/// <summary>
/// Scan a term buffer for a block of messages from and offset up to a limit.
/// </summary>
/// <param name="termBuffer"> to scan for messages. </param>
/// <param name="offset"> at which the scan should begin. </param>
/// <param name="limit"> at which the scan should stop. </param>
/// <returns> the offset at which the scan terminated. </returns>
public static int Scan(DirectBuffer termBuffer, int offset, int limit)
{
do
{
int frameLength = FrameDescriptor.FrameLengthVolatile(termBuffer, offset);
if (frameLength <= 0)
{
break;
}
int alignedFrameLength = BitUtil.Align(frameLength, FrameDescriptor.FRAME_ALIGNMENT);
offset += alignedFrameLength;
if (offset >= limit)
{
if (offset > limit)
{
offset -= alignedFrameLength;
}
break;
}
}while (true);
return(offset);
}
private long HandleEndOfLogCondition(
DirectBuffer termBuffer,
long termOffset,
HeaderWriter header,
int termLength,
int termId)
{
int resultingOffset = FAILED;
if (termOffset <= termLength)
{
resultingOffset = TRIPPED;
if (termOffset < termLength)
{
int offset = (int)termOffset;
int paddingLength = termLength - offset;
header.Write(termBuffer, offset, paddingLength, termId);
FrameDescriptor.FrameType(termBuffer, offset, FrameDescriptor.PADDING_FRAME_TYPE);
FrameDescriptor.FrameLengthOrdered(termBuffer, offset, paddingLength);
}
}
return(Pack(termId, resultingOffset));
}
public static long Read(
DirectBuffer termBuffer,
int offset,
OnAppendHandler handler,
int fragmentsLimit,
ErrorHandler errorHandler)
{
int fragmentsRead = 0;
int capacity = (int)termBuffer.Length;
try {
do
{
int frameLength = FrameDescriptor.FrameLengthVolatile(termBuffer, offset);
if (frameLength <= 0)
{
break;
}
int termOffset = offset;
offset += BitUtil.Align(frameLength, FrameDescriptor.FRAME_ALIGNMENT);
// TODO check for padding
if (!FrameDescriptor.IsPaddingFrame(termBuffer, termOffset))
{
var messageBuffer = new DirectBuffer(frameLength, termBuffer.Data + termOffset);
handler?.Invoke(messageBuffer);
++fragmentsRead;
}
}while (fragmentsRead < fragmentsLimit && offset < capacity);
} catch (Exception t) {
errorHandler?.Invoke(t);
}
return(Pack(offset, fragmentsRead));
}
/// <summary>
/// Insert a packet of frames into the log at the appropriate offset as indicated by the term offset header.
/// </summary>
/// <param name="termBuffer"> into which the packet should be inserted. </param>
/// <param name="offset"> offset in the term at which the packet should be inserted. </param>
/// <param name="packet"> containing a sequence of frames. </param>
/// <param name="length"> of the sequence of frames in bytes. </param>
public static void Insert(DirectBuffer termBuffer, int offset, DirectBuffer packet, int length)
{
int firstFrameLength = packet.ReadInt32(0);
packet.VolatileWriteInt32(0, 0);
termBuffer.WriteBytes(offset, packet, 0, length);
FrameDescriptor.FrameLengthOrdered(termBuffer, offset, firstFrameLength);
}
private static void ResetHeader(
DirectBuffer logMetaDataBuffer,
DirectBuffer termBuffer,
int termOffset,
int termId,
int frameLength)
{
LogBufferDescriptor.ApplyDefaultHeader(logMetaDataBuffer, termBuffer, termOffset);
FrameDescriptor.FrameType(termBuffer, termOffset, HeaderFlyweight.HDR_TYPE_PAD);
FrameDescriptor.FrameTermOffset(termBuffer, termOffset);
FrameDescriptor.FrameTermId(termBuffer, termOffset, termId);
FrameDescriptor.FrameLengthOrdered(termBuffer, termOffset, frameLength);
}
/// <summary>
/// Attempt to unblock the current term at the current offset.
///
/// <ol>
/// <li>Current position length is > 0, then return</li>
/// <li>Current position length is 0, scan forward by frame alignment until, one of the following:
/// <ol>
/// <li>reach a non-0 length, unblock up to indicated position (check original frame length for non-0)</li>
/// <li>reach end of term and tail position >= end of term, unblock up to end of term (check original
/// frame length for non-0)
/// </li>
/// <li>reach tail position < end of term, do NOT unblock</li>
/// </ol>
/// </li>
/// </ol>
/// </summary>
/// <param name="logMetaDataBuffer"> containing the default headers </param>
/// <param name="termBuffer"> to unblock </param>
/// <param name="blockedOffset"> to unblock at </param>
/// <param name="tailOffset"> to unblock up to </param>
/// <param name="termId"> for the current term. </param>
/// <returns> whether unblocking was done, not done, or applied to end of term </returns>
public static TermUnblockerStatus Unblock(
DirectBuffer logMetaDataBuffer,
DirectBuffer termBuffer,
int blockedOffset,
int tailOffset,
int termId)
{
var status = TermUnblockerStatus.NO_ACTION;
int frameLength = FrameDescriptor.FrameLengthVolatile(termBuffer, blockedOffset);
if (frameLength < 0)
{
ResetHeader(logMetaDataBuffer, termBuffer, blockedOffset, termId, -frameLength);
status = TermUnblockerStatus.UNBLOCKED;
}
else if (0 == frameLength)
{
int currentOffset = blockedOffset + FrameDescriptor.FRAME_ALIGNMENT;
while (currentOffset < tailOffset)
{
frameLength = FrameDescriptor.FrameLengthVolatile(termBuffer, currentOffset);
if (frameLength != 0)
{
if (ScanBackToConfirmZeroed(termBuffer, currentOffset, blockedOffset))
{
int length = currentOffset - blockedOffset;
ResetHeader(logMetaDataBuffer, termBuffer, blockedOffset, termId, length);
status = TermUnblockerStatus.UNBLOCKED;
}
break;
}
currentOffset += FrameDescriptor.FRAME_ALIGNMENT;
}
if (currentOffset == termBuffer.Length)
{
if (0 == FrameDescriptor.FrameLengthVolatile(termBuffer, blockedOffset))
{
int length = currentOffset - blockedOffset;
ResetHeader(logMetaDataBuffer, termBuffer, blockedOffset, termId, length);
status = TermUnblockerStatus.UNBLOCKED_TO_END;
}
}
}
return(status);
}
private static bool ScanBackToConfirmZeroed(DirectBuffer buffer, int from, int limit)
{
int i = from - FrameDescriptor.FRAME_ALIGNMENT;
bool allZeros = true;
while (i >= limit)
{
if (0 != FrameDescriptor.FrameLengthVolatile(buffer, i))
{
allZeros = false;
break;
}
i -= FrameDescriptor.FRAME_ALIGNMENT;
}
return(allZeros);
}
/// <summary>
/// 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.
