Java tutorial
/** * 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.curator.framework.schema; import com.google.common.base.Function; import com.google.common.base.Preconditions; import com.google.common.cache.CacheBuilder; import com.google.common.cache.CacheLoader; import com.google.common.cache.LoadingCache; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableMap; import com.google.common.collect.Maps; import org.apache.curator.framework.CuratorFramework; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.Collection; import java.util.Collections; import java.util.List; import java.util.Map; import java.util.concurrent.ExecutionException; /** * Collection of all schemas for a Curator instance */ public class SchemaSet { private final Logger log = LoggerFactory.getLogger(getClass()); private final Map<String, Schema> schemas; private final Map<String, Schema> pathToSchemas; private final List<Schema> regexSchemas; private final CacheLoader<String, Schema> cacheLoader = new CacheLoader<String, Schema>() { @Override public Schema load(String path) throws Exception { for (Schema schema : regexSchemas) { if (schema.getPathRegex().matcher(path).matches()) { log.debug("path -> {}", schema); return schema; } } return nullSchema; } }; private final LoadingCache<String, Schema> regexCache = CacheBuilder.newBuilder().softValues() .build(cacheLoader); private static final Schema nullSchema = new Schema("__null__", null, "", "Null schema", new DefaultSchemaValidator(), Schema.Allowance.CAN, Schema.Allowance.CAN, Schema.Allowance.CAN, true, ImmutableMap.<String, String>of()); private static final Schema defaultSchema = new Schema("__default__", null, "", "Default schema", new DefaultSchemaValidator(), Schema.Allowance.CAN, Schema.Allowance.CAN, Schema.Allowance.CAN, true, ImmutableMap.<String, String>of()); private final boolean useDefaultSchema; /** * Return the default (empty) schema set * * @return default schema set */ public static SchemaSet getDefaultSchemaSet() { return new SchemaSet(Collections.<Schema>emptyList(), true) { @Override public String toDocumentation() { return "Default schema"; } }; } /** * Define a schema set. Schemas are matched in a well defined order: * <ol> * <li>Exact match on full path (i.e. non-regex)</li> * <li>Match on the first regex path, searched in the order given to this constructor</li> * </ol> * * @param schemas the schemas for the set. * @param useDefaultSchema if true, return a default schema when there is no match. Otherwise, an exception is thrown */ public SchemaSet(List<Schema> schemas, boolean useDefaultSchema) { schemas = Preconditions.checkNotNull(schemas, "schemas cannot be null"); this.useDefaultSchema = useDefaultSchema; this.schemas = Maps.uniqueIndex(schemas, new Function<Schema, String>() { @Override public String apply(Schema schema) { return schema.getName(); } }); ImmutableMap.Builder<String, Schema> pathBuilder = ImmutableMap.builder(); ImmutableList.Builder<Schema> regexBuilder = ImmutableList.builder(); for (Schema schema : schemas) { if (schema.getPath() != null) { pathBuilder.put(schema.getPath(), schema); } else { regexBuilder.add(schema); } } pathToSchemas = pathBuilder.build(); regexSchemas = regexBuilder.build(); } /** * Return the schemas * * @return schemas */ public Collection<Schema> getSchemas() { return schemas.values(); } /** * Find the first matching schema for the path and return it * * @param path ZNode full path * @return matching schema or a default schema */ public Schema getSchema(String path) { if (schemas.size() > 0) { Schema schema = pathToSchemas.get(path); if (schema == null) { try { schema = regexCache.get(path); if (schema.equals(nullSchema)) { schema = useDefaultSchema ? defaultSchema : null; } } catch (ExecutionException e) { throw new RuntimeException(e); } } if (schema != null) { return schema; } } if (useDefaultSchema) { return defaultSchema; } throw new SchemaViolation(null, new SchemaViolation.ViolatorData(path, null, null), "No schema found for: " + path); } /** * Utility to return a ZNode path for the given name * * @param client Curator client * @param name path/schema name * @return ZNode path */ public static String getNamedPath(CuratorFramework client, String name) { return client.getSchemaSet().getNamedSchema(name).getRawPath(); } /** * Return the schema with the given key/name * * @param name name * @return schema or null */ public Schema getNamedSchema(String name) { return schemas.get(name); } /** * Build a user displayable documentation string for the schemas in this set * * @return documentation */ public String toDocumentation() { StringBuilder str = new StringBuilder("Curator Schemas:\n\n"); for (Map.Entry<String, Schema> schemaEntry : schemas.entrySet()) { str.append(schemaEntry.getKey()).append('\n').append(schemaEntry.getValue().toDocumentation()) .append('\n'); } return str.toString(); } }