Initial async commit (cremes)

Rakefile

@@ -73,6 +73,11 @@ namespace :test do
     end
   end
 
+  Rake::TestTask.new(:async) do |t|
+    t.test_files = FileList['test/async/*_test.rb']
+    t.verbose    = true
+  end
+
   desc "Run the replica set test suite"
   Rake::TestTask.new(:rs) do |t|
     t.test_files = FileList['test/replica_sets/*_test.rb']

lib/mongo.rb

@@ -57,6 +57,7 @@ require 'mongo/gridfs/grid'
 require 'mongo/gridfs/grid_io'
 if RUBY_PLATFORM =~ /java/
   require 'mongo/gridfs/grid_io_fix'
+  require 'mongo/util/worker_pool'
 end
 require 'mongo/gridfs/grid_file_system'
 

lib/mongo/async/async_collection.rb

@@ -0,0 +1,795 @@
+# encoding: UTF-8
+
+# --
+# Copyright (C) 2008-2010 10gen Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+module Mongo
+
+  # A named collection of documents in a database.
+  class AsyncCollection < Collection
+
+    def initialize(name, db, opts={})
+      super
+      @workers = @connection.workers
+    end
+
+    # Return a sub-collection of this collection by name. If 'users' is a collection, then
+    # 'users.comments' is a sub-collection of users.
+    #
+    # @param [String] name
+    #   the collection to return
+    #
+    # @raise [Mongo::InvalidNSName]
+    #   if passed an invalid collection name
+    #
+    # @return [Collection]
+    #   the specified sub-collection
+    def [](name)
+      name = "#{self.name}.#{name}"
+      return Collection.new(name, db) if !db.strict? || db.collection_names.include?(name)
+      raise "Collection #{name} doesn't exist. Currently in strict mode."
+    end
+
+    # Set a hint field for query optimizer. Hint may be a single field
+    # name, array of field names, or a hash (preferably an [OrderedHash]).
+    # If using MongoDB > 1.1, you probably don't ever need to set a hint.
+    #
+    # @param [String, Array, OrderedHash] hint a single field, an array of
+    #   fields, or a hash specifying fields
+    def hint=(hint=nil)
+      @hint = normalize_hint_fields(hint)
+      self
+    end
+
+    # Query the database.
+    #
+    # The +selector+ argument is a prototype document that all results must
+    # match. For example:
+    #
+    #   collection.find({"hello" => "world"})
+    #
+    # only matches documents that have a key "hello" with value "world".
+    # Matches can have other keys *in addition* to "hello".
+    #
+    # If given an optional block +find+ will yield a Cursor to that block,
+    # close the cursor, and then return nil. This guarantees that partially
+    # evaluated cursors will be closed. If given no block +find+ returns a
+    # cursor.
+    #
+    # @param [Hash] selector
+    #   a document specifying elements which must be present for a
+    #   document to be included in the result set. Note that in rare cases,
+    #   (e.g., with $near queries), the order of keys will matter. To preserve
+    #   key order on a selector, use an instance of BSON::OrderedHash (only applies
+    #   to Ruby 1.8).
+    #
+    # @option opts [Array, Hash] :fields field names that should be returned in the result
+    #   set ("_id" will be included unless explicity excluded). By limiting results to a certain subset of fields,
+    #   you can cut down on network traffic and decoding time. If using a Hash, keys should be field
+    #   names and values should be either 1 or 0, depending on whether you want to include or exclude
+    #   the given field.
+    # @option opts [Integer] :skip number of documents to skip from the beginning of the result set
+    # @option opts [Integer] :limit maximum number of documents to return
+    # @option opts [Array]   :sort an array of [key, direction] pairs to sort by. Direction should
+    #   be specified as Mongo::ASCENDING (or :ascending / :asc) or Mongo::DESCENDING (or :descending / :desc)
+    # @option opts [String, Array, OrderedHash] :hint hint for query optimizer, usually not necessary if using MongoDB > 1.1
+    # @option opts [Boolean] :snapshot (false) if true, snapshot mode will be used for this query.
+    #   Snapshot mode assures no duplicates are returned, or objects missed, which were preset at both the start and
+    #   end of the query's execution. For details see http://www.mongodb.org/display/DOCS/How+to+do+Snapshotting+in+the+Mongo+Database
+    # @option opts [Boolean] :batch_size (100) the number of documents to returned by the database per GETMORE operation. A value of 0
+    #   will let the database server decide how many results to returns. This option can be ignored for most use cases.
+    # @option opts [Boolean] :timeout (true) when +true+, the returned cursor will be subject to
+    #   the normal cursor timeout behavior of the mongod process. When +false+, the returned cursor will never timeout. Note
+    #   that disabling timeout will only work when #find is invoked with a block. This is to prevent any inadvertant failure to
+    #   close the cursor, as the cursor is explicitly closed when block code finishes.
+    #
+    # @raise [ArgumentError]
+    #   if timeout is set to false and find is not invoked in a block
+    #
+    # @raise [RuntimeError]
+    #   if given unknown options
+    #
+    # @core find find-instance_method
+    def find(selector={}, opts={})
+      fields = opts.delete(:fields)
+      fields = ["_id"] if fields && fields.empty?
+      skip   = opts.delete(:skip) || skip || 0
+      limit  = opts.delete(:limit) || 0
+      sort   = opts.delete(:sort)
