>>>>> "DS" == Dan Sugalski <[EMAIL PROTECTED]> writes:
DS> At 05:35 PM 9/21/00 -0400, Uri Guttman wrote:
>> i proposed some of that in my rfc47 (universal async i/o). at the perl
>> level you need a delivery interface as with events.
DS> I'm not really worried about the perl level for this. I'm more
DS> concerned with the low-level internal implementation.
but i am concerned about the language level. this is the language list
and not the internals one. we can deal with how to implement it
later. and saying that perl will do async i/o on files for you is still
a language level issue as the coder may not want that (random access
files, etc.). i think the coder has to be able to request this and not
have it happen automagically.
>> internally i see it being useful too for the speedup of sequential
>> files. but how do you know a file is sequential?
DS> Who cares? If the filehandle's read within a while(), or in list
DS> context, we can use a big readahead buffer and issue a lot of
DS> async I/O requests. For filehandles read with a plain scalar
DS> fetch off a filehandle we can use a smaller readahead buffer.
this again is a language issue. are all filehandles in while loops going
to do this? i think the user need to control it and not let perl guess
how to handle it.
DS> Async writes are a win in any case.
true.
>> most unix kernels do readahead blocks anyway
>> but if you seek, you waste that.
DS> So? We lose in that case, but not by much. If we give full control
DS> to the user programs (and I'd like to) then the user can get fancy
DS> and we'll leave the decision to the program.
that is my point. i don't think we should do any of this withour user
control. it reminds me of the transactions wars we have had. how can
perl figure out the right thing to do in all cases. IMO only the coder
must have the choice.
uri
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