/// <summary>Writes to a stream the given number of bytes specified</summary>
/// <param name="byteAm">the file size in number of bytes to write</param>
/// <param name="out">the outputstream to write to</param>
/// <returns>the number of bytes written + time taken</returns>
/// <exception cref="System.IO.IOException"/>
internal virtual DataWriter.GenerateOutput WriteSegment(long byteAm, OutputStream
@out)
{
long headerLen = GetHeaderLength();
if (byteAm < headerLen)
{
// not enough bytes to write even the header
return(new DataWriter.GenerateOutput(0, 0));
}
// adjust for header length
byteAm -= headerLen;
if (byteAm < 0)
{
byteAm = 0;
}
DataWriter.WriteInfo header = WriteHeader(@out, byteAm);
DataHasher hasher = new DataHasher(header.GetHashValue());
DataWriter.GenerateOutput pRes = WritePieces(byteAm, 0, hasher, @out);
long bytesWritten = pRes.GetBytesWritten() + header.GetBytesWritten();
long timeTaken = header.GetTimeTaken() + pRes.GetTimeTaken();
return(new DataWriter.GenerateOutput(bytesWritten, timeTaken));
}
/// <summary>
/// Generates a full segment (aligned to bytes per long) of the given byte
/// amount size
/// </summary>
/// <param name="byteAm">long aligned size</param>
/// <param name="startOffset">starting hash offset</param>
/// <param name="hasher">hasher to use for generating data given an offset</param>
/// <returns>GenerateResult containing new offset and byte buffer</returns>
private DataWriter.GenerateResult GenerateFullSegment(int byteAm, long startOffset
, DataHasher hasher)
{
if (byteAm <= 0)
{
throw new ArgumentException("Byte amount must be greater than zero and not " + byteAm
);
}
if ((byteAm % Constants.BytesPerLong) != 0)
{
throw new ArgumentException("Byte amount " + byteAm + " must be a multiple of " +
Constants.BytesPerLong);
}
// generate all the segments
ByteBuffer allBytes = ByteBuffer.Wrap(new byte[byteAm]);
long offset = startOffset;
ByteBuffer buf = ByteBuffer.Wrap(new byte[Constants.BytesPerLong]);
for (long i = 0; i < byteAm; i += Constants.BytesPerLong)
{
buf.Rewind();
buf.PutLong(hasher.Generate(offset));
buf.Rewind();
allBytes.Put(buf);
offset += Constants.BytesPerLong;
}
allBytes.Rewind();
return(new DataWriter.GenerateResult(offset, allBytes));
}
/// <summary>Generates a partial segment which is less than bytes per long size</summary>
/// <param name="byteAm">the number of bytes to generate (less than bytes per long)</param>
/// <param name="offset">the staring offset</param>
/// <param name="hasher">hasher to use for generating data given an offset</param>
/// <returns>GenerateResult containing new offset and byte buffer</returns>
private DataWriter.GenerateResult GeneratePartialSegment(int byteAm, long offset,
DataHasher hasher)
{
if (byteAm > Constants.BytesPerLong)
{
throw new ArgumentException("Partial bytes must be less or equal to " + Constants
.BytesPerLong);
}
if (byteAm <= 0)
{
throw new ArgumentException("Partial bytes must be greater than zero and not " +
byteAm);
}
ByteBuffer buf = ByteBuffer.Wrap(new byte[Constants.BytesPerLong]);
buf.PutLong(hasher.Generate(offset));
ByteBuffer allBytes = ByteBuffer.Wrap(new byte[byteAm]);
buf.Rewind();
for (int i = 0; i < byteAm; ++i)
{
allBytes.Put(buf.Get());
}
allBytes.Rewind();
return(new DataWriter.GenerateResult(offset, allBytes));
}
/// <summary>Verifies a buffer of a given size using the given start hash offset</summary>
/// <param name="buf">the buffer to verify</param>
/// <param name="size">the number of bytes to be used in that buffer</param>
/// <param name="startOffset">the start hash offset</param>
/// <param name="hasher">the hasher to use for calculating expected values</param>
/// <returns>ResumeBytes a set of data about the next offset and chunks analyzed</returns>
private DataVerifier.VerifyInfo VerifyBuffer(ByteBuffer buf, int size, long startOffset
, DataHasher hasher)
{
ByteBuffer cmpBuf = ByteBuffer.Wrap(new byte[BytesPerLong]);
long hashOffset = startOffset;
long chunksSame = 0;
long chunksDifferent = 0;
for (long i = 0; i < size; ++i)
{
cmpBuf.Put(buf.Get());
if (!cmpBuf.HasRemaining())
{
cmpBuf.Rewind();
long receivedData = cmpBuf.GetLong();
cmpBuf.Rewind();
long expected = hasher.Generate(hashOffset);
hashOffset += BytesPerLong;
if (receivedData == expected)
{
++chunksSame;
}
else
{
++chunksDifferent;
}
}
}
// any left over??