+      hint   = opts.delete(:hint)
+      snapshot   = opts.delete(:snapshot)
+      batch_size = opts.delete(:batch_size)
+      timeout    = (opts.delete(:timeout) == false) ? false : true
+
+      if timeout == false && !block_given?
+        raise ArgumentError, "Collection#find must be invoked with a block when timeout is disabled."
+      end
+
+      if hint
+        hint = normalize_hint_fields(hint)
+      else
+        hint = @hint        # assumed to be normalized already
+      end
+
+      raise RuntimeError, "Unknown options [#{opts.inspect}]" unless opts.empty?
+
+      cursor = Cursor.new(self, :selector => selector, :fields => fields, :skip => skip, :limit => limit,
+        :order => sort, :hint => hint, :snapshot => snapshot, :timeout => timeout, :batch_size => batch_size)
+
+      if block_given?
+        yield cursor
+        cursor.close
+        nil
+      else
+        cursor
+      end
+    end
+
+    # Return a single object from the database.
+    #
+    # @return [OrderedHash, Nil]
+    #   a single document or nil if no result is found.
+    #
+    # @param [Hash, ObjectId, Nil] spec_or_object_id a hash specifying elements 
+    #   which must be present for a document to be included in the result set or an 
+    #   instance of ObjectId to be used as the value for an _id query.
+    #   If nil, an empty selector, {}, will be used.
+    #
+    # @option opts [Hash]
+    #   any valid options that can be send to Collection#find
+    #
+    # @raise [TypeError]
+    #   if the argument is of an improper type.
+    def find_one(spec_or_object_id=nil, opts={})
+      spec = case spec_or_object_id
+             when nil
+               {}
+             when BSON::ObjectId
+               {:_id => spec_or_object_id}
+             when Hash
+               spec_or_object_id
+             else
+               raise TypeError, "spec_or_object_id must be an instance of ObjectId or Hash, or nil"
+             end
+      find(spec, opts.merge(:limit => -1)).next_document
+    end
+
+    # Save a document to this collection.
+    #
+    # @param [Hash] doc
+    #   the document to be saved. If the document already has an '_id' key,
+    #   then an update (upsert) operation will be performed, and any existing
+    #   document with that _id is overwritten. Otherwise an insert operation is performed.
+    #
+    # @return [ObjectId] the _id of the saved document.
+    #
+    # @option opts [Boolean, Hash] :safe (+false+)
+    #   run the operation in safe mode, which run a getlasterror command on the
+    #   database to report any assertion. In addition, a hash can be provided to
+    #   run an fsync and/or wait for replication of the save (>= 1.5.1). See the options
+    #   for DB#error.
+    #
+    # @raise [OperationFailure] when :safe mode fails.
+    #
+    # @see DB#remove for options that can be passed to :safe.
+    def save(doc, opts={})
+      if doc.has_key?(:_id) || doc.has_key?('_id')
+        id = doc[:_id] || doc['_id']
+        update({:_id => id}, doc, :upsert => true, :safe => opts.fetch(:safe, @safe))
+        id
+      else
+        insert(doc, :safe => opts.fetch(:safe, @safe))
+      end
+    end
+
+    # Insert one or more documents into the collection.
+    #
+    # @param [Hash, Array] doc_or_docs
+    #   a document (as a hash) or array of documents to be inserted.
+    #
+    # @return [ObjectId, Array]
+    #   The _id of the inserted document or a list of _ids of all inserted documents.
+    #
+    # @option opts [Boolean, Hash] :safe (+false+)
+    #   run the operation in safe mode, which run a getlasterror command on the
+    #   database to report any assertion. In addition, a hash can be provided to
+    #   run an fsync and/or wait for replication of the insert (>= 1.5.1). Safe
+    #   options provided here will override any safe options set on this collection,
+    #   its database object, or the current connection. See the options on
+    #   for DB#get_last_error.
+    #
+    # @see DB#remove for options that can be passed to :safe.
+    #
+    # @core insert insert-instance_method
+    def insert(doc_or_docs, opts={})
+      doc_or_docs = [doc_or_docs] unless doc_or_docs.is_a?(Array)
+      doc_or_docs.collect! { |doc| @pk_factory.create_pk(doc) }
+      safe = opts.fetch(:safe, @safe)
+      result = insert_documents(doc_or_docs, @name, true, safe)
+      result.size > 1 ? result : result.first
+    end
+    alias_method :<<, :insert
+
+    # Remove all documents from this collection.
+    #
+    # @param [Hash] selector
+    #   If specified, only matching documents will be removed.
+    #
+    # @option opts [Boolean, Hash] :safe (+false+)
+    #   run the operation in safe mode, which will run a getlasterror command on the
+    #   database to report any assertion. In addition, a hash can be provided to
+    #   run an fsync and/or wait for replication of the remove (>= 1.5.1). Safe
+    #   options provided here will override any safe options set on this collection,
+    #   its database, or the current connection. See the options for DB#get_last_error for more details.
+    #
+    # @example remove all documents from the 'users' collection:
+    #   users.remove
+    #   users.remove({})
+    #
+    # @example remove only documents that have expired:
+    #   users.remove({:expire => {"$lte" => Time.now}})
+    #
+    # @return [Hash, true] Returns a Hash containing the last error object if running in safe mode.
