com.github.pmerienne.cf.block.BlockLocker.java Source code

Introduction

Here is the source code for com.github.pmerienne.cf.block.BlockLocker.java

Source

/**
 * Copyright 2013-2015 Pierre Merienne
 *
 * 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.github.pmerienne.cf.block;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;

public class BlockLocker implements Serializable {

    private static final long serialVersionUID = 8457268238107199404L;

    private final List<Block> toProcesses = new ArrayList<>();

    private final Set<Block> lockedBlocks = new HashSet<Block>();
    private final Set<Long> lockedRows = new HashSet<Long>();
    private final Set<Long> lockedColumns = new HashSet<Long>();

    public synchronized void add(Block block) {
        this.toProcesses.add(block);
    }

    public synchronized void remove(Block block) {
        this.toProcesses.add(block);
    }

    public boolean hasBlocks() {
        return !this.toProcesses.isEmpty();
    }

    public synchronized Block getAndLockRandomBlock() {
        Block unlockedBlock = Iterables.tryFind(this.toProcesses, new Predicate<Block>() {
            @Override
            public boolean apply(Block block) {
                return isUnlocked(block);
            }
        }).orNull();

        if (unlockedBlock != null) {
            this.lock(unlockedBlock);
        }

        return unlockedBlock;
    }

    public synchronized Set<Block> getAndLockRandomBlocks() {
        Collections.shuffle(this.toProcesses);

        Set<Block> unlockedBlocks = new HashSet<>();
        Block unlockedBlock = null;
        do {
            unlockedBlock = this.getAndLockRandomBlock();
            if (unlockedBlock != null) {
                unlockedBlocks.add(unlockedBlock);
            }
        } while (unlockedBlock != null);

        return unlockedBlocks;
    }

    /**
     * Unlock all blocks in row p and all blocks in column q.
     * 
     * @param p
     * @param q
     */
    public synchronized void unlock(Block block) {
        this.lockedBlocks.remove(block);
        this.refreshLockedRowsAndColumns();
    }

    /**
     * Lock all blocks in row p and all blocks in column q.
     * 
     * @param p
     * @param q
     */
    protected synchronized void lock(Block block) {
        this.lockedBlocks.add(block);
        this.refreshLockedRowsAndColumns();
    }

    protected boolean isUnlocked(Block block) {
        return !this.lockedRows.contains(block.p) && !this.lockedColumns.contains(block.q);
    }

    protected synchronized void refreshLockedRowsAndColumns() {
        this.lockedRows.clear();
        this.lockedColumns.clear();

        for (Block lockedBlock : this.lockedBlocks) {
            this.lockedRows.add(lockedBlock.p);
            this.lockedColumns.add(lockedBlock.q);
        }
    }
}