ChangeLogTag: Fri Jun 26 20:41:53 UTC 2009 Adam Mitz <mitza@ociweb.com>

26 files changed, 222 insertions, 44 deletions

diff --git a/TAO/ChangeLog b/TAO/ChangeLog
index 80b564dae93..48226158a3c 100644
--- a/TAO/ChangeLog
+++ b/TAO/ChangeLog
@@ -1,3 +1,42 @@
+Fri Jun 26 20:41:53 UTC 2009  Adam Mitz  <mitza@ociweb.com>
+
+        * tao/Block_Flushing_Strategy.h:
+        * tao/Block_Flushing_Strategy.cpp:
+        * tao/Connection_Handler.h:
+        * tao/Connection_Handler.inl:
+        * tao/Connection_Handler.cpp:
+        * tao/IIOP_Connection_Handler.h:
+        * tao/IIOP_Connection_Handler.cpp:
+        * tao/Transport.h:
+        * tao/Transport.cpp:
+
+          This resolves bug #3704.
+          TAO_Transport::handle_output() now uses an enum return value to
+          distinguish the EWOULDBLOCK case from other normal or error
+          conditions.  The Block_Flushing_Strategy checks for EWOULDBLOCK
+          and calls a new method, handle_write_ready(), on the Connection
+          Handler.  The Connection Handler calls ACE::handle_write_ready()
+          passing the specific handle.
+
+        * tao/Strategies/DIOP_Connection_Handler.h:
+        * tao/Strategies/DIOP_Connection_Handler.cpp:
+        * tao/Strategies/SCIOP_Connection_Handler.h:
+        * tao/Strategies/SCIOP_Connection_Handler.cpp:
+        * tao/Strategies/SHMIOP_Connection_Handler.h:
+        * tao/Strategies/SHMIOP_Connection_Handler.cpp:
+        * tao/Strategies/UIOP_Connection_Handler.h:
+        * tao/Strategies/UIOP_Connection_Handler.cpp:
+        * orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.h:
+        * orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.cpp:
+        * orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.h:
+        * orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.cpp:
+        * orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.h:
+        * orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.cpp:
+        * orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.h:
+        * orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.cpp:
+
+          Added handle_write_ready() to the non-IIOP protocols.
+
 Thu Jun 25 14:17:46 UTC 2009  Adam Mitz  <mitza@ociweb.com>
 
         * TAO_IDL/fe/lex.yy.cpp:
diff --git a/TAO/orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.cpp b/TAO/orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.cpp
index f6d98ad2d85..0dcab5ad0f1 100644
--- a/TAO/orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.cpp
+++ b/TAO/orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.cpp
@@ -304,4 +304,10 @@ TAO::HTIOP::Connection_Handler::set_dscp_codepoint (
   return 0;
 }
 
+int
+TAO::HTIOP::Connection_Handler::handle_write_ready (const ACE_Time_Value *t)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), t);
+}
+
 TAO_END_VERSIONED_NAMESPACE_DECL
diff --git a/TAO/orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.h b/TAO/orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.h
index 64a89eca11c..a0abcad5026 100644
--- a/TAO/orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.h
+++ b/TAO/orbsvcs/orbsvcs/HTIOP/HTIOP_Connection_Handler.h
@@ -117,6 +117,7 @@ namespace TAO
        * @name TAO_Connection Handler overloads
        */
       virtual int release_os_resources (void);
+      virtual int handle_write_ready (const ACE_Time_Value *timeout);
       //@}
 
     private:
diff --git a/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.cpp b/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.cpp
index f7ff15edc43..2b28cb7716f 100644
--- a/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.cpp
+++ b/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.cpp
@@ -456,4 +456,10 @@ TAO_UIPMC_Connection_Handler::set_dscp_codepoint (CORBA::Boolean set_network_pri
   return 0;
 }
 
+int
+TAO_UIPMC_Connection_Handler::handle_write_ready (const ACE_Time_Value *t)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), t);
+}
+
 TAO_END_VERSIONED_NAMESPACE_DECL
diff --git a/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.h b/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.h
index 6b8268a11a4..4e4b0e8d8e0 100644
--- a/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.h
+++ b/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Connection_Handler.h
@@ -132,6 +132,7 @@ protected:
    * @name TAO_Connection Handler overloads
    */
   virtual int release_os_resources (void);
+  virtual int handle_write_ready (const ACE_Time_Value *timeout);
   //@}
 