+    #   Otherwise, returns true.
+    #
+    # @raise [Mongo::OperationFailure] an exception will be raised iff safe mode is enabled
+    #   and the operation fails.
+    #
+    # @see DB#remove for options that can be passed to :safe.
+    #
+    # @core remove remove-instance_method
+    def remove(selector={}, opts={})
+      # Initial byte is 0.
+      safe = opts.fetch(:safe, @safe)
+      message = BSON::ByteBuffer.new("\0\0\0\0")
+      BSON::BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{@name}")
+      message.put_int(0)
+      message.put_binary(BSON::BSON_CODER.serialize(selector, false, true).to_s)
+
+      @logger.debug("MONGODB #{@db.name}['#{@name}'].remove(#{selector.inspect})") if @logger
+      if safe
+        @connection.send_message_with_safe_check(Mongo::Constants::OP_DELETE, message, @db.name, nil, safe)
+      else
+        @connection.send_message(Mongo::Constants::OP_DELETE, message)
+        true
+      end
+    end
+
+    # Update one or more documents in this collection.
+    #
+    # @param [Hash] selector
+    #   a hash specifying elements which must be present for a document to be updated. Note:
+    #   the update command currently updates only the first document matching the
+    #   given selector. If you want all matching documents to be updated, be sure
+    #   to specify :multi => true.
+    # @param [Hash] document
+    #   a hash specifying the fields to be changed in the selected document,
+    #   or (in the case of an upsert) the document to be inserted
+    #
+    # @option opts [Boolean] :upsert (+false+) if true, performs an upsert (update or insert)
+    # @option opts [Boolean] :multi (+false+) update all documents matching the selector, as opposed to
+    #   just the first matching document. Note: only works in MongoDB 1.1.3 or later.
+    # @option opts [Boolean] :safe (+false+) 
+    #   If true, check that the save succeeded. OperationFailure
+    #   will be raised on an error. Note that a safe check requires an extra
+    #   round-trip to the database. Safe options provided here will override any safe
+    #   options set on this collection, its database object, or the current collection.
+    #   See the options for DB#get_last_error for details.
+    #
+    # @return [Hash, true] Returns a Hash containing the last error object if running in safe mode.
+    #   Otherwise, returns true.
+    #
+    # @core update update-instance_method
+    def update(selector, document, opts={})
+      # Initial byte is 0.
+      safe = opts.fetch(:safe, @safe)
+      message = BSON::ByteBuffer.new("\0\0\0\0")
+      BSON::BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{@name}")
+      update_options  = 0
+      update_options += 1 if opts[:upsert]
+      update_options += 2 if opts[:multi]
+      message.put_int(update_options)
+      message.put_binary(BSON::BSON_CODER.serialize(selector, false, true).to_s)
+      message.put_binary(BSON::BSON_CODER.serialize(document, false, true).to_s)
+      @logger.debug("MONGODB #{@db.name}['#{@name}'].update(#{selector.inspect}, #{document.inspect})") if @logger
+      if safe
+        @connection.send_message_with_safe_check(Mongo::Constants::OP_UPDATE, message, @db.name, nil, safe)
+      else
+        @connection.send_message(Mongo::Constants::OP_UPDATE, message, nil)
+      end
+    end
+
+    # Create a new index.
+    #
+    # @param [String, Array] spec
+    #   should be either a single field name or an array of
+    #   [field name, direction] pairs. Directions should be specified
+    #   as Mongo::ASCENDING, Mongo::DESCENDING, or Mongo::GEO2D.
+    #
+    #   Note that geospatial indexing only works with versions of MongoDB >= 1.3.3+. Keep in mind, too,
+    #   that in order to geo-index a given field, that field must reference either an array or a sub-object
+    #   where the first two values represent x- and y-coordinates. Examples can be seen below.
+    #
+    #   Also note that it is permissible to create compound indexes that include a geospatial index as
+    #   long as the geospatial index comes first.
+    #
+    #   If your code calls create_index frequently, you can use Collection#ensure_index to cache these calls
+    #   and thereby prevent excessive round trips to the database.
+    #
+    # @option opts [Boolean] :unique (false) if true, this index will enforce a uniqueness constraint.
+    # @option opts [Boolean] :background (false) indicate that the index should be built in the background. This
+    #   feature is only available in MongoDB >= 1.3.2.
+    # @option opts [Boolean] :drop_dups (nil) If creating a unique index on a collection with pre-existing records,
+    #   this option will keep the first document the database indexes and drop all subsequent with duplicate values.
+    # @option opts [Integer] :min (nil) specify the minimum longitude and latitude for a geo index.
+    # @option opts [Integer] :max (nil) specify the maximum longitude and latitude for a geo index.
+    #
+    # @example Creating a compound index:
+    #   @posts.create_index([['subject', Mongo::ASCENDING], ['created_at', Mongo::DESCENDING]])
+    #
+    # @example Creating a geospatial index:
+    #   @restaurants.create_index([['location', Mongo::GEO2D]])
+    #
+    #   # Note that this will work only if 'location' represents x,y coordinates:
+    #   {'location': [0, 50]}
+    #   {'location': {'x' => 0, 'y' => 50}}
+    #   {'location': {'latitude' => 0, 'longitude' => 50}}
