shardingsphere-features/shardingsphere-sharding/shardingsphere-sharding-common/src/main/java/org/apache/shardingsphere/sharding/strategy/algorithm/sharding/DatetimeShardingAlgorithm.java

/*
 * 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.shardingsphere.sharding.strategy.algorithm.sharding;

import com.google.common.base.Preconditions;
import lombok.Getter;
import lombok.Setter;
import org.apache.shardingsphere.sharding.api.sharding.standard.PreciseShardingValue;
import org.apache.shardingsphere.sharding.api.sharding.standard.RangeShardingValue;
import org.apache.shardingsphere.sharding.api.sharding.standard.StandardShardingAlgorithm;

import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.Properties;

/**
 * Datetime sharding algorithm.
 * 
 * <p>Shard by `y = floor(x/v)` algorithm, which means y begins from 0.
 * v is `PARTITION_SECONDS`, and the minimum time unit is 1 sec.
 * `EPOCH` decides the beginning datetime to shard. </p>
 */
public final class DatetimeShardingAlgorithm implements StandardShardingAlgorithm<Comparable<?>> {
    
    private static final String PARTITION_SECONDS = "partition.seconds";
    
    private static final String EPOCH = "epoch";
    
    private static final String DATETIME_PATTERN = "yyyy-MM-dd HH:mm:ss";
    
    private static final DateTimeFormatter DATE_FORMAT = DateTimeFormatter.ofPattern(DATETIME_PATTERN);
    
    @Getter
    @Setter
    private Properties properties = new Properties();
    
    @Override
    public String doSharding(final Collection<String> availableTargetNames, final PreciseShardingValue<Comparable<?>> shardingValue) {
        checkProperties();
        for (String each : availableTargetNames) {
            if (each.endsWith(doSharding(parseDate(shardingValue.getValue())) + "")) {
                return each;
            }
        }
        throw new UnsupportedOperationException();
    }
    
    @Override
    public Collection<String> doSharding(final Collection<String> availableTargetNames, final RangeShardingValue<Comparable<?>> shardingValue) {
        checkProperties();
        Collection<String> result = new LinkedHashSet<>(availableTargetNames.size());
        int firstPartition = doSharding(parseDate(shardingValue.getValueRange().lowerEndpoint()));
        int lastPartition = doSharding(parseDate(shardingValue.getValueRange().upperEndpoint()));
        for (int i = firstPartition; i <= lastPartition; i++) {
            for (String each : availableTargetNames) {
                if (each.endsWith(i + "")) {
                    result.add(each);
                }
                if (result.size() == availableTargetNames.size()) {
                    return result;
                }
            }
        }
        return result;
    }
    
    private int doSharding(final long shardingValue) {
        int position = (int) (Math.floor(shardingValue / getPartitionValue()));
        return Math.max(0, position);
    }
    
    private void checkProperties() {
        Preconditions.checkNotNull(properties.get(PARTITION_SECONDS), "Sharding partition volume cannot be null.");
        Preconditions.checkState(null != properties.get(EPOCH) && checkDatetimePattern(properties.get(EPOCH).toString()), "%s pattern is required.", DATETIME_PATTERN);
    }
    
    private boolean checkDatetimePattern(final String datetime) {
        try {
            DATE_FORMAT.parse(datetime);
            return true;
        } catch (final DateTimeParseException ex) {
            return false;
        }
    }
    
    private long parseDate(final Comparable<?> shardingValue) {
        LocalTime dateValue = LocalTime.parse(shardingValue.toString(), DATE_FORMAT);
        if (null != properties.get(EPOCH)) {
            return parseDate(dateValue);
        }
        return dateValue.getSecond();
    }
    
    private Long parseDate(final LocalTime dateValue) {
        LocalTime sinceDate = LocalTime.parse(properties.get(EPOCH).toString(), DATE_FORMAT);
        return (long) (dateValue.getSecond() - sinceDate.getSecond());
    }
    
    private long getPartitionValue() {
        return Long.parseLong(properties.get(PARTITION_SECONDS).toString());
    }
    
    @Override
    public String getType() {
        return "DATETIME";
    }
}