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pmonitor() fixes

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pmonitor() is hard to get right, but this seems like
a reasonable improvement:

1. non-blocking I/O so we can drain buffer with impunity
2. drain buffer after poll
3. unregister fd on POLLHUP

Note we may have a unicode splitting problem since we're
decoding chunks of bytes, but that is a problem for another
day I think.
This commit is contained in:
Bob Lantz
2018-08-02 06:58:33 -07:00
parent 3bcecd8e08
commit 5100a38fcd
1 changed files with 12 additions and 19 deletions
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mininet/util.py
+12 -19
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@@ -416,34 +416,27 @@ def pmonitor(popens, timeoutms=500, readline=True,
for host, popen in popens.items():
fd = popen.stdout.fileno()
fdToHost[ fd ] = host
poller.register( fd, POLLIN )
if not readline:
# Use non-blocking reads
flags = fcntl( fd, F_GETFL )
fcntl( fd, F_SETFL, flags | O_NONBLOCK )
def readit( f ):
"Helper function - read line or data"
# Note this will block if readline is True
line = f.readline() if readline else f.read( readmax )
return decode( line )
poller.register( fd, POLLIN | POLLHUP )
flags = fcntl( fd, F_GETFL )
fcntl( fd, F_SETFL, flags | O_NONBLOCK )
while popens:
fds = poller.poll( timeoutms )
if fds:
for fd, event in fds:
host = fdToHost[ fd ]
popen = popens[ host ]
if event & POLLIN:
line = readit( popen.stdout )
yield host, line
if event & POLLHUP:
if event & POLLIN or event & POLLHUP:
while True:
# Drain buffer
line = readit( popen.stdout )
yield host, line
try:
f = popen.stdout
line = decode( f.readline() if readline
else f.read( readmax ) )
except IOError:
line = ''
if line == '':
break
yield host, line
if event & POLLHUP:
poller.unregister( fd )
del popens[ host ]
else: