#include "gdb_assert.h"
#include "gdb_select.h"
+/* Data point to pass to the event handler. */
+typedef union event_data
+{
+ void *ptr;
+ int integer;
+} event_data;
+
typedef struct gdb_event gdb_event;
-typedef void (event_handler_func) (int);
+typedef void (event_handler_func) (event_data);
/* Event for the GDB event system. Events are queued by calling
async_queue_event and serviced later on by gdb_do_one_event. An
event can be, for instance, a file descriptor becoming ready to be
- read. Servicing an event simply means that the procedure PROC will
+ read. Servicing an event simply means that the procedure PROC will
be called. We have 2 queues, one for file handlers that we listen
to in the event loop, and one for the file handlers+events that are
- ready. The procedure PROC associated with each event is always the
- same (handle_file_event). Its duty is to invoke the handler
- associated with the file descriptor whose state change generated
- the event, plus doing other cleanups and such. */
+ ready. The procedure PROC associated with each event is dependant
+ of the event source. In the case of monitored file descriptors, it
+ is always the same (handle_file_event). Its duty is to invoke the
+ handler associated with the file descriptor whose state change
+ generated the event, plus doing other cleanups and such. In the
+ case of async signal handlers, it is
+ invoke_async_signal_handler. */
struct gdb_event
{
- event_handler_func *proc; /* Procedure to call to service this event. */
- int fd; /* File descriptor that is ready. */
- struct gdb_event *next_event; /* Next in list of events or NULL. */
+ /* Procedure to call to service this event. */
+ event_handler_func *proc;
+
+ /* Data to pass to the event handler. */
+ event_data data;
+
+ /* Next in list of events or NULL. */
+ struct gdb_event *next_event;
};
/* Information about each file descriptor we register with the event
be carried out by PROC at a later time, within process_event. This
provides a deferred execution of signal handlers.
Async_init_signals takes care of setting up such an
- asyn_signal_handler for each interesting signal. */
+ async_signal_handler for each interesting signal. */
typedef struct async_signal_handler
{
int ready; /* If ready, call this handler from the main event loop,
}
async_signal_handler;
+/* PROC is a function to be invoked when the READY flag is set. This
+ happens when the event has been marked with
+ MARK_ASYNC_EVENT_HANDLER. The actual work to be done in response
+ to an event will be carried out by PROC at a later time, within
+ process_event. This provides a deferred execution of event
+ handlers. */
+typedef struct async_event_handler
+ {
+ /* If ready, call this handler from the main event loop, using
+ invoke_event_handler. */
+ int ready;
+
+ /* Point to next handler. */
+ struct async_event_handler *next_handler;
+
+ /* Function to call to do the work. */
+ async_event_handler_func *proc;
+
+ /* Argument to PROC. */
+ gdb_client_data client_data;
+ }
+async_event_handler;
+
/* Event queue:
- the first event in the queue is the head of the queue.
}
sighandler_list;
-/* Are any of the handlers ready? Check this variable using
- check_async_ready. This is used by process_event, to determine
- whether or not to invoke the invoke_async_signal_handler
- function. */
-static int async_handler_ready = 0;
-
-static void create_file_handler (int fd, int mask, handler_func * proc, gdb_client_data client_data);
-static void invoke_async_signal_handler (void);
-static void handle_file_event (int event_file_desc);
-static int gdb_wait_for_event (void);
-static int check_async_ready (void);
-static void async_queue_event (gdb_event * event_ptr, queue_position position);
-static gdb_event *create_file_event (int fd);
-static int process_event (void);
-static void handle_timer_event (int dummy);
+/* All the async_event_handlers gdb is interested in are kept onto
+ this list. */
+static struct
+ {
+ /* Pointer to first in handler list. */
+ async_event_handler *first_handler;
+
+ /* Pointer to last in handler list. */
+ async_event_handler *last_handler;
+ }
+async_event_handler_list;
+
+static int invoke_async_signal_handlers (void);
+static void create_file_handler (int fd, int mask, handler_func *proc,
+ gdb_client_data client_data);
+static void handle_file_event (event_data data);
+static void check_async_event_handlers (void);
+static void check_async_signal_handlers (void);
+static int gdb_wait_for_event (int);
static void poll_timers (void);
\f
}
}
+/* Create a generic event, to be enqueued in the event queue for
+ processing. PROC is the procedure associated to the event. DATA
+ is passed to PROC upon PROC invocation. */
+
+static gdb_event *
+create_event (event_handler_func proc, event_data data)
+{
+ gdb_event *event;
+
+ event = xmalloc (sizeof (*event));
+ event->proc = proc;
+ event->data = data;
+
+ return event;
+}
+
/* Create a file event, to be enqueued in the event queue for
processing. The procedure associated to this event is always
handle_file_event, which will in turn invoke the one that was
static gdb_event *
create_file_event (int fd)
{
- gdb_event *file_event_ptr;
+ event_data data;
- file_event_ptr = (gdb_event *) xmalloc (sizeof (gdb_event));
- file_event_ptr->proc = handle_file_event;
- file_event_ptr->fd = fd;
- return (file_event_ptr);
+ data.integer = fd;
+ return create_event (handle_file_event, data);
}
/* Process one event.
