Convert the ast_channel data structure over to the astobj2 framework.

There is a lot that could be said about this, but the patch is a big 
improvement for performance, stability, code maintainability, 
and ease of future code development.

The channel list is no longer an unsorted linked list.  The main container 
for channels is an astobj2 hash table.  All of the code related to searching 
for channels or iterating active channels has been rewritten.  Let n be 
the number of active channels.  Iterating the channel list has gone from 
O(n^2) to O(n).  Searching for a channel by name went from O(n) to O(1).  
Searching for a channel by extension is still O(n), but uses a new method 
for doing so, which is more efficient.

The ast_channel object is now a reference counted object.  The benefits 
here are plentiful.  Some benefits directly related to issues in the 
previous code include:

1) When threads other than the channel thread owning a channel wanted 
   access to a channel, it had to hold the lock on it to ensure that it didn't 
   go away.  This is no longer a requirement.  Holding a reference is 
   sufficient.

2) There are places that now require less dealing with channel locks.

3) There are places where channel locks are held for much shorter periods 
   of time.

4) There are places where dealing with more than one channel at a time becomes 
   _MUCH_ easier.  ChanSpy is a great example of this.  Writing code in the 
   future that deals with multiple channels will be much easier.

Some additional information regarding channel locking and reference count 
handling can be found in channel.h, where a new section has been added that 
discusses some of the rules associated with it.

Mark Michelson also assisted with the development of this patch.  He did the 
conversion of ChanSpy and introduced a new API, ast_autochan, which makes it 
much easier to deal with holding on to a channel pointer for an extended period 
of time and having it get automatically updated if the channel gets masqueraded.
Mark was also a huge help in the code review process.

Thanks to David Vossel for his assistance with this branch, as well.  David 
did the conversion of the DAHDIScan application by making it become a wrapper 
for ChanSpy internally.

The changes come from the svn/asterisk/team/russell/ast_channel_ao2 branch.

Review: http://reviewboard.digium.com/r/203/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@190423 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 116 insertions, 85 deletions