+    #
+    # @example A geospatial index with alternate longitude and latitude:
+    #   @restaurants.create_index([['location', Mongo::GEO2D]], :min => 500, :max => 500)
+    #
+    # @return [String] the name of the index created.
+    #
+    # @core indexes create_index-instance_method
+    def create_index(spec, opts={})
+      opts[:dropDups] = opts.delete(:drop_dups) if opts[:drop_dups]
+      field_spec = parse_index_spec(spec)
+      name = opts.delete(:name) || generate_index_name(field_spec)
+      name = name.to_s if name
+
+      generate_indexes(field_spec, name, opts)
+      name
+    end
+
+    # Calls create_index and sets a flag to not do so again for another X minutes.
+    # this time can be specified as an option when initializing a Mongo::DB object as options[:cache_time]
+    # Any changes to an index will be propogated through regardless of cache time (e.g., a change of index direction)
+    #
+    # The parameters and options for this methods are the same as those for Collection#create_index.
+    #
+    # @example Call sequence:
+    #   Time t: @posts.ensure_index([['subject', Mongo::ASCENDING])  -- calls create_index and
+    #     sets the 5 minute cache
+    #   Time t+2min : @posts.ensure_index([['subject', Mongo::ASCENDING])  -- doesn't do anything
+    #   Time t+3min : @posts.ensure_index([['something_else', Mongo::ASCENDING])  -- calls create_index
+    #     and sets 5 minute cache
+    #   Time t+10min : @posts.ensure_index([['subject', Mongo::ASCENDING])  -- calls create_index and
+    #     resets the 5 minute counter
+    #
+    # @return [String] the name of the index.
+    def ensure_index(spec, opts={})
+      now = Time.now.utc.to_i
+      field_spec = parse_index_spec(spec)
+
+      name = opts.delete(:name) || generate_index_name(field_spec)
+      name = name.to_s if name
+
+      if !@cache[name] || @cache[name] <= now
+        generate_indexes(field_spec, name, opts)
+      end
+
+      # Reset the cache here in case there are any errors inserting. Best to be safe.
+      @cache[name] = now + @cache_time
+      name
+    end
+
+    # Drop a specified index.
+    #
+    # @param [String] name
+    #
+    # @core indexes
+    def drop_index(name)
+      @cache[name.to_s] = nil
+      @db.drop_index(@name, name)
+    end
+
+    # Drop all indexes.
+    #
+    # @core indexes
+    def drop_indexes
+      @cache = {}
+
+      # Note: calling drop_indexes with no args will drop them all.
+      @db.drop_index(@name, '*')
+    end
+
+    # Drop the entire collection. USE WITH CAUTION.
+    def drop
+      @db.drop_collection(@name)
+    end
+
+    # Atomically update and return a document using MongoDB's findAndModify command. (MongoDB > 1.3.0)
+    #
+    # @option opts [Hash] :query ({}) a query selector document for matching the desired document.
+    # @option opts [Hash] :update (nil) the update operation to perform on the matched document.
+    # @option opts [Array, String, OrderedHash] :sort ({}) specify a sort option for the query using any
+    #   of the sort options available for Cursor#sort. Sort order is important if the query will be matching
+    #   multiple documents since only the first matching document will be updated and returned.
+    # @option opts [Boolean] :remove (false) If true, removes the the returned document from the collection.
+    # @option opts [Boolean] :new (false) If true, returns the updated document; otherwise, returns the document
+    #   prior to update.
+    #
+    # @return [Hash] the matched document.
+    #
+    # @core findandmodify find_and_modify-instance_method
+    def find_and_modify(opts={})
+      cmd = BSON::OrderedHash.new
+      cmd[:findandmodify] = @name
+      cmd.merge!(opts)
+      cmd[:sort] = Mongo::Support.format_order_clause(opts[:sort]) if opts[:sort]
+
+      @db.command(cmd)['value']
+    end
+
+    # Perform a map/reduce operation on the current collection.
+    #
+    # @param [String, BSON::Code] map a map function, written in JavaScript.
+    # @param [String, BSON::Code] reduce a reduce function, written in JavaScript.
+    #
+    # @option opts [Hash] :query ({}) a query selector document, like what's passed to #find, to limit
+    #   the operation to a subset of the collection.
+    # @option opts [Array] :sort ([]) an array of [key, direction] pairs to sort by. Direction should
+    #   be specified as Mongo::ASCENDING (or :ascending / :asc) or Mongo::DESCENDING (or :descending / :desc)
+    # @option opts [Integer] :limit (nil) if passing a query, number of objects to return from the collection.
+    # @option opts [String, BSON::Code] :finalize (nil) a javascript function to apply to the result set after the
+    #   map/reduce operation has finished.
+    # @option opts [String] :out (nil) the name of the output collection. If specified, the collection will not be treated as temporary.
+    # @option opts [Boolean] :keeptemp (false) if true, the generated collection will be persisted. default is false.
+    # @option opts [Boolean ] :verbose (false) if true, provides statistics on job execution time.
+    # @option opts [Boolean] :raw (false) if true, return the raw result object from the map_reduce command, and not
+    #   the instantiated collection that's returned by default.
+    #
+    # @return [Collection] a collection containing the results of the operation.
+    #
+    # @see http://www.mongodb.org/display/DOCS/MapReduce Offical MongoDB map/reduce documentation.
