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/*
* Copyright 2014-2017 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.logbuffer;
import org.agrona.*;
import org.agrona.concurrent.UnsafeBuffer;
import org.agrona.concurrent.status.Position;
import static io.aeron.logbuffer.FrameDescriptor.*;
import static io.aeron.protocol.DataHeaderFlyweight.HEADER_LENGTH;
/**
* A term buffer reader.
*
* Note: Reading from the term is thread safe, but each thread needs its own instance of this class.
*/
public class TermReader
{
/**
* Reads data from a term in a log buffer and updates a passed {@link Position} so progress is not lost in the
* event of an exception.
*
* If a fragmentsLimit of 0 or less is passed then at least one read will be attempted.
*
* @param termBuffer to be read for fragments.
* @param termOffset within the buffer that the read should begin.
* @param handler the handler for data that has been read
* @param fragmentsLimit limit the number of fragments read.
* @param header to be used for mapping over the header for a given fragment.
* @param errorHandler to be notified if an error occurs during the callback.
* @param currentPosition prior to reading further fragments
* @param subscriberPosition to be updated after reading with new position
* @return the number of fragments read
*/
public static int read(
final UnsafeBuffer termBuffer,
final int termOffset,
final FragmentHandler handler,
final int fragmentsLimit,
final Header header,
final ErrorHandler errorHandler,
final long currentPosition,
final Position subscriberPosition)
{
int fragmentsRead = 0;
int offset = termOffset;
final int capacity = termBuffer.capacity();
header.buffer(termBuffer);
try
{
do
{
final int frameLength = frameLengthVolatile(termBuffer, offset);
if (frameLength <= 0)
{
break;
}
final int frameOffset = offset;
offset += BitUtil.align(frameLength, FRAME_ALIGNMENT);
if (!isPaddingFrame(termBuffer, frameOffset))
{
header.offset(frameOffset);
handler.onFragment(termBuffer, frameOffset + HEADER_LENGTH, frameLength - HEADER_LENGTH, header);
++fragmentsRead;
}
}
while (fragmentsRead < fragmentsLimit && offset < capacity);
}
catch (final Throwable t)
{
errorHandler.onError(t);
}
finally
{
final long newPosition = currentPosition + (offset - termOffset);
if (newPosition > currentPosition)
{
subscriberPosition.setOrdered(newPosition);
}
}
return fragmentsRead;
}
/**
* Reads data from a term in a log buffer.
*
* If a fragmentsLimit of 0 or less is passed then at least one read will be attempted.
* Note: this method has users outside of Aeron
*
* @param termBuffer to be read for fragments.
* @param termOffset within the buffer that the read should begin.
* @param handler the handler for data that has been read
* @param fragmentsLimit limit the number of fragments read.
* @param header to be used for mapping over the header for a given fragment.
* @param errorHandler to be notified if an error occurs during the callback.
* @return the number of fragments read
*/
public static long read(
final UnsafeBuffer termBuffer,
final int termOffset,
final FragmentHandler handler,
final int fragmentsLimit,
final Header header,
final ErrorHandler errorHandler)
{
int fragmentsRead = 0;
int offset = termOffset;
final int capacity = termBuffer.capacity();
try
{
do
{
final int frameLength = frameLengthVolatile(termBuffer, offset);
if (frameLength <= 0)
{
break;
}
final int frameOffset = offset;
offset += BitUtil.align(frameLength, FRAME_ALIGNMENT);
if (!isPaddingFrame(termBuffer, frameOffset))
{
header.buffer(termBuffer);
header.offset(frameOffset);
handler.onFragment(termBuffer, frameOffset + HEADER_LENGTH, frameLength - HEADER_LENGTH, header);
++fragmentsRead;
}
}
while (fragmentsRead < fragmentsLimit && offset < capacity);
}
catch (final Throwable t)
{
errorHandler.onError(t);
}
return pack(offset, fragmentsRead);
}
/**
* Pack the values for fragmentsRead and offset into a long for returning on the stack.
*
* @param offset value to be packed.
* @param fragmentsRead value to be packed.
* @return a long with both ints packed into it.
*/
public static long pack(final int offset, final int fragmentsRead)
{
return ((long)offset << 32) | fragmentsRead;
}
/**
* The number of fragments that have been read.
*
* @param readOutcome into which the fragments read value has been packed.
* @return the number of fragments that have been read.
*/
public static int fragmentsRead(final long readOutcome)
{
return (int)readOutcome;
}
/**
* The offset up to which the term has progressed.
*
* @param readOutcome into which the offset value has been packed.
* @return the offset up to which the term has progressed.
*/
public static int offset(final long readOutcome)
{
return (int)(readOutcome >>> 32);
}
}