   // helper function used by the set_dscp_codepoint () methods to
diff --git a/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.cpp b/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.cpp
index b11dca07fda..f9af18c659e 100644
--- a/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.cpp
+++ b/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.cpp
@@ -228,4 +228,11 @@ TAO_UIPMC_Mcast_Connection_Handler::add_transport_to_cache (void)
                                                this->transport ());
 }
 
+int
+TAO_UIPMC_Mcast_Connection_Handler::handle_write_ready
+  (const ACE_Time_Value *t)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), t);
+}
+
 TAO_END_VERSIONED_NAMESPACE_DECL
diff --git a/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.h b/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.h
index fc706df0320..913391e3173 100644
--- a/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.h
+++ b/TAO/orbsvcs/orbsvcs/PortableGroup/UIPMC_Mcast_Connection_Handler.h
@@ -127,6 +127,7 @@ protected:
    * @name TAO_Connection Handler overloads
    */
   virtual int release_os_resources (void);
+  virtual int handle_write_ready (const ACE_Time_Value *timeout);
   //@}
 
 };
diff --git a/TAO/orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.cpp b/TAO/orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.cpp
index feb250f3849..0636b60f017 100644
--- a/TAO/orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.cpp
+++ b/TAO/orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.cpp
@@ -440,4 +440,10 @@ TAO::SSLIOP::Connection_Handler::teardown_ssl_state (
   this->current_->teardown (previous_current_impl, setup_done);
 }
 
+int
+TAO::SSLIOP::Connection_Handler::handle_write_ready (const ACE_Time_Value *t)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), t);
+}
+
 TAO_END_VERSIONED_NAMESPACE_DECL
diff --git a/TAO/orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.h b/TAO/orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.h
index fa8e35deb57..2e4e4d3de95 100644
--- a/TAO/orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.h
+++ b/TAO/orbsvcs/orbsvcs/SSLIOP/SSLIOP_Connection_Handler.h
@@ -113,6 +113,7 @@ namespace TAO
        */
       virtual int release_os_resources (void);
       virtual void pos_io_hook (int & return_value);
+      virtual int handle_write_ready (const ACE_Time_Value *timeout);
       //@}
 
     protected:
diff --git a/TAO/tao/Block_Flushing_Strategy.cpp b/TAO/tao/Block_Flushing_Strategy.cpp
index 397e4717006..ce17445599d 100644
--- a/TAO/tao/Block_Flushing_Strategy.cpp
+++ b/TAO/tao/Block_Flushing_Strategy.cpp
@@ -3,6 +3,8 @@
 #include "tao/Block_Flushing_Strategy.h"
 #include "tao/Transport.h"
 #include "tao/Queued_Message.h"
+#include "tao/Connection_Handler.h"
+#include "ace/Countdown_Time.h"
 
 ACE_RCSID(tao, Block_Flushing_Strategy, "$Id$")
 
@@ -21,15 +23,37 @@ TAO_Block_Flushing_Strategy::cancel_output (TAO_Transport *)
 }
 
 int
+TAO_Block_Flushing_Strategy::call_handle_output (TAO_Transport *transport,
+    const TAO::Transport::Drain_Constraints &dc)
+{
+  switch (transport->handle_output (dc).dre_)
+    {
+    case TAO_Transport::DR_ERROR: return -1;
+    case TAO_Transport::DR_QUEUE_EMPTY: // won't happen, fall-through anyway
+    case TAO_Transport::DR_OK: return 0;
+    case TAO_Transport::DR_WOULDBLOCK:
+      {
+        ACE_Countdown_Time counter (dc.timeout ());
+        TAO_Connection_Handler &ch = *transport->connection_handler ();
+        if (ch.handle_write_ready (dc.timeout ()) == -1)
+          {
+            return -1;
+          }
+        return 0;
+      }
+    }
+  return 0;
+}
+
+int
 TAO_Block_Flushing_Strategy::flush_message (TAO_Transport *transport,
                                             TAO_Queued_Message *msg,
                                             ACE_Time_Value *max_wait_time)
 {
+  TAO::Transport::Drain_Constraints dc (max_wait_time, true);
   while (!msg->all_data_sent ())
     {
-      TAO::Transport::Drain_Constraints dc(
-          max_wait_time, true);
-      if (transport->handle_output (dc) == -1)
+      if (this->call_handle_output (transport, dc) == -1)
         return -1;
     }
   return 0;
@@ -39,11 +63,10 @@ int
 TAO_Block_Flushing_Strategy::flush_transport (TAO_Transport *transport,
                                               ACE_Time_Value *max_wait_time)
 {
+  TAO::Transport::Drain_Constraints dc (max_wait_time, true);
   while (!transport->queue_is_empty ())
     {
-      TAO::Transport::Drain_Constraints dc(
-          max_wait_time, true);
-      if (transport->handle_output (dc) == -1)
+      if (this->call_handle_output (transport, dc) == -1)
         return -1;
     }
   return 0;
diff --git a/TAO/tao/Block_Flushing_Strategy.h b/TAO/tao/Block_Flushing_Strategy.h
index b82ec8db0ee..a766e184f30 100644
--- a/TAO/tao/Block_Flushing_Strategy.h
+++ b/TAO/tao/Block_Flushing_Strategy.h
@@ -22,6 +22,14 @@
 
