implement a little logger with log time and query

lib/mongo/connection.rb

@@ -82,7 +82,7 @@ module Mongo
                when nil
                  [['localhost', DEFAULT_PORT]]
                end
-      @options = options
+      @options = options.merge(:logger => Logger.new(STDOUT))
     end
 
     # Return the Mongo::DB named +db_name+. The slave_ok and

lib/mongo/db.rb

@@ -135,6 +135,7 @@ module Mongo
       @semaphore = Object.new
       @semaphore.extend Mutex_m
       @socket = nil
+      @logger = options[:logger]
       connect_to_master
     end
 
@@ -512,8 +513,11 @@ module Mongo
     def send_to_db(message)
       connect_to_master if !connected? && @auto_reconnect
       begin
+        t_start = Time.now
         @socket.print(message.buf.to_s)
-        @socket.flush
+        res = @socket.flush
+        @logger.debug("  MONGODB (#{Time.now - t_start}s)  #{message.query}")
+        res
       rescue => ex
         close
         raise ex

lib/mongo/query.rb

@@ -111,5 +111,9 @@ module Mongo
     def contains_special_fields
       (@order_by != nil && @order_by.length > 0) || @explain || @hint || @snapshot
     end
+
+    def to_s
+      "#find(#{@selector.inspect})" + (@order_by ? ".sort(#{@order_by.inspect})" : "")
+    end
   end
 end