Reload DocService on server reconfigure (#4513)

Motivation:

Previously, `DocService` wasn't able to handle the changed services as a result of `reconfigure`.

```
sb = Server.builder()
           .annotatedService("/hello", new HelloService())
           .serviceUnder("/docs", DocService.builder().build())
...
sb.reconfigure(sb2 -> sb2.annotatedService("/hello2", new HelloService())
                                             .serviceUnder("/docs", DocService.builder().build()))
```

- If a shared `DocService` is used, services wouldn't be updated and the old specification would be used.
- If a new `DocService` is added, appropriate callbacks wouldn't be called and `/specifications.json` would result in a 404.

https://github.com/line/armeria/blob/cae3b6da373101c0976e2d00f1f3cbb706d07e00/core/src/main/java/com/linecorp/armeria/server/docs/DocService.java#L217-L220

We may note that `Server#configs` is immutable, and that `Server#configs` is fixed at the timing when the `serviceAdded` callback is called.

https://github.com/line/armeria/blob/cae3b6da373101c0976e2d00f1f3cbb706d07e00/core/src/main/java/com/linecorp/armeria/server/DefaultServerConfig.java#L246

Modifications:

- Change the timing when `DocService#specifications` is loaded to `DecoratingService#serviceAdded`.

Result:

- Users can use `DocService` even when `Server#reconfigure` is called.

Note: This PR contains changes from #4491 .  Review this PR first 🙏

core/src/main/java/com/linecorp/armeria/server/docs/DocService.java

@@ -64,7 +64,6 @@
 import com.linecorp.armeria.server.HttpService;
 import com.linecorp.armeria.server.Server;
 import com.linecorp.armeria.server.ServerConfig;
-import com.linecorp.armeria.server.ServerListenerAdapter;
 import com.linecorp.armeria.server.Service;
 import com.linecorp.armeria.server.ServiceConfig;
 import com.linecorp.armeria.server.ServiceRequestContext;
@@ -189,23 +188,18 @@ public void serviceAdded(ServiceConfig cfg) throws Exception {
  server = cfg.server();
 
  // Build the Specification after all the services are added to the server.
- server.addListener(new ServerListenerAdapter() {
- @Override
- public void serverStarting(Server server) throws Exception {
- final ServerConfig config = server.config();
- final List<VirtualHost> virtualHosts = config.findVirtualHosts(DocService.this);
-
- final List<ServiceConfig> services =
- config.serviceConfigs().stream()
- .filter(se -> virtualHosts.contains(se.virtualHost()))
- .collect(toImmutableList());
- final ExecutorService executorService = Executors.newSingleThreadExecutor(
- ThreadFactories.newThreadFactory("docservice-loader", true));
- vfs().specificationLoader.updateServices(services, executorService).handle((res, e) -> {
- executorService.shutdown();
- return null;
- });
- }
+ final ServerConfig config = server.config();
+ final List<VirtualHost> virtualHosts = config.findVirtualHosts(this);
+
+ final List<ServiceConfig> services =
+ config.serviceConfigs().stream()
+ .filter(se -> virtualHosts.contains(se.virtualHost()))
+ .collect(toImmutableList());
+ final ExecutorService executorService = Executors.newSingleThreadExecutor(
+ ThreadFactories.newThreadFactory("docservice-loader", true));
+ vfs().specificationLoader.updateServices(services, executorService).handle((res, e) -> {
+ executorService.shutdown();
+ return null;
  });
  }
 

core/src/test/java/com/linecorp/armeria/server/docs/DocServiceReconfigureTest.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2022 LINE Corporation
+ *
+ * LINE Corporation 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:
+ *
+ * https://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 com.linecorp.armeria.server.docs;
+
+import static net.javacrumbs.jsonunit.fluent.JsonFluentAssert.assertThatJson;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import com.linecorp.armeria.server.ServerBuilder;
+import com.linecorp.armeria.server.annotation.Get;
+import com.linecorp.armeria.testing.junit5.server.ServerExtension;
+
+class DocServiceReconfigureTest {
+
+ @RegisterExtension
+ static ServerExtension server = new ServerExtension() {
+ @Override
+ protected void configure(ServerBuilder sb) throws Exception {
+ sb.annotatedService("/service", new Object() {
+ @Get("/before")
+ public void before() {
+ }
+ });
+ sb.serviceUnder("/docs", DocService.builder().build());
+ }
+ };
+
+ @Test
+ void testReconfigure() {
+ String specification = server.blockingWebClient().get("/docs/specification.json").contentUtf8();
+ assertThatJson(specification).node("services").isArray().ofLength(1);
+ assertThatJson(specification).node("services[0].methods").isArray().ofLength(1);
+ assertThatJson(specification).node("services[0].methods[0].name").isEqualTo("before");
+
+ server.server().reconfigure(sb -> {
+ sb.annotatedService("/service", new Object() {
+ @Get("/after")
+ public void after() {
+ }
+ });
+ sb.serviceUnder("/docs", DocService.builder().build());
+ });
+
+ specification = server.blockingWebClient().get("/docs/specification.json").contentUtf8();
+ assertThatJson(specification).node("services").isArray().ofLength(1);
+ assertThatJson(specification).node("services[0].methods").isArray().ofLength(1);
+ assertThatJson(specification).node("services[0].methods[0].name").isEqualTo("after");
+ }
+}