 TAO_BEGIN_VERSIONED_NAMESPACE_DECL
 
+namespace TAO
+{
+  namespace Transport
+  {
+    class Drain_Constraints;
+  }
+}
+
 /**
  * @class TAO_Block_Flushing_Strategy
  *
@@ -37,6 +45,10 @@ public:
                              ACE_Time_Value *max_wait_time);
   virtual int flush_transport (TAO_Transport *transport
                                , ACE_Time_Value *max_wait_time);
+
+private:
+  int call_handle_output (TAO_Transport *transport,
+                          const TAO::Transport::Drain_Constraints &dc);
 };
 
 TAO_END_VERSIONED_NAMESPACE_DECL
diff --git a/TAO/tao/Connection_Handler.cpp b/TAO/tao/Connection_Handler.cpp
index 269ffd38024..7945e538cda 100644
--- a/TAO/tao/Connection_Handler.cpp
+++ b/TAO/tao/Connection_Handler.cpp
@@ -208,7 +208,8 @@ TAO_Connection_Handler::handle_output_eh (
 
   // The default constraints are to never block.
   TAO::Transport::Drain_Constraints dc;
-  return_value = this->transport ()->handle_output (dc);
+  return_value =
+    (this->transport ()->handle_output (dc) == TAO_Transport::DR_OK) ? 0 : -1;
 
   this->pos_io_hook (return_value);
 
diff --git a/TAO/tao/Connection_Handler.h b/TAO/tao/Connection_Handler.h
index 39dfd6e7fae..5300641c744 100644
--- a/TAO/tao/Connection_Handler.h
+++ b/TAO/tao/Connection_Handler.h
@@ -136,6 +136,8 @@ public:
   /// Release the OS resources related to this handler.
   virtual int release_os_resources (void);
 
+  virtual int handle_write_ready (const ACE_Time_Value *timeout);
+
   /*
    * Hook to add public methods from concrete connection handler
    * implementation onto the base connection handler.
diff --git a/TAO/tao/Connection_Handler.inl b/TAO/tao/Connection_Handler.inl
index 3e3397b282f..5c584b64565 100644
--- a/TAO/tao/Connection_Handler.inl
+++ b/TAO/tao/Connection_Handler.inl
@@ -64,6 +64,15 @@ TAO_Connection_Handler::cancel_pending_connection (void)
     }
 }
 
+/// Derived classes should implement this for proper support with the
+/// Blocking Flushing Strategy.
+ACE_INLINE int
+TAO_Connection_Handler::handle_write_ready (const ACE_Time_Value *)
+{
+  return 0;
+}
+
+
 //@@ CONNECTION_HANDLER_SPL_METHODS_ADD_HOOK
 
 TAO_END_VERSIONED_NAMESPACE_DECL
diff --git a/TAO/tao/IIOP_Connection_Handler.cpp b/TAO/tao/IIOP_Connection_Handler.cpp
index 78c638a8aa7..1f27c5472fd 100644
--- a/TAO/tao/IIOP_Connection_Handler.cpp
+++ b/TAO/tao/IIOP_Connection_Handler.cpp
@@ -668,6 +668,13 @@ TAO_IIOP_Connection_Handler::abort (void)
     }
 }
 
