfo> chatRoomInfoFlux);
+  Flux<ChatRoomInfo> writeChatRoomInfo(Flux<ChatRoomInfo> chatRoomInfoFlux);
   Flux<ChatRoomInfo> readChatRoomInfo();
-  void writeChatRoomData(UUID chatRoomId, Flux<Message> messageFlux);
+  Flux<Message> writeChatRoomData(UUID chatRoomId, Flux<Message> messageFlux);
   Flux<Message> readChatRoomData(UUID chatRoomId);
 }