private async Task <ReadData> ReadBufferInternal(byte[] managedBuffer)
{
ReadData readData;
if (bytesToRead == 0)
{
// we knew on open that there was nothing to read
readData.nRead = 0;
readData.eof = true;
return(readData);
}
int toRead = (int)Math.Min((long)managedBuffer.Length, bytesToRead);
Log.LogInformation("About to read buffer length " + toRead);
readData.nRead = await AzureUtils.WrapInRetry(new PeloponneseLogger(Log.Logger), async() =>
{
return(await readStream.ReadAsync(managedBuffer, 0, toRead));
});
if (bytesToRead == Int64.MaxValue)
{
readData.eof = (readData.nRead < toRead);
}
else
{
if (readData.nRead == 0)
{
throw new ApplicationException("Reader " + source.AbsoluteUri + " ran out of data with " + bytesToRead + " bytes remaining to read");
}
bytesToRead -= readData.nRead;
readData.eof = (bytesToRead == 0);
}
Log.LogInformation("Read buffer length " + toRead + " got " + readData.nRead + " eof " + readData.eof);
return(readData);
}
private async Task <long> SeekStartOfLine(long currentOffset, long startOfNextBlock)
{
byte[] buffer = new byte[4 * 1024];
readStream.Seek(currentOffset, SeekOrigin.Begin);
long endOffset;
if (startOfNextBlock == Int64.MaxValue)
{
endOffset = Int64.MaxValue;
}
else
{
// we may need to look as far as the first character in the next block
endOffset = startOfNextBlock + 1;
}
bool foundReturn = false;
while (currentOffset < endOffset)
{
int toRead = (int)Math.Min(buffer.LongLength, endOffset - currentOffset);
int nRead = await AzureUtils.WrapInRetry(new PeloponneseLogger(Log.Logger), async() =>
{
return(await readStream.ReadAsync(buffer, 0, toRead));
});
if (nRead == 0)
{
// we hit end of stream
return(currentOffset);
}
for (int i = 0; i < nRead; ++i)
{
if (buffer[i] == '\n')
{
// the next character is the first character of a line
return(currentOffset + i + 1);
}
else if (foundReturn)
{
// there was a '\r' that wasn't followed by a '\n', i.e. this is
// the first character of a line
return(currentOffset + i);
}
else if (buffer[i] == '\r')
{
// just flag this for now; if the next character is '\n' the next line
// starts after that, otherwise the next line starts with the next character
foundReturn = true;
}
}
currentOffset += nRead;
}
// the next line starts at some character >= startOfNextBlock+1, so it's not our problem
return(currentOffset);
}
