Named call pickup groups. Fixes, missing functionality, and improvements.

* ASTERISK-20383
Missing named call pickup group features:

CHANNEL(callgroup) - Need CHANNEL(namedcallgroup)
CHANNEL(pickupgroup) - Need CHANNEL(namedpickupgroup)
Pickup() - Needs to also select from named pickup groups.

* ASTERISK-20384
Using the pickupexten, the pickup channel selection could fail even though
there was a call it could have picked up.  In a call pickup race when
there are multiple calls to pickup and two extensions try to pickup a
call, it is conceivable that the loser will not pick up any call even
though it could have picked up the next oldest matching call.

Regression because of the named call pickup group feature.

* See ASTERISK-20386 for the implementation improvements.  These are the
changes in channel.c and channel.h.

* Fixed some locking issues in CHANNEL().

(closes issue ASTERISK-20383)
Reported by: rmudgett
(closes issue ASTERISK-20384)
Reported by: rmudgett
(closes issue ASTERISK-20386)
Reported by: rmudgett
Tested by: rmudgett

Review: https://reviewboard.asterisk.org/r/2112/
........

Merged revisions 373220 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@373221 65c4cc65-6c06-0410-ace0-fbb531ad65f3

2 files changed, 139 insertions, 108 deletions

diff --git a/main/channel.c b/main/channel.c
index b25484598..dbc4703b5 100644
--- a/main/channel.c
+++ b/main/channel.c
@@ -8220,97 +8220,86 @@ ast_group_t ast_get_group(const char *s)
 	return group;
 }
 
+/*! \brief Named group member structure */
+struct namedgroup_member {
+	/*! Pre-built hash of group member name. */
+	unsigned int hash;
+	/*! Group member name. (End allocation of name string.) */
+	char name[1];
+};
+
 /*! \brief Comparison function used for named group container */
 static int namedgroup_cmp_cb(void *obj, void *arg, int flags)
 {
-	const struct namedgroup_entry *an = obj;
-	const struct namedgroup_entry *bn = arg;
+	const struct namedgroup_member *an = obj;
+	const struct namedgroup_member *bn = arg;
+
 	return strcmp(an->name, bn->name) ? 0 : CMP_MATCH | CMP_STOP;
 }
 
 /*! \brief Hashing function used for named group container */
 static int namedgroup_hash_cb(const void *obj, const int flags)
 {
-	const struct namedgroup_entry *entry = obj;
-	return entry->hash;
-}
-
-static void namedgroup_dtor(void *obj)
-{
-	ast_free(((struct namedgroup_entry*)obj)->name);
-}
+	const struct namedgroup_member *member = obj;
 
-/*! \internal \brief Actually a refcounted ao2_object. An indirect ao2_container to hide the implementation of namedgroups. */
-struct ast_namedgroups {
-	struct ao2_container *container;
-};
-
-static void ast_namedgroups_dtor(void *obj)
-{
-	ao2_cleanup(((struct ast_namedgroups *)obj)->container);
+	return member->hash;
 }
 
 struct ast_namedgroups *ast_get_namedgroups(const char *s)
 {
-	struct ast_namedgroups *namedgroups;
+	struct ao2_container *namedgroups;
 	char *piece;
 	char *c;
 
-	if (ast_strlen_zero(s)) {
+	if (!s) {
 		return NULL;
 	}
-	c = ast_strdupa(s);
-	if (!c) {
+
+	/*! \brief Remove leading and trailing whitespace */
+	c = ast_trim_blanks(ast_strdupa(ast_skip_blanks(s)));
+	if (ast_strlen_zero(c)) {
 		return NULL;
 	}
 