or an asynchronous event handler can be invoked in response to
the reception of a signal.
If an event was processed (either way), 1 is returned otherwise
- 0 is returned.
+ 0 is returned.
Scan the queue from head to tail, processing therefore the high
priority events first, by invoking the associated event handler
procedure. */
{
gdb_event *event_ptr, *prev_ptr;
event_handler_func *proc;
- int fd;
+ event_data data;
/* First let's see if there are any asynchronous event handlers that
are ready. These would be the result of invoking any of the
signal handlers. */
- if (check_async_ready ())
- {
- invoke_async_signal_handler ();
- return 1;
- }
+ if (invoke_async_signal_handlers ())
+ return 1;
/* Look in the event queue to find an event that is ready
to be processed. */
/* Call the handler for the event. */
proc = event_ptr->proc;
- fd = event_ptr->fd;
+ data = event_ptr->data;
/* Let's get rid of the event from the event queue. We need to
do this now because while processing the event, the proc
xfree (event_ptr);
/* Now call the procedure associated with the event. */
- (*proc) (fd);
+ (*proc) (data);
return 1;
}
int
gdb_do_one_event (void *data)
{
- /* Any events already waiting in the queue? */
+ static int event_source_head = 0;
+ const int number_of_sources = 3;
+ int current = 0;
+
+ /* Any events already waiting in the queue? */
if (process_event ())
+ return 1;
+
+ /* To level the fairness across event sources, we poll them in a
+ round-robin fashion. */
+ for (current = 0; current < number_of_sources; current++)
{
- return 1;
+ switch (event_source_head)
+ {
+ case 0:
+ /* Are any timers that are ready? If so, put an event on the
+ queue. */
+ poll_timers ();
+ break;
+ case 1:
+ /* Are there events already waiting to be collected on the
+ monitored file descriptors? */
+ gdb_wait_for_event (0);
+ break;
+ case 2:
+ /* Are there any asynchronous event handlers ready? */
+ check_async_event_handlers ();
+ break;
+ }
+
+ event_source_head++;
+ if (event_source_head == number_of_sources)
+ event_source_head = 0;
}
- /* Are any timers that are ready? If so, put an event on the queue. */
- poll_timers ();
+ /* Handle any new events collected. */
+ if (process_event ())
+ return 1;
- /* Wait for a new event. If gdb_wait_for_event returns -1,
- we should get out because this means that there are no
- event sources left. This will make the event loop stop,
- and the application exit. */
+ /* Block waiting for a new event. If gdb_wait_for_event returns -1,
+ we should get out because this means that there are no event
+ sources left. This will make the event loop stop, and the
+ application exit. */
- if (gdb_wait_for_event () < 0)
- {
- return -1;
- }
+ if (gdb_wait_for_event (1) < 0)
+ return -1;
- /* Handle any new events occurred while waiting. */
+ /* Handle any new events occurred while waiting. */
if (process_event ())
- {
- return 1;
- }
+ return 1;
- /* If gdb_wait_for_event has returned 1, it means that one
- event has been handled. We break out of the loop. */
+ /* If gdb_wait_for_event has returned 1, it means that one event has
+ been handled. We break out of the loop. */
return 1;
}
through event_ptr->proc. EVENT_FILE_DESC is file descriptor of the
event in the front of the event queue. */
static void
-handle_file_event (int event_file_desc)
+handle_file_event (event_data data)
{
file_handler *file_ptr;
int mask;
int error_mask;
int error_mask_returned;
#endif
+ int event_file_desc = data.integer;
/* Search the file handler list to find one that matches the fd in
the event. */
}
}
-/* Called by gdb_do_one_event to wait for new events on the
- monitored file descriptors. Queue file events as they are
- detected by the poll.
