On Fri, Jan 21, 2005 at 12:42:56PM +0000, Keean Schupke wrote: > Ben Rudiak-Gould wrote: > >If you're reading from a random-access file, there's no way it can > >tell you when the file data is buffered, because it doesn't know which > >part of the file you plan to read. The OS may try to guess for > >readahead purposes, but select()'s behavior can't depend on that guess. > > But surely it does! read only reads the next block... to skip randomly > you must seek... therefore the following sequence does this: > > seek > select > read > > The select should block until one disk block from the file is in memory, > read is defined such that it will return if some data is ready even if it > is not as much as you requested. So in this case if you ask for a > complete file, you may just get one block... or more. > > In other words the API restricts reads to the 'next' block - so seek > knows which block needs to be read into memory...
Wouldn't select always fail, since the block would never be read into memory until you call read? -- David Roundy http://www.darcs.net _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
