Better one:
// There are differences in how skip and seek behave
// when trying to skip more bytes than available in a file
// but ...
long skip(long len) throws IOException {
if ( len > 0 ) {
seek(getPos() + len);
return len;
}
return ( len < 0 ) ? -1 : 0;
}
This should fix HADOOP-1428, if not very efficiently.
Raghu.
Raghu Angadi wrote:
We should force subclasses of FSInputStream to implement skip if skip is
expected to be used. Only way I could think of achieving is to define
long skip(long len) throws IOException {
throw new IOException("Subclasses of FSInputStream should implement
skip");
}
This makes sense for all the current FSInputStreams. But not sure if
there is any way for subclasses to call InputStream.skip() is that makes
sense.
Raghu.
Doug Cutting wrote:
Raghu Angadi wrote:
Also, reading from block supports 'real skip', ie, it does not check
checksum if an entire checksum block (usually 512 bytes) falls within
the skip range. Another reason to implement our own skip.
Yes, I don't see an alternative to implementing skip ourselves. The
optimization in InputStream#skip(), of using a static buffer, requires
this. Hopefully this method, like much of the checksum code, will be
shared between the generic ChecksumFileSystem and DFS's optimized
checksum implementation.
Doug