+int
+TAO_IIOP_Connection_Handler::handle_write_ready (const ACE_Time_Value *timeout)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), timeout);
+}
+
+
 //@@ CONNECTION_HANDLER_SPL_COPY_HOOK_END
 /*
  * End copy hook
diff --git a/TAO/tao/IIOP_Connection_Handler.h b/TAO/tao/IIOP_Connection_Handler.h
index 067c4768be1..a96bf0c8403 100644
--- a/TAO/tao/IIOP_Connection_Handler.h
+++ b/TAO/tao/IIOP_Connection_Handler.h
@@ -123,6 +123,8 @@ protected:
   virtual int release_os_resources (void);
   //@}
 
+  virtual int handle_write_ready (const ACE_Time_Value *timeout);
+
   // helper function used by the set_dscp_codepoint () methods to
   // set the TOS field in the IP packets.
   int set_tos (int tos);
diff --git a/TAO/tao/Strategies/DIOP_Connection_Handler.cpp b/TAO/tao/Strategies/DIOP_Connection_Handler.cpp
index 5aa66011513..193d4521af6 100644
--- a/TAO/tao/Strategies/DIOP_Connection_Handler.cpp
+++ b/TAO/tao/Strategies/DIOP_Connection_Handler.cpp
@@ -435,6 +435,12 @@ TAO_DIOP_Connection_Handler::set_dscp_codepoint (CORBA::Boolean set_network_prio
   return 0;
 }
 
+int
+TAO_DIOP_Connection_Handler::handle_write_ready (const ACE_Time_Value *t)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), t);
+}
+
 TAO_END_VERSIONED_NAMESPACE_DECL
 
 #endif /* TAO_HAS_DIOP && TAO_HAS_DIOP != 0 */
diff --git a/TAO/tao/Strategies/DIOP_Connection_Handler.h b/TAO/tao/Strategies/DIOP_Connection_Handler.h
index fd910d0ced8..f54334bed38 100644
--- a/TAO/tao/Strategies/DIOP_Connection_Handler.h
+++ b/TAO/tao/Strategies/DIOP_Connection_Handler.h
@@ -124,6 +124,7 @@ protected:
    * @name TAO_Connection Handler overloads
    */
   virtual int release_os_resources (void);
+  virtual int handle_write_ready (const ACE_Time_Value *timeout);
   //@}
 
   /// Helper method used by the set_dscp_codepoint () methods
diff --git a/TAO/tao/Strategies/SCIOP_Connection_Handler.cpp b/TAO/tao/Strategies/SCIOP_Connection_Handler.cpp
index 33873fc18bc..c81e4783c9d 100644
--- a/TAO/tao/Strategies/SCIOP_Connection_Handler.cpp
+++ b/TAO/tao/Strategies/SCIOP_Connection_Handler.cpp
@@ -460,6 +460,12 @@ TAO_SCIOP_Connection_Handler::set_dscp_codepoint (CORBA::Boolean set_network_pri
   return 0;
 }
 
+int
+TAO_SCIOP_Connection_Handler::handle_write_ready (const ACE_Time_Value *t)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), t);
+}
+
 TAO_END_VERSIONED_NAMESPACE_DECL
 
 #endif /* TAO_HAS_SCIOP == 1 */
diff --git a/TAO/tao/Strategies/SCIOP_Connection_Handler.h b/TAO/tao/Strategies/SCIOP_Connection_Handler.h
index 6cdc1f4702c..823e684a3f2 100644
--- a/TAO/tao/Strategies/SCIOP_Connection_Handler.h
+++ b/TAO/tao/Strategies/SCIOP_Connection_Handler.h
@@ -117,6 +117,7 @@ protected:
    */
   //  void handle_close_i (void);
   virtual int release_os_resources (void);
+  virtual int handle_write_ready (const ACE_Time_Value *timeout);
   //@}
 
 private:
diff --git a/TAO/tao/Strategies/SHMIOP_Connection_Handler.cpp b/TAO/tao/Strategies/SHMIOP_Connection_Handler.cpp
index 45d8f81c236..2f5a6b4c0d6 100644
--- a/TAO/tao/Strategies/SHMIOP_Connection_Handler.cpp
+++ b/TAO/tao/Strategies/SHMIOP_Connection_Handler.cpp
@@ -266,6 +266,12 @@ TAO_SHMIOP_Connection_Handler::add_transport_to_cache (void)
   return cache.cache_transport (&prop, this->transport ());
 }
 
