Merge pull request ruby-ldap#138 from ruby-ldap/read-queue-by-message_id

Prioritize reads from queue by message ID

Author: mtodd

lib/net/ldap/connection.rb

@@ -111,6 +111,45 @@ def close
     @conn = nil
   end
 
+  # Internal: Reads messages by ID from a queue, falling back to reading from
+  # the connected socket until a message matching the ID is read. Any messages
+  # with mismatched IDs gets queued for subsequent reads by the origin of that
+  # message ID.
+  #
+  # Returns a Net::LDAP::PDU object or nil.
+  def queued_read(message_id)
+    if pdu = message_queue[message_id].shift
+      return pdu
+    end
+
+    # read messages until we have a match for the given message_id
+    while pdu = read
+      if pdu.message_id == message_id
+        return pdu
+      else
+        message_queue[pdu.message_id].push pdu
+        next
+      end
+    end
+
+    pdu
+  end
+
+  # Internal: The internal queue of messages, read from the socket, grouped by
+  # message ID.
+  #
+  # Used by `queued_read` to return messages sent by the server with the given
+  # ID. If no messages are queued for that ID, `queued_read` will `read` from
+  # the socket and queue messages that don't match the given ID for other
+  # readers.
+  #
+  # Returns the message queue Hash.
+  def message_queue
+    @message_queue ||= Hash.new do |hash, key|
+      hash[key] = []
+    end
+  end
+
   # Internal: Reads and parses data from the configured connection.
   #
   # - syntax: the BER syntax to use to parse the read data with
@@ -146,9 +185,9 @@ def read(syntax = Net::LDAP::AsnSyntax)
   #
   # Returns the return value from writing to the connection, which in some
   # cases is the Integer number of bytes written to the socket.
-  def write(request, controls = nil)
+  def write(request, controls = nil, message_id = next_msgid)
     instrument "write.net_ldap_connection" do |payload|
-      packet = [next_msgid.to_ber, request, controls].compact.to_ber_sequence
+      packet = [message_id.to_ber, request, controls].compact.to_ber_sequence
       payload[:content_length] = @conn.write(packet)
     end
   end
@@ -356,7 +395,10 @@ def search(args = {})
     result_pdu = nil
     n_results = 0
 
+    message_id = next_msgid
+
     instrument "search.net_ldap_connection",
+               :message_id => message_id,
                :filter     => search_filter,
                :base       => search_base,
                :scope      => scope,
@@ -403,12 +445,12 @@ def search(args = {})
         controls << sort_control if sort_control
         controls = controls.empty? ? nil : controls.to_ber_contextspecific(0)
 
-        write(request, controls)
+        write(request, controls, message_id)
 
         result_pdu = nil
         controls = []
 
-        while pdu = read
+        while pdu = queued_read(message_id)
           case pdu.app_tag
           when Net::LDAP::PDU::SearchReturnedData
             n_results += 1
@@ -476,6 +518,14 @@ def search(args = {})
 
       result_pdu || OpenStruct.new(:status => :failure, :result_code => 1, :message => "Invalid search")
     end # instrument
+  ensure
+    # clean up message queue for this search
+    messages = message_queue.delete(message_id)
+
+    unless messages.empty?
+      instrument "search_messages_unread.net_ldap_connection",
+                 message_id: message_id, messages: messages
+    end
   end
 
   MODIFY_OPERATIONS = { #:nodoc:

test/test_ldap_connection.rb

@@ -185,20 +185,21 @@ def test_bind_net_ldap_connection_event
 
   def test_search_net_ldap_connection_event
     # search data
-    search_data_ber = Net::BER::BerIdentifiedArray.new([2, [
+    search_data_ber = Net::BER::BerIdentifiedArray.new([1, [
       "uid=user1,ou=OrgUnit2,ou=OrgUnitTop,dc=openldap,dc=ghe,dc=local",
       [ ["uid", ["user1"]] ]
     ]])
     search_data_ber.ber_identifier = Net::LDAP::PDU::SearchReturnedData
-    search_data = [2, search_data_ber]
+    search_data = [1, search_data_ber]
     # search result (end of results)
     search_result_ber = Net::BER::BerIdentifiedArray.new([0, "", ""])
     search_result_ber.ber_identifier = Net::LDAP::PDU::SearchResult
-    search_result = [2, search_result_ber]
+    search_result = [1, search_result_ber]
     @tcp_socket.should_receive(:read_ber).and_return(search_data).
                                           and_return(search_result)
 
     events = @service.subscribe "search.net_ldap_connection"
+    unread = @service.subscribe "search_messages_unread.net_ldap_connection"
 
     result = @connection.search(filter: "(uid=user1)")
     assert result.success?, "should be success"
@@ -209,5 +210,8 @@ def test_search_net_ldap_connection_event
     assert payload.has_key?(:filter)
     assert_equal "(uid=user1)", payload[:filter].to_s
     assert result
+
+    # ensure no unread
+    assert unread.empty?, "should not have any leftover unread messages"
   end
 end