- If there are no events, this function will block in the
- call to poll.
- Return -1 if there are no files descriptors to monitor,
- otherwise return 0. */
+/* Called by gdb_do_one_event to wait for new events on the monitored
+ file descriptors. Queue file events as they are detected by the
+ poll. If BLOCK and if there are no events, this function will
+ block in the call to poll. Return -1 if there are no files
+ descriptors to monitor, otherwise return 0. */
static int
-gdb_wait_for_event (void)
+gdb_wait_for_event (int block)
{
file_handler *file_ptr;
gdb_event *file_event_ptr;
if (use_poll)
{
#ifdef HAVE_POLL
- num_found =
- poll (gdb_notifier.poll_fds,
- (unsigned long) gdb_notifier.num_fds,
- gdb_notifier.timeout_valid ? gdb_notifier.poll_timeout : -1);
+ int timeout;
+
+ if (block)
+ timeout = gdb_notifier.timeout_valid ? gdb_notifier.poll_timeout : -1;
+ else
+ timeout = 0;
+
+ num_found = poll (gdb_notifier.poll_fds,
+ (unsigned long) gdb_notifier.num_fds, timeout);
/* Don't print anything if we get out of poll because of a
- signal. */
+ signal. */
if (num_found == -1 && errno != EINTR)
perror_with_name (("poll"));
#else
}
else
{
+ struct timeval select_timeout;
+
+ struct timeval *timeout_p;
+ if (block)
+ timeout_p = gdb_notifier.timeout_valid
+ ? &gdb_notifier.select_timeout : NULL;
+ else
+ {
+ memset (&select_timeout, 0, sizeof (select_timeout));
+ timeout_p = &select_timeout;
+ }
+
gdb_notifier.ready_masks[0] = gdb_notifier.check_masks[0];
gdb_notifier.ready_masks[1] = gdb_notifier.check_masks[1];
gdb_notifier.ready_masks[2] = gdb_notifier.check_masks[2];
&gdb_notifier.ready_masks[0],
&gdb_notifier.ready_masks[1],
&gdb_notifier.ready_masks[2],
- gdb_notifier.timeout_valid
- ? &gdb_notifier.select_timeout : NULL);
+ timeout_p);
/* Clear the masks after an error from select. */
if (num_found == -1)
FD_ZERO (&gdb_notifier.ready_masks[0]);
FD_ZERO (&gdb_notifier.ready_masks[1]);
FD_ZERO (&gdb_notifier.ready_masks[2]);
- /* Dont print anything is we got a signal, let gdb handle it. */
+
+ /* Dont print anything if we got a signal, let gdb handle
+ it. */
if (errno != EINTR)
perror_with_name (("select"));
}
void
mark_async_signal_handler (async_signal_handler * async_handler_ptr)
{
- ((async_signal_handler *) async_handler_ptr)->ready = 1;
- async_handler_ready = 1;
+ async_handler_ptr->ready = 1;
}
-/* Call all the handlers that are ready. */
-static void
-invoke_async_signal_handler (void)
+/* 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;
- if (async_handler_ready == 0)
- return;
- async_handler_ready = 0;
-
- /* Invoke ready handlers. */
+ /* Invoke ready handlers. */
while (1)
{
}
if (async_handler_ptr == NULL)
break;
+ any_ready = 1;
async_handler_ptr->ready = 0;
(*async_handler_ptr->proc) (async_handler_ptr->client_data);
}
- return;
+ return any_ready;
}
/* Delete an asynchronous handler (ASYNC_HANDLER_PTR).
