switches.rb in switches-0.1.4

- old
+ new

@@ -1,8 +1,8 @@
 require 'yaml'
-require 'rubygems'
-require 'activesupport'
+require 'fileutils'
+require 'active_support'
 
 # TODO not agnostic, expects RAILS_ROOT
 
 module Switches
   CONFIG_DIR = File.join RAILS_ROOT, 'config', 'switches'
@@ -11,19 +11,18 @@
   CAPISTRANO_LOAD_PATH = CAPISTRANO_PATH.gsub "#{RAILS_ROOT}/", '' # => 'config/switches/capistrano_tasks.rb'
   CAPFILE_PATH = File.join RAILS_ROOT, 'Capfile'
   CURRENT_PATH = File.join CONFIG_DIR, 'current.yml'
   DEFAULT_PATH = File.join CONFIG_DIR, 'default.yml'
   BACKUP_PATH  = File.join CONFIG_DIR, 'backup.yml'
+  TRANSACTION_PID_PATH = File.join CONFIG_DIR, 'transaction.pid'
   
   class << self
     def say(str)
       $stderr.puts "[SWITCHES GEM] #{str.gsub "#{RAILS_ROOT}/", ''}"
     end
     
     def setup
-      require 'fileutils'
-      
       say "Making #{CONFIG_DIR}."
       FileUtils.mkdir_p CONFIG_DIR
       
       if File.exists? DEFAULT_PATH
         say "Not putting an example default.yml into #{DEFAULT_PATH} because you already have one."
@@ -66,36 +65,42 @@
     # taken from ActiveSupport::StringInquirer
     def method_missing(method_name, *args)
       suffix = method_name.to_s[-1,1]
       key = method_name.to_s[0..-2]
       
-      if suffix == "?" and current.has_key?(key)
-        current[key]
+      if suffix == "?"
+        if current.has_key?(key)
+          current[key]      # set, so could be true or false
+        else
+          false             # unset, so always false
+        end
       elsif suffix == "="
         current[key] = args.first
         # TEMPORARY since we're not doing a write_current here
       else
         super
       end
     end
     
     def default
       return @_default unless @_default.nil?
-      # say "file system read #{DEFAULT_PATH}"
-      @_default = YAML.load(File.read(DEFAULT_PATH))
+      # say "file system activity #{DEFAULT_PATH}"
+      resolve_transaction!
+      @_default = YAML.load(IO.read(DEFAULT_PATH))
       @_default.stringify_keys!
     rescue Errno::ENOENT
       say "Couldn't read defaults from #{DEFAULT_PATH}."
       say "You probably want to run \"./script/runner 'Switches.setup'\"."
       raise $!
     end
     
     def current
       return @_current unless @_current.nil?
+      resolve_transaction!
       if File.exist?(CURRENT_PATH)
-        # say "file system read #{CURRENT_PATH}"
-        @_current = YAML.load(File.read(CURRENT_PATH))
+        # say "file system activity #{CURRENT_PATH}"
+        @_current = YAML.load(IO.read(CURRENT_PATH))
         @_current.stringify_keys!
       else
         @_current = default.dup
       end
       @_current
@@ -141,23 +146,49 @@
       @_current = nil
     end
     
     def backup
       write_current
+      start_transaction!
+      # say "file system activity #{BACKUP_PATH}"
       FileUtils.cp CURRENT_PATH, BACKUP_PATH
     end
     
     def restore
       if File.exist?(BACKUP_PATH)
         FileUtils.mv BACKUP_PATH, CURRENT_PATH
       else
         raise ArgumentError, "#{BACKUP_PATH} doesn't exist."
       end
+      end_transaction!
       @_current = nil
     end
     
     def write_current
       current # load it first!
       File.open(CURRENT_PATH, 'w') { |f| f.write current.stringify_keys.to_yaml }
+    end
+    
+    def transaction_pid
+      # say "file system activity #{TRANSACTION_PID_PATH}"
+      IO.readlines(TRANSACTION_PID_PATH).first.chomp.to_i if File.exists?(TRANSACTION_PID_PATH)
+    end
+    
+    def resolve_transaction!
+      if transaction_pid.present? and transaction_pid != Process.pid
+        say "Resolving... calling restore"
+        restore
+      end
+    end
+    
+    def start_transaction!
+      resolve_transaction!
+      say "Starting transaction"
+      File.open(TRANSACTION_PID_PATH, 'w') { |f| f.write Process.pid }
+    end
+    
+    def end_transaction!
+      say "Finishing transaction"
+      FileUtils.rm_f TRANSACTION_PID_PATH
     end
   end
 end