Java tutorial
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import org.apache.commons.lang.NullArgumentException; import org.normandra.AbstractTransactional; import org.normandra.DatabaseQuery; import org.normandra.DatabaseSession; import org.normandra.NormandraException; import org.normandra.cache.EntityCache; import org.normandra.data.ColumnAccessor; import org.normandra.meta.ColumnMeta; import org.normandra.meta.EntityMeta; import org.normandra.util.EntityPersistence; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.Serializable; import java.util.*; import java.util.concurrent.*; import java.util.concurrent.atomic.AtomicBoolean; import java.util.stream.Collectors; /** * a cassandra database session * <p> * <p> * Date: 2/1/14 */ public class CassandraDatabaseSession extends AbstractTransactional implements DatabaseSession { private static final Logger logger = LoggerFactory.getLogger(CassandraDatabaseSession.class); private final String keyspaceName; private final Session session; private final EntityCache cache; private final List<RegularStatement> statements = new CopyOnWriteArrayList<>(); private final Map<String, CassandraPreparedStatement> preparedStatements; private final AtomicBoolean closed = new AtomicBoolean(false); private final AtomicBoolean activeUnitOfWork = new AtomicBoolean(false); private final Executor executor; public CassandraDatabaseSession(final String keyspace, final Session session, final Map<String, CassandraPreparedStatement> map, final EntityCache cache, final Executor executor) { if (null == keyspace || keyspace.isEmpty()) { throw new IllegalArgumentException("Keyspace cannot be null/empty."); } if (null == session) { throw new NullArgumentException("session"); } if (null == cache) { throw new NullArgumentException("cache"); } if (null == executor) { throw new NullArgumentException("executor"); } this.keyspaceName = keyspace; this.session = session; this.cache = cache; this.executor = executor; this.preparedStatements = new LinkedHashMap<>(map); } @Override public void close() { // do nothing - session is thread safe and can be shared this.closed.getAndSet(true); this.cache.clear(); } public boolean isClosed() { return this.closed.get(); } public String getKeyspace() { return this.keyspaceName; } public Session getSession() { return this.session; } public Cluster getCluster() { return this.session.getCluster(); } protected ResultSet executeSync(final Statement statement) { final CassandraDatabaseActivity activity = new CassandraDatabaseActivity(statement, this.session); return activity.execute(); } protected Future<ResultSet> executeAsync(final Statement statement) { final CassandraDatabaseActivity activity = new CassandraDatabaseActivity(statement, this.session); final Callable<ResultSet> callable = () -> activity.execute(); final FutureTask<ResultSet> task = new FutureTask<>(callable); this.executor.execute(task); return task; } @Override public void clear() { this.cache.clear(); } @Override public boolean pendingWork() { return this.activeUnitOfWork.get(); } @Override public void beginWork() throws NormandraException { if (this.activeUnitOfWork.get()) { throw new IllegalStateException("Unit of work already active."); } this.activeUnitOfWork.getAndSet(true); } @Override public void commitWork() throws NormandraException { if (!this.activeUnitOfWork.get()) { throw new IllegalStateException("No active transaction."); } if (this.statements.isEmpty()) { return; } try { for (final RegularStatement statement : this.statements) { this.executeSync(statement); } this.statements.clear(); this.activeUnitOfWork.getAndSet(false); } catch (final Exception e) { throw new NormandraException("Unable to commit batch unit of work.", e); } } @Override public void rollbackWork() throws NormandraException { if (!this.activeUnitOfWork.get()) { throw new IllegalStateException("No active transaction."); } this.statements.clear(); this.activeUnitOfWork.getAndSet(false); } @Override public boolean exists(final EntityMeta meta, final Object key) throws NormandraException { if (this.isClosed()) { throw new IllegalStateException("Session is closed."); } if (null == meta || null == key) { return false; } try { final Map<ColumnMeta, Object> columns = meta.getId().fromKey(key); final List<String> namelist = columns.keySet().stream().map(ColumnMeta::getName) .collect(Collectors.toList()); final String[] names = namelist.toArray(new String[namelist.size()]); final Select statement = QueryBuilder.select(names).from(this.keyspaceName, meta.getTable()).limit(1); boolean hasWhere = false; for (final Map.Entry<ColumnMeta, Object> entry : columns.entrySet()) { final ColumnMeta property = entry.getKey(); final Object value = entry.getValue(); statement.where(QueryBuilder.eq(property.getName(), value)); hasWhere = true; } if (!hasWhere) { logger.warn("Unable to #exists value without key - empty where statement for type [" + meta + "]."); return false; } final ResultSet results = this.executeSync(statement); if (null == results) { return false; } final Row row = results.one(); if (null == row) { return false; } final ColumnDefinitions definitions = row.getColumnDefinitions(); return definitions != null && definitions.size() > 0; } catch (final Exception e) { throw new NormandraException("Unable to query entity [" + meta + "] by key [" + key + "].", e); } } @Override public Object get(final EntityMeta meta, final Object key) throws NormandraException { if (this.isClosed()) { throw new IllegalStateException("Session is closed."); } final CassandraEntityQuery query = new CassandraEntityQuery(this, this.cache); return query.query(meta, key); } @Override public List<Object> get(final EntityMeta meta, final Object... keys) throws NormandraException { if (this.isClosed()) { throw new IllegalStateException("Session is closed."); } final CassandraEntityQuery query = new CassandraEntityQuery(this, this.cache); return query.query(meta, keys); } @Override public void delete(final EntityMeta meta, final Object element) throws NormandraException { if (null == element) { throw new NullArgumentException("entity"); } if (this.isClosed()) { throw new IllegalStateException("Session is closed."); } try { final List<Delete> deletes = new ArrayList<>(); boolean hasValue = false; final Delete statement = QueryBuilder.delete().all().from(this.keyspaceName, meta.getTable()); for (final ColumnMeta column : meta.getPrimaryKeys()) { final String name = column.getName(); final ColumnAccessor accessor = meta.getAccessor(column); final Object value = accessor != null ? accessor.getValue(element, this) : null; if (value != null) { hasValue = true; statement.where(QueryBuilder.eq(name, value)); } } if (hasValue) { deletes.add(statement); } if (deletes.isEmpty()) { throw new NormandraException("No column values found - cannot delete entity."); } final RegularStatement batch; if (deletes.size() == 1) { batch = deletes.get(0); } else { final RegularStatement[] list = deletes.toArray(new RegularStatement[deletes.size()]); batch = QueryBuilder.batch(list); } final Object key = meta.getId().fromEntity(element); if (key instanceof Serializable) { this.cache.remove(meta, key); } if (this.activeUnitOfWork.get()) { this.statements.add(batch); } else { this.executeSync(batch); } } catch (final Exception e) { throw new NormandraException("Unable to delete entity [" + element + "] of type [" + meta + "].", e); } } @Override public DatabaseQuery query(final EntityMeta meta, final String query, final Map<String, Object> parameters) throws NormandraException { final CassandraPreparedStatement prepared = this.preparedStatements.get(query); if (null == prepared) { return new CassandraQueryParser(meta, this).parse(query, parameters); } else { return new CassandraDatabaseQuery<>(meta, prepared.bind(parameters), this); } } public Object scalarQuery(final String queryOrName) throws NormandraException { final CassandraDatabaseQuery query; final CassandraPreparedStatement prepared = this.preparedStatements.get(queryOrName); if (null == prepared) { query = new CassandraQueryParser(null, this).parse(queryOrName, Collections.EMPTY_MAP); } else { query = new CassandraDatabaseQuery<>(null, null, this); } final Row row = query.firstRow(); if (null == row) { return null; } return row.getObject(0); } @Override public void save(final EntityMeta meta, final Object element) throws NormandraException { if (this.isClosed()) { throw new IllegalStateException("Session is closed."); } if (null == meta) { throw new NullArgumentException("entity metadata"); } if (null == element) { throw new NullArgumentException("element"); } try { // generate insert/updateInstance statements final CassandraDataHandler helper = new CassandraDataHandler(this); new EntityPersistence(this).save(meta, element, helper); final List<RegularStatement> operations = helper.getOperations(); if (operations.isEmpty()) { throw new IllegalStateException( "No operations or columns identify for update - cannot save empty entity."); } final RegularStatement batch; if (operations.size() == 1) { batch = operations.get(0); } else { final RegularStatement[] list = operations.toArray(new RegularStatement[operations.size()]); batch = QueryBuilder.batch(list); } if (this.activeUnitOfWork.get()) { this.statements.add(batch); } else { this.executeSync(batch); } final Object key = meta.getId().fromEntity(element); this.cache.put(meta, key, element); } catch (final Exception e) { throw new NormandraException("Unable to save entity [" + meta + "] instance [" + element + "].", e); } } }