if (cmpBuf.HasRemaining() && cmpBuf.Position() != 0)
{
// partial capture
// zero fill and compare with zero filled
int curSize = cmpBuf.Position();
while (cmpBuf.HasRemaining())
{
cmpBuf.Put(unchecked ((byte)0));
}
long expected = hasher.Generate(hashOffset);
ByteBuffer tempBuf = ByteBuffer.Wrap(new byte[BytesPerLong]);
tempBuf.PutLong(expected);
tempBuf.Position(curSize);
while (tempBuf.HasRemaining())
{
tempBuf.Put(unchecked ((byte)0));
}
cmpBuf.Rewind();
tempBuf.Rewind();
if (cmpBuf.Equals(tempBuf))
{
++chunksSame;
}
else
{
++chunksDifferent;
}
}
return(new DataVerifier.VerifyInfo(chunksSame, chunksDifferent));
}
/// <summary>
/// Verifies a given number of bytes from a file - less number of bytes may be
/// read if a header can not be read in due to the byte limit
/// </summary>
/// <param name="byteAm">
/// the byte amount to limit to (should be less than or equal to file
/// size)
/// </param>
/// <param name="bytesRead">the starting byte location</param>
/// <param name="in">the input stream to read from</param>
/// <returns>VerifyOutput with data about reads</returns>
/// <exception cref="System.IO.IOException">if a read failure occurs</exception>
/// <exception cref="BadFileException">
/// if a header can not be read or end of file is reached
/// unexpectedly
/// </exception>
/// <exception cref="Org.Apache.Hadoop.FS.Slive.BadFileException"/>
private DataVerifier.VerifyOutput VerifyBytes(long byteAm, long bytesRead, DataInputStream
@in)
{
if (byteAm <= 0)
{
return(new DataVerifier.VerifyOutput(0, 0, 0, 0));
}
long chunksSame = 0;
long chunksDifferent = 0;
long readTime = 0;
long bytesLeft = byteAm;
long bufLeft = 0;
long bufRead = 0;
long seqNum = 0;
DataHasher hasher = null;
ByteBuffer readBuf = ByteBuffer.Wrap(new byte[bufferSize]);
while (bytesLeft > 0)
{
if (bufLeft <= 0)
{
if (bytesLeft < DataWriter.GetHeaderLength())
{
// no bytes left to read a header
break;
}
// time to read a new header
DataVerifier.ReadInfo header = null;
try
{
header = ReadHeader(@in);
}
catch (EOFException)
{
// eof ok on header reads
// but not on data readers
break;
}
++seqNum;
hasher = new DataHasher(header.GetHashValue());
bufLeft = header.GetByteAm();
readTime += header.GetTimeTaken();
bytesRead += header.GetBytesRead();
bytesLeft -= header.GetBytesRead();
bufRead = 0;
// number of bytes to read greater than how many we want to read
if (bufLeft > bytesLeft)
{
bufLeft = bytesLeft;
}
// does the buffer amount have anything??
