org.apache.hadoop.hdfs.server.datanode.CachingStrategy.java Source code

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Here is the source code for org.apache.hadoop.hdfs.server.datanode.CachingStrategy.java

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/**
 * 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.hdfs.server.datanode;

/**
 * The caching strategy we should use for an HDFS read or write operation.
 */
public class CachingStrategy {
    private final Boolean dropBehind; // null = use server defaults
    private final Long readahead; // null = use server defaults

    public static CachingStrategy newDefaultStrategy() {
        return new CachingStrategy(null, null);
    }

    public static CachingStrategy newDropBehind() {
        return new CachingStrategy(true, null);
    }

    public static class Builder {
        private Boolean dropBehind;
        private Long readahead;

        public Builder(CachingStrategy prev) {
            this.dropBehind = prev.dropBehind;
            this.readahead = prev.readahead;
        }

        public Builder setDropBehind(Boolean dropBehind) {
            this.dropBehind = dropBehind;
            return this;
        }

        public Builder setReadahead(Long readahead) {
            this.readahead = readahead;
            return this;
        }

        public CachingStrategy build() {
            return new CachingStrategy(dropBehind, readahead);
        }
    }

    public CachingStrategy(Boolean dropBehind, Long readahead) {
        this.dropBehind = dropBehind;
        this.readahead = readahead;
    }

    public Boolean getDropBehind() {
        return dropBehind;
    }

    public Long getReadahead() {
        return readahead;
    }

    public String toString() {
        return "CachingStrategy(dropBehind=" + dropBehind + ", readahead=" + readahead + ")";
    }
}