add an option in connection to log duration

lib/mongo/connection.rb

@@ -36,7 +36,7 @@ module Mongo
 
     mongo_thread_local_accessor :connections
 
-    attr_reader :logger, :size, :auths, :primary, :safe, :host_to_try,
+    attr_reader :logger, :log_duration, :size, :auths, :primary, :safe, :host_to_try,
       :pool_size, :connect_timeout, :pool_timeout,
       :primary_pool, :socket_class, :op_timeout
 
@@ -63,6 +63,8 @@ module Mongo
     #   to a single, slave node.
     # @option opts [Logger, #debug] :logger (nil) A Logger instance for debugging driver ops. Note that
     #   logging negatively impacts performance; therefore, it should not be used for high-performance apps.
+    # @option opts [Boolean, #debug] :log_duration (nil) A boolean to say if you want see information about log_duration on logger
+    #   like logging, log_duration negatively impacts performance; therefore, it should not be used for high-performance apps.
     # @option opts [Integer] :pool_size (1) The maximum number of socket self.connections allowed per
     #   connection pool. Note: this setting is relevant only for multi-threaded applications.
     # @option opts [Float] :pool_timeout (5.0) When all of the self.connections a pool are checked out,
@@ -568,6 +570,7 @@ module Mongo
 
       if @logger
         write_logging_startup_message
+        @log_duration = opts[:log_duration] || false
       end
 
       should_connect = opts.fetch(:connect, true)

test/connection_test.rb

@@ -148,6 +148,21 @@ class TestConnection < Test::Unit::TestCase
     assert output.string.include?('testing')
   end
 
+  def test_connection_log_duration_with_logger
+    output = StringIO.new
+    logger = Logger.new(output)
+    logger.level = Logger::DEBUG
+    connection = standard_connection(:logger => logger, :log_duration => true)
+    assert logger, connection.logger
+    assert connection.log_duration
+  end
+
+  def test_connection_log_duration_without_logger
+    connection = standard_connection(:log_duration => true)
+    assert_nil connection.logger
+    assert !connection.log_duration
+  end
+
   def test_drop_database
     db = @conn.db('ruby-mongo-will-be-deleted')
     coll = db.collection('temp')