🩹 use memoized response on chat client [spring-projects#2097]

spring-ai-core/src/main/java/org/springframework/ai/chat/client/DefaultChatClient.java

@@ -16,27 +16,9 @@
 
 package org.springframework.ai.chat.client;
 
-import java.io.IOException;
-import java.net.URL;
-import java.nio.charset.Charset;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.function.Consumer;
-
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationRegistry;
 import io.micrometer.observation.contextpropagation.ObservationThreadLocalAccessor;
-import org.springframework.ai.tool.ToolCallbacks;
-import reactor.core.publisher.Flux;
-import reactor.core.scheduler.Schedulers;
-
 import org.springframework.ai.chat.client.advisor.DefaultAroundAdvisorChain;
 import org.springframework.ai.chat.client.advisor.api.AdvisedRequest;
 import org.springframework.ai.chat.client.advisor.api.AdvisedResponse;
@@ -65,6 +47,7 @@
 import org.springframework.ai.model.Media;
 import org.springframework.ai.model.function.FunctionCallback;
 import org.springframework.ai.model.function.FunctionCallbackWrapper;
+import org.springframework.ai.tool.ToolCallbacks;
 import org.springframework.core.Ordered;
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.core.io.Resource;
@@ -73,6 +56,22 @@
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.MimeType;
 import org.springframework.util.StringUtils;
+import reactor.core.publisher.Flux;
+import reactor.core.scheduler.Schedulers;
+
+import java.io.IOException;
+import java.net.URL;
+import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Consumer;
 
 /**
  * The default implementation of {@link ChatClient} as created by the
@@ -393,6 +392,8 @@ public static class DefaultCallResponseSpec implements CallResponseSpec {
 
 		private final DefaultChatClientRequestSpec request;
 
+		private final ThreadLocal<Optional<ChatResponse>> memoizedResponse = ThreadLocal.withInitial(Optional::empty);
+
 		public DefaultCallResponseSpec(DefaultChatClientRequestSpec request) {
 			Assert.notNull(request, "request cannot be null");
 			this.request = request;
@@ -506,13 +507,16 @@ private static String getContentFromChatResponse(@Nullable ChatResponse chatResp
 		@Override
 		@Nullable
 		public ChatResponse chatResponse() {
-			return doGetChatResponse();
+			final var chatResponse = memoizedResponse.get().orElseGet(this::doGetChatResponse);
+			memoizedResponse.set(Optional.ofNullable(chatResponse));
+			return chatResponse;
 		}
 
 		@Override
 		@Nullable
 		public String content() {
-			ChatResponse chatResponse = doGetChatResponse();
+			final var chatResponse = memoizedResponse.get().orElseGet(this::doGetChatResponse);
+			memoizedResponse.set(Optional.ofNullable(chatResponse));
 			return getContentFromChatResponse(chatResponse);
 		}
 
@@ -522,6 +526,8 @@ public static class DefaultStreamResponseSpec implements StreamResponseSpec {
 
 		private final DefaultChatClientRequestSpec request;
 
+		private final ThreadLocal<Optional<Flux<ChatResponse>>> memoizedFlux = ThreadLocal.withInitial(Optional::empty);
+
 		public DefaultStreamResponseSpec(DefaultChatClientRequestSpec request) {
 			Assert.notNull(request, "request cannot be null");
 			this.request = request;
@@ -559,12 +565,18 @@ private Flux<ChatResponse> doGetObservableFluxChatResponse(DefaultChatClientRequ
 
 		@Override
 		public Flux<ChatResponse> chatResponse() {
-			return doGetObservableFluxChatResponse(this.request);
+			final var chatResponseFlux = memoizedFlux.get()
+				.orElseGet(() -> doGetObservableFluxChatResponse(this.request));
+			memoizedFlux.set(Optional.of(chatResponseFlux));
+			return chatResponseFlux;
 		}
 
 		@Override
 		public Flux<String> content() {
-			return doGetObservableFluxChatResponse(this.request).map(r -> {
+			final var chatResponseFlux = memoizedFlux.get()
+				.orElseGet(() -> doGetObservableFluxChatResponse(this.request));
+			memoizedFlux.set(Optional.of(chatResponseFlux));
+			return chatResponseFlux.map(r -> {
 				if (r.getResult() == null || r.getResult().getOutput() == null
 						|| r.getResult().getOutput().getText() == null) {
 					return "";