virajjasani commented on code in PR #6789: URL: https://github.com/apache/hadoop/pull/6789#discussion_r1663043431
########## hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/FlagSet.java: ########## @@ -0,0 +1,278 @@ +/* + * 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.hadoop.fs.impl; + +import java.util.Arrays; +import java.util.EnumSet; +import java.util.List; +import java.util.Map; +import java.util.Objects; +import java.util.Set; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.stream.Collectors; +import javax.annotation.Nullable; + +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.fs.StreamCapabilities; +import org.apache.hadoop.util.ConfigurationHelper; +import org.apache.hadoop.util.Preconditions; + +import static org.apache.hadoop.util.ConfigurationHelper.mapEnumNamesToValues; + +/** + * A set of flags, constructed from a configuration option or from a string, + * with the semantics of + * {@link ConfigurationHelper#parseEnumSet(String, String, Class, boolean)} + * and implementing {@link StreamCapabilities}. + * <p> + * Thread safety: there is no synchronization on a mutable {@code FlagSet}. + * Once declared immutable, flags cannot be changed, so they + * becomes implicitly thread-safe. + */ +public final class FlagSet<E extends Enum<E>> implements StreamCapabilities { + + /** + * Set of flags. + */ + private final Set<E> flags; + + /** + * Is the set immutable? + */ + private final AtomicBoolean immutable = new AtomicBoolean(false); + + /** + * Mapping of prefixed flag names to enum values. + */ + private final Map<String, E> namesToValues; + + /** + * Create a FlagSet. + * @param enumClass class of enum + * @param prefix prefix (with trailing ".") for path capabilities probe + * @param flags flags. A copy of these are made. + */ + private FlagSet(final Class<E> enumClass, + final String prefix, + @Nullable final EnumSet<E> flags) { + + this.flags = flags != null + ? EnumSet.copyOf(flags) + : EnumSet.noneOf(enumClass); + this.namesToValues = mapEnumNamesToValues(prefix, enumClass); + } + + /** + * Get a copy of the flags. + * <p> + * This is immutable. + * @return the flags. + */ + public EnumSet<E> flags() { + return EnumSet.copyOf(flags); + } + + /** + * Probe for the FlagSet being empty. + * @return true if there are no flags set. + */ + public boolean isEmpty() { + return flags.isEmpty(); + } + + /** + * Is a flag enabled? + * @param flag flag to check + * @return true if it is in the set of enabled flags. + */ + public boolean enabled(final E flag) { + return flags.contains(flag); + } Review Comment: If we need it immutable, probably it's good case for builder or constructor so maybe keeping the object mutable is also fine? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org
