Add a simple configuration system that uses sysctl(8) variable format.

lib/twke.rb

@@ -1,8 +1,11 @@
 module Twke
   require 'scamp'
 
-  require 'twke/routes.rb'
-  require 'twke/plugin.rb'
+  $:.unshift File.join(File.dirname(__FILE__), 'twke')
+
+  require 'conf'
+  require 'routes'
+  require 'plugin'
 
   def self.version
     File.read(File.join(File.dirname(__FILE__), '../VERSION')).chomp

lib/twke/conf.rb

@@ -0,0 +1,122 @@
+require 'yaml'
+
+#
+# Simple configuration system.
+#
+# Variable names are dot-separated, similar to how sysctl(8) names
+# work.
+#
+# For example, a 'heroku' module could prefix all variables with
+# "heroku.":
+#
+#    heroku.sites.metrics-prod.giturl
+#    heroku.sites.metrics-prod.token
+#
+# The conf system can also lookup all the sub-variables rooted at a
+# single prefix. So for example, assume the following variables are
+# also set:
+#
+#    heroku.sites.metrics-stg.giturl
+#    heroku.sites.metrics-stg.token
+#
+#   A list command on 'heroku.sites' would return:
+#          ['metrics-prod', 'metrics-stg']
+#
+######
+
+module Twke
+  module Conf
+    class << self
+      attr_accessor :conf
+
+      def conf
+        @conf ||= {}
+      end
+
+      # Everytime a value is modified the config DB is written
+      def set(varname, value)
+        if varname =~ /^\./ || varname =~ /\.$/ || varname.length == 0
+          raise "Invalid variable name"
+        end
+
+        conf[varname.to_s] = value
+
+        save
+      end
+
+      def get(varname)
+        conf[varname.to_s]
+      end
+
+      def exists?(varname)
+        conf.has_key?(varname)
+      end
+
+      #
+      # This will return a list of the unique commands that begin with
+      # the varpfx prefix assumed to be a sub-command prefix.
+      #
+      # For example, assume the following variables are set:
+      #
+      #    net.tcp.foobar => 1
+      #    net.tcp.barbar => 2
+      #
+      # So:
+      #   list('net.tcp') would return: ["barbar", "foobar"]
+      #   list('net') would return: ["tcp"]
+      #
+      #   list('net.tc') would return: []
+      #        Because there are no sub-commands with 'net.tc.' as
+      #        their prefix
+      #
+      def list(varpfx)
+        # Strip leading/trailing periods
+        varpfx = varpfx[1, varpfx.length] if varpfx =~ /^\./
+        varpfx = varpfx[0, varpfx.length - 1] if varpfx =~ /\.$/
+
+        # XXX: Really need a tree structure to do this efficiently
+        conf.keys.inject([]) do |ar, k|
+          if k =~ /^#{varpfx}\./
+            ar << k.gsub(/^#{varpfx}\./, '').split(".")[0]
+          end
+          ar
+        end.sort.uniq
+      end
+
+      def load
+        begin
+          yml = YAML.load_file(config_file)
+          @conf = yml
+        rescue Errno::ENOENT => err
+          @conf = {}
+        rescue => err
+          raise "Unknown error reading config file: #{err.message}"
+        end
+      end
+
+      #
+      # Files are saved atomically.
+      #
+      def save
+        unless File.exist?(config_dir)
+          FileUtils.mkdir_p(config_dir, :mode => 0700)
+        end
+
+        tmpfile = File.join(config_dir, "tmpconfig_#{rand 999999}")
+        File.open(tmpfile, "w") do |f|
+          YAML.dump(conf, f )
+        end
+
+        FileUtils.mv(tmpfile, config_file)
+      end
+
+      def config_dir
+        File.join(ENV['HOME'], '.twke')
+      end
+
+      def config_file
+        File.join(config_dir, 'config.yml')
+      end
+    end
+  end
+end

test/helper.rb

@@ -15,4 +15,5 @@
 require 'twke'
 
 class Test::Unit::TestCase
+  include Twke
 end

test/test_conf.rb

@@ -0,0 +1,51 @@
+require 'helper'
+
+class TestConf < Test::Unit::TestCase
+  def setup
+    FileUtils.rm_rf(Conf::config_file)
+  end
+
+  def teardown
+    FileUtils.rm_rf(Conf::config_file)
+  end
+
+  def validate_settings
+    assert_equal(1, Conf::get('net.tcp.foobar'))
+    assert_equal('blah', Conf::get('net.tcp.barbar'))
+    assert(Conf::exists?('net.tcp.foobar'))
+    assert(Conf::exists?('net.tcp.barbar'))
+    assert(!Conf::exists?('net.tcp'))
+
+    assert_equal(['barbar', 'foobar'].sort, Conf::list('net.tcp'))
+    assert_equal(['tcp'].sort, Conf::list('net'))
+
+    assert_equal([], Conf::list(''))
+    assert_equal([], Conf::list('net.tc'))
+  end
+
+  def test_config
+    Conf::set('net.tcp.foobar', 1)
+    Conf::set('net.tcp.barbar', "blah")
+
+    validate_settings
+
+    ['.sys.blah', 'sys.blah.', ''].each do |bad|
+      begin
+        Conf::set(bad, rand(5))
+      rescue
+        # Should throw exception
+      else
+        assert(false, "Did not throw exception setting: #{bad}")
+      end
+    end
+
+    assert(File.exist?(Conf::config_file), "Conf file doesn't exist")
+
+    # Now reload
+    #
+    Conf::load
+
+    # retest after reload
+    validate_settings
+  end
+end