+    #
+    # @core mapreduce map_reduce-instance_method
+    def map_reduce(map, reduce, opts={})
+      map    = BSON::Code.new(map) unless map.is_a?(BSON::Code)
+      reduce = BSON::Code.new(reduce) unless reduce.is_a?(BSON::Code)
+      raw    = opts.delete(:raw)
+
+      hash = BSON::OrderedHash.new
+      hash['mapreduce'] = self.name
+      hash['map'] = map
+      hash['reduce'] = reduce
+      hash.merge! opts
+
+      result = @db.command(hash)
+      unless Mongo::Support.ok?(result)
+        raise Mongo::OperationFailure, "map-reduce failed: #{result['errmsg']}"
+      end
+
+      if raw
+        result
+      else
+        @db[result["result"]]
+      end
+    end
+    alias :mapreduce :map_reduce
+
+    # Perform a group aggregation.
+    #
+    # @param [Hash] opts the options for this group operation. The minimum required are :initial
+    #   and :reduce.
+    #
+    # @option opts [Array, String, Symbol] :key (nil) Either the name of a field or a list of fields to group by (optional).
+    # @option opts [String, BSON::Code] :keyf (nil) A JavaScript function to be used to generate the grouping keys (optional).
+    # @option opts [String, BSON::Code] :cond ({}) A document specifying a query for filtering the documents over
+    #   which the aggregation is run (optional).
+    # @option opts [Hash] :initial the initial value of the aggregation counter object (required).
+    # @option opts [String, BSON::Code] :reduce (nil) a JavaScript aggregation function (required).
+    # @option opts [String, BSON::Code] :finalize (nil) a JavaScript function that receives and modifies
+    #   each of the resultant grouped objects. Available only when group is run with command
+    #   set to true.
+    #
+    # @return [Array] the command response consisting of grouped items.
+    def group(key, condition={}, initial={}, reduce=nil, finalize=nil)
+      if key.is_a?(Hash)
+        return new_group(key)
+      else
+        warn "Collection#group no longer take a list of paramters. This usage is deprecated." +
+             "Check out the new API at http://api.mongodb.org/ruby/current/Mongo/Collection.html#group-instance_method"
+      end
+
+      reduce = BSON::Code.new(reduce) unless reduce.is_a?(BSON::Code)
+
+      group_command = {
+        "group" => {
+          "ns"      => @name,
+          "$reduce" => reduce,
+          "cond"    => condition,
+          "initial" => initial
+        }
+      }
+
+      if key.is_a?(Symbol)
+        raise MongoArgumentError, "Group takes either an array of fields to group by or a JavaScript function" +
+          "in the form of a String or BSON::Code."
+      end
+
+      unless key.nil?
+        if key.is_a? Array
+          key_type = "key"
+          key_value = {}
+          key.each { |k| key_value[k] = 1 }
+        else
+          key_type  = "$keyf"
+          key_value = key.is_a?(BSON::Code) ? key : BSON::Code.new(key)
+        end
+
+        group_command["group"][key_type] = key_value
+      end
+
+      finalize = BSON::Code.new(finalize) if finalize.is_a?(String)
+      if finalize.is_a?(BSON::Code)
+        group_command['group']['finalize'] = finalize
+      end
+
+      result = @db.command(group_command)
+
+      if Mongo::Support.ok?(result)
+        result["retval"]
+      else
+        raise OperationFailure, "group command failed: #{result['errmsg']}"
+      end
+    end
+
+    private
+
+    def new_group(opts={})
+      reduce   =  opts[:reduce]
+      finalize =  opts[:finalize]
+      cond     =  opts.fetch(:cond, {})
+      initial  =  opts[:initial]
+
+      if !(reduce && initial)
+        raise MongoArgumentError, "Group requires at minimum values for initial and reduce."
+      end
+
+      cmd = {
+        "group" => {
+          "ns"      => @name,
+          "$reduce" => reduce.to_bson_code,
+          "cond"    => cond,
+          "initial" => initial
+        }
+      }
+
+      if finalize
+        cmd['group']['finalize'] = finalize.to_bson_code
+      end
+
+      if key = opts[:key]
+        if key.is_a?(String) || key.is_a?(Symbol)
+          key = [key]
+        end
+        key_value = {}
+        key.each { |k| key_value[k] = 1 }
+        cmd["group"]["key"] = key_value
+      elsif keyf = opts[:keyf]
+        cmd["group"]["$keyf"] = keyf.to_bson_code
+      end
+
+      result = @db.command(cmd)
+      result["retval"]
+    end
+
+    public
+
+    # Return a list of distinct values for +key+ across all
+    # documents in the collection. The key may use dot notation
+    # to reach into an embedded object.
+    #
+    # @param [String, Symbol, OrderedHash] key or hash to group by.
+    # @param [Hash] query a selector for limiting the result set over which to group.
+    #
+    # @example Saving zip codes and ages and returning distinct results.
+    #   @collection.save({:zip => 10010, :name => {:age => 27}})
+    #   @collection.save({:zip => 94108, :name => {:age => 24}})
+    #   @collection.save({:zip => 10010, :name => {:age => 27}})
+    #   @collection.save({:zip => 99701, :name => {:age => 24}})
+    #   @collection.save({:zip => 94108, :name => {:age => 27}})
+    #
+    #   @collection.distinct(:zip)
+    #     [10010, 94108, 99701]
+    #   @collection.distinct("name.age")
+    #     [27, 24]
+    #
+    #   # You may also pass a document selector as the second parameter
+    #   # to limit the documents over which distinct is run:
+    #   @collection.distinct("name.age", {"name.age" => {"$gt" => 24}})
+    #     [27]
+    #
+    # @return [Array] an array of distinct values.
+    def distinct(key, query=nil)
+      raise MongoArgumentError unless [String, Symbol].include?(key.class)
+      command = BSON::OrderedHash.new
+      command[:distinct] = @name
+      command[:key]      = key.to_s
+      command[:query]    = query
+
+      @db.command(command)["values"]
+    end
+
+    # Rename this collection.
+    #
+    # Note: If operating in auth mode, the client must be authorized as an admin to
+    # perform this operation.
+    #
+    # @param [String] new_name the new name for this collection
+    #
+    # @return [String] the name of the new collection.
+    #
+    # @raise [Mongo::InvalidNSName] if +new_name+ is an invalid collection name.
+    def rename(new_name)
+      case new_name
+      when Symbol, String
+      else
+        raise TypeError, "new_name must be a string or symbol"
+      end
+
+      new_name = new_name.to_s
+
+      if new_name.empty? or new_name.include? ".."
+        raise Mongo::InvalidNSName, "collection names cannot be empty"
+      end
+      if new_name.include? "$"
+        raise Mongo::InvalidNSName, "collection names must not contain '$'"
+      end
+      if new_name.match(/^\./) or new_name.match(/\.$/)
+        raise Mongo::InvalidNSName, "collection names must not start or end with '.'"
+      end
+
+      @db.rename_collection(@name, new_name)
+      @name = new_name
+    end
+
+    # Get information on the indexes for this collection.
+    #
+    # @return [Hash] a hash where the keys are index names.
+    #
+    # @core indexes
+    def index_information
+      @db.index_information(@name)
+    end
+
+    # Return a hash containing options that apply to this collection.
+    # For all possible keys and values, see DB#create_collection.
+    #
+    # @return [Hash] options that apply to this collection.
+    def options
+      @db.collections_info(@name).next_document['options']
+    end
+
+    # Return stats on the collection. Uses MongoDB's collstats command.
+    #
+    # @return [Hash]
+    def stats
+      @db.command({:collstats => @name})
+    end
+
+    # Get the number of documents in this collection.
+    #
+    # @return [Integer]
+    def count
+      find().count()
+    end
+
+    alias :size :count
+
+    protected
+
+    def normalize_hint_fields(hint)
+      case hint
+      when String
+        {hint => 1}
+      when Hash
+        hint
+      when nil
+        nil
+      else
+        h = BSON::OrderedHash.new
+        hint.to_a.each { |k| h[k] = 1 }
+        h
+      end
+    end
+
+    private
+
+    def parse_index_spec(spec)
+      field_spec = BSON::OrderedHash.new
+      if spec.is_a?(String) || spec.is_a?(Symbol)
+        field_spec[spec.to_s] = 1
+      elsif spec.is_a?(Array) && spec.all? {|field| field.is_a?(Array) }
+        spec.each do |f|
+          if [Mongo::ASCENDING, Mongo::DESCENDING, Mongo::GEO2D].include?(f[1])
+            field_spec[f[0].to_s] = f[1]
+          else
+            raise MongoArgumentError, "Invalid index field #{f[1].inspect}; " + 
+              "should be one of Mongo::ASCENDING (1), Mongo::DESCENDING (-1) or Mongo::GEO2D ('2d')."
+          end
+        end
+      else
+        raise MongoArgumentError, "Invalid index specification #{spec.inspect}; " + 
+          "should be either a string, symbol, or an array of arrays."
+      end
+      field_spec
+    end
+
+    def generate_indexes(field_spec, name, opts)
+      selector = {
+        :name   => name,
+        :ns     => "#{@db.name}.#{@name}",
+        :key    => field_spec
+      }
+      selector.merge!(opts)
+
+      begin
+      insert_documents([selector], Mongo::DB::SYSTEM_INDEX_COLLECTION, false, true)
+
+      rescue Mongo::OperationFailure => e
+        if selector[:dropDups] && e.message =~ /^11000/
+          # NOP. If the user is intentionally dropping dups, we can ignore duplicate key errors.
+        else
+          raise Mongo::OperationFailure, "Failed to create index #{selector.inspect} with the following error: " +
+           "#{e.message}"
+        end
+      end
+
+      nil
+    end
+
+    # Sends a Mongo::Constants::OP_INSERT message to the database.
+    # Takes an array of +documents+, an optional +collection_name+, and a
+    # +check_keys+ setting.
+    def insert_documents(documents, collection_name=@name, check_keys=true, safe=false)
+      # Initial byte is 0.
+      message = BSON::ByteBuffer.new("\0\0\0\0")
+      BSON::BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{collection_name}")
+      documents.each do |doc|
+        message.put_binary(BSON::BSON_CODER.serialize(doc, check_keys, true).to_s)
+      end
+      raise InvalidOperation, "Exceded maximum insert size of 16,000,000 bytes" if message.size > 16_000_000
+
+      @logger.debug("MONGODB #{@db.name}['#{collection_name}'].insert(#{documents.inspect})") if @logger
+      if safe
+        @connection.send_message_with_safe_check(Mongo::Constants::OP_INSERT, message, @db.name, nil, safe)
+      else
+        @connection.send_message(Mongo::Constants::OP_INSERT, message, nil)
+      end
+      documents.collect { |o| o[:_id] || o['_id'] }
+    end
+
+    def generate_index_name(spec)
+      indexes = []
+      spec.each_pair do |field, direction|
+        indexes.push("#{field}_#{direction}")
+      end
+      indexes.join("_")
+    end
+  end
+
+end

