Make network creation thread-safe, closes #104

lib/vagrant-libvirt/action/create_networks.rb

@@ -2,6 +2,7 @@ require 'log4r'
 require 'vagrant/util/network_ip'
 require 'vagrant/util/scoped_hash_override'
 require 'ipaddr'
+require 'thread'
 
 module VagrantPlugins
   module ProviderLibvirt
@@ -13,6 +14,8 @@ module VagrantPlugins
         include VagrantPlugins::ProviderLibvirt::Util::ErbTemplate
         include VagrantPlugins::ProviderLibvirt::Util::LibvirtUtil
 
+        @@lock = Mutex.new
+
         def initialize(app, env)
           mess = 'vagrant_libvirt::action::create_networks'
           @logger = Log4r::Logger.new(mess)
@@ -74,6 +77,10 @@ module VagrantPlugins
             networks.push(options)
           end
 
+          # only one vm at a time should try to set up networks
+          # otherwise they'll have inconsitent views of current state
+          # and conduct redundant operations that cause errors
+          @@lock.synchronize do
             # Iterate over networks If some network is not
             # available, create it if possible. Otherwise raise an error.
             networks.each do |options|
@@ -112,6 +119,7 @@ module VagrantPlugins
               autostart_network if !@interface_network[:autostart]
               activate_network if !@interface_network[:active]
           end
+        end
 
           @app.call(env)
         end