/**
* Load the cache entry for the given URI from the database.
*
* @param uri the URI of the cached resource for which to return the cache entry
* @return an instance of KiWiCacheEntry representing the caching metadata for the given resource,
* or null in case there is no entry for this resource
* @throws SQLException
*/
public KiWiCacheEntry getCacheEntry(String uri) throws SQLException {
KiWiCacheEntry cached = entryResourceCache.get(uri);
// lookup element in cache first, so we can avoid reconstructing it if it is already there
if (cached != null) {
return cached;
}
PreparedStatement query = connection.getPreparedStatement("load.entry_by_uri");
query.setString(1, uri);
query.setMaxRows(1);
// run the database query and if it yields a result, construct a new node; the method call will
// take care of
// caching the constructed node for future calls
ResultSet result = query.executeQuery();
try {
if (result.next()) {
return constructCacheEntry(result);
} else {
return null;
}
} finally {
result.close();
}
}
/**
* Releases this <code>Connection</code> object's database and JDBC resources immediately instead
* of waiting for them to be automatically released.
*
* <p>Calling the method <code>close</code> on a <code>Connection</code> object that is already
* closed is a no-op.
*
* <p>It is <b>strongly recommended</b> that an application explicitly commits or rolls back an
* active transaction prior to calling the <code>close</code> method. If the <code>close</code>
* method is called and there is an active transaction, the results are implementation-defined.
*
* <p>
*
* @exception java.sql.SQLException SQLException if a database access error occurs
*/
public void close() {
try {
connection.close();
} catch (SQLException e) {
log.error("error closing connection", e);
}
}
/**
* Remove the given cache entry from the database. The cache entry passed as argument must be a
* persistent instance of KiWiCacheEntry.
*
* @param entry
* @throws SQLException
*/
public void removeCacheEntry(CacheEntry entry) throws SQLException {
if (!(entry instanceof KiWiCacheEntry) || ((KiWiCacheEntry) entry).getId() == null) {
throw new IllegalStateException("the passed cache entry is not managed by this connection");
}
PreparedStatement deleteEntry = connection.getPreparedStatement("delete.entry");
deleteEntry.setLong(1, ((KiWiCacheEntry) entry).getId());
deleteEntry.executeUpdate();
entryIdCache.remove(((KiWiCacheEntry) entry).getId());
entryResourceCache.remove(entry.getResource().stringValue());
}
/**
* List all cache entries in the database, regardless of expiry date.
*
* @return a closeable iteration with KiWiCacheEntries; needs to be released by the caller
* @throws SQLException
*/
public CloseableIteration<KiWiCacheEntry, SQLException> listAll() throws SQLException {
PreparedStatement queryExpired = connection.getPreparedStatement("query.entries_all");
final ResultSet result = queryExpired.executeQuery();
return new ResultSetIteration<KiWiCacheEntry>(
result,
new ResultTransformerFunction<KiWiCacheEntry>() {
@Override
public KiWiCacheEntry apply(ResultSet input) throws SQLException {
return constructCacheEntry(result);
}
});
}
/**
* Remove the given cache entry from the database. The cache entry passed as argument must be a
* persistent instance of KiWiCacheEntry.
*
* @param uri URI of the entry to delete
* @throws SQLException
*/
public void removeCacheEntry(String uri) throws SQLException {
PreparedStatement deleteEntry = connection.getPreparedStatement("delete.entry_by_uri");
deleteEntry.setString(1, uri);
deleteEntry.executeUpdate();
KiWiCacheEntry cached = entryResourceCache.get(uri);
if (cached != null) {
entryResourceCache.remove(uri);
entryIdCache.remove(cached.getId());
}
}
/**
* Store the cache entry passed as argument in the database. In case the passed argument is not an
* instance of KiWiCacheEntry, it will first be converted into a KiWiCacheEntry by copying the
* fields. In this case, the stored object will not be the same instance as the object passed as
* argument.
