/*
* Copyright (c) 2002-2017 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* 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 org.neo4j.driver.internal;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import org.neo4j.driver.internal.logging.DelegatingLogger;
import org.neo4j.driver.internal.retry.RetryLogic;
import org.neo4j.driver.internal.spi.Connection;
import org.neo4j.driver.internal.spi.ConnectionProvider;
import org.neo4j.driver.internal.spi.PooledConnection;
import org.neo4j.driver.internal.types.InternalTypeSystem;
import org.neo4j.driver.internal.util.Supplier;
import org.neo4j.driver.v1.AccessMode;
import org.neo4j.driver.v1.Logger;
import org.neo4j.driver.v1.Logging;
import org.neo4j.driver.v1.Record;
import org.neo4j.driver.v1.Session;
import org.neo4j.driver.v1.Statement;
import org.neo4j.driver.v1.StatementResult;
import org.neo4j.driver.v1.Transaction;
import org.neo4j.driver.v1.TransactionWork;
import org.neo4j.driver.v1.Value;
import org.neo4j.driver.v1.Values;
import org.neo4j.driver.v1.exceptions.ClientException;
import org.neo4j.driver.v1.types.TypeSystem;
import static org.neo4j.driver.v1.Values.value;
public class NetworkSession implements Session, SessionResourcesHandler
{
private static final String LOG_NAME = "Session";
private final ConnectionProvider connectionProvider;
private final AccessMode mode;
private final RetryLogic retryLogic;
protected final Logger logger;
private String bookmark;
private PooledConnection currentConnection;
private ExplicitTransaction currentTransaction;
private final AtomicBoolean isOpen = new AtomicBoolean( true );
public NetworkSession( ConnectionProvider connectionProvider, AccessMode mode, RetryLogic retryLogic,
Logging logging )
{
this.connectionProvider = connectionProvider;
this.mode = mode;
this.retryLogic = retryLogic;
this.logger = new DelegatingLogger( logging.getLog( LOG_NAME ), String.valueOf( hashCode() ) );
}
@Override
public StatementResult run( String statementText )
{
return run( statementText, Values.EmptyMap );
}
@Override
public StatementResult run( String statementText, Map<String,Object> statementParameters )
{
Value params = statementParameters == null ? Values.EmptyMap : value( statementParameters );
return run( statementText, params );
}
@Override
public StatementResult run( String statementTemplate, Record statementParameters )
{
Value params = statementParameters == null ? Values.EmptyMap : value( statementParameters.asMap() );
return run( statementTemplate, params );
}
@Override
public StatementResult run( String statementText, Value statementParameters )
{
return run( new Statement( statementText, statementParameters ) );
}
@Override
public StatementResult run( Statement statement )
{
ensureSessionIsOpen();
ensureNoOpenTransactionBeforeRunningSession();
syncAndCloseCurrentConnection();
currentConnection = acquireConnection( mode );
return run( currentConnection, statement, this );
}
public static StatementResult run( Connection connection, Statement statement,
SessionResourcesHandler resourcesHandler )
{
InternalStatementResult result = new InternalStatementResult( connection, resourcesHandler, null, statement );
connection.run( statement.text(), statement.parameters().asMap( Values.ofValue() ),
result.runResponseCollector() );
connection.pullAll( result.pullAllResponseCollector() );
connection.flush();
return result;
}
@Deprecated
@Override
public synchronized void reset()
{
ensureSessionIsOpen();
ensureNoUnrecoverableError();
if ( currentTransaction != null )
{
currentTransaction.markToClose();
setBookmark( currentTransaction.bookmark() );
currentTransaction = null;
}
if ( currentConnection != null )
{
currentConnection.resetAsync();
}
}
@Override
public boolean isOpen()
{
return isOpen.get();
}
@Override
public void close()
{
// Use atomic operation to protect from closing the connection twice (putting back to the pool twice).
if ( !isOpen.compareAndSet( true, false ) )
{
throw new ClientException( "This session has already been closed." );
}
synchronized ( this )
{
if ( currentTransaction != null )
{
try
{
currentTransaction.close();
}
catch ( Throwable e )
{
logger.error( "Failed to close transaction", e );
}
}
}
syncAndCloseCurrentConnection();
}
@Override
public synchronized Transaction beginTransaction()
{
return beginTransaction( mode );
}
@Deprecated
@Override
public synchronized Transaction beginTransaction( String bookmark )
{
setBookmark( bookmark );
return beginTransaction();
}
@Override
public <T> T readTransaction( TransactionWork<T> work )
{
return transaction( AccessMode.READ, work );
}
@Override
public <T> T writeTransaction( TransactionWork<T> work )
{
return transaction( AccessMode.WRITE, work );
}
// Internal method for setting the bookmark explicitly, mainly for testing.
