From 07aad110819778fdf65a43a6d11e9ca46c9881db Mon Sep 17 00:00:00 2001
From: Brandon Heller <brandonh@stanford.edu>
Date: Sat, 13 Mar 2010 21:33:42 -0800
Subject: [PATCH] Add ability to pause and resume any node

---
 mininet/cli.py  | 20 +++++++++++++++++
 mininet/node.py | 60 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)

diff --git a/mininet/cli.py b/mininet/cli.py
index c045a6d..31b1ee4 100644
--- a/mininet/cli.py
+++ b/mininet/cli.py
@@ -157,6 +157,26 @@ class CLI( Cmd ):
         else:
             self.mn.link( *args )
 
+    def do_pause( self, args ):
+        "Temporarily bring a node down."
+        args = args.split()
+        if len(args) != 1:
+            error( 'invalid number of args: pause [node]\n' )
+        elif args[0] not in self.nodemap:
+            error( 'invalid node: %s\n' % args[0] )
+        else:
+            self.nodemap[ args[ 0 ] ].pause()
+
+    def do_resume( self, args ):
+        "Temporarily bring a node up."
+        args = args.split()
+        if len(args) != 1:
+            error( 'invalid number of args: resume [node]\n' )
+        elif args[0] not in self.nodemap:
+            error( 'invalid node: %s\n' % args[0] )
+        else:
+            self.nodemap[ args[ 0 ] ].resume()
+
     def do_exit( self, args ):
         "Exit"
         return 'exited by user command'
diff --git a/mininet/node.py b/mininet/node.py
index d1f593f..06dd07d 100644
--- a/mininet/node.py
+++ b/mininet/node.py
@@ -337,6 +337,12 @@ class Node( object ):
         "Check if an interface is up."
         return 'UP' in self.cmd( 'ifconfig ' + intf )
 
+    def modIntfs( self, action ):
+        """Bring all interfaces up or down.
+           action: string to pass to ifconfig"""
+        for intf in self.intfs.values():
+            result = self.cmd( [ 'ifconfig', intf, action ] )
+
     # Other methods
     def __str__( self ):
         result = self.name + ':'
@@ -351,6 +357,16 @@ class Host( Node ):
     "A host is simply a Node."
     pass
 
+    # Ideally, pausing a host would pause the process.  However, when one
+    # tries to run a command on a paused host, it leads to an exception later.
+    # For now, disable interfaces to "pause" the host.
+    def pause( self ):
+        "Disable interfaces."
+        self.modIntfs('down')
+
+    def resume( self ):
+        "Re-enable interfaces"
+        self.modIntfs('up')
 
 class Switch( Node ):
     """A Switch is a Node that is running (or has execed?)
@@ -405,6 +421,17 @@ class UserSwitch( Switch ):
         self.cmd( 'kill %ofprotocol' )
         self.deleteIntfs()
 
+    def pause( self ):
+        "Pause ofprotocol and ofdatapath."
+        self.cmd( 'kill -STOP %ofdatapath' )
+        self.cmd( 'kill -STOP %ofprotocol' )
+
+    def resume( self ):
+        "Resume ofprotocol and datapath."
+        self.cmd( 'kill -CONT %ofdatapath' )
+        self.cmd( 'kill -CONT %ofprotocol' )
+
+
 class KernelSwitch( Switch ):
     """Kernel-space switch.
        Currently only works in root namespace."""
@@ -452,6 +479,18 @@ class KernelSwitch( Switch ):
         self.cmd( 'kill %ofprotocol' )
         self.deleteIntfs()
 
+    # Since kernel threads cannot receive signals like user-space processes,
+    # disabling the interfaces and ofdatapath is our workaround.
+    def pause( self ):
+        "Disable interfaces and pause ofprotocol."
+        self.cmd( 'kill -STOP %ofprotocol' )
+        self.modIntfs('down')
+
+    def resume( self ):
+        "Re-enable interfaces and resume ofprotocol."
+        self.cmd( 'kill -CONT %ofprotocol' )
+        self.modIntfs('up')
+
 class OVSKernelSwitch( Switch ):
     """Open VSwitch kernel-space switch.
        Currently only works in the root namespace."""
@@ -500,6 +539,18 @@ class OVSKernelSwitch( Switch ):
         self.cmd( 'kill %ovs-openflowd' )
         self.deleteIntfs()
 
+    # Since kernel threads cannot receive signals like user-space processes,
+    # disabling the interfaces and ofdatapath is our workaround.
+    def pause( self ):
+        "Disable interfaces and pause ovs-openflowd."
+        self.cmd( 'kill -STOP %ovs-openflowd' )
+        self.modIntfs('down')
+
+    def resume( self ):
+        "Re-enable interfaces and resume ovs-openflowd."
+        self.cmd( 'kill -CONT %ovs-openflowd' )
+        self.modIntfs('up')
+
 
 class Controller( Node ):
     """A Controller is a Node that is running (or has execed?) an
@@ -530,6 +581,14 @@ class Controller( Node ):
         self.cmd( 'kill %' + self.controller )
         self.terminate()
 
+    def pause( self ):
+        "Pause controller."
+        self.cmd( 'kill -STOP %' + self.controller )
+
+    def resume( self ):
+        "Resume controller."
+        self.cmd( 'kill -CONT %' + self.controller )
+
     def IP( self, intf=None ):
         "Return IP address of the Controller"
         ip = Node.IP( self, intf=intf )
@@ -537,6 +596,7 @@ class Controller( Node ):
             ip = self.defaultIP
         return ip
 
+
 class ControllerParams( object ):
     "Container for controller IP parameters."