From d0b8e8b25db2b5042f7107c6e8974c8910043b7d Mon Sep 17 00:00:00 2001
From: Jamis Buck <jamis@37signals.com>
Date: Tue, 26 Jun 2007 05:11:34 +0000
Subject: [PATCH] Make variable accesses thread safe

git-svn-id: http://svn.rubyonrails.org/rails/tools/capistrano@7127 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
---
 CHANGELOG                                 |  2 ++
 lib/capistrano/configuration/variables.rb | 34 +++++++++++++++--------
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 26964081..b185cfb2 100644
--- a/CHANGELOG
+++ b/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]
diff --git a/lib/capistrano/configuration/variables.rb b/lib/capistrano/configuration/variables.rb
index 79aad638..ce7bc159 100644
--- a/lib/capistrano/configuration/variables.rb
+++ b/lib/capistrano/configuration/variables.rb
@@ -1,3 +1,5 @@
+require 'thread'
+
 module Capistrano
   class Configuration
     module Variables
@@ -37,8 +39,10 @@ module Capistrano
       # Removes any trace of the given variable.
       def unset(variable)
         sym = variable.to_sym
-        @original_procs.delete(sym)
-        @variables.delete(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.
@@ -51,11 +55,13 @@ module Capistrano
       # true if the variable was actually reset.
       def reset!(variable)
         sym = variable.to_sym
-        if @original_procs.key?(sym)
-          @variables[sym] = @original_procs.delete(sym)
-          true
-        else
-          false
+        @variable_lock.synchronize do
+          if @original_procs.key?(sym)
+            @variables[sym] = @original_procs.delete(sym)
+            true
+          else
+            false
+          end
         end
       end
 
@@ -73,12 +79,15 @@ module Capistrano
           return yield(variable) if block_given?
           raise IndexError, "`#{variable}' not found"
         end
-          
-        if @variables[sym].respond_to?(:call)
-          @original_procs[sym] = @variables[sym]
-          @variables[sym] = @variables[sym].call
+
+        @variable_lock.synchronize do
+          if @variables[sym].respond_to?(:call)
+            @original_procs[sym] = @variables[sym]
+            @variables[sym] = @variables[sym].call
+          end
+
+          @variables[sym]
         end
-        @variables[sym]
       end
 
       def [](variable)
@@ -89,6 +98,7 @@ module Capistrano
         initialize_without_variables(*args)
         @variables = {}
         @original_procs = {}
+        @variable_lock = Mutex.new
 
         set :ssh_options, {}
         set :logger, logger