org.apache.lucene.store.IOContext.java Source code

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Here is the source code for org.apache.lucene.store.IOContext.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.lucene.store;

/**
 * IOContext holds additional details on the merge/search context. A IOContext
 * object can never be initialized as null as passed as a parameter to either
 * {@link org.apache.lucene.store.Directory#openInput(String, IOContext)} or
 * {@link org.apache.lucene.store.Directory#createOutput(String, IOContext)}
 */
public class IOContext {

    /**
     * Context is a enumerator which specifies the context in which the Directory
     * is being used for.
     */
    public enum Context {
        MERGE, READ, FLUSH, DEFAULT
    };

    /**
     * An object of a enumerator Context type
     */
    public final Context context;

    public final MergeInfo mergeInfo;

    public final FlushInfo flushInfo;

    public final boolean readOnce;

    public static final IOContext DEFAULT = new IOContext(Context.DEFAULT);

    public static final IOContext READONCE = new IOContext(true);

    public static final IOContext READ = new IOContext(false);

    public IOContext() {
        this(false);
    }

    public IOContext(FlushInfo flushInfo) {
        assert flushInfo != null;
        this.context = Context.FLUSH;
        this.mergeInfo = null;
        this.readOnce = false;
        this.flushInfo = flushInfo;
    }

    public IOContext(Context context) {
        this(context, null);
    }

    private IOContext(boolean readOnce) {
        this.context = Context.READ;
        this.mergeInfo = null;
        this.readOnce = readOnce;
        this.flushInfo = null;
    }

    public IOContext(MergeInfo mergeInfo) {
        this(Context.MERGE, mergeInfo);
    }

    private IOContext(Context context, MergeInfo mergeInfo) {
        assert context != Context.MERGE || mergeInfo != null : "MergeInfo must not be null if context is MERGE";
        assert context != Context.FLUSH : "Use IOContext(FlushInfo) to create a FLUSH IOContext";
        this.context = context;
        this.readOnce = false;
        this.mergeInfo = mergeInfo;
        this.flushInfo = null;
    }

    /**
     * This constructor is used to initialize a {@link IOContext} instance with a new value for the readOnce variable. 
     * @param ctxt {@link IOContext} object whose information is used to create the new instance except the readOnce variable.
     * @param readOnce The new {@link IOContext} object will use this value for readOnce. 
     */
    public IOContext(IOContext ctxt, boolean readOnce) {
        this.context = ctxt.context;
        this.mergeInfo = ctxt.mergeInfo;
        this.flushInfo = ctxt.flushInfo;
        this.readOnce = readOnce;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((context == null) ? 0 : context.hashCode());
        result = prime * result + ((flushInfo == null) ? 0 : flushInfo.hashCode());
        result = prime * result + ((mergeInfo == null) ? 0 : mergeInfo.hashCode());
        result = prime * result + (readOnce ? 1231 : 1237);
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        IOContext other = (IOContext) obj;
        if (context != other.context)
            return false;
        if (flushInfo == null) {
            if (other.flushInfo != null)
                return false;
        } else if (!flushInfo.equals(other.flushInfo))
            return false;
        if (mergeInfo == null) {
            if (other.mergeInfo != null)
                return false;
        } else if (!mergeInfo.equals(other.mergeInfo))
            return false;
        if (readOnce != other.readOnce)
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "IOContext [context=" + context + ", mergeInfo=" + mergeInfo + ", flushInfo=" + flushInfo
                + ", readOnce=" + readOnce + "]";
    }

}