/*
* Syncany, www.syncany.org
* Copyright (C) 2011-2014 Philipp C. Heckel <philipp.heckel@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.syncany.database.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Logger;
import org.syncany.database.ChunkEntry;
import org.syncany.database.ChunkEntry.ChunkChecksum;
import org.syncany.database.VectorClock;
/**
* The chunk data access object (DAO) writes and queries the SQL database for information
* on {@link ChunkEntry}s. It translates the relational data in the "chunk" table to
* Java objects.
*
* @author Philipp C. Heckel <philipp.heckel@gmail.com>
*/
public class ChunkSqlDao extends AbstractSqlDao {
protected static final Logger logger = Logger.getLogger(ChunkSqlDao.class.getSimpleName());
private Map<ChunkChecksum, ChunkEntry> chunkCache;
public ChunkSqlDao(Connection connection) {
super(connection);
this.chunkCache = null;
}
/**
* Writes a list of {@link ChunkEntry}s to the database using <tt>INSERT</tt>s and the given connection.
*
* <p><b>Note:</b> This method executes, but <b>does not commit</b> the query.
*
* @param connection The connection used to execute the statements
* @param databaseVersionId
* @param chunks List of {@link ChunkEntry}s to be inserted in the database
* @throws SQLException If the SQL statement fails
*/
public void writeChunks(Connection connection, long databaseVersionId, Collection<ChunkEntry> chunks) throws SQLException {
if (chunks.size() > 0) {
PreparedStatement preparedStatement = getStatement(connection, "chunk.insert.all.writeChunks.sql");
for (ChunkEntry chunk : chunks) {
preparedStatement.setString(1, chunk.getChecksum().toString());
preparedStatement.setLong(2, databaseVersionId);
preparedStatement.setInt(3, chunk.getSize());
preparedStatement.addBatch();
}
preparedStatement.executeBatch();
preparedStatement.close();
}
}
/**
* Removes unreferenced chunks from the database. Unreferenced chunks are chunks
* that are not referenced by any file content or multichunk.
*
* <p>During the cleanup process, when file versions are deleted, unused chunks
* are left over. This method removes these chunks from the database.
*
* <p><b>Note:</b> This method executes, but <b>does not commit</b> the query.
*/
public void removeUnreferencedChunks() {
try (PreparedStatement preparedStatement = getStatement("chunk.delete.all.removeUnreferencesChunks.sql")) {
preparedStatement.execute();
preparedStatement.close();
}
catch (SQLException e) {
throw new RuntimeException(e);
}
}
/**
* Queries the database of a chunk with the given checksum.
*
* <p>Note: When first called, this method loads the <b>chunk cache</b> and keeps
* this cache until it is cleared explicitly with {@link #clearCache()}.
*
* <p>Also note that this method will return <tt>null</tt> if the chunk has been
* added after the cache has been filled.
*
* @param chunkChecksum Chunk checksum of the chunk to be selected
* @return Returns the chunk entry, or <tt>null</tt> if the chunk does not exist.
*/
public synchronized ChunkEntry getChunk(ChunkChecksum chunkChecksum) {
if (chunkCache == null) {
loadChunkCache();
}
return chunkCache.get(chunkChecksum);
}
/**
* Clears the chunk cache loaded by {@link #getChunk(ChunkChecksum) getChunk()}
* and resets the cache. If {@link #getChunk(ChunkChecksum) getChunk()} is called
* after the cache is cleared, it is re-populated.
*/
public synchronized void clearCache() {
if (chunkCache != null) {
chunkCache.clear();
chunkCache = null;
}
}
/**
* Queries the SQL database for all chunks that <b>originally appeared</b> in the
* database version identified by the given vector clock.
*
* <p><b>Note:</b> This method does <b>not</b> select all the chunks that are referenced
* in the database version. In particular, it <b>does not return</b> chunks that appeared
* in previous other database versions.
*
* @param vectorClock Vector clock that identifies the database version
* @return Returns all chunks that originally belong to a database version
*/
public Map<ChunkChecksum, ChunkEntry> getChunks(VectorClock vectorClock) {
try (PreparedStatement preparedStatement = getStatement("chunk.select.all.getChunksForDatabaseVersion.sql")) {
preparedStatement.setString(1, vectorClock.toString());
try (ResultSet resultSet = preparedStatement.executeQuery()) {
return createChunkEntries(resultSet);
}
}
catch (SQLException e) {
throw new RuntimeException(e);
}
}
protected Map<ChunkChecksum, ChunkEntry> createChunkEntries(ResultSet resultSet) throws SQLException {
Map<ChunkChecksum, ChunkEntry> chunks = new HashMap<ChunkChecksum, ChunkEntry>();
while (resultSet.next()) {
ChunkEntry chunkEntry = createChunkEntryFromRow(resultSet);
chunks.put(chunkEntry.getChecksum(), chunkEntry);
}
return chunks;
}
protected ChunkEntry createChunkEntryFromRow(ResultSet resultSet) throws SQLException {
ChunkChecksum chunkChecksum = ChunkChecksum.parseChunkChecksum(resultSet.getString("checksum"));
return new ChunkEntry(chunkChecksum, resultSet.getInt("size"));
}
protected void loadChunkCache() {
try (PreparedStatement preparedStatement = getStatement("chunk.select.all.loadChunkCache.sql")) {
try (ResultSet resultSet = preparedStatement.executeQuery()) {
chunkCache = createChunkEntries(resultSet);
}
}
catch (SQLException e) {
throw new RuntimeException(e);
}
}
/**
* no commit
*/
public void updateDirtyChunksNewDatabaseId(long newDatabaseVersionId) {
try (PreparedStatement preparedStatement = getStatement("chunk.update.dirty.updateDirtyChunksNewDatabaseId.sql")) {
preparedStatement.setLong(1, newDatabaseVersionId);
preparedStatement.executeUpdate();
}
catch (SQLException e) {
throw new RuntimeException(e);
}
}
}