I think keeping the status quo is the right outcome. The /proc filesystem is intentionally providing incorrect information because providing correct information is deemed to be too expensive (have to compute contents of file for stat?). Reading /proc is sufficiently expensive that the extra realloc of an empty buffer is noise. Be thankful that reading files in /proc works at all!
On Thu, Jul 28, 2016 at 11:28 PM, Fabian Lange <lange.fab...@gmail.com> wrote: > Hi, > yes something like that. I have no strong opinion. After discovering > this, I switched to a hand rolled implementation with file name > depended estimated buffer sizes. > But usually inside the JDK, Edge cases are handled better, usually > with some Math.min()/Math.max logic. > > IMHO that really depends how common it could be that > SeekableBytesChannel returns a size of 0 while actually containing > data. > If the proc files are the only realistic scenario, then maybe my > concern is not that valid > > Fabian > > On Fri, Jul 29, 2016 at 8:21 AM, <e...@zusammenkunft.net> wrote: > > Hello, > > > > > > > > It could always read with a initial buffer of 0.5-16k and return a > truncated > > copy if it read less (and a omit truncation by returning shared static 0 > > length array if empty). But this will only optimize the 0 byte case. > > > > > > > > > > Gruss > > Bernd > > -- > > http://bernd.eckenfels.net > > From Win 10 Mobile > > > > > > > > Von: Martin Buchholz > > Gesendet: Freitag, 29. Juli 2016 03:33 > > An: Fabian Lange > > Cc: core-libs-dev > > Betreff: Re: Files.read/readAllBytes can loop once with zero size buffer > > > > > > > > What do you suggest instead? > > > > > > > > The extra allocation of a zero-size buffer is not that bad. > > > > > > > > I think it's best to optimize for files with correct metadata, while > > > > tolerating ones with buggy metadata. > > > > > > > > On Thu, Jul 28, 2016 at 1:13 PM, Fabian Lange <lange.fab...@gmail.com> > > > > wrote: > > > > > > > >> Hi, > > > >> I just noticed that when one uses Files.readAllBytes() to read for > > > >> example from the Linux proc file system, where file size is claimed to > > > >> be 0, Files.read() will allocate a buffer of size 0 before then > > > >> adjusting in a second loop (arraycopying the zero size buffer) > > > >> > > > >> In my opinion an initial size of 0 should not be used. > > > >> I admit this might be a regression for files which are really empty > > > >> and return an empty byte array, but I think it is actually more common > > > >> to read from files which incorrectly report to be zero sized. > > > >> > > > >> Fabian > > > >> > > > > >
