readBin on binary non-blocking connections (Windows & Unix differences/bugs)

Thanks Gabor.

Unfortunately read/writeLines won't work in this particular
application.  Nor does readChar, as the returned values are not of a
fixed size.  I need to read each unknown length "character" up until
an embedded null.  readBin does this (almost) perfectly.

My current workaround is to simply force blocking=TRUE on Windows
users, but that seems not to be the right answer.

An alternate approach may be to rewrite readBin to allow for some sort
of buffering mechanism.  If readBin first reads in data as raw(), it
would be possible to test for an error and return via some switch
statement the appropriate length zero vector.

The main issue is that by reading in raw bytes I have to explicitly
convert to the appropriate data types (nul terminated character
strings in this case).

The second (bigger?) issue is that all readBin calls would have to
first look to the buffer before reading from the connection again.
This would require the buffer to be available --- either as an R
connection addition, or as a global variable.

The best option of course is for readBin to correctly catch the error
cases, but without guidance from those who know the full details of
sockets in R, I am afraid that option isn't realistic at this moment.

Jeff

On Mon, May 18, 2009 at 1:01 PM, Gabor Grothendieck

readBin on binary non-blocking connections (Windows & Unix differences/bugs)

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