[registry] refactoring into a abstract and factory

* a new abstract class AbstractAccessor is the new base
  for all concrete database implementations.
* a factory now, dynamically discovers those implementations
  in the registry/ directory and will create the configured
  type for the plugins.
* again: this makes db keys case-sensitive (aka 'the correct
  way of doing things' -.-)
* re-added tokyocabinet

1 files changed, 326 insertions, 0 deletions

diff --git a/lib/rbot/registry.rb b/lib/rbot/registry.rb
new file mode 100644
index 00000000..6c18df21
--- /dev/null
+++ b/lib/rbot/registry.rb
@@ -0,0 +1,326 @@
+#-- vim:sw=2:et
+#++
+#
+# :title: Registry: Persistent storage interface and factory
+# 
+# This class provides persistent storage for plugins via a hash interface.
+# The default mode is an object store, so you can store ruby objects and
+# reference them with hash keys. This is because the default store/restore
+# methods of the plugins' RegistryAccessor are calls to Marshal.dump and
+# Marshal.restore,
+# for example:
+#   blah = Hash.new
+#   blah[:foo] = "fum"
+#   @registry[:blah] = blah
+# then, even after the bot is shut down and disconnected, on the next run you
+# can access the blah object as it was, with:
+#   blah = @registry[:blah]
+# The registry can of course be used to store simple strings, fixnums, etc as
+# well, and should be useful to store or cache plugin data or dynamic plugin
+# configuration.
+#
+# WARNING:
+# in object store mode, don't make the mistake of treating it like a live
+# object, e.g. (using the example above)
+#   @registry[:blah][:foo] = "flump"
+# will NOT modify the object in the registry - remember that Registry#[]
+# returns a Marshal.restore'd object, the object you just modified in place
+# will disappear. You would need to:
+#   blah = @registry[:blah]
+#   blah[:foo] = "flump"
+#   @registry[:blah] = blah
+#
+# If you don't need to store objects, and strictly want a persistant hash of
+# strings, you can override the store/restore methods to suit your needs, for
+# example (in your plugin):
+#   def initialize
+#     class << @registry
+#       def store(val)
+#         val
+#       end
+#       def restore(val)
+#         val
+#       end
+#     end
+#   end
+# Your plugins section of the registry is private, it has its own namespace
+# (derived from the plugin's class name, so change it and lose your data).
+# Calls to registry.each etc, will only iterate over your namespace.
+
+module Irc
+class Bot
+
+class Registry
+
+  # Dynamically loads the specified registry type library.
+  def initialize(format=nil)
+    @libpath = File.join(File.dirname(__FILE__), 'registry')
+    @format = format
+    load File.join(@libpath, @format+'.rb') if format
+  end
+
+  # Returns a list of supported registry database formats.
+  def discover
+    Dir.glob(File.join(@libpath, '*.rb')).map do |name|
+      File.basename(name, File.extname(name))
+    end
+  end
+
+  # Creates a new Accessor object for the specified database filename.
+  def create(path, filename)
+    # The get_impl method will return a list of all the classes that
+    # implement the accessor interface, since we only ever load one
+    # (the configured one) accessor implementation, we can just assume
+    # it to be the correct accessor to use.
+    cls = AbstractAccessor.get_impl.first
+    cls.new(File.join(path, 'registry_' + @format, filename.downcase))
+  end
+
+  # Helper method that will return a list of supported registry formats.
+  def self.formats
+    @@formats ||= Registry.new.discover
+  end
+
+  # Abstract database accessor (a hash-like interface).
+  class AbstractAccessor
+
+    # lets the user define a recovery procedure in case the Marshal
+    # deserialization fails, it might be manually recover data.
+    # NOTE: weird legacy stuff, used by markov plugin (WTH?)
+    attr_accessor :recovery
+
+    def initialize(filename)
+      debug 'init registry accessor for: ' + filename
+      @filename = filename
+      @name = File.basename filename
+      @registry = nil
+      @default = nil
+      @recovery = nil
+    end
+
+    def sub_registry(prefix)
+      path = File.join(@filename.gsub(/\.[^\/\.]+$/,''), prefix.to_s)
+      return self.class.new(path)
+    end
+
+    # creates the registry / subregistry folders
+    def create_folders
+      debug 'create folders for: ' + @filename
+      dirs = File.dirname(@filename).split("/")
+      dirs.length.times { |i|
+        dir = dirs[0,i+1].join("/")+"/"
+        unless File.exist?(dir)
+          Dir.mkdir(dir)
+        end
+      }
+    end
+
+    # Will return true if the database file exists.
+    def dbexists?
+      File.exists? @filename
+    end
+
+    # convert value to string form for storing in the registry