diff --git a/main/features.c b/main/features.c
index 62263142a..5c311625e 100644
--- a/main/features.c
+++ b/main/features.c
@@ -720,11 +720,13 @@ static int park_call_full(struct ast_channel *chan, struct ast_channel *peer, st
 			if ((c = strrchr(other_side, ';'))) {
 				*++c = '1';
 			}
-			if ((tmpchan = ast_get_channel_by_name_locked(other_side))) {
+			if ((tmpchan = ast_channel_get_by_name(other_side))) {
+				ast_channel_lock(tmpchan);
 				if ((base_peer = ast_bridged_channel(tmpchan))) {
 					ast_copy_string(pu->peername, base_peer->name, sizeof(pu->peername));
 				}
 				ast_channel_unlock(tmpchan);
+				tmpchan = ast_channel_unref(tmpchan);
 			}
 		} else {
 			ast_copy_string(pu->peername, S_OR(args->orig_chan_name, peer->name), sizeof(pu->peername));
@@ -2883,33 +2885,35 @@ int ast_bridge_call(struct ast_channel *chan,struct ast_channel *peer,struct ast
 	      to attend to; if the chan or peer changed names,
 	      we have the before and after attached CDR's.
 	*/
-	
+
 	if (new_chan_cdr) {
 		struct ast_channel *chan_ptr = NULL;
- 
- 		if (strcasecmp(orig_channame, chan->name) != 0) { 
- 			/* old channel */
- 			chan_ptr = ast_get_channel_by_name_locked(orig_channame);
- 			if (chan_ptr) {
- 				if (!ast_bridged_channel(chan_ptr)) {
- 					struct ast_cdr *cur;
- 					for (cur = chan_ptr->cdr; cur; cur = cur->next) {
- 						if (cur == chan_cdr) {
- 							break;
- 						}
- 					}
- 					if (cur)
- 						ast_cdr_specialized_reset(chan_cdr,0);
- 				}
- 				ast_channel_unlock(chan_ptr);
- 			}
- 			/* new channel */
- 			ast_cdr_specialized_reset(new_chan_cdr,0);
- 		} else {
- 			ast_cdr_specialized_reset(chan_cdr,0); /* nothing changed, reset the chan_cdr  */
- 		}
+
+		if (strcasecmp(orig_channame, chan->name) != 0) { 
+			/* old channel */
+			if ((chan_ptr == ast_channel_get_by_name(orig_channame))) {
+				ast_channel_lock(chan_ptr);
+				if (!ast_bridged_channel(chan_ptr)) {
+					struct ast_cdr *cur;
+					for (cur = chan_ptr->cdr; cur; cur = cur->next) {
+						if (cur == chan_cdr) {
+							break;
+						}
+					}
+					if (cur) {
+						ast_cdr_specialized_reset(chan_cdr, 0);
+					}
+				}
+				ast_channel_unlock(chan_ptr);
+				chan_ptr = ast_channel_unref(chan_ptr);
+			}
+			/* new channel */
+			ast_cdr_specialized_reset(new_chan_cdr, 0);
+		} else {
+			ast_cdr_specialized_reset(chan_cdr, 0); /* nothing changed, reset the chan_cdr  */
+		}
 	}
-	
+
 	{
 		struct ast_channel *chan_ptr = NULL;
 		new_peer_cdr = pick_unlocked_cdr(peer->cdr); /* the proper chan cdr, if there are forked cdrs */
@@ -2917,8 +2921,8 @@ int ast_bridge_call(struct ast_channel *chan,struct ast_channel *peer,struct ast
 			ast_set_flag(new_peer_cdr, AST_CDR_FLAG_POST_DISABLED); /* DISABLED is viral-- it will propagate across a bridge */
 		if (strcasecmp(orig_peername, peer->name) != 0) { 
 			/* old channel */
-			chan_ptr = ast_get_channel_by_name_locked(orig_peername);
-			if (chan_ptr) {
+			if ((chan_ptr = ast_channel_get_by_name(orig_peername))) {
+				ast_channel_lock(chan_ptr);
 				if (!ast_bridged_channel(chan_ptr)) {
 					struct ast_cdr *cur;
 					for (cur = chan_ptr->cdr; cur; cur = cur->next) {
@@ -2926,15 +2930,17 @@ int ast_bridge_call(struct ast_channel *chan,struct ast_channel *peer,struct ast
 							break;
 						}
 					}
-					if (cur)
-						ast_cdr_specialized_reset(peer_cdr,0);
+					if (cur) {
+						ast_cdr_specialized_reset(peer_cdr, 0);
+					}
 				}
 				ast_channel_unlock(chan_ptr);
+				chan_ptr = ast_channel_unref(chan_ptr);
 			}
 			/* new channel */
-			ast_cdr_specialized_reset(new_peer_cdr,0);
+			ast_cdr_specialized_reset(new_peer_cdr, 0);
 		} else {
-			ast_cdr_specialized_reset(peer_cdr,0); /* nothing changed, reset the peer_cdr  */
+			ast_cdr_specialized_reset(peer_cdr, 0); /* nothing changed, reset the peer_cdr  */
 		}
 	}
 	
@@ -4157,12 +4163,8 @@ static int action_bridge(struct mansession *s, const struct message *m)
 		return 0;
 	}
 
-	/* The same code must be executed for chana and chanb.  To avoid a
-	 * theoretical deadlock, this code is separated so both chana and chanb will
-	 * not hold locks at the same time. */
-
 	/* Start with chana */
-	chana = ast_get_channel_by_name_prefix_locked(channela, strlen(channela));
+	chana = ast_channel_get_by_name_prefix(channela, strlen(channela));
 
 	/* send errors if any of the channels could not be found/locked */
 	if (!chana) {
@@ -4180,16 +4182,16 @@ static int action_bridge(struct mansession *s, const struct message *m)
 	if (!(tmpchana = ast_channel_alloc(0, AST_STATE_DOWN, NULL, NULL, NULL, 
 		NULL, NULL, 0, "Bridge/%s", chana->name))) {
 		astman_send_error(s, m, "Unable to create temporary channel!");
-		ast_channel_unlock(chana);
+		chana = ast_channel_unref(chana);
 		return 1;
 	}
 
 	do_bridge_masquerade(chana, tmpchana);
-	ast_channel_unlock(chana);
-	chana = NULL;
+
+	chana = ast_channel_unref(chana);
 
 	/* now do chanb */
-	chanb = ast_get_channel_by_name_prefix_locked(channelb, strlen(channelb));
+	chanb = ast_channel_get_by_name_prefix(channelb, strlen(channelb));
 	/* send errors if any of the channels could not be found/locked */
 	if (!chanb) {
 		char buf[256];
@@ -4208,12 +4210,13 @@ static int action_bridge(struct mansession *s, const struct message *m)
 		NULL, NULL, 0, "Bridge/%s", chanb->name))) {
 		astman_send_error(s, m, "Unable to create temporary channels!");
 		ast_hangup(tmpchana);
-		ast_channel_unlock(chanb);
+		chanb = ast_channel_unref(chanb);
 		return 1;
 	}
+
 	do_bridge_masquerade(chanb, tmpchanb);
-	ast_channel_unlock(chanb);
-	chanb = NULL;
+
+	chanb = ast_channel_unref(chanb);
 
 	/* make the channels compatible, send error if we fail doing so */
 	if (ast_channel_make_compatible(tmpchana, tmpchanb)) {
@@ -4408,21 +4411,24 @@ static int manager_park(struct mansession *s, const struct message *m)
 		return 0;
 	}
 
-	ch1 = ast_get_channel_by_name_locked(channel);
-	if (!ch1) {
+	if (!(ch1 = ast_channel_get_by_name(channel))) {
 		snprintf(buf, sizeof(buf), "Channel does not exist: %s", channel);
 		astman_send_error(s, m, buf);
 		return 0;
 	}
 
-	ch2 = ast_get_channel_by_name_locked(channel2);
-	if (!ch2) {
+	if (!(ch2 = ast_channel_get_by_name(channel2))) {
 		snprintf(buf, sizeof(buf), "Channel does not exist: %s", channel2);
 		astman_send_error(s, m, buf);
-		ast_channel_unlock(ch1);
+		ast_channel_unref(ch1);
 		return 0;
 	}
 
+	ast_channel_lock(ch1);
+	while (ast_channel_trylock(ch2)) {
+		CHANNEL_DEADLOCK_AVOIDANCE(ch1);
+	}
+
 	if (!ast_strlen_zero(timeout)) {
 		sscanf(timeout, "%d", &to);
 	}
@@ -4438,19 +4444,26 @@ static int manager_park(struct mansession *s, const struct message *m)
 	ast_channel_unlock(ch1);
 	ast_channel_unlock(ch2);
 
+	ch1 = ast_channel_unref(ch1);
+	ch2 = ast_channel_unref(ch2);
+
 	return 0;
 }
 
-static int find_channel_by_group(struct ast_channel *c, void *data) {
-	struct ast_channel *chan = data;
+static int find_channel_by_group(void *obj, void *arg, void *data, int flags)
+{
+	struct ast_channel *c = data;
+	struct ast_channel *chan = obj;
 
-	return !c->pbx &&
+	int i = !c->pbx &&
 		/* Accessing 'chan' here is safe without locking, because there is no way for
 		   the channel do disappear from under us at this point.  pickupgroup *could*
 		   change while we're here, but that isn't a problem. */
 		(c != chan) &&
 		(chan->pickupgroup & c->callgroup) &&
 		((c->_state == AST_STATE_RINGING) || (c->_state == AST_STATE_RING));
+
+	return i ? CMP_MATCH | CMP_STOP : 0;
 }
 
 /*!
@@ -4463,43 +4476,57 @@ static int find_channel_by_group(struct ast_channel *c, void *data) {
 */
 int ast_pickup_call(struct ast_channel *chan)
 {
-	struct ast_channel *cur = ast_channel_search_locked(find_channel_by_group, chan);
-
-	if (cur) {
-		struct ast_party_connected_line connected_caller;
-
-		int res = -1;
-		ast_debug(1, "Call pickup on chan '%s' by '%s'\n",cur->name, chan->name);
-
-		connected_caller = cur->connected;
-		connected_caller.source = AST_CONNECTED_LINE_UPDATE_SOURCE_ANSWER;
-		ast_channel_update_connected_line(chan, &connected_caller);
-
-		ast_party_connected_line_collect_caller(&connected_caller, &chan->cid);
-		connected_caller.source = AST_CONNECTED_LINE_UPDATE_SOURCE_ANSWER;
-		ast_channel_queue_connected_line_update(chan, &connected_caller);
+	struct ast_channel *cur;
+	struct ast_party_connected_line connected_caller;
+	int res;
+	const char *chan_name;
+	const char *cur_name;
 