// This method does not prevent setting the bookmark to null since that
// is a valid requirement for some test scenarios.
void setBookmark( String bookmark )
{
if( bookmark != null )
{
this.bookmark = bookmark;
}
}
@Override
public String lastBookmark()
{
return bookmark;
}
@Override
public TypeSystem typeSystem()
{
return InternalTypeSystem.TYPE_SYSTEM;
}
@Override
public synchronized void onResultConsumed()
{
closeCurrentConnection();
}
@Override
public synchronized void onTransactionClosed( ExplicitTransaction tx )
{
if ( currentTransaction != null && currentTransaction == tx )
{
closeCurrentConnection();
setBookmark( currentTransaction.bookmark() );
currentTransaction = null;
}
}
@Override
public synchronized void onConnectionError( boolean recoverable )
{
// must check if transaction has been closed
if ( currentTransaction != null )
{
if ( recoverable )
{
currentTransaction.failure();
}
else
{
currentTransaction.markToClose();
}
}
}
private <T> T transaction( final AccessMode mode, final TransactionWork<T> work )
{
return retryLogic.retry( new Supplier<T>()
{
@Override
public T get()
{
try ( Transaction tx = beginTransaction( mode ) )
{
try
{
T result = work.execute( tx );
tx.success();
return result;
}
catch ( Throwable t )
{
// mark transaction for failure if the given unit of work threw exception
// this will override any success marks that were made by the unit of work
tx.failure();
throw t;
}
}
}
} );
}
private synchronized Transaction beginTransaction( AccessMode mode )
{
ensureSessionIsOpen();
ensureNoOpenTransactionBeforeOpeningTransaction();
syncAndCloseCurrentConnection();
currentConnection = acquireConnection( mode );
currentTransaction = new ExplicitTransaction( currentConnection, this, bookmark);
currentConnection.setResourcesHandler( this );
return currentTransaction;
}
private void ensureNoUnrecoverableError()
{
if ( currentConnection != null && currentConnection.hasUnrecoverableErrors() )
{
throw new ClientException( "Cannot run more statements in the current session as an unrecoverable error " +
"has happened. Please close the current session and re-run your statement in a" +
" new session." );
}
}
//should be called from a synchronized block
private void ensureNoOpenTransactionBeforeRunningSession()
{
if ( currentTransaction != null )
{
throw new ClientException( "Statements cannot be run directly on a session with an open transaction;" +
" either run from within the transaction or use a different session." );
}
}
//should be called from a synchronized block
private void ensureNoOpenTransactionBeforeOpeningTransaction()
{
if ( currentTransaction != null )
{
throw new ClientException( "You cannot begin a transaction on a session with an open transaction;" +
" either run from within the transaction or use a different session." );
}
}
private void ensureSessionIsOpen()
{
if ( !isOpen.get() )
{
throw new ClientException(
"No more interaction with this session is allowed " +
"as the current session is already closed or marked as closed. " +
"You get this error either because you have a bad reference to a session that has already be " +
"closed " +
"or you are trying to reuse a session that you have called `reset` on it." );
}
}
private PooledConnection acquireConnection( AccessMode mode )
{
PooledConnection connection = connectionProvider.acquireConnection( mode );
logger.debug( "Acquired connection " + connection.hashCode() );
return connection;
}
boolean currentConnectionIsOpen()
{
return currentConnection != null && currentConnection.isOpen();
}
private void syncAndCloseCurrentConnection()
{
closeCurrentConnection( true );
}
private void closeCurrentConnection()
{
closeCurrentConnection( false );
}
private void closeCurrentConnection( boolean sync )
{
if ( currentConnection == null )
{
return;
}
PooledConnection connection = currentConnection;
currentConnection = null;
try
{
if ( sync && connection.isOpen() )
{
connection.sync();
}
}
finally
{
connection.close();
logger.debug( "Released connection " + connection.hashCode() );
}
}
}