/* Event loop machinery for GDB, the GNU debugger.
- Copyright (C) 1999-2015 Free Software Foundation, Inc.
+ Copyright (C) 1999-2016 Free Software Foundation, Inc.
Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
This file is part of GDB.
#include "event-loop.h"
#include "event-top.h"
#include "queue.h"
+#include "ser-event.h"
#ifdef HAVE_POLL
#if defined (HAVE_POLL_H)
#endif
#include <sys/types.h>
-#include <sys/time.h>
+#include "gdb_sys_time.h"
#include "gdb_select.h"
#include "observer.h"
/* Ptr to head of file handler list. */
file_handler *first_file_handler;
+ /* Next file handler to handle, for the select variant. To level
+ the fairness across event sources, we serve file handlers in a
+ round-robin-like fashion. The number and order of the polled
+ file handlers may change between invocations, but this is good
+ enough. */
+ file_handler *next_file_handler;
+
#ifdef HAVE_POLL
/* Ptr to array of pollfd structures. */
struct pollfd *poll_fds;
+ /* Next file descriptor to handle, for the poll variant. To level
+ the fairness across event sources, we poll the file descriptors
+ in a round-robin-like fashion. The number and order of the
+ polled file descriptors may change between invocations, but
+ this is good enough. */
+ int next_poll_fds_index;
+
/* Timeout in milliseconds for calls to poll(). */
int poll_timeout;
#endif
static int poll_timers (void);
\f
+/* This event is signalled whenever an asynchronous handler needs to
+ defer an action to the event loop. */
+static struct serial_event *async_signal_handlers_serial_event;
+
+/* Callback registered with ASYNC_SIGNAL_HANDLERS_SERIAL_EVENT. */
+
+static void
+async_signals_handler (int error, gdb_client_data client_data)
+{
+ /* Do nothing. Handlers are run by invoke_async_signal_handlers
+ from instead. */
+}
+
+void
+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);
+}
+
/* Process one high level event. If nothing is ready at this time,
wait for something to happen (via gdb_wait_for_event), then process
it. Returns >0 if something was done otherwise returns <0 (this
change the data associated with it. */
if (file_ptr == NULL)
{
- file_ptr = (file_handler *) xmalloc (sizeof (file_handler));
+ file_ptr = XNEW (file_handler);
file_ptr->fd = fd;
file_ptr->ready_mask = 0;
file_ptr->next_file = gdb_notifier.first_file_handler;
* sizeof (struct pollfd)));
else
gdb_notifier.poll_fds =
- (struct pollfd *) xmalloc (sizeof (struct pollfd));
+ XNEW (struct pollfd);
(gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->fd = fd;
(gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->events = mask;
(gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->revents = 0;
file_ptr->mask = mask;
}
+/* Return the next file handler to handle, and advance to the next
+ file handler, wrapping around if the end of the list is
+ reached. */
+
+static file_handler *
+get_next_file_handler_to_handle_and_advance (void)
+{
+ file_handler *curr_next;
+
+ /* The first time around, this is still NULL. */
+ if (gdb_notifier.next_file_handler == NULL)
+ gdb_notifier.next_file_handler = gdb_notifier.first_file_handler;
+
+ curr_next = gdb_notifier.next_file_handler;
+ gdb_assert (curr_next != NULL);
+
+ /* Advance. */
+ gdb_notifier.next_file_handler = curr_next->next_file;
+ /* Wrap around, if necessary. */
+ if (gdb_notifier.next_file_handler == NULL)
+ gdb_notifier.next_file_handler = gdb_notifier.first_file_handler;
+
+ return curr_next;
+}
+
/* Remove the file descriptor FD from the list of monitored fd's:
i.e. we don't care anymore about events on the FD. */
void
file_ptr->mask = 0;
+ /* If this file handler was going to be the next one to be handled,
+ advance to the next's next, if any. */
+ if (gdb_notifier.next_file_handler == file_ptr)
+ {
+ if (file_ptr->next_file == NULL
+ && file_ptr == gdb_notifier.first_file_handler)
+ gdb_notifier.next_file_handler = NULL;
+ else
+ get_next_file_handler_to_handle_and_advance ();
+ }
+
/* Get rid of the file handler in the file handler list. */
if (file_ptr == gdb_notifier.first_file_handler)
gdb_notifier.first_file_handler = file_ptr->next_file;
{
file_handler *file_ptr;
int num_found = 0;
- int i;