-		res = ast_answer(chan);
-		if (res)
-			ast_log(LOG_WARNING, "Unable to answer '%s'\n", chan->name);
-		res = ast_queue_control(chan, AST_CONTROL_ANSWER);
-		if (res)
-			ast_log(LOG_WARNING, "Unable to queue answer on '%s'\n", chan->name);
-		res = ast_channel_masquerade(cur, chan);
-		if (res)
-			ast_log(LOG_WARNING, "Unable to masquerade '%s' into '%s'\n", chan->name, cur->name);		/* Done */
-		if (!ast_strlen_zero(pickupsound)) {
-			ast_stream_and_wait(cur, pickupsound, "");
-		}
-		ast_channel_unlock(cur);
-		return res;
-	} else	{
+	if (!(cur = ast_channel_callback(find_channel_by_group, NULL, chan, 0))) {
 		ast_debug(1, "No call pickup possible...\n");
 		if (!ast_strlen_zero(pickupfailsound)) {
 			ast_stream_and_wait(chan, pickupfailsound, "");
 		}
+		return -1;
 	}
-	return -1;
+
+	ast_channel_lock_both(cur, chan);
+
+	cur_name = ast_strdupa(cur->name);
+	chan_name = ast_strdupa(chan->name);
+
+	ast_debug(1, "Call pickup on chan '%s' by '%s'\n", cur_name, chan_name);
+
+	connected_caller = cur->connected;
+	connected_caller.source = AST_CONNECTED_LINE_UPDATE_SOURCE_ANSWER;
+	ast_channel_update_connected_line(chan, &connected_caller);
+
+	ast_party_connected_line_collect_caller(&connected_caller, &chan->cid);
+	connected_caller.source = AST_CONNECTED_LINE_UPDATE_SOURCE_ANSWER;
+	ast_channel_queue_connected_line_update(chan, &connected_caller);
+
+	ast_channel_unlock(cur);
+	ast_channel_unlock(chan);
+
+	if (ast_answer(chan)) {
+		ast_log(LOG_WARNING, "Unable to answer '%s'\n", chan_name);
+	}
+
+	if (ast_queue_control(chan, AST_CONTROL_ANSWER)) {
+		ast_log(LOG_WARNING, "Unable to queue answer on '%s'\n", chan_name);
+	}
+
+	if ((res = ast_channel_masquerade(cur, chan))) {
+		ast_log(LOG_WARNING, "Unable to masquerade '%s' into '%s'\n", chan_name, cur_name);
+	}
+
+	if (!ast_strlen_zero(pickupsound)) {
+		ast_stream_and_wait(cur, pickupsound, "");
+	}
+
+	cur = ast_channel_unref(cur);
+
+	return res;
 }
 
 static char *app_bridge = "Bridge";
@@ -4559,8 +4586,8 @@ static int bridge_exec(struct ast_channel *chan, void *data)
 	}
 
 	/* make sure we have a valid end point */
-	if (!(current_dest_chan = ast_get_channel_by_name_prefix_locked(args.dest_chan, 
-		strlen(args.dest_chan)))) {
+	if (!(current_dest_chan = ast_channel_get_by_name_prefix(args.dest_chan,
+			strlen(args.dest_chan)))) {
 		ast_log(LOG_WARNING, "Bridge failed because channel %s does not exists or we "
 			"cannot get its lock\n", args.dest_chan);
 		manager_event(EVENT_FLAG_CALL, "BridgeExec",
@@ -4573,8 +4600,9 @@ static int bridge_exec(struct ast_channel *chan, void *data)
 	}
 
 	/* answer the channel if needed */
-	if (current_dest_chan->_state != AST_STATE_UP)
+	if (current_dest_chan->_state != AST_STATE_UP) {
 		ast_answer(current_dest_chan);
+	}
 
 	/* try to allocate a place holder where current_dest_chan will be placed */
 	if (!(final_dest_chan = ast_channel_alloc(0, AST_STATE_DOWN, NULL, NULL, NULL, 
@@ -4601,6 +4629,7 @@ static int bridge_exec(struct ast_channel *chan, void *data)
 					"Channel2: %s\r\n", chan->name, final_dest_chan->name);
 		ast_hangup(final_dest_chan); /* may be we should return this channel to the PBX? */
 		pbx_builtin_setvar_helper(chan, "BRIDGERESULT", "INCOMPATIBLE");
+		current_dest_chan = ast_channel_unref(current_dest_chan);
 		return 0;
 	}
 
@@ -4618,6 +4647,8 @@ static int bridge_exec(struct ast_channel *chan, void *data)
 		}
 	}
 	
+	current_dest_chan = ast_channel_unref(current_dest_chan);
+
 	/* do the bridge */
 	ast_bridge_call(chan, final_dest_chan, &bconfig);