* Event handler. Serializes different kinds of events to allow for
* a uniform interface, central state storage, and centralized
* interdependency logic.
+ *
+ * This is a compatibility wrapper over Glib's GMainLoop. New code should
+ * use Glib's interface directly.
+ *
+ * Each event_handle is associated with a unique GSource, identified by it
+ * event_source_id.
*/
#include "amanda.h"
-#include "event.h"
-#include "queue.h"
#include "conffile.h"
+#include "event.h"
+#include "glib-util.h"
+
+/* TODO: use mem chunks to allocate event_handles */
+/* TODO: lock stuff for threading */
+/* Write a debugging message if the config variable debug_event
+ * is greater than or equal to i */
#define event_debug(i, ...) do { \
if ((i) <= debug_event) { \
dbprintf(__VA_ARGS__); \
struct event_handle {
event_fn_t fn; /* function to call when this fires */
void *arg; /* argument to pass to previous function */
+
event_type_t type; /* type of event */
event_id_t data; /* type data */
- time_t lastfired; /* timestamp of last fired (EV_TIME only) */
- LIST_ENTRY(event_handle) le; /* queue handle */
-};
-/*
- * eventq is a queue of currently active events.
- * cache is a queue of unused handles. We keep a few around to avoid
- * malloc overhead when doing a lot of register/releases.
- */
-static struct {
- LIST_HEAD(, event_handle) listhead;
- int qlength;
-} eventq = {
- LIST_HEAD_INITIALIZER(eventq.listhead), 0
-}, cache = {
- LIST_HEAD_INITIALIZER(eventq.listhead), 0
+ GSource *source; /* Glib event source, if one exists */
+ guint source_id; /* ID of the glib event source */
+
+ gboolean has_fired; /* for use by event_wait() */
+ gboolean is_dead; /* should this event be deleted? */
};
-#define eventq_first(q) LIST_FIRST(&q.listhead)
-#define eventq_next(eh) LIST_NEXT(eh, le)
-#define eventq_add(q, eh) LIST_INSERT_HEAD(&q.listhead, eh, le);
-#define eventq_remove(eh) LIST_REMOVE(eh, le);
-/*
- * How many items we can have in the handle cache before we start
- * freeing.
- */
-#define CACHEDEPTH 10
+/* A list of all extant event_handle objects, used for searching for particular
+ * events and for deleting dead events */
+GSList *all_events;
/*
- * A table of currently set signal handlers.
+ * Utility functions
*/
-static struct sigtabent {
- event_handle_t *handle; /* handle for this signal */
- int score; /* number of signals recvd since last checked */
- void (*oldhandler)(int);/* old handler (for unsetting) */
-} sigtable[NSIG];
-
-static const char *event_type2str(event_type_t);
-#define fire(eh) (*(eh)->fn)((eh)->arg)
-static void signal_handler(int);
-static event_handle_t *gethandle(void);
-static void puthandle(event_handle_t *);
-static int event_loop_wait (event_handle_t *, const int);
+
+static const char *event_type2str(event_type_t type);
+
+/* "Fire" an event handle, by calling its callback function */
+#define fire(eh) do { \
+ event_debug(1, "firing %p: %s/%jd\n", eh, event_type2str((eh)->type), (eh)->data); \
+ (*(eh)->fn)((eh)->arg); \
+ (eh)->has_fired = TRUE; \
+} while(0)
+
+/* Adapt a Glib callback to an event_handle_t callback; assumes that the
+ * user_ptr for the Glib callback is a pointer to the event_handle_t. */
+static gboolean
+event_handle_callback(
+ gpointer user_ptr)
+{
+ event_handle_t *hdl = (event_handle_t *)user_ptr;
+
+ /* if the handle is dead, then don't fire the callback; this means that
+ * we're in the process of freeing the event */
+ if (!hdl->is_dead) {
+ fire(hdl);
+ }
+
+ /* don't ever let GMainLoop destroy GSources */
+ return TRUE;
+}
/*
- * Add a new event. See the comment in event.h for what the arguments
- * mean.
+ * Public functions
*/
+
event_handle_t *
event_register(
event_id_t data,
void *arg)
{
event_handle_t *handle;
+ GIOCondition cond;
+ /* sanity-checking */
if ((type == EV_READFD) || (type == EV_WRITEFD)) {
/* make sure we aren't given a high fd that will overflow a fd_set */
if (data >= (int)FD_SETSIZE) {
- error(_("event_register: Invalid file descriptor %lu"), data);
+ error(_("event_register: Invalid file descriptor %jd"), data);
/*NOTREACHED*/
}
-#if !defined(__lint) /* Global checking knows that these are never called */
- } else if (type == EV_SIG) {
- /* make sure signals are within range */
- if (data >= NSIG) {
- error(_("event_register: Invalid signal %lu"), data);
- /*NOTREACHED*/
- }
- if (sigtable[data].handle != NULL) {
- error(_("event_register: signal %lu already registered"), data);
- /*NOTREACHED*/
+ } else if (type == EV_TIME) {
+ if (data <= 0) {
+ error(_("event_register: interval for EV_TIME must be greater than 0; got %jd"), data);
}
- } else if (type >= EV_DEAD) {
- error(_("event_register: Invalid event type %d"), type);
- /*NOTREACHED*/
-#endif
}
- handle = gethandle();
+ handle = g_new0(event_handle_t, 1);
handle->fn = fn;
handle->arg = arg;
handle->type = type;
handle->data = data;
- handle->lastfired = -1;
- eventq_add(eventq, handle);
- eventq.qlength++;
+ handle->is_dead = FALSE;
- event_debug(1, _("event: register: %p->data=%lu, type=%s\n"),
+ event_debug(1, _("event: register: %p->data=%jd, type=%s\n"),
handle, handle->data, event_type2str(handle->type));
- return (handle);
+
+ /* add to the list of events */
+ all_events = g_slist_prepend(all_events, (gpointer)handle);
+
+ /* and set up the GSource for this event */
+ switch (type) {
+ case EV_READFD:
+ case EV_WRITEFD:
+ /* create a new source */
+ if (type == EV_READFD) {
+ cond = G_IO_IN | G_IO_HUP | G_IO_ERR;
+ } else {
+ cond = G_IO_OUT | G_IO_ERR;
+ }
+
+ handle->source = new_fdsource(data, cond);
+
+ /* attach it to the default GMainLoop */
+ g_source_attach(handle->source, NULL);
+ handle->source_id = g_source_get_id(handle->source);
+
+ /* And set its callbacks */
+ g_source_set_callback(handle->source, event_handle_callback,
+ (gpointer)handle, NULL);
+
+ /* drop our reference to it, so when it's detached, it will be
+ * destroyed. */
+ g_source_unref(handle->source);
+ break;
+
+ case EV_TIME:
+ /* Glib provides a nice shortcut for timeouts. The *1000 converts
+ * seconds to milliseconds. */
+ handle->source_id = g_timeout_add(data * 1000, event_handle_callback,
+ (gpointer)handle);
+
+ /* But it doesn't give us the source directly.. */
+ handle->source = g_main_context_find_source_by_id(NULL, handle->source_id);
+ break;
+
+ case EV_WAIT:
+ /* nothing to do -- these are handled independently of GMainLoop */
+ break;
+
+ default:
+ error(_("Unknown event type %s"), event_type2str(type));
+ }
+
+ return handle;
}
/*
event_release(
event_handle_t *handle)
{
-
assert(handle != NULL);
- event_debug(1, _("event: release (mark): %p data=%lu, type=%s\n"),
+ event_debug(1, _("event: release (mark): %p data=%jd, type=%s\n"),
handle, handle->data,
event_type2str(handle->type));
- assert(handle->type != EV_DEAD);
-
- /*
- * For signal events, we need to specially remove then from the
- * signal event table.
- */
- if (handle->type == EV_SIG) {
- struct sigtabent *se = &sigtable[handle->data];
-
- assert(se->handle == handle);
- signal((int)handle->data, se->oldhandler);
- se->handle = NULL;
- se->score = 0;
- }
-
- /*
- * Decrement the qlength now since this is no longer a real
- * event.
- */
- eventq.qlength--;
+ assert(!handle->is_dead);
- /*
- * Mark it as dead and leave it for the loop to remove.
- */
- handle->type = EV_DEAD;
+ /* Mark it as dead and leave it for the event_loop to remove */
+ handle->is_dead = TRUE;
}
/*
event_wakeup(
event_id_t id)
{
- event_handle_t *eh;
+ GSList *iter;
+ GSList *tofire = NULL;
int nwaken = 0;
- event_debug(1, _("event: wakeup: enter (%lu)\n"), id);
+ event_debug(1, _("event: wakeup: enter (%jd)\n"), id);
- for (eh = eventq_first(eventq); eh != NULL; eh = eventq_next(eh)) {
+ /* search for any and all matching events, and record them. This way
+ * we have determined the whole list of events we'll be firing *before*
+ * we fire any of them. */
+ for (iter = all_events; iter != NULL; iter = g_slist_next(iter)) {
+ event_handle_t *eh = (event_handle_t *)iter->data;
+ if (eh->type == EV_WAIT && eh->data == id && !eh->is_dead) {
+ tofire = g_slist_append(tofire, (gpointer)eh);
+ }
+ }
- if (eh->type == EV_WAIT && eh->data == id) {
- event_debug(1, _("event: wakeup: %p id=%lu\n"), eh, id);
+ /* fire them */
+ for (iter = tofire; iter != NULL; iter = g_slist_next(iter)) {
+ event_handle_t *eh = (event_handle_t *)iter->data;
+ if (eh->type == EV_WAIT && eh->data == id && !eh->is_dead) {
+ event_debug(1, _("A: event: wakeup triggering: %p id=%jd\n"), eh, id);
fire(eh);
nwaken++;
}
}
+
+ /* and free the temporary list */
+ g_slist_free(tofire);
+
return (nwaken);
}
/*
- * The event loop. We need to be specially careful here with adds and
- * deletes. Since adds and deletes will often happen while this is running,
- * we need to make sure we don't end up referencing a dead event handle.
+ * The event loop.
*/
+
+static void event_loop_wait (event_handle_t *, const int);
+
void
event_loop(
- const int dontblock)
+ int nonblock)
{
- event_loop_wait((event_handle_t *)NULL, dontblock);
+ event_loop_wait(NULL, nonblock);
}
-
-
-int
+void
event_wait(
event_handle_t *eh)
{
- return event_loop_wait(eh, 0);
+ event_loop_wait(eh, 0);
}
-/*
- * The event loop. We need to be specially careful here with adds and
- * deletes. Since adds and deletes will often happen while this is running,
- * we need to make sure we don't end up referencing a dead event handle.
+/* Flush out any dead events in all_events. Be careful that this
+ * isn't called while someone is iterating over all_events.
+ *
+ * @param wait_eh: the event handle we're waiting on, which shouldn't
+ * be flushed.
*/
-static int
-event_loop_wait(
- event_handle_t *wait_eh,
- const int dontblock)
+static void
+flush_dead_events(event_handle_t *wait_eh)
{
-#ifdef ASSERTIONS
- static int entry = 0;
-#endif
- SELECT_ARG_TYPE readfds, writefds, errfds, werrfds;
- struct timeval timeout, *tvptr;
- int ntries, maxfd, rc;
- long interval;
- time_t curtime;
- event_handle_t *eh, *nexteh;
- struct sigtabent *se;
- int event_wait_fired = 0;
- int see_event;
-
- event_debug(1, _("event: loop: enter: dontblock=%d, qlength=%d, eh=%p\n"),
- dontblock, eventq.qlength, wait_eh);
-
- /*
- * If we have no events, we have nothing to do
- */
- if (eventq.qlength == 0)
- return 0;
-
- /*
- * We must not be entered twice
- */
- assert(++entry == 1);
-
- ntries = 0;
-
- /*
- * Save a copy of the current time once, to reduce syscall load
- * slightly.
- */
- curtime = time(NULL);
-
- do {
- if (debug_event >= 1) {
- event_debug(1, _("event: loop: dontblock=%d, qlength=%d eh=%p\n"),
- dontblock, eventq.qlength, wait_eh);
- for (eh = eventq_first(eventq); eh != NULL; eh = eventq_next(eh)) {
- event_debug(1, _("%p): %s data=%lu fn=%p arg=%p\n"),
- eh, event_type2str(eh->type), eh->data, eh->fn,
- eh->arg);
- }
- }
- /*
- * Set ourselves up with no timeout initially.
- */
- timeout.tv_sec = 0;
- timeout.tv_usec = 0;
-
- /*
- * If we can block, initially set the tvptr to NULL. If
- * we come across timeout events in the loop below, they
- * will set it to an appropriate buffer. If we don't
- * see any timeout events, then tvptr will remain NULL
- * and the select will properly block indefinately.
- *
- * If we can't block, set it to point to the timeout buf above.
- */
- if (dontblock)
- tvptr = &timeout;
- else
- tvptr = NULL;
-
- /*
- * Rebuild the select bitmasks each time.
- */
- FD_ZERO(&readfds);
- FD_ZERO(&writefds);
- FD_ZERO(&errfds);
- maxfd = 0;
-
- see_event = (wait_eh == (event_handle_t *)NULL);
- /*
- * Run through each event handle and setup the events.
- * We save our next pointer early in case we GC some dead
- * events.
- */
- for (eh = eventq_first(eventq); eh != NULL; eh = nexteh) {
- nexteh = eventq_next(eh);
-
- switch (eh->type) {
-
- /*
- * Read fds just get set into the select bitmask
- */
- case EV_READFD:
- FD_SET((int)eh->data, &readfds);
- FD_SET((int)eh->data, &errfds);
- maxfd = max(maxfd, (int)eh->data);
- see_event |= (eh == wait_eh);
- break;
-
- /*
- * Likewise with write fds
- */
- case EV_WRITEFD:
- FD_SET((int)eh->data, &writefds);
- FD_SET((int)eh->data, &errfds);
- maxfd = max(maxfd, (int)eh->data);
- see_event |= (eh == wait_eh);
- break;
-
- /*
- * Only set signals that aren't already set to avoid unnecessary
- * syscall overhead.
- */
- case EV_SIG:
- se = &sigtable[eh->data];
- see_event |= (eh == wait_eh);
-
- if (se->handle == eh)
- break;
-
- /* no previous handle */
- assert(se->handle == NULL);
- se->handle = eh;
- se->score = 0;
- /*@ignore@*/
- se->oldhandler = signal((int)eh->data, signal_handler);
- /*@end@*/
- break;
-
- /*
- * Compute the timeout for this select
- */
- case EV_TIME:
- /* if we're not supposed to block, then leave it at 0 */
- if (dontblock)
- break;
-
- if (eh->lastfired == -1)
- eh->lastfired = curtime;
-
- interval = (long)(eh->data - (curtime - eh->lastfired));
- if (interval < 0)
- interval = 0;
-
- if (tvptr != NULL)
- timeout.tv_sec = min(timeout.tv_sec, interval);
- else {
- /* this is the first timeout */
- tvptr = &timeout;
- timeout.tv_sec = interval;
- }
- see_event |= (eh == wait_eh);
- break;
-
- /*
- * Wait events are processed immediately by event_wakeup()
- */
- case EV_WAIT:
- see_event |= (eh == wait_eh);
- break;
-
- /*
- * Prune dead events
- */
- case EV_DEAD:
- eventq_remove(eh);
- puthandle(eh);
- break;
-
- default:
- assert(0);
- break;
- }
- }
-
- if(!see_event) {
- assert(--entry == 0);
- return 0;
- }
+ GSList *iter, *next;
- /*
- * Let 'er rip
- */
- event_debug(1,
- _("event: select: dontblock=%d, maxfd=%d, timeout=%ld\n"),
- dontblock, maxfd,
- tvptr != NULL ? timeout.tv_sec : -1);
- rc = select(maxfd + 1, &readfds, &writefds, &errfds, tvptr);
- event_debug(1, _("event: select returns %d\n"), rc);
-
- /*
- * Select errors can mean many things. Interrupted events should
- * not be fatal, since they could be delivered signals which still
- * need to have their events fired.
- */
- if (rc < 0) {
- if (errno != EINTR) {
- if (++ntries > 5) {
- error(_("select failed: %s"), strerror(errno));
- /*NOTREACHED*/
- }
- continue;
- }
- /* proceed if errno == EINTR, we may have caught a signal */
+ for (iter = all_events; iter != NULL; iter = next) {
+ event_handle_t *hdl = (event_handle_t *)iter->data;
+ next = g_slist_next(iter);
- /* contents cannot be trusted */
- FD_ZERO(&readfds);
- FD_ZERO(&writefds);
- FD_ZERO(&errfds);
- }
+ /* (handle the case when wait_eh is dead by simply not deleting
+ * it; the next run of event_loop will take care of it) */
+ if (hdl->is_dead && hdl != wait_eh) {
+ all_events = g_slist_delete_link(all_events, iter);
+ if (hdl->source) g_source_destroy(hdl->source);
- /*
- * Grab the current time again for use in timed events.
- */
- curtime = time(NULL);
-
- /*
- * We need to copy the errfds into werrfds, so file descriptors
- * that are being polled for both reading and writing have
- * both of their poll events 'see' the error.
- */
- memcpy(&werrfds, &errfds, SIZEOF(werrfds));
-
- /*
- * Now run through the events and fire the ones that are ready.
- * Don't handle file descriptor events if the select failed.
- */
- for (eh = eventq_first(eventq); eh != NULL; eh = eventq_next(eh)) {
-
- switch (eh->type) {
-
- /*
- * Read fds: just fire the event if set in the bitmask
- */
- case EV_READFD:
- if (FD_ISSET((int)eh->data, &readfds) ||
- FD_ISSET((int)eh->data, &errfds)) {
- FD_CLR((int)eh->data, &readfds);
- FD_CLR((int)eh->data, &errfds);
- fire(eh);
- if(eh == wait_eh) event_wait_fired = 1;
- }
- break;
-
- /*
- * Write fds: same as Read fds
- */
- case EV_WRITEFD:
- if (FD_ISSET((int)eh->data, &writefds) ||
- FD_ISSET((int)eh->data, &werrfds)) {
- FD_CLR((int)eh->data, &writefds);
- FD_CLR((int)eh->data, &werrfds);
- fire(eh);
- if(eh == wait_eh) event_wait_fired = 1;
- }
- break;
-
- /*
- * Signal events: check the score for fires, and run the
- * event if we got one.
- */
- case EV_SIG:
- se = &sigtable[eh->data];
- if (se->score > 0) {
- assert(se->handle == eh);
- se->score = 0;
- fire(eh);
- if(eh == wait_eh) event_wait_fired = 1;
- }
- break;
-
- /*
- * Timed events: check the interval elapsed since last fired,
- * and set it off if greater or equal to requested interval.
- */
- case EV_TIME:
- if (eh->lastfired == -1)
- eh->lastfired = curtime;
- if ((curtime - eh->lastfired) >= (time_t)eh->data) {
- eh->lastfired = curtime;
- fire(eh);
- if(eh == wait_eh) event_wait_fired = 1;
- }
- break;
-
- /*
- * Wait events are handled immediately by event_wakeup()
- * Dead events are handled by the pre-select loop.
- */
- case EV_WAIT:
- case EV_DEAD:
- break;
-
- default:
- assert(0);
- break;
- }
+ amfree(hdl);
}
- } while (!dontblock && eventq.qlength > 0 && event_wait_fired == 0);
-
- assert(--entry == 0);
-
- return (event_wait_fired == 1);
+ }
}
-/*
- * Generic signal handler. Used to count caught signals for the event
- * loop.
- */
-static void
-signal_handler(
- int signo)
+/* Return TRUE if we have any events outstanding that can be dispatched
+ * by GMainLoop. Recall EV_WAIT events appear in all_events, but are
+ * not dispatched by GMainLoop. */
+static gboolean
+any_mainloop_events(void)
{
+ GSList *iter;
+
+ for (iter = all_events; iter != NULL; iter = g_slist_next(iter)) {
+ event_handle_t *hdl = (event_handle_t *)iter->data;
+ if (hdl->type != EV_WAIT)
+ return TRUE;
+ }
- assert((signo >= 0) && ((size_t)signo < (size_t)(sizeof(sigtable) / sizeof(sigtable[0]))));
- sigtable[signo].score++;
+ return FALSE;
}
-/*
- * Return a new handle. Take from the handle cache if not empty. Otherwise,
- * alloc a new one.
- */
-static event_handle_t *
-gethandle(void)
+static void
+event_loop_wait(
+ event_handle_t *wait_eh,
+ int nonblock)
{
- event_handle_t *eh;
+ event_debug(1, _("event: loop: enter: nonblockg=%d, eh=%p\n"), nonblock, wait_eh);
+
+ /* If we're waiting for a specific event, then reset its has_fired flag */
+ if (wait_eh) {
+ wait_eh->has_fired = FALSE;
+ }
- if ((eh = eventq_first(cache)) != NULL) {
- assert(cache.qlength > 0);
- eventq_remove(eh);
- cache.qlength--;
- return (eh);
+ /* Keep looping until there are no events, or until wait_eh has fired */
+ while (1) {
+ /* clean up first, so we don't accidentally check a dead source */
+ flush_dead_events(wait_eh);
+
+ /* if there's nothing to wait for, then don't block, but run an
+ * iteration so that any other users of GMainLoop will get a chance
+ * to run. */
+ if (!any_mainloop_events())
+ break;
+
+ /* Do an interation */
+ g_main_context_iteration(NULL, !nonblock);
+
+ /* If the event we've been waiting for has fired or been released, as
+ * appropriate, we're done. See the comments for event_wait in event.h
+ * for the skinny on this weird expression. */
+ if (wait_eh && ((wait_eh->type == EV_WAIT && wait_eh->is_dead)
+ || (wait_eh->type != EV_WAIT && wait_eh->has_fired)))
+ break;
+
+ /* Don't loop if we're not blocking */
+ if (nonblock)
+ break;
}
- assert(cache.qlength == 0);
- return (alloc(SIZEOF(*eh)));
+
+ /* extra cleanup, to keep all_events short, and to delete wait_eh if it
+ * has been released. */
+ flush_dead_events(NULL);
+
}
-/*
- * Free a handle. If there's space in the handle cache, put it there.
- * Otherwise, free it.
- */
-static void
-puthandle(
- event_handle_t *eh)
+GMainLoop *
+default_main_loop(void)
{
-
- if (cache.qlength > CACHEDEPTH) {
- amfree(eh);
- return;
- }
- eventq_add(cache, eh);
- cache.qlength++;
+ static GMainLoop *loop = NULL;
+ if (!loop)
+ loop = g_main_loop_new(NULL, TRUE);
+ return loop;
}
/*
#define X(s) { s, stringize(s) }
X(EV_READFD),
X(EV_WRITEFD),
- X(EV_SIG),
X(EV_TIME),
X(EV_WAIT),
- X(EV_DEAD),
#undef X
};
size_t i;
return (event_types[i].name);
return (_("BOGUS EVENT TYPE"));
}
+
+/*
+ * FDSource -- a source for a file descriptor
+ *
+ * We could use Glib's GIOChannel for this, but it adds some buffering
+ * and Unicode functionality that we really don't want. The custom GSource
+ * is simple enough anyway, and the Glib documentation describes it in prose.
+ */
+
+typedef struct FDSource {
+ GSource source; /* must be the first element in the struct */
+ GPollFD pollfd; /* Our file descriptor */
+} FDSource;
+
+static gboolean
+fdsource_prepare(
+ GSource *source G_GNUC_UNUSED,
+ gint *timeout_)
+{
+ *timeout_ = -1; /* block forever, as far as we're concerned */
+ return FALSE;
+}
+
+static gboolean
+fdsource_check(
+ GSource *source)
+{
+ FDSource *fds = (FDSource *)source;
+
+ /* we need to be dispatched if any interesting events have been received by the FD */
+ return fds->pollfd.events & fds->pollfd.revents;
+}
+
+static gboolean
+fdsource_dispatch(
+ GSource *source G_GNUC_UNUSED,
+ GSourceFunc callback,
+ gpointer user_data)
+{
+ if (callback)
+ return callback(user_data);
+
+ /* Don't automatically detach the event source if there's no callback. */
+ return TRUE;
+}
+
+GSource *
+new_fdsource(gint fd, GIOCondition events)
+{
+ static GSourceFuncs *fdsource_funcs = NULL;
+ GSource *src;
+ FDSource *fds;
+
+ /* initialize these here to avoid a compiler warning */
+ if (!fdsource_funcs) {
+ fdsource_funcs = g_new0(GSourceFuncs, 1);
+ fdsource_funcs->prepare = fdsource_prepare;
+ fdsource_funcs->check = fdsource_check;
+ fdsource_funcs->dispatch = fdsource_dispatch;
+ }
+
+ src = g_source_new(fdsource_funcs, sizeof(FDSource));
+ fds = (FDSource *)src;
+
+ fds->pollfd.fd = fd;
+ fds->pollfd.events = events;
+ g_source_add_poll(src, &fds->pollfd);
+
+ return src;
+}
+
+/*
+ * ChildWatchSource -- a source for a file descriptor
+ *
+ * Newer versions of glib provide equivalent functionality; consider
+ * optionally using that, protected by a GLIB_CHECK_VERSION condition.
+ */
+
+/* Versions before glib-2.4.0 didn't include a child watch source, and versions
+ * before 2.6.0 used unreliable signals. On these versions, we implement
+ * a "dumb" version of our own invention. This is dumb in the sense that it
+ * doesn't use SIGCHLD to detect a dead child, preferring to just poll at
+ * exponentially increasing interals. Writing a smarter implementation runs into
+ * some tricky race conditions and extra machinery. Since there are few, if any,
+ * users of a glib version this old, such machinery wouldn't get much testing.
+ */
+#if (GLIB_MAJOR_VERSION < 2 || (GLIB_MAJOR_VERSION == 2 && GLIB_MINOR_VERSION < 6))
+typedef struct ChildWatchSource {
+ GSource source; /* must be the first element in the struct */
+
+ pid_t pid;
+
+ gint dead;
+ gint status;
+
+ gint timeout;
+} ChildWatchSource;
+
+/* this corresponds to rapid checks for about 10 seconds, after which the
+ * waitpid() check occurs every 2 seconds. */
+#define CWS_BASE_TIMEOUT 20
+#define CWS_MULT_TIMEOUT 1.1
+#define CWS_MAX_TIMEOUT 2000
+
+static gboolean
+child_watch_source_prepare(
+ GSource *source,
+ gint *timeout_)
+{
+ ChildWatchSource *cws = (ChildWatchSource *)source;
+
+ *timeout_ = cws->timeout;
+
+ cws->timeout *= CWS_MULT_TIMEOUT;
+ if (cws->timeout > CWS_MAX_TIMEOUT) cws->timeout = CWS_MAX_TIMEOUT;
+
+ return FALSE;
+}
+
+static gboolean
+child_watch_source_check(
+ GSource *source)
+{
+ ChildWatchSource *cws = (ChildWatchSource *)source;
+
+ /* is it dead? */
+ if (!cws->dead && waitpid(cws->pid, &cws->status, WNOHANG) > 0) {
+ cws->dead = TRUE;
+ }
+
+ return cws->dead;
+}
+
+static gboolean
+child_watch_source_dispatch(
+ GSource *source G_GNUC_UNUSED,
+ GSourceFunc callback,
+ gpointer user_data)
+{
+ ChildWatchSource *cws = (ChildWatchSource *)source;
+
+ /* this shouldn't happen, but just in case */
+ if (cws->dead) {
+ if (!callback) {
+ g_warning("child %jd died before callback was registered", (uintmax_t)cws->pid);
+ return FALSE;
+ }
+
+ ((ChildWatchFunc)callback)(cws->pid, cws->status, user_data);
+
+ /* Un-queue this source unconditionally -- the child can't die twice */
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+GSource *
+new_child_watch_source(pid_t pid)
+{
+ static GSourceFuncs *child_watch_source_funcs = NULL;
+ GSource *src;
+ ChildWatchSource *cws;
+
+ /* initialize these here to avoid a compiler warning */
+ if (!child_watch_source_funcs) {
+ child_watch_source_funcs = g_new0(GSourceFuncs, 1);
+ child_watch_source_funcs->prepare = child_watch_source_prepare;
+ child_watch_source_funcs->check = child_watch_source_check;
+ child_watch_source_funcs->dispatch = child_watch_source_dispatch;
+ }
+
+ src = g_source_new(child_watch_source_funcs, sizeof(ChildWatchSource));
+ cws = (ChildWatchSource *)src;
+
+ cws->pid = pid;
+ cws->dead = FALSE;
+ cws->timeout = CWS_BASE_TIMEOUT;
+
+ return src;
+}
+#else
+/* In more recent versions of glib, we just use the built-in glib source */
+GSource *
+new_child_watch_source(pid_t pid)
+{
+ return g_child_watch_source_new(pid);
+}
+#endif
projects / debian / amanda / blobdiff