Cygwin: pty: Reduce unecessary input transfer.

- Currently, input transfer is performed every time one line is read(),
  if the non-cygwin app is running in the background. With this patch,
  transfer is triggered by setpgid() rather than read() so that the
  unnecessary input transfer can be reduced much in that situation.

1 files changed, 45 insertions, 33 deletions

diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index c4b6128..4d4d599 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -656,18 +656,19 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
       bool enable_pcon = false;
       HANDLE ptys_from_master = NULL;
       HANDLE ptys_input_available_event = NULL;
-      HANDLE ptys_output_mutex = NULL;
+      HANDLE ptys_pcon_mutex = NULL;
+      HANDLE ptys_input_mutex = NULL;
       tty *ptys_ttyp = NULL;
-      _minor_t ptys_unit = 0;
       if (!iscygwin () && ptys_primary && is_console_app (runpath))
 	{
 	  bool nopcon = mode != _P_OVERLAY && mode != _P_WAIT;
 	  if (disable_pcon || !ptys_primary->term_has_pcon_cap (envblock))
 	    nopcon = true;
+	  ptys_ttyp = ptys_primary->get_ttyp ();
+	  WaitForSingleObject (ptys_primary->pcon_mutex, INFINITE);
 	  if (ptys_primary->setup_pseudoconsole (nopcon))
 	    enable_pcon = true;
-	  ptys_ttyp = ptys_primary->get_ttyp ();
-	  ptys_unit = ptys_primary->get_minor ();
+	  ReleaseMutex (ptys_primary->pcon_mutex);
 	  ptys_from_master = ptys_primary->get_handle ();
 	  DuplicateHandle (GetCurrentProcess (), ptys_from_master,
 			   GetCurrentProcess (), &ptys_from_master,
@@ -677,14 +678,21 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	  DuplicateHandle (GetCurrentProcess (), ptys_input_available_event,
 			   GetCurrentProcess (), &ptys_input_available_event,
 			   0, 0, DUPLICATE_SAME_ACCESS);
-	  DuplicateHandle (GetCurrentProcess (), ptys_primary->output_mutex,
-			   GetCurrentProcess (), &ptys_output_mutex,
+	  DuplicateHandle (GetCurrentProcess (), ptys_primary->pcon_mutex,
+			   GetCurrentProcess (), &ptys_pcon_mutex,
+			   0, 0, DUPLICATE_SAME_ACCESS);
+	  DuplicateHandle (GetCurrentProcess (), ptys_primary->input_mutex,
+			   GetCurrentProcess (), &ptys_input_mutex,
 			   0, 0, DUPLICATE_SAME_ACCESS);
-	  if (!enable_pcon)
-	    fhandler_pty_slave::transfer_input (fhandler_pty_slave::to_nat,
-						ptys_primary->get_handle_cyg (),
-						ptys_ttyp, ptys_unit,
-						ptys_input_available_event);
+	  if (!enable_pcon && ptys_ttyp->getpgid () == myself->pgid
+	      && ptys_ttyp->pcon_input_state_eq (tty::to_cyg))
+	    {
+	      WaitForSingleObject (ptys_input_mutex, INFINITE);
+	      fhandler_pty_slave::transfer_input (tty::to_nat,
+				    ptys_primary->get_handle_cyg (),
+				    ptys_ttyp, ptys_input_available_event);
+	      ReleaseMutex (ptys_input_mutex);
+	    }
 	}
 
       /* Set up needed handles for stdio */
@@ -969,20 +977,22 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	  if (ptys_ttyp)
 	    {
 	      ptys_ttyp->wait_pcon_fwd ();
-	      /* Do not transfer input if another process using pseudo
-		 console exists. */
-	      WaitForSingleObject (ptys_output_mutex, INFINITE);
-	      if (!fhandler_pty_common::get_console_process_id
-			      (myself->exec_dwProcessId, false, true, true))
-		fhandler_pty_slave::transfer_input (fhandler_pty_slave::to_cyg,
-						    ptys_from_master,
-						    ptys_ttyp, ptys_unit,
-						    ptys_input_available_event);
+	      if (ptys_ttyp->getpgid () == myself->pgid
+		  && ptys_ttyp->pcon_input_state_eq (tty::to_nat))
+		{
+		  WaitForSingleObject (ptys_input_mutex, INFINITE);
+		  fhandler_pty_slave::transfer_input (tty::to_cyg,
+					    ptys_from_master, ptys_ttyp,
+					    ptys_input_available_event);
+		  ReleaseMutex (ptys_input_mutex);
+		}
 	      CloseHandle (ptys_from_master);
+	      CloseHandle (ptys_input_mutex);
 	      CloseHandle (ptys_input_available_event);
+	      WaitForSingleObject (ptys_pcon_mutex, INFINITE);
 	      fhandler_pty_slave::close_pseudoconsole (ptys_ttyp);
-	      ReleaseMutex (ptys_output_mutex);
-	      CloseHandle (ptys_output_mutex);
+	      ReleaseMutex (ptys_pcon_mutex);
+	      CloseHandle (ptys_pcon_mutex);
 	    }
 	  if (cons_native)
 	    {
@@ -1002,20 +1012,22 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	  if (ptys_ttyp)
 	    {
 	      ptys_ttyp->wait_pcon_fwd ();
-	      /* Do not transfer input if another process using pseudo
-		 console exists. */
-	      WaitForSingleObject (ptys_output_mutex, INFINITE);
-	      if (!fhandler_pty_common::get_console_process_id
-			      (myself->exec_dwProcessId, false, true, true))
-		fhandler_pty_slave::transfer_input (fhandler_pty_slave::to_cyg,
-						    ptys_from_master,
-						    ptys_ttyp, ptys_unit,
-						    ptys_input_available_event);
+	      if (ptys_ttyp->getpgid () == myself->pgid
+		  && ptys_ttyp->pcon_input_state_eq (tty::to_nat))
+		{
+		  WaitForSingleObject (ptys_input_mutex, INFINITE);
+		  fhandler_pty_slave::transfer_input (tty::to_cyg,
+					    ptys_from_master, ptys_ttyp,
+					    ptys_input_available_event);
+		  ReleaseMutex (ptys_input_mutex);
+		}
 	      CloseHandle (ptys_from_master);
+	      CloseHandle (ptys_input_mutex);
 	      CloseHandle (ptys_input_available_event);
+	      WaitForSingleObject (ptys_pcon_mutex, INFINITE);
 	      fhandler_pty_slave::close_pseudoconsole (ptys_ttyp);
-	      ReleaseMutex (ptys_output_mutex);
-	      CloseHandle (ptys_output_mutex);
+	      ReleaseMutex (ptys_pcon_mutex);
+	      CloseHandle (ptys_pcon_mutex);
 	    }
 	  if (cons_native)
 	    {