com.hippo.leveldb.impl.InternalKeyComparator.java Source code

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Here is the source code for com.hippo.leveldb.impl.InternalKeyComparator.java

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/**
 * Copyright (C) 2011 the original author or authors.
 * See the notice.md file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * Licensed 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 com.hippo.leveldb.impl;

import java.util.Arrays;
import java.util.Comparator;
import java.util.Iterator;

import com.google.common.primitives.Longs;
import com.hippo.leveldb.table.UserComparator;

public class InternalKeyComparator implements Comparator<InternalKey> {
    private final UserComparator userComparator;

    public InternalKeyComparator(UserComparator userComparator) {
        this.userComparator = userComparator;
    }

    public UserComparator getUserComparator() {
        return userComparator;
    }

    public String name() {
        return this.userComparator.name();
    }

    @Override
    public int compare(InternalKey left, InternalKey right) {
        InternalKey lKey = left;
        InternalKey rKey = right;

        if (lKey.original() && !lKey.simplified()) {
            lKey = lKey.simplify();
        }
        if (rKey.original() && !rKey.simplified()) {
            rKey = rKey.simplify();
        }

        int result = userComparator.compare(lKey.getUserKey(), rKey.getUserKey());
        if (result != 0) {
            return result;
        }

        if (lKey.original() && rKey.original()) {
            result = Longs.compare(right.version(), left.version());// reverse
            if (result != 0) {
                return result;
            }
        }

        return Longs.compare(right.getSequenceNumber(), left.getSequenceNumber()); // reverse sorted version numbers
    }

    /**
     * Returns {@code true} if each element in {@code iterable} after the first is
     * greater than or equal to the element that preceded it, according to this
     * ordering. Note that this is always true when the iterable has fewer than
     * two elements.
     */
    public boolean isOrdered(InternalKey... keys) {
        return isOrdered(Arrays.asList(keys));
    }

    /**
     * Returns {@code true} if each element in {@code iterable} after the first is
     * greater than or equal to the element that preceded it, according to this
     * ordering. Note that this is always true when the iterable has fewer than
     * two elements.
     */
    public boolean isOrdered(Iterable<InternalKey> keys) {
        Iterator<InternalKey> iterator = keys.iterator();
        if (!iterator.hasNext()) {
            return true;
        }

        InternalKey previous = iterator.next();
        while (iterator.hasNext()) {
            InternalKey next = iterator.next();
            if (compare(previous, next) > 0) {
                return false;
            }
            previous = next;
        }
        return true;
    }
}