Added multipoll and multiping examples.

examples/README

@@ -35,6 +35,15 @@ miniedit.py:
 
 This example demonstrates creating a network via a graphical editor.
 
+multiping.py:
+
+This example demonstrates one method for 
+monitoring output from multiple hosts, using node.monitor().
+
+multipoll.py:
+
+This example demonstrates monitoring output files from multiple hosts.
+
 multitest.py:
 
 This example creates a network and runs multiple tests on it.

examples/multiping.py

@@ -0,0 +1,94 @@
+#!/usr/bin/python
+
+"""
+multiping.py: monitor multiple sets of hosts using ping
+
+This demonstrates how one may send a simple shell script to
+multiple hosts and monitor their output interactively for a period=
+of time.
+"""
+
+from mininet.net import Mininet
+from mininet.node import Node
+from mininet.topo import SingleSwitchTopo
+from mininet.log import setLogLevel
+
+from select import poll, POLLIN
+from time import time
+
+def chunks( l, n ):
+    "Divide list l into chunks of size n - thanks Stackoverflow"
+    return [ l[ i : i + n ] for i in range( 0, len( l ), n ) ]
+
+def startpings( host, targetips ):
+    "Tell host to repeatedly ping targets"
+
+    targetips.append( '10.0.0.200' )
+
+    targetips = ' '.join( targetips )
+    
+    # BL: Not sure why loopback intf isn't up!
+    host.cmd( 'ifconfig lo up' )
+
+    
+    # Simple ping loop
+    cmd = ( 'while true; do '
+            ' for ip in %s; do ' % targetips  +
+            '  echo -n %s "->" $ip ' % host.IP() +
+            '   `ping -c1 -w 1 $ip | grep packets` ;'
+            '  sleep 1;'
+            ' done; '
+            'done &' )
+    
+    print ( '*** Host %s (%s) will be pinging ips: %s' %
+           ( host.name, host.IP(), targetips ) )
+
+    host.cmd( cmd )
+
+def multiping( netsize, chunksize, seconds):
+    "Ping subsets of size chunksize in net of size netsize"
+    
+    # Create network and identify subnets
+    topo = SingleSwitchTopo( netsize )
+    net = Mininet( topo=topo )
+    net.start()
+    hosts = net.hosts
+    subnets = chunks( hosts, chunksize )
+
+    # Create polling object
+    fds = [ host.stdout.fileno() for host in hosts ]
+    poller = poll()
+    for fd in fds:
+        poller.register( fd, POLLIN )
+    
+    # Start pings
+    for subnet in subnets:
+        ips = [ host.IP() for host in subnet ]
+        for host in subnet:
+            startpings( host, ips )
+    
+    # Monitor output
+    endTime = time() + seconds
+    while time() < endTime:
+        readable = poller.poll(1000)
+        for fd, _mask in readable:
+            node = Node.outToNode[ fd ]
+            print '%s:' % node.name, node.monitor().strip()
+
+    # Stop pings
+    for host in hosts:
+        host.cmd( 'kill %while' )
+    
+    net.stop()
+
+
+if __name__ == '__main__':
+    setLogLevel( 'info' )
+    multiping( netsize=20, chunksize=4, seconds=10 )
+
+    
+    
+
+    
+    
+    

examples/multipoll.py

@@ -0,0 +1,83 @@
+#!/usr/bin/python
+
+"""
+Simple example of sending output to multiple files and
+monitoring them
+"""
+
+from mininet.topo import SingleSwitchTopo
+from mininet.net import Mininet
+from mininet.log import setLogLevel
+from mininet.util import quietRun
+
+from time import time, sleep
+from select import poll, POLLIN
+from subprocess import Popen, PIPE
+
+def monitorFiles( outfiles, seconds, timeoutms ):
+    devnull = open( '/dev/null', 'w' )
+    tails, fdToFile, fdToHost = {}, {}, {}
+    for h, outfile in outfiles.iteritems():
+        tail = Popen( [ 'tail', '-f', outfile ],
+                     stdout=PIPE, stderr=devnull )
+        fd = tail.stdout.fileno()
+        tails[ h ] = tail
+        fdToFile[ fd ] = tail.stdout
+        fdToHost[ fd ] = h
+    # Prepare to poll output files
+    readable = poll()
+    for t in tails.values():
+        readable.register( t.stdout.fileno(), POLLIN )
+    # Run until a set number of seconds have elapsed
+    endTime = time() + seconds
+    while time() < endTime:
+        fdlist = readable.poll(timeoutms)
+        if fdlist:
+            for fd, _flags in fdlist:
+                f = fdToFile[ fd ]
+                host = fdToHost[ fd ]
+                # Wait for a line of output
+                line = f.readline().strip()
+                yield host, line
+        else:
+            # If we timed out, return nothing
+            yield None, ''
+    for t in tails.values():
+        t.terminate()
+    devnull.close()  # Not really necessary
+
+
+def monitorTest( N=3, seconds=3 ):
+    "Run pings and monitor multiple hosts"
+    topo = SingleSwitchTopo( N )
+    net = Mininet( topo )
+    net.start()
+    hosts = net.hosts
+    print "Starting test..."
+    server = hosts[ 0 ]
+    outfiles, errfiles = {}, {}
+    for h in hosts:
+        # Create and/or erase output files
+        outfiles[ h ] = '/tmp/%s.out' % h.name
+        errfiles[ h ] = '/tmp/%s.err' % h.name
+        h.cmd( 'echo >', outfiles[ h ] )
+        h.cmd( 'echo >', errfiles[ h ] )
+        # Start pings
+        h.cmdPrint('ping', server.IP(), 
+                   '>', outfiles[ h ],
+                   '2>', errfiles[ h ],
+                   '&' )
+    print "Monitoring output for", seconds, "seconds"
+    for h, line in monitorFiles( outfiles, seconds, timeoutms=500 ):
+        if h:
+            print '%s: %s' % ( h.name, line )
+    for h in hosts:
+        h.cmd('kill %ping')
+    net.stop()
+
+
+if __name__ == '__main__':
+    setLogLevel('info')
+    monitorTest()
+
+