(*async_handler_ptr) = NULL;
}
-/* Is it necessary to call invoke_async_signal_handler? */
-static int
-check_async_ready (void)
+/* Create an asynchronous event handler, allocating memory for it.
+ Return a pointer to the newly created handler. PROC is the
+ function to call with CLIENT_DATA argument whenever the handler is
+ invoked. */
+async_event_handler *
+create_async_event_handler (async_event_handler_func *proc,
+ gdb_client_data client_data)
+{
+ async_event_handler *h;
+
+ h = xmalloc (sizeof (*h));
+ h->ready = 0;
+ h->next_handler = NULL;
+ h->proc = proc;
+ h->client_data = client_data;
+ if (async_event_handler_list.first_handler == NULL)
+ async_event_handler_list.first_handler = h;
+ else
+ async_event_handler_list.last_handler->next_handler = h;
+ async_event_handler_list.last_handler = h;
+ return h;
+}
+
+/* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information
+ will be used by gdb_do_one_event. The caller will be whoever
+ created the event source, and wants to signal that the event is
+ ready to be handled. */
+void
+mark_async_event_handler (async_event_handler *async_handler_ptr)
+{
+ async_handler_ptr->ready = 1;
+}
+
+struct async_event_handler_data
+{
+ async_event_handler_func* proc;
+ gdb_client_data client_data;
+};
+
+static void
+invoke_async_event_handler (event_data data)
+{
+ struct async_event_handler_data *hdata = data.ptr;
+ async_event_handler_func* proc = hdata->proc;
+ gdb_client_data client_data = hdata->client_data;
+
+ xfree (hdata);
+ (*proc) (client_data);
+}
+
+/* Check if any asynchronous event handlers are ready, and queue
+ events in the ready queue for any that are. */
+static void
+check_async_event_handlers (void)
+{
+ async_event_handler *async_handler_ptr;
+ struct async_event_handler_data *hdata;
+ struct gdb_event *event_ptr;
+ event_data data;
+
+ for (async_handler_ptr = async_event_handler_list.first_handler;
+ async_handler_ptr != NULL;
+ async_handler_ptr = async_handler_ptr->next_handler)
+ {
+ if (async_handler_ptr->ready)
+ {
+ async_handler_ptr->ready = 0;
+
+ hdata = xmalloc (sizeof (*hdata));
+
+ hdata->proc = async_handler_ptr->proc;
+ hdata->client_data = async_handler_ptr->client_data;
+
+ data.ptr = hdata;
+
+ event_ptr = create_event (invoke_async_event_handler, data);
+ async_queue_event (event_ptr, TAIL);
+ }
+ }
+}
+
+/* Delete an asynchronous handler (ASYNC_HANDLER_PTR).
+ Free the space allocated for it. */
+void
+delete_async_event_handler (async_event_handler **async_handler_ptr)
{
- return async_handler_ready;
+ async_event_handler *prev_ptr;
+
+ if (async_event_handler_list.first_handler == *async_handler_ptr)
+ {
+ async_event_handler_list.first_handler = (*async_handler_ptr)->next_handler;
+ if (async_event_handler_list.first_handler == NULL)
+ async_event_handler_list.last_handler = NULL;
+ }
+ else
+ {
+ prev_ptr = async_event_handler_list.first_handler;
+ while (prev_ptr && prev_ptr->next_handler != *async_handler_ptr)
+ prev_ptr = prev_ptr->next_handler;
+ prev_ptr->next_handler = (*async_handler_ptr)->next_handler;
+ if (async_event_handler_list.last_handler == (*async_handler_ptr))
+ async_event_handler_list.last_handler = prev_ptr;
+ }
+ xfree (*async_handler_ptr);
+ *async_handler_ptr = NULL;
}
/* Create a timer that will expire in MILLISECONDS from now. When the
}
/* When a timer event is put on the event queue, it will be handled by
- this function. Just call the assiciated procedure and delete the
- timer event from the event queue. Repeat this for each timer that
- has expired. */
+ this function. Just call the associated procedure and delete the
+ timer event from the event queue. Repeat this for each timer that
+ has expired. */
static void
-handle_timer_event (int dummy)
+handle_timer_event (event_data dummy)
{
struct timeval time_now;
struct gdb_timer *timer_ptr, *saved_timer;
{
event_ptr = (gdb_event *) xmalloc (sizeof (gdb_event));
event_ptr->proc = handle_timer_event;
- event_ptr->fd = timer_list.first_timer->timer_id;
+ event_ptr->data.integer = timer_list.first_timer->timer_id;
async_queue_event (event_ptr, TAIL);
}
sources to listen on. External event sources can be plugged into
the loop.
