Make variable accesses thread safe

git-svn-id: http://svn.rubyonrails.org/rails/tools/capistrano@7127 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Make variable accesses thread safe [via Adrian Danieli]
+
 * Make user input for yes/no prompts work correctly in the Mercurial module [Matthew Elder]
 
 * Use single quotes to escape semicolon in find command, instead of a backslash [via michael.italia@gmail.com]

lib/capistrano/configuration/variables.rb

@@ -1,3 +1,5 @@
+require 'thread'
+
 module Capistrano
   class Configuration
     module Variables
@@ -37,9 +39,11 @@ module Capistrano
       # Removes any trace of the given variable.
       def unset(variable)
         sym = variable.to_sym
+        @variable_lock.synchronize do
           @original_procs.delete(sym)
           @variables.delete(sym)
         end
+      end
 
       # Returns true if the variable has been defined, and false otherwise.
       def exists?(variable)
@@ -51,6 +55,7 @@ module Capistrano
       # true if the variable was actually reset.
       def reset!(variable)
         sym = variable.to_sym
+        @variable_lock.synchronize do
           if @original_procs.key?(sym)
             @variables[sym] = @original_procs.delete(sym)
             true
@@ -58,6 +63,7 @@ module Capistrano
             false
           end
         end
+      end
 
       # Access a named variable. If the value of the variable responds_to? :call,
       # #call will be invoked (without parameters) and the return value cached
@@ -74,12 +80,15 @@ module Capistrano
           raise IndexError, "`#{variable}' not found"
         end
 
+        @variable_lock.synchronize do
           if @variables[sym].respond_to?(:call)
             @original_procs[sym] = @variables[sym]
             @variables[sym] = @variables[sym].call
           end
+
           @variables[sym]
         end
+      end
 
       def [](variable)
         fetch(variable, nil)
@@ -89,6 +98,7 @@ module Capistrano
         initialize_without_variables(*args)
         @variables = {}
         @original_procs = {}
+        @variable_lock = Mutex.new
 
         set :ssh_options, {}
         set :logger, logger