[HACKERS] A portable code question
In the little fix I came up with for psql last night, I need to be able
to ensure that something sent to a pipe (and then to stdout) completes
before issuing the prompt directly to stdout.
I did this with: system ('sleep 1');, but I'm fairly sure that is
not portable nor does it ENSURE completion.
What's the proper way to do this? And what's a good book on writing
portable code?
--
Mike Nolan
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Re: [HACKERS] A portable code question
Assuming you're using file streams to write to the pipe, fflush() will do
the trick.
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Sent: Thursday, June 26, 2003 2:20 PM
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Subject: [HACKERS] A portable code question
In the little fix I came up with for psql last night, I need to be able
to ensure that something sent to a pipe (and then to stdout) completes
before issuing the prompt directly to stdout.
I did this with: system ('sleep 1');, but I'm fairly sure that is
not portable nor does it ENSURE completion.
What's the proper way to do this? And what's a good book on writing
portable code?
--
Mike Nolan
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TIP 8: explain analyze is your friend
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Re: [HACKERS] A portable code question
Or if you want this behaviour all the time, one call of
setvbuf(mypipe,(char *)0,_IONBF,0);
should do the trick (much easier than remebering to have to call fflush()
all the time).
If not using streams, and just calling write(), then you probably don't have
to worry.
andrew
BTW, system('sleep 1'); probably won't compile, and 'system(sleep 1);'
is bad news. Try man 3 sleep for more info.
Assuming you're using file streams to write to the pipe, fflush() will
do the trick.
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From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of
[EMAIL PROTECTED]
Sent: Thursday, June 26, 2003 2:20 PM
To: pgsql hackers list
Subject: [HACKERS] A portable code question
In the little fix I came up with for psql last night, I need to be
able to ensure that something sent to a pipe (and then to stdout)
completes before issuing the prompt directly to stdout.
I did this with: system ('sleep 1');, but I'm fairly sure that is
not portable nor does it ENSURE completion.
What's the proper way to do this? And what's a good book on writing
portable code?
--
Mike Nolan
---(end of
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Re: [HACKERS] A portable code question
Assuming you're using file streams to write to the pipe, fflush() will do
the trick.
The problem is that the pipe (from \o |tee ) is intermingling writes
to stdout by tee with direct writes to stdout from within psql.
I do issue a fflush, because that's necessary to make the pipe do its
thing, but the next line of code also does a write to stdout and the pipe
generally doesn't have time to complete that write to stdout, resulting
in intermingled output. (fflush makes sure the pipe GETS the stream,
it doesn't wait around to make sure it's DONE with it, probably because
there's no way for whatever the pipe calls to report back when it is done.)
This is a bit of a hack, but adding an option to the \o code so that it
writes simultaneously to the pipe and to stdout instead of using tee
looks like a lot more work, especially since the code appears to have a
couple of other places where intermingling to stdout is possible,
especially if readline is used.
Throwing in system('sleep 1'); was the way I resolved the timing
question here, but that may not be portable enough for inclusion into
the code base.
--
Mike Nolan
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