-	namedgroups = ao2_alloc_options(sizeof(*namedgroups), ast_namedgroups_dtor, AO2_ALLOC_OPT_LOCK_NOLOCK);
+	namedgroups = ao2_container_alloc_options(AO2_ALLOC_OPT_LOCK_NOLOCK, 19,
+		namedgroup_hash_cb, namedgroup_cmp_cb);
 	if (!namedgroups) {
 		return NULL;
 	}
-	namedgroups->container = ao2_container_alloc_options(AO2_ALLOC_OPT_LOCK_NOLOCK, 19, namedgroup_hash_cb, namedgroup_cmp_cb);
-	if (!namedgroups->container) {
-		ao2_ref(namedgroups, -1);
-		return NULL;
-	}
-
-	/*! \brief Remove leading and trailing whitespace */
-	c = ast_strip(c);
 
 	while ((piece = strsep(&c, ","))) {
-		struct namedgroup_entry *entry;
+		struct namedgroup_member *member;
+		size_t len;
 
 		/* remove leading/trailing whitespace */
 		piece = ast_strip(piece);
-		if (strlen(piece) == 0) {
-			ast_log(LOG_ERROR, "Syntax error parsing named group configuration '%s' at '%s'. Ignoring.\n", s, piece);
+
+		len = strlen(piece);
+		if (!len) {
 			continue;
 		}
 
-		entry = ao2_alloc_options(sizeof(*entry), namedgroup_dtor, AO2_ALLOC_OPT_LOCK_NOLOCK);
-		if (!entry) {
-			ao2_ref(namedgroups, -1);
-			return NULL;
-		}
-		entry->name = ast_strdup(piece);
-		if (!entry->name) {
-			ao2_ref(entry, -1);
+		member = ao2_alloc_options(sizeof(*member) + len, NULL, AO2_ALLOC_OPT_LOCK_NOLOCK);
+		if (!member) {
 			ao2_ref(namedgroups, -1);
 			return NULL;
 		}
-		entry->hash = ast_str_hash(entry->name);
+		strcpy(member->name, piece);/* Safe */
+		member->hash = ast_str_hash(member->name);
+
 		/* every group name may exist only once, delete duplicates */
-		ao2_find(namedgroups->container, entry, OBJ_POINTER | OBJ_UNLINK | OBJ_NODATA);
-		ao2_link(namedgroups->container, entry);
-		ao2_ref(entry, -1);
+		ao2_find(namedgroups, member, OBJ_POINTER | OBJ_UNLINK | OBJ_NODATA);
+		ao2_link(namedgroups, member);
+		ao2_ref(member, -1);
 	}
 
-	if (ao2_container_count(namedgroups->container) == 0) {
+	if (!ao2_container_count(namedgroups)) {
+		/* There were no group names specified. */
 		ao2_ref(namedgroups, -1);
 		namedgroups = NULL;
 	}
 
-	return namedgroups;
+	return (struct ast_namedgroups *) namedgroups;
 }
 
 struct ast_namedgroups *ast_unref_namedgroups(struct ast_namedgroups *groups)
@@ -8560,26 +8549,24 @@ char *ast_print_group(char *buf, int buflen, ast_group_t group)
 	return buf;
 }
 
-/*! \brief Print named call group and named pickup group ---*/
 char *ast_print_namedgroups(struct ast_str **buf, struct ast_namedgroups *group)
 {
-	struct namedgroup_entry *ng;
+	struct ao2_container *grp = (struct ao2_container *) group;
+	struct namedgroup_member *ng;
 	int first = 1;
 	struct ao2_iterator it;
 
-	if (group == NULL) {
+	if (!grp) {
 		return ast_str_buffer(*buf);
 	}
 
-	it = ao2_iterator_init(group->container, 0);
-	while ((ng = ao2_iterator_next(&it))) {
+	for (it = ao2_iterator_init(grp, 0); (ng = ao2_iterator_next(&it)); ao2_ref(ng, -1)) {
 		if (!first) {
 			ast_str_append(buf, 0, ", ");
 		} else {
 			first = 0;
 		}
 		ast_str_append(buf, 0, "%s", ng->name);
-		ao2_ref(ng, -1);
 	}
 	ao2_iterator_destroy(&it);
 