/* Make sure all output is done before getting another event. */
gdb_flush (gdb_stdout);
}
}
+ /* Avoid looking at poll_fds[i]->revents if no event fired. */
+ if (num_found <= 0)
+ return 0;
+
/* Run event handlers. We always run just one handler and go back
to polling, in case a handler changes the notifier list. Since
events for sources we haven't consumed yet wake poll/select
immediately, no event is lost. */
+ /* To level the fairness across event descriptors, we handle them in
+ a round-robin-like fashion. The number and order of descriptors
+ may change between invocations, but this is good enough. */
if (use_poll)
{
#ifdef HAVE_POLL
- for (i = 0; (i < gdb_notifier.num_fds) && (num_found > 0); i++)
- {
- if ((gdb_notifier.poll_fds + i)->revents)
- num_found--;
- else
- continue;
+ int i;
+ int mask;
- for (file_ptr = gdb_notifier.first_file_handler;
- file_ptr != NULL;
- file_ptr = file_ptr->next_file)
- {
- if (file_ptr->fd == (gdb_notifier.poll_fds + i)->fd)
- break;
- }
+ while (1)
+ {
+ if (gdb_notifier.next_poll_fds_index >= gdb_notifier.num_fds)
+ gdb_notifier.next_poll_fds_index = 0;
+ i = gdb_notifier.next_poll_fds_index++;
- if (file_ptr)
- {
- int mask = (gdb_notifier.poll_fds + i)->revents;
+ gdb_assert (i < gdb_notifier.num_fds);
+ if ((gdb_notifier.poll_fds + i)->revents)
+ break;
+ }
- handle_file_event (file_ptr, mask);
- return 1;
- }
+ for (file_ptr = gdb_notifier.first_file_handler;
+ file_ptr != NULL;
+ file_ptr = file_ptr->next_file)
+ {
+ if (file_ptr->fd == (gdb_notifier.poll_fds + i)->fd)
+ break;
}
+ gdb_assert (file_ptr != NULL);
+
+ mask = (gdb_notifier.poll_fds + i)->revents;
+ handle_file_event (file_ptr, mask);
+ return 1;
#else
internal_error (__FILE__, __LINE__,
_("use_poll without HAVE_POLL"));
}
else
{
- for (file_ptr = gdb_notifier.first_file_handler;
- (file_ptr != NULL) && (num_found > 0);
- file_ptr = file_ptr->next_file)
+ /* See comment about even source fairness above. */
+ int mask = 0;
+
+ do
{
- int mask = 0;
+ file_ptr = get_next_file_handler_to_handle_and_advance ();
if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[0]))
mask |= GDB_READABLE;
mask |= GDB_WRITABLE;
if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[2]))
mask |= GDB_EXCEPTION;
-
- if (!mask)
- continue;
- else
- num_found--;
-
- handle_file_event (file_ptr, mask);
- return 1;
}
+ while (mask == 0);
+
+ handle_file_event (file_ptr, mask);
+ return 1;
}
return 0;
}
{
async_signal_handler *async_handler_ptr;
- async_handler_ptr =
- (async_signal_handler *) xmalloc (sizeof (async_signal_handler));
+ async_handler_ptr = XNEW (async_signal_handler);
async_handler_ptr->ready = 0;
async_handler_ptr->next_handler = NULL;
async_handler_ptr->proc = proc;
mark_async_signal_handler (async_signal_handler * async_handler_ptr)
{
async_handler_ptr->ready = 1;
+ serial_event_set (async_signal_handlers_serial_event);
+}
+
+/* See event-loop.h. */
+
+void
+clear_async_signal_handler (async_signal_handler *async_handler_ptr)
+{
+ async_handler_ptr->ready = 0;
+}
+
+/* See event-loop.h. */
+
+int
+async_signal_handler_is_marked (async_signal_handler *async_handler_ptr)
+{
+ return async_handler_ptr->ready;
}
/* Call all the handlers that are ready. Returns true if any was
indeed ready. */
+
static int
invoke_async_signal_handlers (void)
{
async_signal_handler *async_handler_ptr;
int any_ready = 0;
- /* Invoke ready handlers. */
+ /* We're going to handle all pending signals, so no need to wake up
+ the event loop again the next time around. Note this must be
+ cleared _before_ calling the callbacks, to avoid races. */
+ serial_event_clear (async_signal_handlers_serial_event);
+
+ /* Invoke all ready handlers. */
while (1)
{
{
async_event_handler *h;
- h = xmalloc (sizeof (*h));
+ h = XNEW (struct async_event_handler);
h->ready = 0;
h->next_handler = NULL;
h->proc = proc;
gettimeofday (&time_now, NULL);
- timer_ptr = (struct gdb_timer *) xmalloc (sizeof (*timer_ptr));
+ timer_ptr = XNEW (struct gdb_timer);
timer_ptr->when.tv_sec = time_now.tv_sec + delta.tv_sec;
timer_ptr->when.tv_usec = time_now.tv_usec + delta.tv_usec;
/* Carry? */
projects / deliverable / binutils-gdb.git / blobdiff