public void seek(long desired)
{
if (desired == 0 && bytes.Count == 0)
{
logEmptySeek(name);
return;
}
int i = 0;
foreach (DiskRange curRange in bytes)
{
if (desired == 0 && curRange.getData().remaining() == 0)
{
logEmptySeek(name);
return;
}
if (curRange.getOffset() <= desired &&
(desired - curRange.getOffset()) < curRange.getLength())
{
currentOffset = desired;
currentRange = i;
this.range = curRange.getData().duplicate();
int pos = range.position();
pos += (int)(desired - curRange.getOffset()); // this is why we duplicate
this.range.position(pos);
return;
}
++i;
}
// if they are seeking to the precise end, go ahead and let them go there
int segments = bytes.Count;
if (segments != 0 && desired == bytes[segments - 1].getEnd())
{
currentOffset = desired;
currentRange = segments - 1;
DiskRange curRange = bytes[currentRange];
this.range = curRange.getData().duplicate();
int pos = range.position();
pos += (int)(desired - curRange.getOffset()); // this is why we duplicate
this.range.position(pos);
return;
}
throw new ArgumentException("Seek in " + name + " to " +
desired + " is outside of the data");
}
private void seek(long desired)
{
if (desired == 0 && bytes.Count == 0)
{
logEmptySeek(name);
return;
}
int i = 0;
foreach (DiskRange range in bytes)
{
if (range.getOffset() <= desired && desired < range.getEnd())
{
currentRange = i;
compressed = range.getData().duplicate();
int pos = compressed.position();
pos += (int)(desired - range.getOffset());
compressed.position(pos);
currentOffset = desired;
return;
}
++i;
}
// if they are seeking to the precise end, go ahead and let them go there
int segments = bytes.Count;
if (segments != 0 && desired == bytes[segments - 1].getEnd())
{
DiskRange range = bytes[segments - 1];
currentRange = segments - 1;
compressed = range.getData().duplicate();
compressed.position(compressed.limit());
currentOffset = desired;
return;
}
throw new IOException("Seek outside of data in " + this + " to " + desired);
}
/* slices a read only contiguous buffer of chunkLength */
private ByteBuffer slice(int chunkLength)
{
int len = chunkLength;
long oldOffset = currentOffset;
ByteBuffer slice;
if (compressed.remaining() >= len)
{
slice = compressed.slice();
// simple case
slice.limit(len);
currentOffset += len;
compressed.position(compressed.position() + len);
return(slice);
}
else if (currentRange >= (bytes.Count - 1))
{
// nothing has been modified yet
throw new IOException("EOF in " + this + " while trying to read " +
chunkLength + " bytes");
}
if (LOG.isDebugEnabled())
{
LOG.debug(String.Format(
"Crossing into next BufferChunk because compressed only has %d bytes (needs %d)",
compressed.remaining(), len));
}
// we need to consolidate 2 or more buffers into 1
// first copy out compressed buffers
ByteBuffer copy = allocateBuffer(chunkLength, compressed.isDirect());
currentOffset += compressed.remaining();
len -= compressed.remaining();
copy.put(compressed);
for (int i = currentRange; i < bytes.Count && len > 0; i++)
{
++currentRange;
if (LOG.isDebugEnabled())
{
LOG.debug(String.Format("Read slow-path, >1 cross block reads with {0}", this.ToString()));
}
DiskRange range = bytes[i];
compressed = range.getData().duplicate();
if (compressed.remaining() >= len)
{
slice = compressed.slice();
slice.limit(len);
copy.put(slice);
currentOffset += len;
compressed.position(compressed.position() + len);
return(copy);
}
currentOffset += compressed.remaining();
len -= compressed.remaining();
copy.put(compressed);
}
// restore offsets for exception clarity
seek(oldOffset);
throw new IOException("EOF in " + this + " while trying to read " +
chunkLength + " bytes");
}