@@ -8598,16 +8585,24 @@ static int namedgroup_match(void *obj, void *arg, int flags)
 
 int ast_namedgroups_intersect(struct ast_namedgroups *a, struct ast_namedgroups *b)
 {
-	/*
-	 * Do a and b intersect? Since b is hash table average time complexity is O(|a|)
-	 */
 	void *match;
+	struct ao2_container *group_a = (struct ao2_container *) a;
+	struct ao2_container *group_b = (struct ao2_container *) b;
 
 	if (!a || !b) {
 		return 0;
 	}
 
-	match = ao2_callback(a->container, 0, namedgroup_match, b->container);
+	/*
+	 * Do groups a and b intersect?  Since a and b are hash tables,
+	 * the average time complexity is:
+	 * O(a.count <= b.count ? a.count : b.count)
+	 */
+	if (ao2_container_count(group_b) < ao2_container_count(group_a)) {
+		/* Traverse over the smaller group. */
+		SWAP(group_a, group_b);
+	}
+	match = ao2_callback(group_a, 0, namedgroup_match, group_b);
 	ao2_cleanup(match);
 
 	return match != NULL;
diff --git a/main/features.c b/main/features.c
index 0650129c0..f89ca816d 100644
--- a/main/features.c
+++ b/main/features.c
@@ -7707,80 +7707,117 @@ int ast_can_pickup(struct ast_channel *chan)
 static int find_channel_by_group(void *obj, void *arg, void *data, int flags)
 {
 	struct ast_channel *target = obj;/*!< Potential pickup target */
-	struct ast_channel *chan = data;/*!< Channel wanting to pickup call */
+	struct ast_channel *chan = arg;/*!< Channel wanting to pickup call */
+
+	if (chan == target) {
+		return 0;
+	}
 
 	ast_channel_lock(target);
+	if (ast_can_pickup(target)) {
+		/* Lock both channels. */
+		while (ast_channel_trylock(chan)) {
+			ast_channel_unlock(target);
+			sched_yield();
+			ast_channel_lock(target);
+		}
 
-	/*
-	 * Both, callgroup and namedcallgroup pickup variants are matched independently.
-	 * Checking for named group match is done last since it's a rather expensive operation.
-	 */
-	if (chan != target && ast_can_pickup(target)
-		&& ((ast_channel_pickupgroup(chan) & ast_channel_callgroup(target))
-			|| (ast_namedgroups_intersect(ast_channel_named_pickupgroups(chan), ast_channel_named_callgroups(target))))) {
 		/*
-		 * Return with the channel unlocked on purpose, else we would lock many channels with the chance for deadlock
+		 * Both callgroup and namedcallgroup pickup variants are
+		 * matched independently.  Checking for named group match is
+		 * done last since it's a more expensive operation.
 		 */
-		ast_channel_unlock(target);
-		return CMP_MATCH;
+		if ((ast_channel_pickupgroup(chan) & ast_channel_callgroup(target))
+			|| (ast_namedgroups_intersect(ast_channel_named_pickupgroups(chan),
+				ast_channel_named_callgroups(target)))) {
+			struct ao2_container *candidates = data;/*!< Candidate channels found. */
+
+			/* This is a candidate to pickup */
+			ao2_link(candidates, target);
+		}
+		ast_channel_unlock(chan);
 	}
 	ast_channel_unlock(target);
 
 	return 0;
 }
 
-/*!
- * \brief Pickup a call
- * \param chan channel that initiated pickup.
- *
- * Walk list of channels, checking it is not itself, channel is pbx one,
- * check that the callgroup for both channels are the same and the channel is ringing.
- * Answer calling channel, flag channel as answered on queue, masq channels together.
- */
-int ast_pickup_call(struct ast_channel *chan)
+struct ast_channel *ast_pickup_find_by_group(struct ast_channel *chan)
 {
+	struct ao2_container *candidates;/*!< Candidate channels found to pickup. */
 	struct ast_channel *target;/*!< Potential pickup target */
-	struct ao2_iterator *targets_it;/*!< Potential pickup targets, must find the oldest of them */
-	struct ast_channel *candidate;/*!< Potential new older target */
-	int res = -1;
-	ast_debug(1, "pickup attempt by %s\n", ast_channel_name(chan));
 
