[libdispatch-dev] [PATCH 12/17] extract source-type-specific initialization to per-type functions

[Paolo Bonzini]

As a first step towards eliminating struct kevent from source.c,
some of the initialization is moved to separate functions.  This
introduces a per-source-type function pointer that is called when
creating a source.

The code is not 100% equal, but the only difference is that an
assertion is delayed to after the full initialization---which is
arguably better.
---
 src/source.c |   63 +++++++++++++++++++++++++++++++++++++++------------------
 1 files changed, 43 insertions(+), 20 deletions(-)

diff --git a/src/source.c b/src/source.c
index b4f769d..d41bbda 100644
--- a/src/source.c
+++ b/src/source.c
@@ -925,13 +925,29 @@ dispatch_source_attr_copy(dispatch_source_attr_t proto)
 struct dispatch_source_type_s {
 	struct kevent ke;
 	uint64_t mask;
+	void (*init) (dispatch_source_t ds,
+		      dispatch_source_type_t type,
+		      uintptr_t handle,
+		      unsigned long mask,
+		      dispatch_queue_t q);
 };
 
+static void dispatch_source_type_timer_init (dispatch_source_t ds,
+					     dispatch_source_type_t type,
+					     uintptr_t handle,
+					     unsigned long mask,
+					     dispatch_queue_t q)
+{
+	ds->ds_needs_rearm = true;
+	ds->ds_timer.flags = mask;
+}
+
 const struct dispatch_source_type_s _dispatch_source_type_timer = {
 	.ke = {
 		.filter = DISPATCH_EVFILT_TIMER,
 	},
 	.mask = DISPATCH_TIMER_INTERVAL|DISPATCH_TIMER_ONESHOT|DISPATCH_TIMER_ABSOLUTE|DISPATCH_TIMER_WALL_CLOCK,
+	.init = dispatch_source_type_timer_init
 };
 
 const struct dispatch_source_type_s _dispatch_source_type_read = {
@@ -999,6 +1015,18 @@ const struct dispatch_source_type_s _dispatch_source_type_vfs = {
 };
 
 #ifdef HAVE_MACH
+
+static void dispatch_source_type_mach_send_init (dispatch_source_t ds,
+					     	 dispatch_source_type_t type,
+					         uintptr_t handle,
+						 unsigned long mask,
+						 dispatch_queue_t q)
+{
+	static dispatch_once_t pred;
+	ds->ds_is_level = false;
+	dispatch_once_f(&pred, NULL, _dispatch_mach_notify_source_init);
+}
+
 const struct dispatch_source_type_s _dispatch_source_type_mach_send = {
 	.ke = {
 		.filter = EVFILT_MACHPORT,
@@ -1006,14 +1034,25 @@ const struct dispatch_source_type_s _dispatch_source_type_mach_send = {
 		.fflags = DISPATCH_MACHPORT_DEAD,
 	},
 	.mask = DISPATCH_MACH_SEND_DEAD,
+	.init = dispatch_source_type_mach_send_init
 };
 
+static void dispatch_source_type_mach_recv_init (dispatch_source_t ds,
+					     	 dispatch_source_type_t type,
+					         uintptr_t handle,
+						 unsigned long mask,
+						 dispatch_queue_t q)
+{
+	ds->ds_is_level = false;
+}
+
 const struct dispatch_source_type_s _dispatch_source_type_mach_recv = {
 	.ke = {
 		.filter = EVFILT_MACHPORT,
 		.flags = EV_DISPATCH,
 		.fflags = DISPATCH_MACHPORT_RECV,
 	},
+	.init = dispatch_source_type_mach_recv_init
 };
 #endif
 
@@ -1097,38 +1136,22 @@ dispatch_source_create(dispatch_source_type_t type,
 	ds->ds_dkev = dk;
 	ds->ds_pending_data_mask = dk->dk_kevent.fflags;
 	if ((EV_DISPATCH|EV_ONESHOT) & proto_kev->flags) {
-#ifdef HAVE_MACH
-		if (proto_kev->filter != EVFILT_MACHPORT) {
-			ds->ds_is_level = true;
-		}
-#endif
+		ds->ds_is_level = true;
 		ds->ds_needs_rearm = true;
 	} else if (!(EV_CLEAR & proto_kev->flags)) {
 		// we cheat and use EV_CLEAR to mean a "flag thingy"
 		ds->ds_is_adder = true;
 	}
 	
-	// If its a timer source, it needs to be re-armed
-	if (type->ke.filter == DISPATCH_EVFILT_TIMER) {
-		ds->ds_needs_rearm = true;
+	// Some sources require special processing
+	if (type->init) {
+		type->init (ds, type, handle, mask, q);
 	}
-	
 	dispatch_assert(!(ds->ds_is_level && ds->ds_is_adder));
 #if DISPATCH_DEBUG
 	dispatch_debug(ds, __FUNCTION__);
 #endif
 
-	// Some sources require special processing
-#ifdef HAVE_MACH
-	if (type == DISPATCH_SOURCE_TYPE_MACH_SEND) {
-		static dispatch_once_t pred;
-		dispatch_once_f(&pred, NULL, _dispatch_mach_notify_source_init);
-	} else
-#endif
-	if (type == DISPATCH_SOURCE_TYPE_TIMER) {
-		ds->ds_timer.flags = mask;
-	}
-
 	_dispatch_retain(ds->do_targetq);
 	return ds;
 	
-- 
1.6.2.5