/*******************************************************************************
* 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.net.URL;
import java.nio.charset.Charset;
import javax.annotation.Nonnull;
import net.sf.qualitycheck.Check;
import net.sf.qualitycheck.exception.IllegalStateOfArgumentException;
import net.sf.uadetector.datareader.DataReader;
import net.sf.uadetector.exception.CanNotOpenStreamException;
import net.sf.uadetector.internal.data.Data;
import net.sf.uadetector.internal.util.UrlUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This abstract implementation provides basic update functionality to be able to update the <em>UAS data</em> in your
* data store. During initialization the passed in fallback data store will be used and an update process will be
* triggered. The update operation itself works as background task to avoid blocking (for example when reading data by a
* network connection and the remote host is not available or really slow).
* <p>
* Such a store must always have an usable instance of {@link Data} and should be initialized with the supplied UAS file
* in the <em>uadetector-resources</em> module.
*
* @author André Rouél
*/
public abstract class AbstractRefreshableDataStore implements RefreshableDataStore {
/**
* Corresponding default logger for this class
*/
private static final Logger LOG = LoggerFactory.getLogger(AbstractRefreshableDataStore.class);
/**
* Runtime check that the passed instance of {@link Data} is not empty (respectively {@link Data#EMPTY}).
*
* @param data
* instance of {@code Data}
* @throws net.sf.qualitycheck.exception.IllegalStateOfArgumentException
* if the passed instance is empty
*/
private static Data checkData(final Data data) {
if (Data.EMPTY.equals(data)) {
throw new IllegalStateOfArgumentException("Argument 'data' must not be empty.");
}
return data;
}
/**
* Current the character set in which the <em>UAS data</em> will be read
*/
private final Charset charset;
/**
* Current <em>UAS data</em>
*/
private Data data;
/**
* The {@code URL} to get <em>UAS data</em>
*/
private final URL dataUrl;
/**
* Default data store which will be used during initialization of a {@code DataStore} and can be used in emergency
* cases.
*/
private final DataStore fallback;
/**
* The data reader to read in <em>UAS data</em>
*/
private final DataReader reader;
/**
* Update operation which runs itself in background (non-blocking)
*/
private UpdateOperation updateOperation = new UpdateOperationTask(this);
/**
* The {@code URL} to get the latest version information of <em>UAS data</em>
*/
private final URL versionUrl;
/**
* Constructs an {@code AbstractDataStore} by reading the given {@code dataUrl} as <em>UAS data</em>.
*
* @param reader
* data reader to read the given {@code dataUrl}
* @param dataUrl
* URL to <em>UAS data</em>
* @param versionUrl
* URL to version information about the given <em>UAS data</em>
* @param charset
* the character set in which the data should be read
* @param fallback
* <em>UAS data</em> as fallback in case the data on the specified resource can not be read correctly
* @throws net.sf.qualitycheck.exception.IllegalNullArgumentException
* if one of the given arguments is {@code null}
* @throws net.sf.qualitycheck.exception.IllegalStateOfArgumentException
* if the given strings are not valid URLs
*/
protected AbstractRefreshableDataStore(@Nonnull final DataReader reader, @Nonnull final String dataUrl,
@Nonnull final String versionUrl, @Nonnull final Charset charset, @Nonnull final DataStore fallback) {
this(reader, UrlUtil.build(dataUrl), UrlUtil.build(versionUrl), charset, fallback);
}
/**
* Constructs an {@code AbstractDataStore} by reading the given {@code dataUrl} as <em>UAS data</em>.
*
* @param reader
* data reader to read the given {@code dataUrl}
* @param dataUrl
* URL to <em>UAS data</em>
* @param versionUrl
* URL to version information about the given <em>UAS data</em>
* @param charset
* the character set in which the data should be read
* @param fallback
* <em>UAS data</em> as fallback in case the data on the specified resource can not be read correctly
* @throws net.sf.qualitycheck.exception.IllegalNullArgumentException
* if the given argument is {@code null}
* @throws net.sf.qualitycheck.exception.IllegalStateOfArgumentException
* if the created instance of {@link Data} is empty
*/
protected AbstractRefreshableDataStore(@Nonnull final DataReader reader, @Nonnull final URL dataUrl, @Nonnull final URL versionUrl,
@Nonnull final Charset charset, final DataStore fallback) {
Check.notNull(reader, "reader");
Check.notNull(charset, "charset");
Check.notNull(dataUrl, "dataUrl");
Check.notNull(versionUrl, "versionUrl");
Check.notNull(fallback, "fallback");
this.reader = reader;
this.dataUrl = dataUrl;
this.versionUrl = versionUrl;
this.charset = charset;
this.fallback = fallback;
data = checkData(fallback.getData());
}
@Override
public Charset getCharset() {
return charset;
}
@Override
public Data getData() {
return data;
}
@Override
public DataReader getDataReader() {
return reader;
}
@Override
public URL getDataUrl() {
return dataUrl;
}
@Override
public DataStore getFallback() {
return fallback;
}
@Override
public UpdateOperation getUpdateOperation() {
return updateOperation;
}
@Override
public URL getVersionUrl() {
return versionUrl;
}
/**
* Triggers the update of the <code>DataStore</code>. When this action is executed, the current data URL will be
* read in and the <code>DataReader</code> parses and builds a new Data instance. Finally, the currently set
* <code>Data</code> reference will be replaced by the new one.
* <p>
* <b>Attention</b>: This method is implemented as background task. You can not assume that you immediately get an
* updated data store.
*/
@Override
public void refresh() {
try {
updateOperation.run();
} catch (final CanNotOpenStreamException e) {
LOG.warn(String.format(MSG_URL_NOT_READABLE, e.getLocalizedMessage()));
} catch (final IllegalArgumentException e) {
LOG.warn(MSG_FAULTY_CONTENT + " " + e.getLocalizedMessage());
} catch (final RuntimeException e) {
LOG.warn(MSG_FAULTY_CONTENT, e);
}
}
/**
* Sets new <em>UAS data</em> in the store.
*
* @param data
* <em>UAS data</em> to override the current ({@code null} is not allowed)
* @throws net.sf.qualitycheck.exception.IllegalNullArgumentException
* if the given argument is {@code null}
* @throws net.sf.qualitycheck.exception.IllegalStateOfArgumentException
* if the given instance of {@code Data} is empty
*/
protected void setData(@Nonnull final Data data) {
Check.notNull(data, "data");
this.data = checkData(data);
// add some useful UAS data informations to the log
if (LOG.isDebugEnabled()) {
LOG.debug(data.toStats());
}
}
/**
* Sets a new update operation.
*
* @param updateOperation
* operation to override the current ({@code null} is not allowed)
* @throws net.sf.qualitycheck.exception.IllegalNullArgumentException
* if the given argument is {@code null}
*/
protected void setUpdateOperation(@Nonnull final UpdateOperation updateOperation) {
Check.notNull(updateOperation, "updateOperation");
this.updateOperation = updateOperation;
}
}