/*******************************************************************************
* Copyright 2013 André Rouél
*
* 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 net.sf.uadetector.datastore;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.concurrent.ExecutorService;
import java.util.regex.Pattern;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import net.sf.qualitycheck.Check;
import net.sf.uadetector.internal.util.ExecutorServices;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Provides a basic implementation to update UAS data in the background when calling {@link #run()}.
*
* @author André Rouél
*/
public abstract class AbstractUpdateOperation implements UpdateOperation {
/**
* Defines an empty version string
*/
private static final String EMPTY_VERSION = "";
/**
* Corresponding default logger for this class
*/
private static final Logger LOG = LoggerFactory.getLogger(AbstractUpdateOperation.class);
/**
* Message for the log when no update is available.<br>
* <br>
* <b>Message sample</b>: No update available. Current version is '<em>20120301-01</em>'.<br>
* <b>First placeholder</b>: current version
*/
private static final String MSG_NO_UPDATE_AVAILABLE = "No update available. Current version is '%s'.";
/**
* Message for the log when an online update check is not possible.<br>
* <br>
* <b>Message sample</b>: Can not check for an updated version. Are you sure you have an established internet
* connection?
*/
private static final String MSG_NO_UPDATE_CHECK_POSSIBLE = "Can not check for an updated version. Are you sure you have an established internet connection?";
/**
* Message for the log when an exception occur during the update check.<br>
* <br>
* <b>Message sample</b>: Can not check for an updated version: <em>java.net.ConnectException</em>:
* <em>Connection refused</em><br>
* <b>First placeholder</b>: class name of exception<br>
* <b>Second placeholder</b>: exception message
*/
private static final String MSG_NO_UPDATE_CHECK_POSSIBLE__DEBUG = "Can not check for an updated version: %s: %s";
/**
* Message for the log when an update is available.<br>
* <br>
* <b>Message sample</b>: An update is available. Current version is '<em>20120301-01</em>' and remote version is '
* <em>20120401-01</em>'.<br>
* <b>First placeholder</b>: current version<br>
* <b>Second placeholder</b>: new remote version
*/
private static final String MSG_UPDATE_AVAILABLE = "An update is available. Current version is '%s' and remote version is '%s'.";
/**
* Pattern of a typical version of <i>UAS data</i>
*/
private static final Pattern VERSION_PATTERN = Pattern.compile("\\d{8}\\-\\d{2}");
/**
* Checks a given newer version against an older one.
*
* @param newer
* possible newer version
* @param older
* possible older version
* @return {@code true} if the first argument is newer than the second argument, otherwise {@code false}
*/
static boolean hasUpdate(final String newer, final String older) {
return VERSION_PATTERN.matcher(newer).matches() && VERSION_PATTERN.matcher(older).matches() ? newer.compareTo(older) > 0 : false;
}
/**
* Reads the current User-Agent data version from <a
* href="http://data.udger.com">http://data.udger.com</a>.
*
* @param url
* a URL which the version information can be loaded
* @return a version string or {@code null}
* @throws IOException
* if an I/O exception occurs
*/
@Nullable
private static String retrieveRemoteVersion(@Nonnull final URL url, @Nonnull final Charset charset) throws IOException {
final InputStream stream = url.openStream();
final InputStreamReader reader = new InputStreamReader(stream, charset);
final LineNumberReader lnr = new LineNumberReader(reader);
final String line = lnr.readLine();
lnr.close();
reader.close();
stream.close();
return line;
}
/**
* {@link ExecutorService} to run the update operation of the UAS data in background
*/
private final ExecutorService executorService = ExecutorServices.createBackgroundExecutor();
/**
* Time of last update check in milliseconds
*/
private long lastUpdateCheck = 0;
/**
* The data store for instances that implements {@link net.sf.uadetector.internal.data.Data}
*/
private final RefreshableDataStore store;
public AbstractUpdateOperation(@Nonnull final RefreshableDataStore dataStore) {
Check.notNull(dataStore, "dataStore");
store = dataStore;
}
/**
* Shortcut to get the current version of the UAS data in the {@link net.sf.uadetector.datastore.DataStore}.
*
* @return current version of UAS data
*/
@Nonnull
private String getCurrentVersion() {
return store.getData().getVersion();
}
/**
* Gets the time of the last update check in milliseconds.
*
* @return time of the last update check in milliseconds
*/
@Override
public long getLastUpdateCheck() {
return lastUpdateCheck;
}
/**
* Fetches the current version information over HTTP and compares it with the last version of the most recently
* imported data.
*
* @return {@code true} if an update exists, otherwise {@code false}
*/
protected boolean isUpdateAvailable() {
boolean result = false;
String version = EMPTY_VERSION;
try {
version = retrieveRemoteVersion(store.getVersionUrl(), store.getCharset());
} catch (final IOException e) {
LOG.info(MSG_NO_UPDATE_CHECK_POSSIBLE);
LOG.debug(String.format(MSG_NO_UPDATE_CHECK_POSSIBLE__DEBUG, e.getClass().getName(), e.getLocalizedMessage()));
}
if (hasUpdate(version, getCurrentVersion())) {
LOG.debug(String.format(MSG_UPDATE_AVAILABLE, getCurrentVersion(), version));
result = true;
} else {
LOG.debug(String.format(MSG_NO_UPDATE_AVAILABLE, getCurrentVersion()));
}
lastUpdateCheck = System.currentTimeMillis();
return result;
}
/**
* Executes the update at some time in the future (as soon as possible) within a new thread.
*/
@Override
public void run() {
executorService.execute(new Runnable() {
@Override
public void run() {
call();
}
});
}
/**
* Shuts down the corresponding background executor as soon as possible, but at the latest specified default time.
*
* @see ExecutorServices#shutdown(ExecutorService)
*/
@Override
public void shutdown() {
ExecutorServices.shutdown(executorService);
}
}