lib/mongo/async/async_cursor.rb

@@ -0,0 +1,275 @@
+# encoding: UTF-8
+
+# Copyright (C) 2008-2010 10gen Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+module Mongo
+
+  # A cursor with async enhancements.
+  class AsyncCursor < Cursor
+    include Mongo::Conversions
+    include Enumerable
+
+    def initialize(collection, opts={})
+      super
+
+      @worker_pool = @connection.worker_pool
+    end
+
+    # Get the next document specified the cursor options.
+    #
+    # @return [Hash, Nil] the next document or Nil if no documents remain.
+    def next_document(opts={}, &blk)
+      if opts[:async]
+        async_exec(method(:next_document), nil, opts[:callback] || &blk)
+      else
+        super()
+      end
+    end
+
+    # Determine whether this cursor has any remaining results.
+    #
+    # @return [Boolean]
+    def has_next?(opts={}, &blk)
+      if opts[:async]
+        async_exec(method(:has_next?), nil, opts[:callback] || &blk)
+      else
+        super()
+      end
+    end
+
+    # Get the size of the result set for this query.
+    #
+    # @param [Boolean] whether of not to take notice of skip and limit
+    #
+    # @return [Integer] the number of objects in the result set for this query.
+    #
+    # @raise [OperationFailure] on a database error.
+    def count(skip_and_limit = false, opts={}, &blk)
+      if opts[:async]
+        async_exec(method(:count), [skip_and_limit], opts[:callback] || &blk)
+      else
+        super
+      end
+    end
+
+    # Iterate over each document in this cursor, yielding it to the given
+    # block.
+    #
+    # Iterating over an entire cursor will close it.
+    #
+    # @yield passes each document to a block for processing.
+    #
+    # @example if 'comments' represents a collection of comments:
+    #   comments.find.each do |doc|
+    #     puts doc['user']
+    #   end
+    def each(opts={}, &blk)
+      if opts[:async]
+        opts[:callback] ||= blk
+        async_each(opts)
+      else
+        super()
+      end
+    end
+
+    # Receive all the documents from this cursor as an array of hashes.
+    #
+    # Notes:
+    #
+    # If you've already started iterating over the cursor, the array returned
+    # by this method contains only the remaining documents. See Cursor#rewind! if you
+    # need to reset the cursor.
+    #
+    # Use of this method is discouraged - in most cases, it's much more
+    # efficient to retrieve documents as you need them by iterating over the cursor.
+    #
+    # @return [Array] an array of documents.
+    def to_a(opts={}, &blk)
+      if opts[:async]
+        opts[:callback] ||= blk
+        async_each(opts)
+      else
+        super
+      end
+    end
+
+    # Get the explain plan for this cursor.
+    #
+    # @return [Hash] a document containing the explain plan for this cursor.
+    #
+    # @core explain explain-instance_method
+    def explain(opts={}, &blk)
+      if opts[:async]
+        async_exec(method(:explain), nil, opts[:callback] || &blk)
+      else
+        super
+      end
+    end
+
+    # Close the cursor.
+    #
+    # Note: if a cursor is read until exhausted (read until Mongo::Constants::OP_QUERY or
+    # Mongo::Constants::OP_GETMORE returns zero for the cursor id), there is no need to
+    # close it manually.
+    #
+    # Note also: Collection#find takes an optional block argument which can be used to
+    # ensure that your cursors get closed.
+    #
+    # @return [True]
+    def close(opts={}, &blk)
+      if opts[:async]
+        async_exec(method(:async), nil, opts[:callback] || blk)
+      else
+        if @cursor_id && @cursor_id != 0
+          message = BSON::ByteBuffer.new([0, 0, 0, 0])
+          message.put_int(1)
+          message.put_long(@cursor_id)
+          @logger.debug("MONGODB cursor.close #{@cursor_id}") if @logger
+          @connection.send_message(Mongo::Constants::OP_KILL_CURSORS, message, nil)
+        end
+        @cursor_id = 0
+        @closed    = true
+      end
+    end
+
+    private
+
+    # Returns the number of documents available in the current batch without
+    # causing a blocking call.
+    #
+    # When it returns 0, the next call to #has_next? or #next_document will
+    # block as it goes to the server to fetch more documents.
+    def num_in_batch
+      @cache.length
+    end
+
+    # Return the number of documents remaining for this cursor.
+    def num_remaining
+      refresh if @cache.length == 0
+      @cache.length
+    end
+
+    def refresh
+      return if send_initial_query || @cursor_id.zero?
+      message = BSON::ByteBuffer.new([0, 0, 0, 0])
+
+      # DB name.
+      BSON::BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{@collection.name}")
+
+      # Number of results to return.
+      if @limit > 0
+        limit = @limit - @returned
+        if @batch_size > 0
+          limit = limit < @batch_size ? limit : @batch_size
+        end
+        message.put_int(limit)
+      else
+        message.put_int(@batch_size)
+      end
+
+      # Cursor id.
+      message.put_long(@cursor_id)
+      @logger.debug("MONGODB cursor.refresh() for cursor #{@cursor_id}") if @logger
+      results, @n_received, @cursor_id = @connection.receive_message(
+          Mongo::Constants::OP_GET_MORE, message, nil, @socket, @command)
+      @returned += @n_received
+      @cache += results
+      close_cursor_if_query_complete
+    end
+
+    ## Async helper methods
+
+    def async_each(opts)
+      callback = opts[:callback]
+      num_returned = opts[:num_returned] || 0
+      in_batch = num_in_batch
+      count = 0
+
+      while count < in_batch && (@limit <= 0 || num_returned < @limit)
+        exception, doc = nil, nil
+        begin
+          doc = next_document
+        rescue => e
+          exception = e
+        end
+
+        callback.call exception, doc
+        num_returned += 1
+        count += 1
+      end
+
+      # block executed by the call to has_next?; when true, call #async_each again
+      # otherwise the cursor is exhausted
+      return_to_each = Proc.new do |error, more|
+        unless error
+          method(:async_each).call({:callback => callback, :num_returned => num_returned}) if more
+        else
+          # pass the exception through to the block for handling
+          callback.call error, nil
+        end
+      end
+
+      async_exec method(:has_next?), nil, return_to_each
+    end
+
+    def async_to_a(opts)
+      rows = opts[:rows] || []
+      callback = opts[:callback]
+      num_returned = opts[:num_returned] || 0
+      in_batch = num_in_batch
+      count = 0
+
+      # loop through all the docs in this batch since we know +in_batch+ documents are
+      # available without blocking
+      while count < in_batch && (@limit <= 0 || num_returned < @limit)
+        exception = nil
+        begin
+          rows << next_document
+        rescue => e
+          exception = e
+        end
+
+        callback.call exception, nil if exception
+        num_returned += 1
+        count += 1
+      end
+
+      # block executed by the call to has_next?; when true, call #each again
+      # otherwise the cursor is exhausted
+      return_to_a = Proc.new do |error, more|
+        unless error
+          if more
+            method(:async_to_a).call({:callback => callback, :rows => rows, :num_returned => num_returned})
+          else
+            callback.call nil, rows
+          end
+        else
+          # pass the exception through to the block for handling
+          callback.call error, nil
+        end
+      end
+
+      async_exec method(:has_next?), nil, return_to_a
+    end
+
+    def async_exec(command, opts, callback)
+      raise ArgumentError, "Must pass a :callback proc or a block when executing in async mode!" unless callback
+
+      opts.delete :async if opts
+
+      @workers.enqueue command, [opts], callback
+    end
+  end
+end