- There are 3 main components:
+ There are 4 main components:
- a list of file descriptors to be monitored, GDB_NOTIFIER.
+ - a list of asynchronous event sources to be monitored,
+ ASYNC_EVENT_HANDLER_LIST.
- a list of events that have occurred, EVENT_QUEUE.
- a list of signal handling functions, SIGHANDLER_LIST.
- GDB_NOTIFIER keeps track of the event sources. Event sources for
- gdb are currently the UI and the target. Gdb communicates with the
- command line user interface via the readline library and usually
- communicates with remote targets via a serial port. Serial ports
- are represented in GDB as file descriptors and select/poll calls.
- For native targets instead, the communication consists of calls to
- ptrace and waits (via signals) or calls to poll/select (via file
- descriptors). In the current gdb, the code handling events related
- to the target resides in the wait_for_inferior function and in
- various target specific files (*-tdep.c).
+ GDB_NOTIFIER keeps track of the file descriptor based event
+ sources. ASYNC_EVENT_HANDLER_LIST keeps track of asynchronous
+ event sources that are signalled by some component of gdb, usually
+ a target_ops instance. Event sources for gdb are currently the UI
+ and the target. Gdb communicates with the command line user
+ interface via the readline library and usually communicates with
+ remote targets via a serial port. Serial ports are represented in
+ GDB as file descriptors and select/poll calls. For native targets
+ instead, the communication varies across operating system debug
+ APIs, but usually consists of calls to ptrace and waits (via
+ signals) or calls to poll/select (via file descriptors). In the
+ current gdb, the code handling events related to the target resides
+ in wait_for_inferior for synchronous targets; or, for asynchronous
+ capable targets, by having the target register either a target
+ controlled file descriptor and/or an asynchronous event source in
+ the event loop, with the fetch_inferior_event function as the event
+ callback. In both the synchronous and asynchronous cases, usually
+ the target event is collected through the target_wait interface.
+ The target is free to install other event sources in the event loop
+ if it so requires.
EVENT_QUEUE keeps track of the events that have happened during the
last iteration of the event loop, and need to be processed. An
typedef void *gdb_client_data;
struct async_signal_handler;
+struct async_event_handler;
typedef void (handler_func) (int, gdb_client_data);
typedef void (sig_handler_func) (gdb_client_data);
+typedef void (async_event_handler_func) (gdb_client_data);
typedef void (timer_handler_func) (gdb_client_data);
/* Where to add an event onto the event queue, by queue_event. */
void gdb_call_async_signal_handler (struct async_signal_handler *handler,
int immediate_p);
+
+/* Create and register an asynchronous event source in the event loop,
+ and set PROC as its callback. CLIENT_DATA is passed as argument to
+ PROC upon its invocation. Returns a pointer to an opaque structure
+ used to mark as ready and to later delete this event source from
+ the event loop. */
+extern struct async_event_handler *
+ create_async_event_handler (async_event_handler_func *proc,
+ gdb_client_data client_data);
+
+/* Remove the event source pointed by HANDLER_PTR created by
+ CREATE_ASYNC_EVENT_HANDLER from the event loop, and release it. */
+extern void
+ delete_async_event_handler (struct async_event_handler **handler_ptr);
+
+/* Call the handler from HANDLER the next time through the event
+ loop. */
+extern void mark_async_event_handler (struct async_event_handler *handler);
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