*
* @param entry the cache entry to store
* @throws SQLException
*/
public void storeCacheEntry(CacheEntry entry) throws SQLException {
KiWiCacheEntry kEntry;
if (entry instanceof KiWiCacheEntry) {
kEntry = (KiWiCacheEntry) entry;
} else {
kEntry = new KiWiCacheEntry();
kEntry.setExpiryDate(entry.getExpiryDate());
kEntry.setLastRetrieved(entry.getLastRetrieved());
kEntry.setUpdateCount(entry.getUpdateCount());
kEntry.setResource(entry.getResource());
kEntry.setTripleCount(entry.getTripleCount());
}
if (!(entry.getResource() instanceof KiWiResource)
|| ((KiWiResource) entry.getResource()).getId() < 0) {
throw new IllegalStateException(
"the resource contained in the cache entry is not a KiWiResource!");
}
// needed before the entry can be inserted
connection.flushBatch();
kEntry.setId(connection.getNextSequence());
PreparedStatement insertEntry = connection.getPreparedStatement("store.entry");
insertEntry.setLong(1, kEntry.getId());
insertEntry.setTimestamp(2, new Timestamp(kEntry.getLastRetrieved().getTime()));
insertEntry.setTimestamp(3, new Timestamp(kEntry.getExpiryDate().getTime()));
insertEntry.setLong(4, ((KiWiNode) kEntry.getResource()).getId());
insertEntry.setInt(5, kEntry.getUpdateCount());
insertEntry.setInt(6, kEntry.getTripleCount());
insertEntry.executeUpdate();
log.debug("persisted ld-cache entry with id {}", kEntry.getId());
entryIdCache.put(kEntry.getId(), kEntry);
entryResourceCache.put(kEntry.getResource().stringValue(), kEntry);
}
public KiWiCacheEntry constructCacheEntry(ResultSet row) throws SQLException {
Long id = row.getLong("id");
KiWiCacheEntry cached = entryIdCache.get(id);
// lookup element in cache first, so we can avoid reconstructing it if it is already there
if (cached != null) {
return cached;
}
KiWiCacheEntry entry = new KiWiCacheEntry();
entry.setId(id);
entry.setLastRetrieved(new Date(row.getTimestamp("retrieved_at").getTime()));
entry.setExpiryDate(new Date(row.getTimestamp("expires_at").getTime()));
entry.setUpdateCount(row.getInt("update_count"));
entry.setResource((URI) connection.loadNodeById(row.getLong("resource_id")));
entry.setTripleCount(row.getInt("triple_count"));
entryIdCache.put(id, entry);
entryResourceCache.put(entry.getResource().stringValue(), entry);
return entry;
}
public LDCachingKiWiPersistenceConnection(KiWiConnection connection) throws SQLException {
this.connection = connection;
entryResourceCache = connection.getCacheManager().getCacheByName("ldcache-entry-uri");
entryIdCache = connection.getCacheManager().getCacheByName("ldcache-entry-id");
}
/**
* Return the KiWi version of the database this connection is operating on. This query is
* necessary for checking proper state of a database when initialising the system.
*
* @return
*/
public int getDatabaseVersion() throws SQLException {
return connection.getDatabaseVersion();
}
/**
* Return a collection of database tables contained in the database. This query is used for
* checking whether the database needs to be created when initialising the system.
*
* @return
* @throws java.sql.SQLException
*/
public Set<String> getDatabaseTables() throws SQLException {
return connection.getDatabaseTables();
}
/**
* Store a new node in the database. The method will retrieve a new database id for the node and
* update the passed object. Afterwards, the node data will be inserted into the database using
* appropriate INSERT statements. The caller must make sure the connection is committed and closed
* properly.
*
* <p>If the node already has an ID, the method will do nothing (assuming that it is already
* persistent)
*
* @param node
* @throws java.sql.SQLException
*/
public void storeNode(KiWiNode node) throws SQLException {
connection.storeNode(node);
}
/**
* Undoes all changes made in the current transaction and releases any database locks currently
* held by this <code>Connection</code> object. This method should be used only when auto-commit
* mode has been disabled.
*
* @exception java.sql.SQLException if a database access error occurs, this method is called while
* participating in a distributed transaction, this method is called on a closed connection or
* this <code>Connection</code> object is in auto-commit mode
*/
public void rollback() throws SQLException {
connection.rollback();
}
/**
* Retrieves whether this <code>Connection</code> object has been closed. A connection is closed
* if the method <code>close</code> has been called on it or if certain fatal errors have
* occurred. This method is guaranteed to return <code>true</code> only when it is called after
* the method <code>Connection.close</code> has been called.
*
* <p>This method generally cannot be called to determine whether a connection to a database is
* valid or invalid. A typical client can determine that a connection is invalid by catching any
* exceptions that might be thrown when an operation is attempted.
*
* @return <code>true</code> if this <code>Connection</code> object is closed; <code>false</code>
* if it is still open
* @exception java.sql.SQLException if a database access error occurs
*/
public boolean isClosed() throws SQLException {
return connection.isClosed();
}
/**
* Makes all changes made since the previous commit/rollback permanent and releases any database
* locks currently held by this <code>Connection</code> object. This method should be used only
* when auto-commit mode has been disabled.
*
* @exception java.sql.SQLException if a database access error occurs, this method is called while
* participating in a distributed transaction, if this method is called on a closed conection
* or this <code>Connection</code> object is in auto-commit mode
*/
public void commit() throws SQLException {
connection.commit();
}
