convenience variable (@pxref{Convenience Vars}) as a @code{gdb.Value}.
@end defun
+@findex gdb.post_event
+@defun post_event event
+Put @var{event}, a callable object taking no arguments, into
+@value{GDBN}'s internal event queue. This callable will be invoked at
+some later point, during @value{GDBN}'s event processing. Events
+posted using @code{post_event} will be run in the order in which they
+were posted; however, there is no way to know when they will be
+processed relative to other events inside @value{GDBN}.
+
+@value{GDBN} is not thread-safe. If your Python program uses multiple
+threads, you must be careful to only call @value{GDBN}-specific
+functions in the main @value{GDBN} thread. @code{post_event} ensures
+this. For example:
+
+@smallexample
+(@value{GDBP}) python
+>import threading
+>
+>class Writer():
+> def __init__(self, message):
+> self.message = message;
+> def __call__(self):
+> gdb.write(self.message)
+>
+>class MyThread1 (threading.Thread):
+> def run (self):
+> gdb.post_event(Writer("Hello "))
+>
+>class MyThread2 (threading.Thread):
+> def run (self):
+> gdb.post_event(Writer("World\n"))
+>
+>MyThread1().start()
+>MyThread2().start()
+>end
+(@value{GDBP}) Hello World
+@end smallexample
+@end defun
+
@findex gdb.write
@defun write string
Print a string to @value{GDBN}'s paginated standard output stream.
#include "value.h"
#include "language.h"
#include "exceptions.h"
+#include "event-loop.h"
#include <ctype.h>
\f
+/* Posting and handling events. */
+
+/* A single event. */
+struct gdbpy_event
+{
+ /* The Python event. This is just a callable object. */
+ PyObject *event;
+ /* The next event. */
+ struct gdbpy_event *next;
+};
+
+/* All pending events. */
+static struct gdbpy_event *gdbpy_event_list;
+/* The final link of the event list. */
+static struct gdbpy_event **gdbpy_event_list_end;
+
+/* We use a file handler, and not an async handler, so that we can
+ wake up the main thread even when it is blocked in poll(). */
+static int gdbpy_event_fds[2];
+
+/* The file handler callback. This reads from the internal pipe, and
+ then processes the Python event queue. This will always be run in
+ the main gdb thread. */
+static void
+gdbpy_run_events (int err, gdb_client_data ignore)
+{
+ struct cleanup *cleanup;
+ char buffer[100];
+ int r;
+
+ cleanup = ensure_python_env (get_current_arch (), current_language);
+
+ /* Just read whatever is available on the fd. It is relatively
+ harmless if there are any bytes left over. */
+ r = read (gdbpy_event_fds[0], buffer, sizeof (buffer));
+
+ while (gdbpy_event_list)
+ {
+ /* Dispatching the event might push a new element onto the event
+ loop, so we update here "atomically enough". */
+ struct gdbpy_event *item = gdbpy_event_list;
+ gdbpy_event_list = gdbpy_event_list->next;
+ if (gdbpy_event_list == NULL)
+ gdbpy_event_list_end = &gdbpy_event_list;
+
+ /* Ignore errors. */
+ if (PyObject_CallObject (item->event, NULL) == NULL)
+ PyErr_Clear ();
+
+ Py_DECREF (item->event);
+ xfree (item);
+ }
+
+ do_cleanups (cleanup);
+}
+
+/* Submit an event to the gdb thread. */
+static PyObject *
+gdbpy_post_event (PyObject *self, PyObject *args)
+{
+ struct gdbpy_event *event;
+ PyObject *func;
+ int wakeup;
+
+ if (!PyArg_ParseTuple (args, "O", &func))
+ return NULL;
+
+ if (!PyCallable_Check (func))
+ {
+ PyErr_SetString (PyExc_RuntimeError,
+ _("Posted event is not callable"));
+ return NULL;
+ }
+
+ Py_INCREF (func);
+
+ /* From here until the end of the function, we have the GIL, so we
+ can operate on our global data structures without worrying. */
+ wakeup = gdbpy_event_list == NULL;
+
+ event = XNEW (struct gdbpy_event);
+ event->event = func;
+ event->next = NULL;
+ *gdbpy_event_list_end = event;
+ gdbpy_event_list_end = &event->next;
+
+ /* Wake up gdb when needed. */
+ if (wakeup)
+ {
+ char c = 'q'; /* Anything. */
+ if (write (gdbpy_event_fds[1], &c, 1) != 1)
+ return PyErr_SetFromErrno (PyExc_IOError);
+ }
+
+ Py_RETURN_NONE;
+}
+
+/* Initialize the Python event handler. */
+static void
+gdbpy_initialize_events (void)
+{
+ if (!pipe (gdbpy_event_fds))
+ {
+ gdbpy_event_list_end = &gdbpy_event_list;
+ add_file_handler (gdbpy_event_fds[0], gdbpy_run_events, NULL);
+ }
+}
+
/* Printing. */
/* A python function to write a single string using gdb's filtered
gdbpy_initialize_lazy_string ();
gdbpy_initialize_thread ();
gdbpy_initialize_inferior ();
+ gdbpy_initialize_events ();
PyRun_SimpleString ("import gdb");
PyRun_SimpleString ("gdb.pretty_printers = []");
Parse String as an expression, evaluate it, and return the result as a Value."
},
+ { "post_event", gdbpy_post_event, METH_VARARGS,
+ "Post an event into gdb's event loop." },
+
{ "target_charset", gdbpy_target_charset, METH_NOARGS,
"target_charset () -> string.\n\
Return the name of the current target charset." },
projects / binutils-gdb.git / commitdiff