-	/*
-	 * Transfer all pickup-able channels to another container-iterator.
-	 * Iterate it to find the oldest channel.
-	 */
-	targets_it = (struct ao2_iterator *) ast_channel_callback(find_channel_by_group,
-		NULL, chan, OBJ_MULTIPLE);
-	if (!targets_it) {
-		/* Search really failed. */
-		goto no_pickup_calls;
+	candidates = ao2_container_alloc_options(AO2_ALLOC_OPT_LOCK_NOLOCK, 1, NULL, NULL);
+	if (!candidates) {
+		return NULL;
 	}
 
+	/* Find all candidate targets by group. */
+	ast_channel_callback(find_channel_by_group, chan, candidates, 0);
+
+	/* Find the oldest pickup target candidate */
 	target = NULL;
-	while ((candidate = ao2_iterator_next(targets_it))) {
-		if (!target) {
-			target = candidate;
-			continue;
+	for (;;) {
+		struct ast_channel *candidate;/*!< Potential new older target */
+		struct ao2_iterator iter;
+
+		iter = ao2_iterator_init(candidates, 0);
+		while ((candidate = ao2_iterator_next(&iter))) {
+			if (!target) {
+				/* First target. */
+				target = candidate;
+				continue;
+			}
+			if (ast_tvcmp(ast_channel_creationtime(candidate), ast_channel_creationtime(target)) < 0) {
+				/* We have a new target. */
+				ast_channel_unref(target);
+				target = candidate;
+				continue;
+			}
+			ast_channel_unref(candidate);
 		}
-		if (ast_tvcmp(ast_channel_creationtime(candidate), ast_channel_creationtime(target)) < 0) {
-			ast_channel_unref(target);
-			target = candidate;
-			continue;
+		ao2_iterator_destroy(&iter);
+		if (!target) {
+			/* No candidates found. */
+			break;
 		}
-		ast_channel_unref(candidate);
-	}
-	ao2_iterator_destroy(targets_it);
-	if (target) {
+
 		/* The found channel must be locked and ref'd. */
 		ast_channel_lock(target);
+
 		/* Recheck pickup ability */
-		if (!ast_can_pickup(target)) {
-			/* Someone else picked it up or the call went away. */
-			ast_channel_unlock(target);
-			target = ast_channel_unref(target);
+		if (ast_can_pickup(target)) {
+			/* This is the channel to pickup. */
+			break;
 		}
+
+		/* Someone else picked it up or the call went away. */
+		ast_channel_unlock(target);
+		ao2_unlink(candidates, target);
+		target = ast_channel_unref(target);
 	}
+	ao2_ref(candidates, -1);
+
+	return target;
+}
+
+/*!
+ * \brief Pickup a call
+ * \param chan channel that initiated pickup.
+ *
+ * Walk list of channels, checking it is not itself, channel is pbx one,
+ * check that the callgroup for both channels are the same and the channel is ringing.
+ * Answer calling channel, flag channel as answered on queue, masq channels together.
+ */
+int ast_pickup_call(struct ast_channel *chan)
+{
+	struct ast_channel *target;/*!< Potential pickup target */
+	int res = -1;
+
+	ast_debug(1, "pickup attempt by %s\n", ast_channel_name(chan));
 
+	/* The found channel is already locked. */
+	target = ast_pickup_find_by_group(chan);
 	if (target) {
 		ast_log(LOG_NOTICE, "pickup %s attempt by %s\n", ast_channel_name(target), ast_channel_name(chan));
 
@@ -7796,7 +7833,6 @@ int ast_pickup_call(struct ast_channel *chan)
 		target = ast_channel_unref(target);
 	}
 
-no_pickup_calls:
 	if (res < 0) {
 		ast_debug(1, "No call pickup possible... for %s\n", ast_channel_name(chan));
 		if (!ast_strlen_zero(pickupfailsound)) {