lib/mongo/cursor.rb

@@ -223,11 +223,8 @@ module Mongo
     #     puts doc['user']
     #   end
     def each
-      #num_returned = 0
-      #while has_next? && (@limit <= 0 || num_returned < @limit)
       while doc = next_document
-        yield doc #next_document
+        yield doc
-        #num_returned += 1
       end
     end
 
@@ -285,7 +282,9 @@ module Mongo
     # Is this cursor closed?
     #
     # @return [Boolean]
-    def closed?; @closed; end
+    def closed?
+      @closed || (@cursor_id && @cursor_id.zero?)
+    end
 
     # Returns an integer indicating which query options have been selected.
     #

lib/mongo/util/worker_pool.rb

@@ -0,0 +1,55 @@
+module Mongo
+  module Async
+
+    class WorkerPool
+      attr_reader :workers
+
+      def initialize size
+        @jobs = Queue.new
+        @workers = Queue.new
+
+        @size = size
+        spawn_pool @size
+      end
+
+      def enqueue command, args, callback
+        # call compact to remove any nil arguments
+        @jobs << [command, args.compact, callback]
+      end
+
+      private
+
+      def spawn_pool size
+        size.times do
+          thread = Thread.new do
+            while true do
+              do_work
+            end
+          end
+
+          thread.abort_on_exception = true
+          @workers << thread
+        end
+      end
+
+      def do_work
+        # blocks on #pop until a job is available
+        command, cmd_args, callback = @jobs.pop
+        exception, result = nil, nil
+
+        # Call the original command with its arguments; capture
+        # and save any result and/or exception
+        begin
+          result = command.call *cmd_args
+        rescue => e
+          exception = e
+        end
+
+        # Execute the callback and pass in the exception and result;
+        # in successful cases, the exception should be nil
+        callback.call exception, result
+      end
+    end # Workers
+
+  end # Async
+end # Mongo