if (bufLeft <= 0)
{
continue;
}
}
// figure out the buffer size to read
int bufSize = bufferSize;
if (bytesLeft < bufSize)
{
bufSize = (int)bytesLeft;
}
if (bufLeft < bufSize)
{
bufSize = (int)bufLeft;
}
// read it in
try
{
readBuf.Rewind();
long startTime = Timer.Now();
@in.ReadFully(((byte[])readBuf.Array()), 0, bufSize);
readTime += Timer.Elapsed(startTime);
}
catch (EOFException e)
{
throw new BadFileException("Could not read the number of expected data bytes " +
bufSize + " due to unexpected end of file during sequence " + seqNum, e);
}
// update the counters
bytesRead += bufSize;
bytesLeft -= bufSize;
bufLeft -= bufSize;
// verify what we read
readBuf.Rewind();
// figure out the expected hash offset start point
long vOffset = DetermineOffset(bufRead);
// now update for new position
bufRead += bufSize;
// verify
DataVerifier.VerifyInfo verifyRes = VerifyBuffer(readBuf, bufSize, vOffset, hasher
);
// update the verification counters
chunksSame += verifyRes.GetSame();
chunksDifferent += verifyRes.GetDifferent();
}
return(new DataVerifier.VerifyOutput(chunksSame, chunksDifferent, bytesRead, readTime
));
}
/// <summary>
/// Writes a set of bytes to the output stream, for full segments it will write
/// out the complete segment but for partial segments, ie when the last
/// position does not fill up a full long then a partial set will be written
/// out containing the needed bytes from the expected full segment
/// </summary>
/// <param name="byteAm">the amount of bytes to write</param>
/// <param name="startPos">a BYTES_PER_LONG aligned start position</param>
/// <param name="hasher">hasher to use for generating data given an offset</param>
/// <param name="out">the output stream to write to</param>
/// <returns>how many bytes were written</returns>
/// <exception cref="System.IO.IOException"/>
private DataWriter.GenerateOutput WritePieces(long byteAm, long startPos, DataHasher
hasher, OutputStream @out)
{
if (byteAm <= 0)
{
return(new DataWriter.GenerateOutput(0, 0));
}
if (startPos < 0)
{
startPos = 0;
}
int leftOver = (int)(byteAm % bufferSize);
long fullPieces = byteAm / bufferSize;
long offset = startPos;
long bytesWritten = 0;
long timeTaken = 0;
// write the full pieces that fit in the buffer size
for (long i = 0; i < fullPieces; ++i)
{
DataWriter.GenerateResult genData = GenerateFullSegment(bufferSize, offset, hasher
);
offset = genData.GetOffset();
ByteBuffer gBuf = genData.GetBuffer();
{
byte[] buf = ((byte[])gBuf.Array());
long startTime = Timer.Now();
@out.Write(buf);
timeTaken += Timer.Elapsed(startTime);
bytesWritten += buf.Length;
}
}
if (leftOver > 0)
{
ByteBuffer leftOverBuf = ByteBuffer.Wrap(new byte[leftOver]);
int bytesLeft = leftOver % Constants.BytesPerLong;
leftOver = leftOver - bytesLeft;
// collect the piece which do not fit in the buffer size but is
// also greater or eq than BYTES_PER_LONG and a multiple of it
if (leftOver > 0)
{
DataWriter.GenerateResult genData = GenerateFullSegment(leftOver, offset, hasher);
offset = genData.GetOffset();
leftOverBuf.Put(genData.GetBuffer());
}
// collect any single partial byte segment
if (bytesLeft > 0)
{
DataWriter.GenerateResult genData = GeneratePartialSegment(bytesLeft, offset, hasher
);
offset = genData.GetOffset();
leftOverBuf.Put(genData.GetBuffer());
}
// do the write of both
leftOverBuf.Rewind();
{
byte[] buf = ((byte[])leftOverBuf.Array());
long startTime = Timer.Now();
@out.Write(buf);
timeTaken += Timer.Elapsed(startTime);
bytesWritten += buf.Length;
}
}
return(new DataWriter.GenerateOutput(bytesWritten, timeTaken));
}
