Package org.apache.tinkerpop.gremlin.server.op

Class AbstractOpProcessor

java.lang.Object

org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor

All Implemented Interfaces:

AutoCloseable, OpProcessor

Direct Known Subclasses:

AbstractEvalOpProcessor, TraversalOpProcessor

public abstract class AbstractOpProcessor
extends Object
implements OpProcessor

A base OpProcessor implementation that processes an Iterator of results in a generalized way while ensuring that graph transactions are properly managed.

Author:

Stephen Mallette (http://stephen.genoprime.com)

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	manageTransactions	When set to true, transactions are always managed otherwise they can be overridden by the request.
static long	WRITE_PAUSE_TIME_MS	Length of time to pause writes in milliseconds when the high watermark is exceeded.
static com.codahale.metrics.Meter	writePausesMeter	Tracks the rate of pause to writes when the high watermark is exceeded.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractOpProcessor(boolean manageTransactions)

Method Summary

Modifier and Type	Method	Description
protected static void	attemptCommit(RequestMessage msg, GraphManager graphManager, boolean strict)
protected static void	attemptRollback(RequestMessage msg, GraphManager graphManager, boolean strict)
protected static Optional<Throwable>	determineIfSpecialException(Throwable ex)	Check if any exception in the chain is TemporaryException or Failure then respond with the right error code so that the client knows to retry.
protected Map<String,Object>	generateResultMetaData(io.netty.channel.ChannelHandlerContext ctx, RequestMessage msg, ResponseStatusCode code, Iterator itty, Settings settings)	Generates response result meta-data to put on a ResponseMessage.
protected Map<String,Object>	generateStatusAttributes(io.netty.channel.ChannelHandlerContext ctx, RequestMessage msg, ResponseStatusCode code, Iterator itty, Settings settings)	Generates response status meta-data to put on a ResponseMessage.
protected void	handleIterator(Context context, Iterator itty)	Provides a generic way of iterating a result set back to the client.
protected boolean	isForceFlushed(io.netty.channel.ChannelHandlerContext ctx, RequestMessage msg, Iterator itty)	Determines if a Frame should be force flushed outside of the resultIterationBatchSize and the termination of the iterator.
protected void	iterateComplete(io.netty.channel.ChannelHandlerContext ctx, RequestMessage msg, Iterator itty)	Called when iteration within handleIterator(Context, Iterator) is on its final pass and the final frame is about to be sent back to the client.
protected static Frame	makeFrame(Context ctx, RequestMessage msg, MessageSerializer<?> serializer, boolean useBinary, List<Object> aggregate, ResponseStatusCode code, Map<String,Object> responseMetaData, Map<String,Object> statusAttributes)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.AutoCloseable

close

Methods inherited from interface org.apache.tinkerpop.gremlin.server.OpProcessor

getName, init, select

Field Detail

WRITE_PAUSE_TIME_MS

public static final long WRITE_PAUSE_TIME_MS

Length of time to pause writes in milliseconds when the high watermark is exceeded.

See Also:

Constant Field Values

writePausesMeter

public static final com.codahale.metrics.Meter writePausesMeter

Tracks the rate of pause to writes when the high watermark is exceeded.

manageTransactions

protected final boolean manageTransactions

When set to true, transactions are always managed otherwise they can be overridden by the request.

Constructor Detail

AbstractOpProcessor

protected AbstractOpProcessor(boolean manageTransactions)

Method Detail

determineIfSpecialException

protected static Optional<Throwable> determineIfSpecialException(Throwable ex)

Check if any exception in the chain is TemporaryException or Failure then respond with the right error code so that the client knows to retry.

handleIterator

protected void handleIterator(Context context,
                              Iterator itty)
                       throws InterruptedException

Provides a generic way of iterating a result set back to the client.

Parameters:

context - The Gremlin Server Context object containing settings, request message, etc.

itty - The result to iterator

Throws:

InterruptedException

iterateComplete

protected void iterateComplete(io.netty.channel.ChannelHandlerContext ctx,
                               RequestMessage msg,
                               Iterator itty)

Called when iteration within handleIterator(Context, Iterator) is on its final pass and the final frame is about to be sent back to the client. This method only gets called on successful iteration of the entire result.

isForceFlushed

protected boolean isForceFlushed(io.netty.channel.ChannelHandlerContext ctx,
                                 RequestMessage msg,
                                 Iterator itty)

Determines if a Frame should be force flushed outside of the resultIterationBatchSize and the termination of the iterator. By default this method return false.

Parameters:

itty - a reference to the current Iterator of results - it is not meant to be forwarded in this method

generateResultMetaData

protected Map<String,Object> generateResultMetaData(io.netty.channel.ChannelHandlerContext ctx,
                                                          RequestMessage msg,
                                                          ResponseStatusCode code,
                                                          Iterator itty,
                                                          Settings settings)

Generates response result meta-data to put on a ResponseMessage.

Parameters:

itty - a reference to the current Iterator of results - it is not meant to be forwarded in this method

generateStatusAttributes

protected Map<String,Object> generateStatusAttributes(io.netty.channel.ChannelHandlerContext ctx,
                                                            RequestMessage msg,
                                                            ResponseStatusCode code,
                                                            Iterator itty,
                                                            Settings settings)

Generates response status meta-data to put on a ResponseMessage.

Parameters:

itty - a reference to the current Iterator of results - it is not meant to be forwarded in this method

makeFrame

protected static Frame makeFrame(Context ctx,
                                 RequestMessage msg,
                                 MessageSerializer<?> serializer,
                                 boolean useBinary,
                                 List<Object> aggregate,
                                 ResponseStatusCode code,
                                 Map<String,Object> responseMetaData,
                                 Map<String,Object> statusAttributes)
                          throws Exception

Throws:

Exception

attemptCommit

protected static void attemptCommit(RequestMessage msg,
                                    GraphManager graphManager,
                                    boolean strict)

attemptRollback

protected static void attemptRollback(RequestMessage msg,
                                      GraphManager graphManager,
                                      boolean strict)