/// </summary>
/// <param name="termBuffer"> to be read for fragments. </param>
/// <param name="offset"> offset within the buffer that the read should begin. </param>
/// <param name="handler"> the handler for data that has been read </param>
/// <param name="fragmentsLimit"> limit the number of fragments read. </param>
/// <param name="header"> to be used for mapping over the header for a given fragment. </param>
/// <param name="errorHandler"> to be notified if an error occurs during the callback. </param>
/// <returns> the number of fragments read </returns>
public static long Read(
DirectBuffer termBuffer,
int offset,
FragmentHandler handler,
int fragmentsLimit,
Header header,
ErrorHandler errorHandler)
{
int fragmentsRead = 0;
int capacity = (int)termBuffer.Length;
try {
do
{
int frameLength = FrameDescriptor.FrameLengthVolatile(termBuffer, offset);
if (frameLength <= 0)
{
break;
}
int termOffset = offset;
offset += BitUtil.Align(frameLength, FrameDescriptor.FRAME_ALIGNMENT);
if (!FrameDescriptor.IsPaddingFrame(termBuffer, termOffset))
{
header.Buffer = termBuffer;
header.Offset = termOffset;
handler?.Invoke(termBuffer, termOffset + DataHeaderFlyweight.HEADER_LENGTH, frameLength - DataHeaderFlyweight.HEADER_LENGTH, header);
++fragmentsRead;
}
}while (fragmentsRead < fragmentsLimit && offset < capacity);
} catch (Exception t) {
errorHandler?.Invoke(t);
}
return(Pack(offset, fragmentsRead));
}
/**
* Scan the term buffer for availability of new messages from a given offset up to a maxLength of bytes.
*
* @param termBuffer to be scanned for new messages
* @param offset at which the scan should begin.
* @param maxLength in bytes of how much should be scanned.
* @return resulting status of the scan which packs the available bytes and padding into a long.
*/
public static long ScanForAvailability(DirectBuffer termBuffer, int offset, int maxLength)
{
checked
{
maxLength = Math.Min(maxLength, (int)termBuffer.Length - offset);
int available = 0;
int padding = 0;
do
{
int termOffset = offset + available;
int frameLength = FrameDescriptor.FrameLengthVolatile(termBuffer, termOffset);
if (frameLength <= 0)
{
break;
}
int alignedFrameLength = BitUtil.Align(frameLength, FrameDescriptor.FRAME_ALIGNMENT);
if (FrameDescriptor.IsPaddingFrame(termBuffer, termOffset))
{
padding = alignedFrameLength - DataHeaderFlyweight.HEADER_LENGTH;
alignedFrameLength = DataHeaderFlyweight.HEADER_LENGTH;
}
available += alignedFrameLength;
if (available > maxLength)
{
available -= alignedFrameLength;
padding = 0;
break;
}
} while (0 == padding && available < maxLength);
return(Pack(padding, available));
}
}
/**
* Scan for gaps from the rebuildOffset up to the high-water-mark. Each gap will be reported to the {@link GapHandler}.
*
* @param termBuffer to be scanned for a gap.
* @param termId of the current term buffer.
* @param rebuildOffset at which to start scanning.
* @param hwmOffset at which to stop scanning.
* @param handler to call if a gap is found.
* @return offset of last contiguous frame
*/
public static int ScanForGap(
DirectBuffer termBuffer, int termId, int rebuildOffset, int hwmOffset, GapHandler handler)
{
do
{
int frameLength = FrameDescriptor.FrameLengthVolatile(termBuffer, rebuildOffset);
if (frameLength <= 0)
{
break;
}
rebuildOffset += BitUtil.Align(frameLength, FrameDescriptor.FRAME_ALIGNMENT);
}while (rebuildOffset < hwmOffset);
int gapBeginOffset = rebuildOffset;
if (rebuildOffset < hwmOffset)
{
int limit = hwmOffset - ALIGNED_HEADER_LENGTH;
while (rebuildOffset < limit)
{
rebuildOffset += FrameDescriptor.FRAME_ALIGNMENT;
if (0 != termBuffer.VolatileReadInt32(rebuildOffset))
{
rebuildOffset -= ALIGNED_HEADER_LENGTH;
break;
}
}
int gapLength = (rebuildOffset - gapBeginOffset) + ALIGNED_HEADER_LENGTH;
handler?.Invoke(termId, termBuffer, gapBeginOffset, gapLength);
}
return(gapBeginOffset);
}