+int
+TAO_SHMIOP_Connection_Handler::handle_write_ready (const ACE_Time_Value *t)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), t);
+}
+
 TAO_END_VERSIONED_NAMESPACE_DECL
 
 #endif /*(TAO_HAS_SHMIOP) && (TAO_HAS_SHMIOP != 0) */
diff --git a/TAO/tao/Strategies/SHMIOP_Connection_Handler.h b/TAO/tao/Strategies/SHMIOP_Connection_Handler.h
index ce3d080d4b0..0dc238ae6b2 100644
--- a/TAO/tao/Strategies/SHMIOP_Connection_Handler.h
+++ b/TAO/tao/Strategies/SHMIOP_Connection_Handler.h
@@ -93,6 +93,7 @@ protected:
    * @name TAO_Connection Handler overloads
    */
   virtual int release_os_resources (void);
+  virtual int handle_write_ready (const ACE_Time_Value *timeout);
   //@}
 
 private:
diff --git a/TAO/tao/Strategies/UIOP_Connection_Handler.cpp b/TAO/tao/Strategies/UIOP_Connection_Handler.cpp
index 8364a47784f..a52abb6c64b 100644
--- a/TAO/tao/Strategies/UIOP_Connection_Handler.cpp
+++ b/TAO/tao/Strategies/UIOP_Connection_Handler.cpp
@@ -238,6 +238,12 @@ TAO_UIOP_Connection_Handler::add_transport_to_cache (void)
   return cache.cache_transport (&prop, this->transport ());
 }
 
+int
+TAO_UIOP_Connection_Handler::handle_write_ready (const ACE_Time_Value *t)
+{
+  return ACE::handle_write_ready (this->peer ().get_handle (), t);
+}
+
 TAO_END_VERSIONED_NAMESPACE_DECL
 
 #endif /*TAO_HAS_UIOP == 1*/
diff --git a/TAO/tao/Strategies/UIOP_Connection_Handler.h b/TAO/tao/Strategies/UIOP_Connection_Handler.h
index 6b40184b3e2..8ab218fd69b 100644
--- a/TAO/tao/Strategies/UIOP_Connection_Handler.h
+++ b/TAO/tao/Strategies/UIOP_Connection_Handler.h
@@ -90,6 +90,7 @@ protected:
    * @name TAO_Connection Handler overloads
    */
   virtual int release_os_resources (void);
+  virtual int handle_write_ready (const ACE_Time_Value *timeout);
   //@}
 };
 
diff --git a/TAO/tao/Transport.cpp b/TAO/tao/Transport.cpp
index 9494364a241..e2102707cb1 100644
--- a/TAO/tao/Transport.cpp
+++ b/TAO/tao/Transport.cpp
@@ -521,7 +521,7 @@ TAO_Transport::update_transport (void)
  *  Methods called and used in the output path of the ORB.
  *
  */
-int
+TAO_Transport::Drain_Result
 TAO_Transport::handle_output (TAO::Transport::Drain_Constraints const & dc)
 {
   if (TAO_debug_level > 3)
@@ -538,7 +538,7 @@ TAO_Transport::handle_output (TAO::Transport::Drain_Constraints const & dc)
   // The flushing strategy (potentially via the Reactor) wants to send
   // more data, first check if there is a current message that needs
   // more sending...
-  int const retval = this->drain_queue (dc);
+  Drain_Result const retval = this->drain_queue (dc);
 
   if (TAO_debug_level > 3)
     {
@@ -546,7 +546,7 @@ TAO_Transport::handle_output (TAO::Transport::Drain_Constraints const & dc)
                   ACE_TEXT ("TAO (%P|%t) - Transport[%d]::handle_output, ")
                   ACE_TEXT ("drain_queue returns %d/%d\n"),
                   this->id (),
-                  retval, ACE_ERRNO_GET));
+                  static_cast<int> (retval.dre_), ACE_ERRNO_GET));
     }
 
   // Any errors are returned directly to the Reactor
@@ -592,14 +592,14 @@ TAO_Transport::send_message_block_chain_i (const ACE_Message_Block *mb,
 
   synch_message.push_back (this->head_, this->tail_);
 
