tevent: add support for immediate events

They're like directly triggered timed events,
but you can preallocated them and scheduling them
will not fail.

metze

8 files changed, 295 insertions, 34 deletions

diff --git a/lib/tevent/libtevent.m4 b/lib/tevent/libtevent.m4
index c316823a71..20730b17d6 100644
--- a/lib/tevent/libtevent.m4
+++ b/lib/tevent/libtevent.m4
@@ -26,7 +26,8 @@ AC_SUBST(TEVENT_LIBS)
 
 TEVENT_CFLAGS="-I$teventdir"
 
-TEVENT_OBJ="tevent.o tevent_fd.o tevent_timed.o tevent_signal.o tevent_debug.o tevent_util.o"
+TEVENT_OBJ="tevent.o tevent_debug.o tevent_util.o"
+TEVENT_OBJ="$TEVENT_OBJ tevent_fd.o tevent_timed.o tevent_immediate.o tevent_signal.o"
 TEVENT_OBJ="$TEVENT_OBJ tevent_req.o tevent_wakeup.o tevent_queue.o"
 TEVENT_OBJ="$TEVENT_OBJ tevent_standard.o tevent_select.o"
 
diff --git a/lib/tevent/tevent.c b/lib/tevent/tevent.c
index 31dc58d98e..ba2d93f4b9 100644
--- a/lib/tevent/tevent.c
+++ b/lib/tevent/tevent.c
@@ -143,6 +143,7 @@ int tevent_common_context_destructor(struct tevent_context *ev)
 {
 	struct tevent_fd *fd, *fn;
 	struct tevent_timer *te, *tn;
+	struct tevent_immediate *ie, *in;
 	struct tevent_signal *se, *sn;
 
 	if (ev->pipe_fde) {
@@ -162,6 +163,13 @@ int tevent_common_context_destructor(struct tevent_context *ev)
 		DLIST_REMOVE(ev->timer_events, te);
 	}
 
+	for (ie = ev->immediate_events; ie; ie = in) {
+		in = ie->next;
+		ie->event_ctx = NULL;
+		ie->cancel_fn = NULL;
+		DLIST_REMOVE(ev->immediate_events, ie);
+	}
+
 	for (se = ev->signal_events; se; se = sn) {
 		sn = se->next;
 		se->event_ctx = NULL;
@@ -350,6 +358,47 @@ struct tevent_timer *_tevent_add_timer(struct tevent_context *ev,
 }
 
 /*
+  allocate an immediate event
+  return NULL on failure (memory allocation error)
+*/
+struct tevent_immediate *_tevent_create_immediate(TALLOC_CTX *mem_ctx,
+						  const char *location)
+{
+	struct tevent_immediate *im;
+
+	im = talloc(mem_ctx, struct tevent_immediate);
+	if (im == NULL) return NULL;
+
+	im->prev		= NULL;
+	im->next		= NULL;
+	im->event_ctx		= NULL;
+	im->create_location	= location;
+	im->handler		= NULL;
+	im->private_data	= NULL;
+	im->handler_name	= NULL;
+	im->schedule_location	= NULL;
+	im->cancel_fn		= NULL;
+	im->additional_data	= NULL;
+
+	return im;
+}
+
+/*
+  schedule an immediate event
+  return NULL on failure
+*/
+void _tevent_schedule_immediate(struct tevent_immediate *im,
+				struct tevent_context *ev,
+				tevent_immediate_handler_t handler,
+				void *private_data,
+				const char *handler_name,
+				const char *location)
+{
+	ev->ops->schedule_immediate(im, ev, handler, private_data,
+				    handler_name, location);
+}
+
+/*
   add a signal event
 
   sa_flags are flags to sigaction(2)
diff --git a/lib/tevent/tevent.h b/lib/tevent/tevent.h
index 4a3f51ae5e..6e64a8cdd9 100644
--- a/lib/tevent/tevent.h
+++ b/lib/tevent/tevent.h
@@ -37,6 +37,7 @@ struct tevent_context;
 struct tevent_ops;
 struct tevent_fd;
 struct tevent_timer;
+struct tevent_immediate;
 struct tevent_signal;
 
 /* event handler types */
@@ -52,6 +53,9 @@ typedef void (*tevent_timer_handler_t)(struct tevent_context *ev,
 				       struct tevent_timer *te,
 				       struct timeval current_time,
 				       void *private_data);
+typedef void (*tevent_immediate_handler_t)(struct tevent_context *ctx,
+					   struct tevent_immediate *im,
+					   void *private_data);
 typedef void (*tevent_signal_handler_t)(struct tevent_context *ev,
 					struct tevent_signal *se,
 					int signum,
@@ -87,6 +91,21 @@ struct tevent_timer *_tevent_add_timer(struct tevent_context *ev,
 	_tevent_add_timer(ev, mem_ctx, next_event, handler, private_data, \
 			  #handler, __location__)
 
+struct tevent_immediate *_tevent_create_immediate(TALLOC_CTX *mem_ctx,
+						  const char *location);
+#define tevent_create_immediate(mem_ctx) \
+	_tevent_create_immediate(mem_ctx, __location__)
+
+void _tevent_schedule_immediate(struct tevent_immediate *im,
+				struct tevent_context *ctx,
+				tevent_immediate_handler_t handler,
+				void *private_data,
+				const char *handler_name,
+				const char *location);
+#define tevent_schedule_immediate(im, ctx, handler, private_data) \
+	_tevent_schedule_immediate(im, ctx, handler, private_data, \
+				   #handler, __location__);
+
 struct tevent_signal *_tevent_add_signal(struct tevent_context *ev,
 					 TALLOC_CTX *mem_ctx,
 					 int signum,
diff --git a/lib/tevent/tevent_epoll.c b/lib/tevent/tevent_epoll.c
index 32544593de..7c7f389d5b 100644
--- a/lib/tevent/tevent_epoll.c
+++ b/lib/tevent/tevent_epoll.c
@@ -404,8 +404,13 @@ static int epoll_event_loop_once(struct tevent_context *ev, const char *location
 		 					   struct epoll_event_context);
 	struct timeval tval;
 
-	if (epoll_ev->ev->signal_events &&
-	    tevent_common_check_signal(epoll_ev->ev)) {
+	if (ev->signal_events &&
+	    tevent_common_check_signal(ev)) {
+		return 0;
+	}
+
+	if (ev->immediate_events &&
+	    tevent_common_loop_immediate(ev)) {
 		return 0;
 	}
 
@@ -420,15 +425,16 @@ static int epoll_event_loop_once(struct tevent_context *ev, const char *location
 }
 
 static const struct tevent_ops epoll_event_ops = {
-	.context_init	= epoll_event_context_init,
-	.add_fd		= epoll_event_add_fd,
-	.set_fd_close_fn= tevent_common_fd_set_close_fn,
-	.get_fd_flags	= tevent_common_fd_get_flags,
-	.set_fd_flags	= epoll_event_set_fd_flags,
-	.add_timer	= tevent_common_add_timer,
-	.add_signal	= tevent_common_add_signal,
-	.loop_once	= epoll_event_loop_once,
-	.loop_wait	= tevent_common_loop_wait,
+	.context_init		= epoll_event_context_init,
+	.add_fd			= epoll_event_add_fd,
+	.set_fd_close_fn	= tevent_common_fd_set_close_fn,
+	.get_fd_flags		= tevent_common_fd_get_flags,
+	.set_fd_flags		= epoll_event_set_fd_flags,
+	.add_timer		= tevent_common_add_timer,
+	.schedule_immediate	= tevent_common_schedule_immediate,
+	.add_signal		= tevent_common_add_signal,
+	.loop_once		= epoll_event_loop_once,
+	.loop_wait		= tevent_common_loop_wait,
 };
 
 bool tevent_epoll_init(void)
diff --git a/lib/tevent/tevent_immediate.c b/lib/tevent/tevent_immediate.c
new file mode 100644
index 0000000000..1ac293e175
--- /dev/null
+++ b/lib/tevent/tevent_immediate.c
@@ -0,0 +1,139 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   common events code for immediate events
+
+   Copyright (C) Stefan Metzmacher 2009
+
+     ** NOTE! The following LGPL license applies to the tevent
+     ** library. This does NOT imply that all of Samba is released
+     ** under the LGPL
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 3 of the License, or (at your option) any later version.
+
+   This library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "replace.h"
+#include "tevent.h"
+#include "tevent_internal.h"
+#include "tevent_util.h"
+
+static void tevent_common_immediate_cancel(struct tevent_immediate *im)
+{
+	if (!im->event_ctx) {
+		return;
+	}
+
+	tevent_debug(im->event_ctx, TEVENT_DEBUG_TRACE,
+		     "Cancel immediate event %p \"%s\"\n",
+		     im, im->handler_name);
+
+	/* let the backend free im->additional_data */
+	if (im->cancel_fn) {
+		im->cancel_fn(im);
+	}
+
+	DLIST_REMOVE(im->event_ctx->immediate_events, im);
+	im->event_ctx		= NULL;
+	im->handler		= NULL;
+	im->private_data	= NULL;
+	im->handler_name	= NULL;
+	im->schedule_location	= NULL;
+	im->cancel_fn		= NULL;
+	im->additional_data	= NULL;
+
+	talloc_set_destructor(im, NULL);
+}
+
+/*
+  destroy an immediate event
+*/
+static int tevent_common_immediate_destructor(struct tevent_immediate *im)
+{
+	tevent_common_immediate_cancel(im);
+	return 0;
+}
+
+/*
+ * schedule an immediate event on
+ */
+void tevent_common_schedule_immediate(struct tevent_immediate *im,
+				      struct tevent_context *ev,
+				      tevent_immediate_handler_t handler,
+				      void *private_data,
+				      const char *handler_name,
+				      const char *location)
+{
+	tevent_common_immediate_cancel(im);
+
+	if (!handler) {
+		return;
+	}
+
+	im->event_ctx		= ev;
+	im->handler		= handler;
+	im->private_data	= private_data;
+	im->handler_name	= handler_name;
+	im->schedule_location	= location;
+	im->cancel_fn		= NULL;
+	im->additional_data	= NULL;
+
+	DLIST_ADD_END(ev->immediate_events, im, struct tevent_immediate *);
+	talloc_set_destructor(im, tevent_common_immediate_destructor);
+
+	tevent_debug(ev, TEVENT_DEBUG_TRACE,
+		     "Schedule immediate event \"%s\": %p\n",
+		     handler_name, im);
+}
+
+/*
+  trigger the first immediate event and return true
+  if no event was triggered return false
+*/
+bool tevent_common_loop_immediate(struct tevent_context *ev)
+{
+	struct tevent_immediate *im = ev->immediate_events;
+	tevent_immediate_handler_t handler;
+	void *private_data;
+
+	if (!im) {
+		return false;
+	}
+
+	tevent_debug(ev, TEVENT_DEBUG_TRACE,
+		     "Run immediate event \"%s\": %p\n",
+		     im->handler_name, im);
+
+	/*
+	 * remember the handler and then clear the event
+	 * the handler might reschedule the event
+	 */
+	handler = im->handler;
+	private_data = im->private_data;
+
+	DLIST_REMOVE(im->event_ctx->immediate_events, im);
+	im->event_ctx		= NULL;
+	im->handler		= NULL;
+	im->private_data	= NULL;
+	im->handler_name	= NULL;
+	im->schedule_location	= NULL;
+	im->cancel_fn		= NULL;
+	im->additional_data	= NULL;
+
+	talloc_set_destructor(im, NULL);
+
+	handler(ev, im, private_data);
+
+	return true;
+}
+
diff --git a/lib/tevent/tevent_internal.h b/lib/tevent/tevent_internal.h
index f63a58aadd..cf54242da1 100644
--- a/lib/tevent/tevent_internal.h
+++ b/lib/tevent/tevent_internal.h
@@ -143,6 +143,15 @@ struct tevent_ops {
 					  void *private_data,
 					  const char *handler_name,
 					  const char *location);
+
+	/* immediate event functions */
+	void (*schedule_immediate)(struct tevent_immediate *im,
+				   struct tevent_context *ev,
+				   tevent_immediate_handler_t handler,
+				   void *private_data,
+				   const char *handler_name,
+				   const char *location);
+
 	/* signal functions */
 	struct tevent_signal *(*add_signal)(struct tevent_context *ev,
 					    TALLOC_CTX *mem_ctx,
@@ -188,6 +197,21 @@ struct tevent_timer {
 	void *additional_data;
 };
 
+struct tevent_immediate {
+	struct tevent_immediate *prev, *next;
+	struct tevent_context *event_ctx;
+	tevent_immediate_handler_t handler;
+	/* this is private for the specific handler */
+	void *private_data;
+	/* this is for debugging only! */
+	const char *handler_name;
+	const char *create_location;
+	const char *schedule_location;
+	/* this is private for the events_ops implementation */
+	void (*cancel_fn)(struct tevent_immediate *im);
+	void *additional_data;
+};
+
 struct tevent_signal {
 	struct tevent_signal *prev, *next;
 	struct tevent_context *event_ctx;
@@ -222,6 +246,9 @@ struct tevent_context {
 	/* list of timed events - used by common code */
 	struct tevent_timer *timer_events;
 
+	/* list of immediate events - used by common code */
+	struct tevent_immediate *immediate_events;
+
 	/* list of signal events - used by common code */
 	struct tevent_signal *signal_events;
 
@@ -273,6 +300,14 @@ struct tevent_timer *tevent_common_add_timer(struct tevent_context *ev,
 					     const char *location);
 struct timeval tevent_common_loop_timer_delay(struct tevent_context *);
 
+void tevent_common_schedule_immediate(struct tevent_immediate *im,
+				      struct tevent_context *ev,
+				      tevent_immediate_handler_t handler,
+				      void *private_data,
+				      const char *handler_name,
+				      const char *location);
+bool tevent_common_loop_immediate(struct tevent_context *ev);
+
 struct tevent_signal *tevent_common_add_signal(struct tevent_context *ev,
 					       TALLOC_CTX *mem_ctx,
 					       int signum,
diff --git a/lib/tevent/tevent_select.c b/lib/tevent/tevent_select.c
index 1c295d7ca4..d97418991a 100644
--- a/lib/tevent/tevent_select.c
+++ b/lib/tevent/tevent_select.c
@@ -210,8 +210,13 @@ static int select_event_loop_once(struct tevent_context *ev, const char *locatio
 		 					   struct select_event_context);
 	struct timeval tval;
 
-	if (select_ev->ev->signal_events &&
-	    tevent_common_check_signal(select_ev->ev)) {
+	if (ev->signal_events &&
+	    tevent_common_check_signal(ev)) {
+		return 0;
+	}
+
+	if (ev->immediate_events &&
+	    tevent_common_loop_immediate(ev)) {
 		return 0;
 	}
 
@@ -224,15 +229,16 @@ static int select_event_loop_once(struct tevent_context *ev, const char *locatio
 }
 
 static const struct tevent_ops select_event_ops = {
-	.context_init	= select_event_context_init,
-	.add_fd		= select_event_add_fd,
-	.set_fd_close_fn= tevent_common_fd_set_close_fn,
-	.get_fd_flags	= tevent_common_fd_get_flags,
-	.set_fd_flags	= tevent_common_fd_set_flags,
-	.add_timer	= tevent_common_add_timer,
-	.add_signal	= tevent_common_add_signal,
-	.loop_once	= select_event_loop_once,
-	.loop_wait	= tevent_common_loop_wait,
+	.context_init		= select_event_context_init,
+	.add_fd			= select_event_add_fd,
+	.set_fd_close_fn	= tevent_common_fd_set_close_fn,
+	.get_fd_flags		= tevent_common_fd_get_flags,
+	.set_fd_flags		= tevent_common_fd_set_flags,
+	.add_timer		= tevent_common_add_timer,
+	.schedule_immediate	= tevent_common_schedule_immediate,
+	.add_signal		= tevent_common_add_signal,
+	.loop_once		= select_event_loop_once,
+	.loop_wait		= tevent_common_loop_wait,
 };
 
 bool tevent_select_init(void)
diff --git a/lib/tevent/tevent_standard.c b/lib/tevent/tevent_standard.c
index 88db6a1725..c3f8b36e84 100644
--- a/lib/tevent/tevent_standard.c
+++ b/lib/tevent/tevent_standard.c
@@ -524,8 +524,13 @@ static int std_event_loop_once(struct tevent_context *ev, const char *location)
 		 					   struct std_event_context);
 	struct timeval tval;
 
-	if (std_ev->ev->signal_events &&
-	    tevent_common_check_signal(std_ev->ev)) {
+	if (ev->signal_events &&
+	    tevent_common_check_signal(ev)) {
+		return 0;
+	}
+
+	if (ev->immediate_events &&
+	    tevent_common_loop_immediate(ev)) {
 		return 0;
 	}
 
@@ -544,15 +549,16 @@ static int std_event_loop_once(struct tevent_context *ev, const char *location)
 }
 
 static const struct tevent_ops std_event_ops = {
-	.context_init	= std_event_context_init,
-	.add_fd		= std_event_add_fd,
-	.set_fd_close_fn= tevent_common_fd_set_close_fn,
-	.get_fd_flags	= tevent_common_fd_get_flags,
-	.set_fd_flags	= std_event_set_fd_flags,
-	.add_timer	= tevent_common_add_timer,
-	.add_signal	= tevent_common_add_signal,
-	.loop_once	= std_event_loop_once,
-	.loop_wait	= tevent_common_loop_wait,
+	.context_init		= std_event_context_init,
+	.add_fd			= std_event_add_fd,
+	.set_fd_close_fn	= tevent_common_fd_set_close_fn,
+	.get_fd_flags		= tevent_common_fd_get_flags,
+	.set_fd_flags		= std_event_set_fd_flags,
+	.add_timer		= tevent_common_add_timer,
+	.schedule_immediate	= tevent_common_schedule_immediate,
+	.add_signal		= tevent_common_add_signal,
+	.loop_once		= std_event_loop_once,
+	.loop_wait		= tevent_common_loop_wait,
 };