+    # defaults to Marshal.dump(val) but you can override this in your module's
+    # registry object to use any method you like.
+    # For example, if you always just handle strings use:
+    #   def store(val)
+    #     val
+    #   end
+    def store(val)
+      Marshal.dump(val)
+    end
+
+    # restores object from string form, restore(store(val)) must return val.
+    # If you override store, you should override restore to reverse the
+    # action.
+    # For example, if you always just handle strings use:
+    #   def restore(val)
+    #     val
+    #   end
+    def restore(val)
+      begin
+        Marshal.restore(val)
+      rescue Exception => e
+        error _("failed to restore marshal data for #{val.inspect}, attempting recovery or fallback to default")
+        debug e
+        if defined? @recovery and @recovery
+          begin
+            return @recovery.call(val)
+          rescue Exception => ee
+            error _("marshal recovery failed, trying default")
+            debug ee
+          end
+        end
+        return default
+      end
+    end
+
+    # Returned instead of nil if key wasnt found.
+    def set_default (default)
+      @default = default
+    end
+
+    def default
+      @default && (@default.dup rescue @default)
+    end
+
+    # Opens the database (if not already open) for read/write access.
+    def registry
+      create_folders unless dbexists?
+    end
+
+    # Forces flush/sync the database on disk.
+    def flush
+      return unless @registry
+      @registry.flush
+    end
+
+    # Should optimize/vacuum the database.
+    def optimize
+      return unless @registry
+      @registry.optimize
+    end
+
+    # Closes the database.
+    def close
+      return unless @registry
+      @registry.close
+      @registry = nil
+    end
+
+    # lookup a key in the registry
+    def [](key)
+      if dbexists? and registry.has_key?(key.to_s)
+        return restore(registry[key.to_s])
+      else
+        return default
+      end
+    end
+
+    # set a key in the registry
+    def []=(key,value)
+      registry[key.to_s] = store(value)
+    end
+
+    # like Hash#each
+    def each(&block)
+      return nil unless dbexists?
+      registry.each do |key|
+        block.call(key, self[key])
+      end
+    end
+
+    alias each_pair each
+
+    # like Hash#each_key
+    def each_key(&block)
+      self.each do |key|
+        block.call(key)
+      end
+    end
+
+    # like Hash#each_value
+    def each_value(&block)
+      self.each do |key, value|
+        block.call(value)
+      end
+    end
+
+    # just like Hash#has_key?
+    def has_key?(key)
+      return nil unless dbexists?
+      return registry.has_key?(key.to_s)
+    end
+
+    alias include? has_key?
+    alias member? has_key?
+    alias key? has_key?
+
+    # just like Hash#has_value?
+    def has_value?(value)
+      return nil unless dbexists?
+      return registry.has_value?(store(value))
+    end
+
+    # just like Hash#index?
+    def index(value)
+      self.each do |k,v|
+        return k if v == value
+      end
+      return nil
+    end
+
+    # delete a key from the registry
+    def delete(key)
+      return default unless dbexists?
+      return registry.delete(key.to_s)
+    end
+
+    # returns a list of your keys
+    def keys
+      return [] unless dbexists?
+      return registry.keys
+    end
+
+    # just like Hash#has_both?
+    def has_both?(key, value)
+      return false unless dbexists?
+      registry.has_key?(key.to_s) and registry.has_value?(store(value))
+    end
+
+    # Return an array of all associations [key, value] in your namespace
+    def to_a
+      return [] unless dbexists?
+      ret = Array.new
+      self.each {|key, value|
+        ret << [key, value]
+      }
+      return ret
+    end
+
+    # Return an hash of all associations {key => value} in your namespace
+    def to_hash
+      return {} unless dbexists?
+      ret = Hash.new
+      self.each {|key, value|
+        ret[key] = value
+      }
+      return ret
+    end
+
+    # empties the registry (restricted to your namespace)
+    def clear
+      return unless dbexists?
+      registry.clear
+    end
+    alias truncate clear
+
+    # returns an array of the values in your namespace of the registry
+    def values
+      return [] unless dbexists?
+      ret = Array.new
+      self.each {|k,v|
+        ret << v
+      }
+      return ret
+    end
+
+    # returns the number of keys in your registry namespace
+    def length
+      return 0 unless dbexists?
+      registry.length
+    end
+    alias size length
+
+    # Returns all classes from the namespace that implement this interface
+    def self.get_impl
+      ObjectSpace.each_object(Class).select { |klass| klass < self }
+    end
+  end
+
+end # Registry
+
+end # Bot
+end # Irc
+