org.n52.sos.cache.AbstractCacheScheduler.java Source code

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Here is the source code for org.n52.sos.cache.AbstractCacheScheduler.java

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/**
 * Copyright (C) 2012 52North Initiative for Geospatial Open Source Software GmbH
 *
 * 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 org.n52.sos.cache;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import org.joda.time.DateTime;
import org.joda.time.LocalTime;
import org.joda.time.MutableDateTime;
import org.n52.sos.cache.quartz.QuartzCacheScheduler;
import org.n52.sos.db.AccessGDB;
import org.n52.util.CommonUtilities;
import org.n52.util.logging.Logger;

public abstract class AbstractCacheScheduler {

    private static final Logger LOGGER = Logger.getLogger(AbstractCacheScheduler.class.getName());

    public static final long ONE_HOUR_MS = 1000 * 60 * 60;
    public static final long FIFTEEN_MINS_MS = 1000 * 60 * 15;

    private List<AbstractEntityCache<?>> candidates = new ArrayList<>();
    private boolean updateCacheOnStartup;
    private AccessGDB geoDB;

    private File lockFile;

    private LocalTime cacheUpdateTime;

    public AbstractCacheScheduler(AccessGDB geoDB, boolean updateCacheOnStartup, LocalTime cacheUpdateTime) {
        this.geoDB = geoDB;
        this.updateCacheOnStartup = updateCacheOnStartup;
        this.cacheUpdateTime = cacheUpdateTime;

        String dbName;
        dbName = resolveDatabaseName(geoDB);

        /*
         * first use the PUMC, others might depend on it
         */
        try {
            candidates.add(PropertyUnitMappingCache.instance(dbName));
        } catch (FileNotFoundException e) {
            LOGGER.warn(e.getMessage(), e);
        }

        try {
            candidates.add(ObservationOfferingCache.instance(dbName));
        } catch (FileNotFoundException e) {
            LOGGER.warn(e.getMessage(), e);
        }
    }

    private String resolveDatabaseName(AccessGDB geoDB) {
        String dbName;
        if (geoDB != null) {
            dbName = geoDB.getDatabaseName();
        } else {
            dbName = "Airquality_E2a";
        }
        return dbName;
    }

    protected AccessGDB getGeoDB() {
        return this.geoDB;
    }

    public abstract void shutdown();

    public List<AbstractEntityCache<?>> getCandidates() {
        return candidates;
    }

    public boolean isUpdateCacheOnStartup() {
        return updateCacheOnStartup;
    }

    public LocalTime getCacheUpdateTime() {
        return this.cacheUpdateTime;
    }

    protected void freeCacheUpdateLock() throws IOException {
        synchronized (AbstractCacheScheduler.class) {
            File lockFile = resolveCacheLockFile();

            if (lockFile.exists()) {
                lockFile.delete();
            }
        }
    }

    protected synchronized File resolveCacheLockFile() throws FileNotFoundException {
        if (lockFile == null) {
            File dir = CommonUtilities.resolveCacheBaseDir(resolveDatabaseName(geoDB));
            lockFile = new File(dir, "cache.lock");
        }

        return lockFile;
    }

    public abstract void forceUpdate();

    public boolean isCurrentyLocked() {
        synchronized (AbstractCacheScheduler.class) {
            File lockFile;
            try {
                lockFile = resolveCacheLockFile();
            } catch (FileNotFoundException e) {
                return false;
            }

            return lockFile.exists();
        }
    }

    protected boolean retrieveCacheUpdateLock() throws IOException {
        synchronized (AbstractCacheScheduler.class) {
            File lockFile = resolveCacheLockFile();

            if (!lockFile.exists()) {
                boolean worked = lockFile.createNewFile();
                if (worked) {
                    return true;
                } else {
                    LOGGER.info("Could not create cache.lock file!");
                    return false;
                }
            }
        }

        return false;
    }

    public MutableDateTime resolveNextScheduleDate(LocalTime localTime, DateTime referenceTime) {
        /*
         * every 4am, starting with next
         */
        MutableDateTime mdt = referenceTime.toMutableDateTime();
        mdt.setHourOfDay(localTime.getHourOfDay());
        mdt.setMinuteOfHour(localTime.getMinuteOfHour());
        mdt.setSecondOfMinute(localTime.getSecondOfMinute());

        if (!referenceTime.isBefore(mdt)) {
            mdt.addDays(1);
        }

        Random random = new Random();
        mdt.addSeconds(random.nextInt(11) * 2);
        return mdt;
    }

    protected List<AbstractEntityCache<?>> cacheUpdateRequired() throws FileNotFoundException {
        List<AbstractEntityCache<?>> result = new ArrayList<>();

        for (AbstractEntityCache<?> cand : getCandidates()) {
            if (cand.requiresUpdate()) {
                result.add(cand);
            }
        }

        return result;
    }

    public static class Instance {

        private static AbstractCacheScheduler instance;

        public static synchronized AbstractCacheScheduler init(AccessGDB geoDB, boolean updateCacheOnStartup,
                LocalTime cacheUpdateTime) {
            if (instance == null) {
                instance = new QuartzCacheScheduler(geoDB, updateCacheOnStartup, cacheUpdateTime);
            }
            return instance;
        }

        public static synchronized AbstractCacheScheduler instance() {
            return instance;
        }

    }

}