org.waveprotocol.box.server.persistence.blocks.impl.aggregator.AggregationLevel.java Source code

Introduction

Here is the source code for org.waveprotocol.box.server.persistence.blocks.impl.aggregator.AggregationLevel.java

Source

/**
 * 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.waveprotocol.box.server.persistence.blocks.impl.aggregator;

import org.waveprotocol.box.server.persistence.blocks.VersionNode;

import org.waveprotocol.wave.model.operation.wave.WaveletOperation;
import org.waveprotocol.wave.model.util.CollectionUtils;
import org.waveprotocol.wave.model.util.Preconditions;
import org.waveprotocol.wave.model.wave.undo.WaveAggregateOp;

import com.google.common.collect.ImmutableList;

import java.util.List;

/**
 * @author akaplanov@gmail.com (A. Kaplanov)
 */
class AggregationLevel {
    private final int base;
    private final int level;
    private final List<AggregationJump> toCompose = CollectionUtils.newLinkedList();

    /**
     * Creates aggregation on fragment.
     */
    AggregationLevel(int base, int level, VersionNode startNode, VersionNode endNode) {
        this.base = base;
        this.level = level;
        initState(startNode, endNode);
    }

    /**
     * Gets source aggregation node.
     */
    VersionNode getSourceNode() {
        if (toCompose.isEmpty()) {
            return null;
        }
        return toCompose.get(0).getSourceNode();
    }

    /**
     * Adds composed operation from previous node.
     *
     * @param jump aggregation jump from previous level.
     * @return aggregation jump from this level or null.
     */
    AggregationJump addJump(AggregationJump jump) {
        toCompose.add(jump);
        AggregationJump composeJump = null;
        if (toCompose.size() == base) {
            composeJump = compose(toCompose, level);
            toCompose.clear();
        }
        return composeJump;
    }

    /**
     * Completes aggregation operations.
     */
    AggregationJump complete() {
        AggregationJump jump = null;
        if (!toCompose.isEmpty()) {
            jump = aggregate(toCompose, level);
            toCompose.clear();
        }
        return jump;
    }

    private void initState(VersionNode startNode, VersionNode endNode) {
        int pecursiveComposeStep = (int) Math.pow(base, level);
        List<AggregationJump> pecursiveCompose = CollectionUtils.newLinkedList();
        for (VersionNode node = startNode; node != endNode; node = node.getNextNode()) {
            AggregationJump op = new AggregationJump(node, node.getNextNode(),
                    node.getNextNode().getFromPreviousVersionOperation());
            pecursiveCompose.add(op);
            if (pecursiveCompose.size() == pecursiveComposeStep) {
                AggregationJump jump = aggregate(pecursiveCompose, level - 1);
                toCompose.add(jump);
                pecursiveCompose.clear();
            }
        }
    }

    private static AggregationJump aggregate(List<AggregationJump> toAggregate, int level) {
        if (toAggregate.size() > 1) {
            return compose(toAggregate, level);
        } else {
            return concatenate(toAggregate, level);
        }
    }

    private static AggregationJump compose(List<AggregationJump> toCompose, int level) {
        Preconditions.checkArgument(toCompose.size() > 1, "Operations list to compose size < 2");
        VersionNode sourceVersion = toCompose.get(0).getSourceNode();
        VersionNode targetVersion = toCompose.get(toCompose.size() - 1).getTargetNode();
        List<WaveAggregateOp> operations = CollectionUtils.newLinkedList();
        for (AggregationJump segmentOperation : toCompose) {
            if (segmentOperation.getOperations() != null) {
                for (WaveletOperation operation : segmentOperation.getOperations()) {
                    operations.add(WaveAggregateOp.createAggregate(operation));
                }
            }
        }
        ImmutableList<WaveletOperation> composed = ImmutableList.of();
        if (!operations.isEmpty()) {
            composed = WaveAggregateOp.compose(operations)
                    .toWaveletOperationsWithVersions(targetVersion.getVersion(), null);
        }
        return new AggregationJump(sourceVersion, targetVersion, composed, level, true);
    }

    private static AggregationJump concatenate(List<AggregationJump> toConcatenate, int level) {
        Preconditions.checkArgument(!toConcatenate.isEmpty(), "Operations list to concatenate size is empty");
        VersionNode sourceVersion = toConcatenate.get(0).getSourceNode();
        VersionNode targetVersion = toConcatenate.get(toConcatenate.size() - 1).getTargetNode();
        ImmutableList.Builder<WaveletOperation> concatenated = ImmutableList.builder();
        for (AggregationJump jump : toConcatenate) {
            if (jump.getOperations() != null) {
                concatenated.addAll(jump.getOperations());
            }
        }
        return new AggregationJump(sourceVersion, targetVersion, concatenated.build(), level, false);
    }
}