[improve][broker]Enable custom metadata stores

pulsar-metadata/src/main/java/org/apache/pulsar/metadata/api/MetadataStoreProvider.java

@@ -0,0 +1,37 @@
+/*
+ * 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.pulsar.metadata.api;
+
+public interface MetadataStoreProvider {
+
+
+    /**
+     * Scheme of the urls that MetadataSores provided by this object can handle.
+     */
+    String urlScheme();
+
+    /**
+     * Creates a new MetadataStore.
+     * @throws MetadataStoreException if any exception happens while creating the metadata store.
+     */
+    MetadataStore create(
+            String metadataURL,
+            MetadataStoreConfig metadataStoreConfig,
+            boolean enableSessionWatcher) throws MetadataStoreException;
+}

pulsar-metadata/src/main/java/org/apache/pulsar/metadata/impl/MetadataStoreFactoryImpl.java

@@ -18,13 +18,26 @@
  */
 package org.apache.pulsar.metadata.impl;
 
+import java.util.HashMap;
+import java.util.Map;
+import lombok.extern.slf4j.Slf4j;
 import org.apache.pulsar.metadata.api.MetadataStore;
 import org.apache.pulsar.metadata.api.MetadataStoreConfig;
 import org.apache.pulsar.metadata.api.MetadataStoreException;
+import org.apache.pulsar.metadata.api.MetadataStoreProvider;
 import org.apache.pulsar.metadata.api.extended.MetadataStoreExtended;
 
+@Slf4j
 public class MetadataStoreFactoryImpl {
 
+    public static final String METADATASTORE_PROVIDERS_PROPERTY = "pulsar.metadatastore.providers";
+
+    private static Map<String, MetadataStoreProvider> providers;
+
+    static {
+        loadProviders();
+    }
+
     public static MetadataStore create(String metadataURL, MetadataStoreConfig metadataStoreConfig) throws
             MetadataStoreException {
         return newInstance(metadataURL, metadataStoreConfig, false);
@@ -45,7 +58,7 @@ public static MetadataStoreExtended createExtended(String metadataURL, MetadataS
     private static MetadataStore newInstance(String metadataURL, MetadataStoreConfig metadataStoreConfig,
                                              boolean enableSessionWatcher)
             throws MetadataStoreException {
-
+        MetadataStoreProvider provider;
         if (metadataURL.startsWith(LocalMemoryMetadataStore.MEMORY_SCHEME_IDENTIFIER)) {
             return new LocalMemoryMetadataStore(metadataURL, metadataStoreConfig);
         } else if (metadataURL.startsWith(RocksdbMetadataStore.ROCKSDB_SCHEME_IDENTIFIER)) {
@@ -55,11 +68,42 @@ private static MetadataStore newInstance(String metadataURL, MetadataStoreConfig
         } else if (metadataURL.startsWith(ZKMetadataStore.ZK_SCHEME_IDENTIFIER)) {
             return new ZKMetadataStore(metadataURL.substring(ZKMetadataStore.ZK_SCHEME_IDENTIFIER.length()),
                     metadataStoreConfig, enableSessionWatcher);
+        } else if ((provider = findProvider(metadataURL)) != null){
+            return provider.create(metadataURL, metadataStoreConfig, enableSessionWatcher);
         } else {
             return new ZKMetadataStore(metadataURL, metadataStoreConfig, enableSessionWatcher);
         }
     }
 
+    static void loadProviders() {
+        String factoryClasses = System.getProperty(METADATASTORE_PROVIDERS_PROPERTY);
+        providers = new HashMap<>();
+        if (factoryClasses == null) {
+            return;
+        }
+        String[] classNames = factoryClasses.split(",");
+        for (String className : classNames) {
+            try {
+                Class<? extends MetadataStoreProvider> clazz =
+                        (Class<? extends MetadataStoreProvider>) Class.forName(className);
+                MetadataStoreProvider provider = clazz.getConstructor().newInstance();
+                String scheme = provider.urlScheme();
+                providers.put(scheme, provider);
+            } catch (Exception e) {
+                log.warn("Failed to load metadata store provider class for name '{}'", className, e);
+            }
+        }
+    }
+
+    private static MetadataStoreProvider findProvider(String metadataURL) {
+        for (Map.Entry<String, MetadataStoreProvider> entry : providers.entrySet()) {
+            if (metadataURL.startsWith(entry.getKey())) {
+                return entry.getValue();
+            }
+        }
+        return null;
+    }
+
     /**
      * Removes the identifier from the full metadata url.
      *
@@ -70,6 +114,7 @@ private static MetadataStore newInstance(String metadataURL, MetadataStoreConfig
      * @return
      */
     public static String removeIdentifierFromMetadataURL(String metadataURL) {
+        MetadataStoreProvider provider;
         if (metadataURL.startsWith(LocalMemoryMetadataStore.MEMORY_SCHEME_IDENTIFIER)) {
             return metadataURL.substring(LocalMemoryMetadataStore.MEMORY_SCHEME_IDENTIFIER.length());
         } else if (metadataURL.startsWith(RocksdbMetadataStore.ROCKSDB_SCHEME_IDENTIFIER)) {
@@ -78,6 +123,8 @@ public static String removeIdentifierFromMetadataURL(String metadataURL) {
             return metadataURL.substring(EtcdMetadataStore.ETCD_SCHEME_IDENTIFIER.length());
         } else if (metadataURL.startsWith(ZKMetadataStore.ZK_SCHEME_IDENTIFIER)) {
             return metadataURL.substring(ZKMetadataStore.ZK_SCHEME_IDENTIFIER.length());
+        } else if ((provider = findProvider(metadataURL)) != null) {
+            return metadataURL.substring(provider.urlScheme().length());
         }
         return metadataURL;
     }

pulsar-metadata/src/test/java/org/apache/pulsar/metadata/impl/MetadataStoreFactoryImplTest.java

@@ -0,0 +1,125 @@
+/*
+ * 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.pulsar.metadata.impl;
+
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertTrue;
+import org.apache.pulsar.metadata.api.GetResult;
+import org.apache.pulsar.metadata.api.MetadataStore;
+import org.apache.pulsar.metadata.api.MetadataStoreConfig;
+import org.apache.pulsar.metadata.api.MetadataStoreException;
+import org.apache.pulsar.metadata.api.MetadataStoreProvider;
+import org.apache.pulsar.metadata.api.Stat;
+import org.apache.pulsar.metadata.api.extended.CreateOption;
+import org.testng.annotations.AfterClass;
+import org.testng.annotations.BeforeClass;
+import org.testng.annotations.Test;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+
+public class MetadataStoreFactoryImplTest {
+
+    private static Object originalProperty;
+
+    @BeforeClass
+    public void setMetadataStoreProperty() {
+        originalProperty = System.getProperties().get(MetadataStoreFactoryImpl.METADATASTORE_PROVIDERS_PROPERTY);
+        System.setProperty(MetadataStoreFactoryImpl.METADATASTORE_PROVIDERS_PROPERTY,
+                MyMetadataStoreProvider.class.getName());
+        MetadataStoreFactoryImpl.loadProviders();
+    }
+
+    @AfterClass
+    public void resetMetadataStoreProperty() {
+        if (originalProperty != null) {
+            System.getProperties().put(MetadataStoreFactoryImpl.METADATASTORE_PROVIDERS_PROPERTY, originalProperty);
+        }
+        MetadataStoreFactoryImpl.loadProviders();
+    }
+
+
+    @Test
+    public void testCreateWithProvider() throws MetadataStoreException{
+        MetadataStore instance = MetadataStoreFactoryImpl.create(
+                "custom://localhost",
+                MetadataStoreConfig.builder().build());
+        assertTrue(instance instanceof MyMetadataStore);
+    }
+
+
+    @Test
+    public void testRemoveIdentifierFromMetadataURL() {
+        assertEquals(MetadataStoreFactoryImpl.removeIdentifierFromMetadataURL("zk:host:port"), "host:port");
+        assertEquals(MetadataStoreFactoryImpl.removeIdentifierFromMetadataURL("rocksdb:/data/dir"), "/data/dir");
+        assertEquals(MetadataStoreFactoryImpl.removeIdentifierFromMetadataURL("etcd:host:port"), "host:port");
+        assertEquals(MetadataStoreFactoryImpl.removeIdentifierFromMetadataURL("memory:name"), "name");
+        assertEquals(MetadataStoreFactoryImpl.removeIdentifierFromMetadataURL("http://unknown/url/scheme"), "http://unknown/url/scheme");
+        assertEquals(MetadataStoreFactoryImpl.removeIdentifierFromMetadataURL("custom:suffix"), "suffix");
+    }
+
+    public static class MyMetadataStoreProvider implements MetadataStoreProvider {
+
+        @Override
+        public String urlScheme() {
+            return "custom:";
+        }
+
+        @Override
+        public MetadataStore create(String metadataURL, MetadataStoreConfig metadataStoreConfig,
+                                    boolean enableSessionWatcher) throws MetadataStoreException {
+            return new MyMetadataStore();
+        }
+    }
+
+    public static class MyMetadataStore extends AbstractMetadataStore {
+        protected MyMetadataStore() {
+            super("custom");
+        }
+
+        @Override
+        protected CompletableFuture<List<String>> getChildrenFromStore(String path) {
+            return null;
+        }
+
+        @Override
+        protected CompletableFuture<Boolean> existsFromStore(String path) {
+            return null;
+        }
+
+        @Override
+        protected CompletableFuture<Optional<GetResult>> storeGet(String path) {
+            return null;
+        }
+
+        @Override
+        protected CompletableFuture<Void> storeDelete(String path, Optional<Long> expectedVersion) {
+            return null;
+        }
+
+        @Override
+        protected CompletableFuture<Stat> storePut(String path, byte[] data, Optional<Long> optExpectedVersion,
+                                                   EnumSet<CreateOption> options) {
+            return null;
+        }
+    }
+
+
+}