Bob Lantz
ee15ce2243
Although we could use print() from __future__, this messes up scripts which use examples as modules. The simple, if not nicest for 2.7, solution is to use info(), output() and other mininet.log functions. The disadvantage is that we may have to adjust things if we change info() to add automatic newlines, but we can burn that bridge in Mininet 3.x.
84 lines
2.4 KiB
Python
Executable File
84 lines
2.4 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 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.iteritems():
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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, 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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