[GitHub] [flink] zentol commented on a change in pull request #17385: [FLINK-24367][tests] Add FallbackAkkaRpcSystemLoader

[GitBox <gi...@apache.org>]

zentol commented on a change in pull request #17385:
URL: https://github.com/apache/flink/pull/17385#discussion_r720038585



##########
File path: flink-rpc/flink-rpc-akka-loader/src/test/java/org/apache/flink/runtime/rpc/akka/FallbackAkkaRpcSystemLoader.java
##########
@@ -0,0 +1,139 @@
+/*
+ * 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.runtime.rpc.akka;
+
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.core.classloading.SubmoduleClassLoader;
+import org.apache.flink.runtime.rpc.RpcSystem;
+import org.apache.flink.runtime.rpc.RpcSystemLoader;
+import org.apache.flink.util.OperatingSystem;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import java.util.ServiceLoader;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * Fallback {@link RpcSystemLoader} that does not rely on the flink-rpc-akka fat jar (like {@link
+ * AkkaRpcSystemLoader}) but instead uses the flink-rpc-akka/target/classes and maven to load the
+ * rpc system.
+ */
+public class FallbackAkkaRpcSystemLoader implements RpcSystemLoader {
+    private static final Logger LOG = LoggerFactory.getLogger(FallbackAkkaRpcSystemLoader.class);
+
+    @Override
+    public RpcSystem loadRpcSystem(Configuration config) {
+        try {
+            LOG.debug(
+                    "Using Fallback AkkaRpcSystemLoader; this loader will invoke maven to retrieve the dependencies of flink-rpc-akka.");
+
+            final ClassLoader flinkClassLoader = RpcSystem.class.getClassLoader();
+
+            // flink-rpc/flink-rpc-akka
+            final Path akkaRpcModuleDirectory =
+                    findAkkaRpcModuleDirectory(getCurrentWorkingDirectory());
+
+            // flink-rpc/flink-rpc-akka/target/classes
+            final Path akkaRpcModuleClassesDirectory =
+                    akkaRpcModuleDirectory.resolve(Paths.get("target", "classes"));
+
+            // flink-rpc/flink-rpc-akka/target/dependencies
+            final Path akkaRpcModuleDependenciesDirectory =
+                    akkaRpcModuleDirectory.resolve(Paths.get("target", "dependencies"));
+
+            if (!Files.exists(akkaRpcModuleDependenciesDirectory)) {
+                downloadDependencies(akkaRpcModuleDirectory, akkaRpcModuleDependenciesDirectory);
+            } else {
+                LOG.debug(
+                        "Re-using previously downloaded flink-rpc-akka dependencies. If you are experiencing strange issues, try clearing '{}'.",
+                        akkaRpcModuleDependenciesDirectory);
+            }
+
+            // assemble URL collection containing target/classes and each jar
+            final List<URL> urls = new ArrayList<>();
+            urls.add(akkaRpcModuleClassesDirectory.toUri().toURL());
+            try (final Stream<Path> files = Files.list(akkaRpcModuleDependenciesDirectory)) {
+                final List<Path> collect =
+                        files.filter(path -> path.getFileName().toString().endsWith(".jar"))
+                                .collect(Collectors.toList());
+
+                for (Path path : collect) {
+                    urls.add(path.toUri().toURL());
+                }
+            }
+
+            final SubmoduleClassLoader submoduleClassLoader =
+                    new SubmoduleClassLoader(urls.toArray(new URL[0]), flinkClassLoader);
+
+            return new CleanupOnCloseRpcSystem(
+                    ServiceLoader.load(RpcSystem.class, submoduleClassLoader).iterator().next(),

Review comment:
       We still want to close the classloader eventually.




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