-  int const n = this->drain_queue_i (dc);
+  Drain_Result const n = this->drain_queue_i (dc);
 
-  if (n == -1)
+  if (n == DR_ERROR)
     {
       synch_message.remove_from_list (this->head_, this->tail_);
       return -1; // Error while sending...
     }
-  else if (n == 1)
+  else if (n == DR_QUEUE_EMPTY)
     {
       bytes_transferred = total_length;
       return 1;  // Empty queue, message was sent..
@@ -780,14 +780,14 @@ TAO_Transport::send_synch_message_helper_i (TAO_Synch_Queued_Message &synch_mess
   TAO::Transport::Drain_Constraints dc(
       max_wait_time, this->using_blocking_io_for_synch_messages());
 
-  int const n = this->drain_queue_i (dc);
+  Drain_Result const n = this->drain_queue_i (dc);
 
-  if (n == -1)
+  if (n == DR_ERROR)
     {
       synch_message.remove_from_list (this->head_, this->tail_);
       return -1; // Error while sending...
     }
-  else if (n == 1)
+  else if (n == DR_QUEUE_EMPTY)
     {
       return 1;  // Empty queue, message was sent..
     }
@@ -911,13 +911,13 @@ TAO_Transport::handle_timeout (const ACE_Time_Value & /* current_time */,
   return 0;
 }
 
-int
+TAO_Transport::Drain_Result
 TAO_Transport::drain_queue (TAO::Transport::Drain_Constraints const & dc)
 {
-  ACE_GUARD_RETURN (ACE_Lock, ace_mon, *this->handler_lock_, -1);
-  int const retval = this->drain_queue_i (dc);
+  ACE_GUARD_RETURN (ACE_Lock, ace_mon, *this->handler_lock_, DR_ERROR);
+  Drain_Result const retval = this->drain_queue_i (dc);
 
-  if (retval == 1)
+  if (retval == DR_QUEUE_EMPTY)
     {
       // ... there is no current message or it was completely
       // sent, cancel output...
@@ -926,13 +926,13 @@ TAO_Transport::drain_queue (TAO::Transport::Drain_Constraints const & dc)
 
       flushing_strategy->cancel_output (this);
 
-      return 0;
+      return DR_OK;
     }
 
   return retval;
 }
 
-int
+TAO_Transport::Drain_Result
 TAO_Transport::drain_queue_helper (int &iovcnt, iovec iov[],
     TAO::Transport::Drain_Constraints const & dc)
 {
@@ -973,7 +973,7 @@ TAO_Transport::drain_queue_helper (int &iovcnt, iovec iov[],
              ACE_TEXT ("send() returns 0\n"),
              this->id ()));
         }
-      return -1;
+      return DR_ERROR;
     }
   else if (retval == -1)
     {
@@ -987,10 +987,10 @@ TAO_Transport::drain_queue_helper (int &iovcnt, iovec iov[],
 
       if (errno == EWOULDBLOCK || errno == EAGAIN)
         {
-          return 0;
+          return DR_WOULDBLOCK;
         }
 
-      return -1;
+      return DR_ERROR;
     }
 
   // ... now we need to update the queue, removing elements
@@ -1013,10 +1013,11 @@ TAO_Transport::drain_queue_helper (int &iovcnt, iovec iov[],
          this->id(), byte_count, (this->head_ == 0)));
     }
 
-  return 1;
+  return DR_QUEUE_EMPTY;
+  // drain_queue_i will check if the queue is actually empty
 }
 
-int
+TAO_Transport::Drain_Result
 TAO_Transport::drain_queue_i (TAO::Transport::Drain_Constraints const & dc)
 {
   // This is the vector used to send data, it must be declared outside
@@ -1068,23 +1069,24 @@ TAO_Transport::drain_queue_i (TAO::Transport::Drain_Constraints const & dc)
       // IOV_MAX elements ...
       if (iovcnt == ACE_IOV_MAX)
         {
-          int const retval = this->drain_queue_helper (iovcnt, iov, dc);
-
-          now = ACE_High_Res_Timer::gettimeofday_hr ();
+          Drain_Result const retval =
+            this->drain_queue_helper (iovcnt, iov, dc);
 
           if (TAO_debug_level > 4)
             {
               ACE_DEBUG ((LM_DEBUG,
                  ACE_TEXT ("TAO (%P|%t) - Transport[%d]::drain_queue_i, ")
                  ACE_TEXT ("helper retval = %d\n"),
-                 this->id (), retval));
+                 this->id (), static_cast<int> (retval.dre_)));
             }
 
-          if (retval != 1)
+          if (retval != DR_QUEUE_EMPTY)
             {
               return retval;
             }
 
+          now = ACE_High_Res_Timer::gettimeofday_hr ();
+
           i = this->head_;
           continue;
         }
@@ -1095,17 +1097,17 @@ TAO_Transport::drain_queue_i (TAO::Transport::Drain_Constraints const & dc)
 
   if (iovcnt != 0)
     {
-      int const retval = this->drain_queue_helper (iovcnt, iov, dc);
+      Drain_Result const retval = this->drain_queue_helper (iovcnt, iov, dc);
 
       if (TAO_debug_level > 4)
         {
           ACE_DEBUG ((LM_DEBUG,
               ACE_TEXT ("TAO (%P|%t) - Transport[%d]::drain_queue_i, ")
               ACE_TEXT ("helper retval = %d\n"),
-              this->id (), retval));
+              this->id (), static_cast<int> (retval.dre_)));
         }
 
-      if (retval != 1)
+      if (retval != DR_QUEUE_EMPTY)
         {
           return retval;
         }
@@ -1121,10 +1123,10 @@ TAO_Transport::drain_queue_i (TAO::Transport::Drain_Constraints const & dc)
           this->reset_flush_timer ();
         }
 
-      return 1;
+      return DR_QUEUE_EMPTY;
     }
 
-  return 0;
+  return DR_OK;
 }
 
 void
diff --git a/TAO/tao/Transport.h b/TAO/tao/Transport.h
index 40ab7fac84e..0c8d325d82c 100644
--- a/TAO/tao/Transport.h
+++ b/TAO/tao/Transport.h
@@ -364,8 +364,35 @@ public:
    */
   TAO_Wait_Strategy *wait_strategy (void) const;
 
+  enum Drain_Result_Enum
+    {
+      DR_ERROR = -1,
+      DR_OK = 0,
+      DR_QUEUE_EMPTY = 1, // used internally, not returned from drain_queue()
+      DR_WOULDBLOCK = 2
+    };
+
+  /// The handle_output and drain_queue* functions return objects of this
+  /// struct instead of the enum value directly so the compiler will catch
+  /// any uses that assign the return value to an int.
+  struct Drain_Result
+  {
+    Drain_Result (Drain_Result_Enum dre) : dre_(dre) {}
+    Drain_Result_Enum dre_;
+
+    bool operator== (Drain_Result rhs) const
+    {
+      return this->dre_ == rhs.dre_;
+    }
+
+    bool operator!= (Drain_Result rhs) const
+    {
+      return this->dre_ != rhs.dre_;
+    }
+  };
+
   /// Callback method to reactively drain the outgoing data queue
-  int handle_output (TAO::Transport::Drain_Constraints const & c);
+  Drain_Result handle_output (TAO::Transport::Drain_Constraints const & c);
 
   /// Get the bidirectional flag
   int bidirectional_flag (void) const;
@@ -895,14 +922,11 @@ private:
   /**
    * As the outgoing data is drained this method is invoked to send as
    * much of the current message as possible.
-   *
-   * Returns 0 if there is more data to send, -1 if there was an error
-   * and 1 if the message was completely sent.
    */
-  int drain_queue (TAO::Transport::Drain_Constraints const & dc);
+  Drain_Result drain_queue (TAO::Transport::Drain_Constraints const & dc);
 
   /// Implement drain_queue() assuming the lock is held
-  int drain_queue_i (TAO::Transport::Drain_Constraints const & dc);
+  Drain_Result drain_queue_i (TAO::Transport::Drain_Constraints const & dc);
 
   /// Check if there are messages pending in the queue
   /**
@@ -914,7 +938,7 @@ private:
   bool queue_is_empty_i (void) const;
 
   /// A helper routine used in drain_queue_i()
-  int drain_queue_helper (int &iovcnt, iovec iov[],
+  Drain_Result drain_queue_helper (int &iovcnt, iovec iov[],
       TAO::Transport::Drain_Constraints const & dc);
 
   /// These classes need privileged access to: