gdb: give names to event loop file handlers

Assign names to event loop file handlers.  They will be used in debug
messages when file handlers are invoked.

In GDB, each UI used to get its own unique number, until commit
cbe256847e19 ("Remove ui::num").  Re-introduce this field, and use it to
make a unique name for the handler.

I'm not too sure what goes on in ser-base.c, all I know is that it's
what is used when debugging remotely.  I've just named the main handler
"serial".  It would be good to have unique names there too.  For instance
when debugging with two different remote connections, we'd ideally want
the handlers to have unique names.  I didn't do it in this patch though.

gdb/ChangeLog:

	* async-event.c (initialize_async_signal_handlers): Pass name to
	add_file_handler
	* event-top.c (ui_register_input_event_handler): Likewise.
	* linux-nat.c (linux_nat_target::async): Likewise.
	* run-on-main-thread.c (_initialize_run_on_main_thread):
	Likewise
	* ser-base.c (reschedule): Likewise.
	(ser_base_async): Likewise.
	* tui/tui-io.c: Likewise.
	* top.h (struct ui) <num>: New field.
	* top.c (highest_ui_num): New variable.
	(ui::ui): Initialize num.

gdbserver/ChangeLog:

	* linux-low.cc (linux_process_target::async): Pass name to
	add_file_handler.
	* remote-utils.cc (handle_accept_event): Likewise.
	(remote_open): Likewise.

gdbsupport/ChangeLog:

	* event-loop.h (add_file_handler): Add "name" parameter.
	* event-loop.cc (struct file_handler) <name>: New field.
	(create_file_handler): Add "name" parameter, assign it to file
	handler.
	(add_file_handler): Add "name" parameter.

Change-Id: I9f1545f73888ebb6778eb653a618ca44d105f92c

15 files changed, 85 insertions, 30 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8788c60..48caf1e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,20 @@
 2020-10-02  Simon Marchi  <simon.marchi@polymtl.ca>
 
+	* async-event.c (initialize_async_signal_handlers): Pass name to
+	add_file_handler
+	* event-top.c (ui_register_input_event_handler): Likewise.
+	* linux-nat.c (linux_nat_target::async): Likewise.
+	* run-on-main-thread.c (_initialize_run_on_main_thread):
+	Likewise
+	* ser-base.c (reschedule): Likewise.
+	(ser_base_async): Likewise.
+	* tui/tui-io.c: Likewise.
+	* top.h (struct ui) <num>: New field.
+	* top.c (highest_ui_num): New variable.
+	(ui::ui): Initialize num.
+
+2020-10-02  Simon Marchi  <simon.marchi@polymtl.ca>
+
 	* observable.h <inferior_created>: Remove parameters.  Update all
 	listeners.
 	* inferior.h (post_create_inferior): Remove target parameter.
diff --git a/gdb/async-event.c b/gdb/async-event.c
index ffc0edc..e5cd63e 100644
--- a/gdb/async-event.c
+++ b/gdb/async-event.c
@@ -114,7 +114,7 @@ initialize_async_signal_handlers (void)
   async_signal_handlers_serial_event = make_serial_event ();
 
   add_file_handler (serial_event_fd (async_signal_handlers_serial_event),
-		    async_signals_handler, NULL);
+		    async_signals_handler, NULL, "async-signals");
 }
 
 
diff --git a/gdb/event-top.c b/gdb/event-top.c
index ac0f370..c96f104 100644
--- a/gdb/event-top.c
+++ b/gdb/event-top.c
@@ -524,7 +524,8 @@ stdin_event_handler (int error, gdb_client_data client_data)
 void
 ui_register_input_event_handler (struct ui *ui)
 {
-  add_file_handler (ui->input_fd, stdin_event_handler, ui);
+  add_file_handler (ui->input_fd, stdin_event_handler, ui,
+		    string_printf ("ui-%d", ui->num));
 }
 
 /* See top.h.  */
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index fbb5388..7b9b267 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -4123,7 +4123,8 @@ linux_nat_target::async (int enable)
       if (!linux_async_pipe (1))
 	{
 	  add_file_handler (linux_nat_event_pipe[0],
-			    handle_target_event, NULL);
+			    handle_target_event, NULL,
+			    "linux-nat");
 	  /* There may be pending events to handle.  Tell the event loop
 	     to poll them.  */
 	  async_file_mark ();
diff --git a/gdb/run-on-main-thread.c b/gdb/run-on-main-thread.c
index 2cc93e4..1e7bb5f 100644
--- a/gdb/run-on-main-thread.c
+++ b/gdb/run-on-main-thread.c
@@ -94,5 +94,6 @@ void
 _initialize_run_on_main_thread ()
 {
   runnable_event = make_serial_event ();
-  add_file_handler (serial_event_fd (runnable_event), run_events, nullptr);
+  add_file_handler (serial_event_fd (runnable_event), run_events, nullptr,
+		    "run-on-main-thread");
 }
diff --git a/gdb/ser-base.c b/gdb/ser-base.c
index 84ca8c6..cb503f6 100644
--- a/gdb/ser-base.c
+++ b/gdb/ser-base.c
@@ -83,7 +83,7 @@ reschedule (struct serial *scb)
 	case NOTHING_SCHEDULED:
 	  if (scb->bufcnt == 0)
 	    {
-	      add_file_handler (scb->fd, fd_event, scb);
+	      add_file_handler (scb->fd, fd_event, scb, "serial");
 	      next_state = FD_SCHEDULED;
 	    }
 	  else
@@ -95,7 +95,7 @@ reschedule (struct serial *scb)
 	  if (scb->bufcnt == 0)
 	    {
 	      delete_timer (scb->async_state);
-	      add_file_handler (scb->fd, fd_event, scb);
+	      add_file_handler (scb->fd, fd_event, scb, "serial");
 	      next_state = FD_SCHEDULED;
 	    }
 	  else
@@ -597,7 +597,7 @@ ser_base_async (struct serial *scb,
       reschedule (scb);
 
       if (scb->error_fd != -1)
-	add_file_handler (scb->error_fd, handle_error_fd, scb);
+	add_file_handler (scb->error_fd, handle_error_fd, scb, "serial-error");
     }
   else
     {
diff --git a/gdb/top.c b/gdb/top.c
index c50fb4d..6233575 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -270,10 +270,14 @@ void (*deprecated_call_command_hook) (struct cmd_list_element * c,
 
 void (*deprecated_context_hook) (int id);
 
+/* The highest UI number ever assigned.  */
+static int highest_ui_num;
+
 /* See top.h.  */
 
 ui::ui (FILE *instream_, FILE *outstream_, FILE *errstream_)
   : next (nullptr),
+    num (++highest_ui_num),
     call_readline (nullptr),
     input_handler (nullptr),
     command_editing (0),
diff --git a/gdb/top.h b/gdb/top.h
index 92b0964..fd99297 100644
--- a/gdb/top.h
+++ b/gdb/top.h
@@ -65,6 +65,9 @@ struct ui
   /* Pointer to next in singly-linked list.  */
   struct ui *next;
 
+  /* Convenient handle (UI number).  Unique across all UIs.  */
+  int num;
+
   /* The UI's command line buffer.  This is to used to accumulate
      input until we have a whole command line.  */
   struct buffer line_buffer;
diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index 1a2764e..a4f9317 100644
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -921,7 +921,7 @@ tui_initialize_io (void)
   (void) fcntl (tui_readline_pipe[0], F_SETFL, O_NDELAY);
 #endif
 #endif
-  add_file_handler (tui_readline_pipe[0], tui_readline_output, 0);
+  add_file_handler (tui_readline_pipe[0], tui_readline_output, 0, "tui");
 #else
   tui_rl_outstream = stdout;
 #endif
diff --git a/gdbserver/ChangeLog b/gdbserver/ChangeLog
index d667a20..9ed90ba 100644
--- a/gdbserver/ChangeLog
+++ b/gdbserver/ChangeLog
@@ -1,3 +1,10 @@
+2020-10-02  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* linux-low.cc (linux_process_target::async): Pass name to
+	add_file_handler.
+	* remote-utils.cc (handle_accept_event): Likewise.
+	(remote_open): Likewise.
+
 2020-10-01  Kamil Rytarowski  <n54@gmx.com>
 
 	* netbsd-i386-low.cc: Add.
diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index 70d5521..1ae72a2 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -6092,7 +6092,8 @@ linux_process_target::async (bool enable)
 
 	  /* Register the event loop handler.  */
 	  add_file_handler (linux_event_pipe[0],
-			    handle_target_event, NULL);
+			    handle_target_event, NULL,
+			    "linux-low");
 
 	  /* Always trigger a linux_wait.  */
 	  async_file_mark ();
diff --git a/gdbserver/remote-utils.cc b/gdbserver/remote-utils.cc
index c26668d..5a6ceb1 100644
--- a/gdbserver/remote-utils.cc
+++ b/gdbserver/remote-utils.cc
@@ -194,7 +194,7 @@ handle_accept_event (int err, gdb_client_data client_data)
   enable_async_notification (remote_desc);
 
   /* Register the event loop handler.  */
-  add_file_handler (remote_desc, handle_serial_event, NULL);
+  add_file_handler (remote_desc, handle_serial_event, NULL, "remote-net");
 
   /* We have a new GDB connection now.  If we were disconnected
      tracing, there's a window where the target could report a stop
@@ -331,7 +331,7 @@ remote_open (const char *name)
       enable_async_notification (remote_desc);
 
       /* Register the event loop handler.  */
-      add_file_handler (remote_desc, handle_serial_event, NULL);
+      add_file_handler (remote_desc, handle_serial_event, NULL, "remote-stdio");
     }
 #ifndef USE_WIN32API
   else if (port_str == NULL)
@@ -372,7 +372,8 @@ remote_open (const char *name)
       enable_async_notification (remote_desc);
 
       /* Register the event loop handler.  */
-      add_file_handler (remote_desc, handle_serial_event, NULL);
+      add_file_handler (remote_desc, handle_serial_event, NULL,
+			"remote-device");
     }
 #endif /* USE_WIN32API */
   else
@@ -398,7 +399,8 @@ remote_open (const char *name)
       fflush (stderr);
 
       /* Register the event loop handler.  */
-      add_file_handler (listen_desc, handle_accept_event, NULL);
+      add_file_handler (listen_desc, handle_accept_event, NULL,
+			"remote-listen");
     }
 }
 
diff --git a/gdbsupport/ChangeLog b/gdbsupport/ChangeLog
index 216fad1..b54bfb9 100644
--- a/gdbsupport/ChangeLog
+++ b/gdbsupport/ChangeLog
@@ -1,3 +1,11 @@
+2020-10-02  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* event-loop.h (add_file_handler): Add "name" parameter.
+	* event-loop.cc (struct file_handler) <name>: New field.
+	(create_file_handler): Add "name" parameter, assign it to file
+	handler.
+	(add_file_handler): Add "name" parameter.
+
 2020-10-01  Kamil Rytarowski  <n54@gmx.com>
 
 	* agent.cc (gdb_connect_sync_socket): Preinitialize addr with zeros.
diff --git a/gdbsupport/event-loop.cc b/gdbsupport/event-loop.cc
index 59436d4..0d78122 100644
--- a/gdbsupport/event-loop.cc
+++ b/gdbsupport/event-loop.cc
@@ -61,6 +61,9 @@ struct file_handler
   /* Argument to pass to proc.  */
   gdb_client_data client_data;
 
+  /* User-friendly name of this handler.  Heap-allocated, owned by this.*/
+  std::string *name;
+
   /* Was an error detected on this fd?  */
   int error;
 
@@ -160,7 +163,8 @@ static struct
 timer_list;
 
 static void create_file_handler (int fd, int mask, handler_func *proc,
-				 gdb_client_data client_data);
+				 gdb_client_data client_data,
+				 std::string &&name);
 static int gdb_wait_for_event (int);
 static int update_wait_timeout (void);
 static int poll_timers (void);
@@ -231,13 +235,11 @@ gdb_do_one_event (void)
   return 1;
 }
 
-
+/* See event-loop.h  */
 
-/* Wrapper function for create_file_handler, so that the caller
-   doesn't have to know implementation details about the use of poll
-   vs. select.  */
 void
-add_file_handler (int fd, handler_func * proc, gdb_client_data client_data)
+add_file_handler (int fd, handler_func *proc, gdb_client_data client_data,
+		  std::string &&name)
 {
 #ifdef HAVE_POLL
   struct pollfd fds;
@@ -263,21 +265,18 @@ add_file_handler (int fd, handler_func * proc, gdb_client_data client_data)
   if (use_poll)
     {
 #ifdef HAVE_POLL
-      create_file_handler (fd, POLLIN, proc, client_data);
+      create_file_handler (fd, POLLIN, proc, client_data, std::move (name));
 #else
       internal_error (__FILE__, __LINE__,
 		      _("use_poll without HAVE_POLL"));
 #endif
     }
   else
-    create_file_handler (fd, GDB_READABLE | GDB_EXCEPTION, 
-			 proc, client_data);
+    create_file_handler (fd, GDB_READABLE | GDB_EXCEPTION,
+			 proc, client_data, std::move (name));
 }
 
-/* Add a file handler/descriptor to the list of descriptors we are
-   interested in.
-
-   FD is the file descriptor for the file/stream to be listened to.
+/* Helper for add_file_handler.
 
    For the poll case, MASK is a combination (OR) of POLLIN,
    POLLRDNORM, POLLRDBAND, POLLPRI, POLLOUT, POLLWRNORM, POLLWRBAND:
@@ -289,8 +288,8 @@ add_file_handler (int fd, handler_func * proc, gdb_client_data client_data)
    occurs for FD.  CLIENT_DATA is the argument to pass to PROC.  */
 
 static void
-create_file_handler (int fd, int mask, handler_func * proc, 
-		     gdb_client_data client_data)
+create_file_handler (int fd, int mask, handler_func * proc,
+		     gdb_client_data client_data, std::string &&name)
 {
   file_handler *file_ptr;
 
@@ -358,6 +357,7 @@ create_file_handler (int fd, int mask, handler_func * proc,
   file_ptr->proc = proc;
   file_ptr->client_data = client_data;
   file_ptr->mask = mask;
+  file_ptr->name = new std::string (std::move (name));
 }
 
 /* Return the next file handler to handle, and advance to the next
@@ -489,6 +489,8 @@ delete_file_handler (int fd)
 	;
       prev_ptr->next_file = file_ptr->next_file;
     }
+
+  delete file_ptr->name;
   xfree (file_ptr);
 }
 
diff --git a/gdbsupport/event-loop.h b/gdbsupport/event-loop.h
index 2eaaa0c..d7478b0 100644
--- a/gdbsupport/event-loop.h
+++ b/gdbsupport/event-loop.h
@@ -78,8 +78,18 @@ typedef void (timer_handler_func) (gdb_client_data);
 
 extern int gdb_do_one_event (void);
 extern void delete_file_handler (int fd);
-extern void add_file_handler (int fd, handler_func *proc, 
-			      gdb_client_data client_data);
+
+/* Add a file handler/descriptor to the list of descriptors we are
+   interested in.
+
+   FD is the file descriptor for the file/stream to be listened to.
+
+   NAME is a user-friendly name for the handler.  */
+
+extern void add_file_handler (int fd, handler_func *proc,
+			      gdb_client_data client_data,
+			      std::string &&name);
+
 extern int create_timer (int milliseconds, 
 			 timer_handler_func *proc, 
 			 gdb_client_data client_data);