[GitHub] [kafka] tombentley commented on a change in pull request #9136: KAFKA-10211: Add DirectoryConfigProvider

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

tombentley commented on a change in pull request #9136:
URL: https://github.com/apache/kafka/pull/9136#discussion_r467984879



##########
File path: clients/src/main/java/org/apache/kafka/common/config/provider/DirectoryConfigProvider.java
##########
@@ -0,0 +1,98 @@
+/*
+ * 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.kafka.common.config.provider;
+
+import org.apache.kafka.common.config.ConfigData;
+import org.apache.kafka.common.config.ConfigException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.FileFilter;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * An implementation of {@link ConfigProvider} based on a directory of files.
+ * Property keys correspond to the names of the regular (i.e. non-directory)
+ * files in a directory given by the path parameter.
+ * Property values are taken from the file contents corresponding to each key.
+ */
+public class DirectoryConfigProvider implements ConfigProvider {
+
+    private final Logger log = LoggerFactory.getLogger(getClass());
+
+    @Override
+    public void configure(Map<String, ?> configs) { }
+
+    @Override
+    public void close() throws IOException { }
+
+    /**
+     * Retrieves the data contained in regular files in the directory given by {@code path}.
+     * Non-regular files (such as directories) in the given directory are silently ignored.
+     * @param path the directory where data files reside.
+     * @return the configuration data.
+     */
+    @Override
+    public ConfigData get(String path) {
+        return get(path, File::isFile);
+    }
+
+    /**
+     * Retrieves the data contained in the regular files named by {@code keys} in the directory given by {@code path}.
+     * Non-regular files (such as directories) in the given directory are silently ignored.
+     * @param path the directory where data files reside.
+     * @param keys the keys whose values will be retrieved.
+     * @return the configuration data.
+     */
+    @Override
+    public ConfigData get(String path, Set<String> keys) {
+        return get(path, pathname ->
+                pathname.isFile()
+                        && keys.contains(pathname.getName()));
+    }
+
+    private ConfigData get(String path, FileFilter fileFilter) {
+        Map<String, String> map = new HashMap<>();
+        if (path != null && !path.isEmpty()) {
+            File dir = new File(path);
+            if (!dir.isDirectory()) {
+                log.warn("The path {} is not a directory", path);
+            } else {
+                for (File file : dir.listFiles(fileFilter)) {

Review comment:
       That's a good point about null being used for the error case as well as the directory case. Thanks.




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