Bob Lantz
af4921adc5
items() vs. iteritems() and decode() bytes in monitorFiles Probably not strictly correct if bytes are split - we still need to deal with this properly.
85 lines
2.5 KiB
Python
Executable File
85 lines
2.5 KiB
Python
Executable File
#!/usr/bin/python
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"""
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Simple example of sending output to multiple files and
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monitoring them
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"""
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from mininet.topo import SingleSwitchTopo
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from mininet.net import Mininet
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from mininet.log import info, setLogLevel
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from mininet.util import decode
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from time import time
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from select import poll, POLLIN
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from subprocess import Popen, PIPE
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def monitorFiles( outfiles, seconds, timeoutms ):
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"Monitor set of files and return [(host, line)...]"
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devnull = open( '/dev/null', 'w' )
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tails, fdToFile, fdToHost = {}, {}, {}
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for h, outfile in outfiles.items():
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tail = Popen( [ 'tail', '-f', outfile ],
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stdout=PIPE, stderr=devnull )
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fd = tail.stdout.fileno()
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tails[ h ] = tail
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fdToFile[ fd ] = tail.stdout
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fdToHost[ fd ] = h
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# Prepare to poll output files
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readable = poll()
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for t in tails.values():
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readable.register( t.stdout.fileno(), POLLIN )
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# Run until a set number of seconds have elapsed
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endTime = time() + seconds
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while time() < endTime:
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fdlist = readable.poll(timeoutms)
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if fdlist:
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for fd, _flags in fdlist:
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f = fdToFile[ fd ]
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host = fdToHost[ fd ]
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# Wait for a line of output
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line = f.readline().strip()
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yield host, decode( line )
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else:
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# If we timed out, return nothing
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yield None, ''
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for t in tails.values():
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t.terminate()
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devnull.close() # Not really necessary
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def monitorTest( N=3, seconds=3 ):
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"Run pings and monitor multiple hosts"
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topo = SingleSwitchTopo( N )
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net = Mininet( topo )
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net.start()
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hosts = net.hosts
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info( "Starting test...\n" )
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server = hosts[ 0 ]
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outfiles, errfiles = {}, {}
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for h in hosts:
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# Create and/or erase output files
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outfiles[ h ] = '/tmp/%s.out' % h.name
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errfiles[ h ] = '/tmp/%s.err' % h.name
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h.cmd( 'echo >', outfiles[ h ] )
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h.cmd( 'echo >', errfiles[ h ] )
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# Start pings
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h.cmdPrint('ping', server.IP(),
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'>', outfiles[ h ],
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'2>', errfiles[ h ],
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'&' )
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info( "Monitoring output for", seconds, "seconds\n" )
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for h, line in monitorFiles( outfiles, seconds, timeoutms=500 ):
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if h:
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info( '%s: %s\n' % ( h.name, line ) )
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for h in hosts:
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h.cmd('kill %ping')
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net.stop()
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if __name__ == '__main__':
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setLogLevel('info')
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monitorTest()
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