| /* |
| * 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.drill.exec.store; |
| |
| import java.util.Collection; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.Map; |
| import java.util.Set; |
| |
| import org.apache.drill.common.logical.StoragePluginConfig; |
| import org.apache.drill.common.map.CaseInsensitiveMap; |
| import org.apache.drill.exec.store.StoragePluginRegistry.PluginException; |
| import org.apache.drill.shaded.guava.com.google.common.base.Preconditions; |
| |
| /** |
| * Holds maps to storage plugins. Supports name => plugin and config => plugin |
| * mappings. Name map is case insensitive. Assumes a unique config => plugin |
| * mapping. This map holds only enabled plugins; those which are disabled appear |
| * only in the persistent store. |
| * <p> |
| * The two maps are synchronized by this class, allowing the maps themselves |
| * to not be of the concurrent variety. |
| * <p> |
| * This is inspired by ConcurrentMap but provides a secondary key mapping that allows an alternative lookup mechanism. |
| * The class is responsible for internally managing consistency between the two maps. This class is threadsafe. |
| * Name map is case insensitive. |
| * |
| * <h4>Concurrency</h4> |
| * |
| * All map access is protected to avoid race conditions across the two maps. |
| * Callers should generally remove/replace methods which take the old value |
| * as a form of optimistic concurrency: the change is made only if the value |
| * found in the map is that which is expected. |
| * <p> |
| * Plugin open and close is <b>not</b> done in this map as both operations |
| * could take considerable time and must not hold locks. The caller is |
| * responsible for checking return statuses and performing the needed |
| * close. (The one exception is final close, which is done here.) |
| */ |
| class StoragePluginMap implements Iterable<PluginHandle>, AutoCloseable { |
| |
| private final Map<String, PluginHandle> nameMap = CaseInsensitiveMap.newHashMap(); |
| private final Map<StoragePluginConfig, PluginHandle> configMap = new HashMap<>(); |
| |
| /** |
| * Put a plugin. Replaces, and closes, any existing plugin. Safe for putting |
| * the same plugin twice. Also safe for putting a different |
| * |
| * @return the replaced entry, if any, which the caller should close |
| * @throws PluginException for an attempt to replace a system plugin |
| */ |
| public synchronized PluginHandle put(PluginHandle plugin) throws PluginException { |
| PluginHandle oldPlugin = nameMap.put(plugin.name(), plugin); |
| if (oldPlugin != null) { |
| if (oldPlugin == plugin || oldPlugin.config().equals(plugin.config())) { |
| return null; |
| } |
| if (oldPlugin.isIntrinsic()) { |
| // Put the old one back |
| nameMap.put(oldPlugin.name(), oldPlugin); |
| throw PluginException.systemPluginException("replace", plugin.name()); |
| } |
| configMap.remove(oldPlugin.config()); |
| } |
| configMap.put(plugin.config(), plugin); |
| return oldPlugin; |
| } |
| |
| /** |
| * Put the given plugin, but only if no plugin already exists for the |
| * name. |
| * @param plugin the new plugin |
| * @return the resulting entry, the old one that already existed, |
| * or the new one |
| */ |
| public synchronized PluginHandle putIfAbsent(PluginHandle plugin) { |
| PluginHandle oldPlugin = nameMap.putIfAbsent(plugin.name(), plugin); |
| if (oldPlugin != null) { |
| return oldPlugin; |
| } else { |
| configMap.put(plugin.config(), plugin); |
| return plugin; |
| } |
| } |
| |
| public synchronized PluginHandle get(String name) { |
| return nameMap.get(name); |
| } |
| |
| /** |
| * Retrieve a plugin by config. Configs are compared by value: two instances |
| * with the same values compare as identical (assuming the plugin config |
| * implementation is correct.) |
| */ |
| public synchronized PluginHandle get(StoragePluginConfig config) { |
| return configMap.get(config); |
| } |
| |
| /** |
| * Replaces one plugin with another, but only if the map contains the old |
| * one. |
| * |
| * @param oldPlugin the expected old plugin to be replaced |
| * @param newPlugin the new plugin to insert |
| * @return true if the new plugin was inserted, false if not because |
| * the old plugin was not found in the map |
| * @throws PluginException for an attempt to replace a system plugin |
| */ |
| public synchronized boolean replace(PluginHandle oldPlugin, PluginHandle newPlugin) |
| throws PluginException { |
| Preconditions.checkArgument(oldPlugin != null); |
| Preconditions.checkArgument(newPlugin != null); |
| Preconditions.checkArgument(oldPlugin.name().equalsIgnoreCase(newPlugin.name())); |
| Preconditions.checkArgument(oldPlugin != newPlugin); |
| if (oldPlugin.isIntrinsic()) { |
| throw PluginException.systemPluginException("replace", oldPlugin.name()); |
| } |
| boolean ok = nameMap.replace(oldPlugin.name(), oldPlugin, newPlugin); |
| if (ok) { |
| configMap.remove(oldPlugin.config(), oldPlugin); |
| configMap.put(newPlugin.config(), newPlugin); |
| } |
| return ok; |
| } |
| |
| /** |
| * Removes and returns a plugin by name and closes it. This form is not |
| * concurrency-safe: another user could have deleted and recreated the |
| * plugin between the time the current user viewed the plugin and decided |
| * to delete it. |
| * |
| * @return the doomed plugin if the plugin was removed, null if there was |
| * no entry by the given name |
| * @throws PluginException for an attempt to remove a system plugin |
| * @see {@link #remove(PluginHandle) |
| */ |
| public synchronized PluginHandle remove(String name) throws PluginException { |
| PluginHandle plugin = get(name); |
| if (plugin == null) { |
| return null; |
| } |
| if (plugin.isIntrinsic()) { |
| throw PluginException.systemPluginException("remove", name); |
| } |
| nameMap.remove(name); |
| configMap.remove(plugin.config(), plugin); |
| return plugin; |
| } |
| |
| /** |
| * Given a name and a config (which is presumed to have become disabled), |
| * remove and return any existing plugin. Only matches if the name is found and the |
| * named plugin has the same config as the one to remove to enforce |
| * optimistic concurrency. |
| * |
| * @param name plugin name |
| * @param oldConfig expected config of the doomed plugin |
| * @return true if the plugin was removed and closed, false otherwise |
| * @throws PluginException for an attempt to remove a system plugin |
| */ |
| public synchronized PluginHandle remove(String name, StoragePluginConfig oldConfig) throws PluginException { |
| PluginHandle oldEntry = nameMap.get(name); |
| if (oldEntry == null || !oldEntry.config().equals(oldConfig)) { |
| return null; |
| } |
| if (oldEntry.isIntrinsic()) { |
| throw PluginException.systemPluginException("remove", name); |
| } |
| nameMap.remove(oldEntry.name()); |
| if (configMap.remove(oldEntry.config()) != oldEntry) { |
| // This is a programming error. |
| throw new IllegalStateException(String.format( |
| "Config entry was modified while in the plugin cache: '%s', class %s", |
| name, oldConfig.getClass().getName())); |
| } |
| return oldEntry; |
| } |
| |
| @Override |
| public synchronized Iterator<PluginHandle> iterator() { |
| return nameMap.values().iterator(); |
| } |
| |
| /** |
| * Returns set of plugin names of this {@link StoragePluginMap} |
| * |
| * @return plugin names |
| */ |
| public synchronized Set<String> getNames() { |
| return nameMap.keySet(); |
| } |
| |
| public synchronized Collection<PluginHandle> plugins() { |
| return nameMap.values(); |
| } |
| |
| public synchronized Set<StoragePluginConfig> configs() { |
| return configMap.keySet(); |
| } |
| |
| // Closes all plugins. Can take some time if plugins are slow to close |
| // (Suffer network timeouts, for example.) Not synchronized as should |
| // only be done during final Drillbit shutdown. |
| @Override |
| public void close() { |
| // Plugin handles do not derive from AutoCloseable. Handles must handle |
| // any errors on close so that things work when the loading cache decides |
| // to evict a plugin. So, we just use a simple per-handle iteration here. |
| plugins().stream() |
| .forEach(e -> e.close()); |
| configMap.clear(); |
| nameMap.clear(); |
| } |
| |
| public Set<String> names() { |
| return nameMap.keySet(); |
| } |
| } |