io.aeron.ImageControlledFragmentAssembler Maven / Gradle / Ivy
Show all versions of aeron-client Show documentation
/*
* Copyright 2014-2019 Real Logic Ltd.
*
* 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 io.aeron;
import io.aeron.logbuffer.ControlledFragmentHandler;
import io.aeron.logbuffer.Header;
import org.agrona.DirectBuffer;
import static io.aeron.logbuffer.FrameDescriptor.*;
/**
* A {@link ControlledFragmentHandler} that sits in a chain-of-responsibility pattern that reassembles fragmented
* messages so that the next handler in the chain only sees whole messages. This is for a single session on an
* {@link Image} and not for multiple session {@link Image}s in a {@link Subscription}.
*
* Unfragmented messages are delegated without copy. Fragmented messages are copied to a temporary
* buffer for reassembly before delegation.
*
* The {@link Header} passed to the delegate on assembling a message will be that of the last fragment.
*
* @see Image#controlledPoll(ControlledFragmentHandler, int)
* @see Image#controlledPeek(long, ControlledFragmentHandler, long)
*/
public class ImageControlledFragmentAssembler implements ControlledFragmentHandler
{
private final ControlledFragmentHandler delegate;
private final BufferBuilder builder;
/**
* Construct an adapter to reassemble message fragments and delegate on whole messages.
*
* @param delegate onto which whole messages are forwarded.
*/
public ImageControlledFragmentAssembler(final ControlledFragmentHandler delegate)
{
this(delegate, 0, false);
}
/**
* Construct an adapter to reassemble message fragments and delegate on whole messages.
*
* @param delegate onto which whole messages are forwarded.
* @param initialBufferLength to be used for the session.
*/
public ImageControlledFragmentAssembler(final ControlledFragmentHandler delegate, final int initialBufferLength)
{
this(delegate, initialBufferLength, false);
}
/**
* Construct an adapter to reassemble message fragments and delegate on whole messages.
*
* @param delegate onto which whole messages are forwarded.
* @param initialBufferLength to be used for the session.
* @param isDirectByteBuffer is the underlying buffer to be a direct {@link java.nio.ByteBuffer}?
*/
public ImageControlledFragmentAssembler(
final ControlledFragmentHandler delegate, final int initialBufferLength, final boolean isDirectByteBuffer)
{
this.delegate = delegate;
this.builder = new BufferBuilder(initialBufferLength, isDirectByteBuffer);
}
/**
* Get the delegate unto which assembled messages are delegated.
*
* @return the delegate unto which assembled messages are delegated.
*/
public ControlledFragmentHandler delegate()
{
return delegate;
}
/**
* Get the {@link BufferBuilder} for resetting this assembler.
*
* @return the {@link BufferBuilder} for resetting this assembler.
*/
BufferBuilder bufferBuilder()
{
return builder;
}
/**
* The implementation of {@link ControlledFragmentHandler} that reassembles and forwards whole messages.
*
* @param buffer containing the data.
* @param offset at which the data begins.
* @param length of the data in bytes.
* @param header representing the meta data for the data.
*/
public Action onFragment(final DirectBuffer buffer, final int offset, final int length, final Header header)
{
final byte flags = header.flags();
Action action = Action.CONTINUE;
if ((flags & UNFRAGMENTED) == UNFRAGMENTED)
{
action = delegate.onFragment(buffer, offset, length, header);
}
else
{
if ((flags & BEGIN_FRAG_FLAG) == BEGIN_FRAG_FLAG)
{
builder.reset().append(buffer, offset, length);
}
else
{
final int limit = builder.limit();
builder.append(buffer, offset, length);
if ((flags & END_FRAG_FLAG) == END_FRAG_FLAG)
{
final int msgLength = builder.limit();
action = delegate.onFragment(builder.buffer(), 0, msgLength, header);
if (Action.ABORT == action)
{
builder.limit(limit);
}
else
{
builder.reset();
}
}
}
}
return action;
}
}