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

4 files changed, 65 insertions, 25 deletions

diff --git a/funcs/func_channel.c b/funcs/func_channel.c
index 5cf262154..bd6eaae42 100644
--- a/funcs/func_channel.c
+++ b/funcs/func_channel.c
@@ -352,7 +352,8 @@ static int func_channels_read(struct ast_channel *chan, const char *function, ch
 	regex_t re;
 	int res;
 	size_t buflen = 0;
-	
+	struct ast_channel_iterator *iter;
+
 	buf[0] = '\0';
 
 	if (!ast_strlen_zero(data)) {
@@ -363,7 +364,15 @@ static int func_channels_read(struct ast_channel *chan, const char *function, ch
 		}
 	}
 
-	for (c = ast_channel_walk_locked(NULL); c; ast_channel_unlock(c), c = ast_channel_walk_locked(c)) {
+	if (!(iter = ast_channel_iterator_all_new(0))) {
+		if (!ast_strlen_zero(data)) {
+			regfree(&re);
+		}
+		return -1;
+	}
+
+	while ((c = ast_channel_iterator_next(iter))) {
+		ast_channel_lock(c);
 		if (ast_strlen_zero(data) || regexec(&re, c->name, 0, NULL, 0) == 0) {
 			size_t namelen = strlen(c->name);
 			if (buflen + namelen + (ast_strlen_zero(buf) ? 0 : 1) + 1 < maxlen) {
@@ -377,8 +386,12 @@ static int func_channels_read(struct ast_channel *chan, const char *function, ch
 				ast_log(LOG_WARNING, "Number of channels exceeds the available buffer space.  Output will be truncated!\n");
 			}
 		}
+		ast_channel_unlock(c);
+		c = ast_channel_unref(c);
 	}
 
+	ast_channel_iterator_destroy(iter);
+
 	if (!ast_strlen_zero(data)) {
 		regfree(&re);
 	}
diff --git a/funcs/func_global.c b/funcs/func_global.c
index 74df1757c..a501aee58 100644
--- a/funcs/func_global.c
+++ b/funcs/func_global.c
@@ -134,6 +134,7 @@ static int shared_read(struct ast_channel *chan, const char *cmd, char *data, ch
 		AST_APP_ARG(var);
 		AST_APP_ARG(chan);
 	);
+	struct ast_channel *c_ref = NULL;
 
 	if (ast_strlen_zero(data)) {
 		ast_log(LOG_WARNING, "SHARED() requires an argument: SHARED(<var>[,<chan>])\n");
@@ -145,15 +146,20 @@ static int shared_read(struct ast_channel *chan, const char *cmd, char *data, ch
 	if (!ast_strlen_zero(args.chan)) {
 		char *prefix = alloca(strlen(args.chan) + 2);
 		sprintf(prefix, "%s-", args.chan);
-		if (!(chan = ast_get_channel_by_name_locked(args.chan)) && !(chan = ast_get_channel_by_name_prefix_locked(prefix, strlen(prefix)))) {
+		if (!(c_ref = ast_channel_get_by_name(args.chan)) && !(c_ref = ast_channel_get_by_name_prefix(prefix, strlen(prefix)))) {
 			ast_log(LOG_ERROR, "Channel '%s' not found!  Variable '%s' will be blank.\n", args.chan, args.var);
 			return -1;
 		}
-	} else
-		ast_channel_lock(chan);
+		chan = c_ref;
+	}
+
+	ast_channel_lock(chan);
 
 	if (!(varstore = ast_channel_datastore_find(chan, &shared_variable_info, NULL))) {
 		ast_channel_unlock(chan);
+		if (c_ref) {
+			c_ref = ast_channel_unref(c_ref);
+		}
 		return -1;
 	}
 
@@ -170,6 +176,10 @@ static int shared_read(struct ast_channel *chan, const char *cmd, char *data, ch
 
 	ast_channel_unlock(chan);
 
+	if (c_ref) {
+		c_ref = ast_channel_unref(c_ref);
+	}
+
 	return 0;
 }
 
@@ -182,6 +192,7 @@ static int shared_write(struct ast_channel *chan, const char *cmd, char *data, c
 		AST_APP_ARG(var);
 		AST_APP_ARG(chan);
 	);
+	struct ast_channel *c_ref = NULL;
 
 	if (ast_strlen_zero(data)) {
 		ast_log(LOG_WARNING, "SHARED() requires an argument: SHARED(<var>[,<chan>])\n");
@@ -193,17 +204,22 @@ static int shared_write(struct ast_channel *chan, const char *cmd, char *data, c
 	if (!ast_strlen_zero(args.chan)) {
 		char *prefix = alloca(strlen(args.chan) + 2);
 		sprintf(prefix, "%s-", args.chan);
-		if (!(chan = ast_get_channel_by_name_locked(args.chan)) && !(chan = ast_get_channel_by_name_prefix_locked(prefix, strlen(prefix)))) {
+		if (!(c_ref = ast_channel_get_by_name(args.chan)) && !(c_ref = ast_channel_get_by_name_prefix(prefix, strlen(prefix)))) {
 			ast_log(LOG_ERROR, "Channel '%s' not found!  Variable '%s' not set to '%s'.\n", args.chan, args.var, value);
 			return -1;
 		}
-	} else
-		ast_channel_lock(chan);
+		chan = c_ref;
+	}
+
+	ast_channel_lock(chan);
 
 	if (!(varstore = ast_channel_datastore_find(chan, &shared_variable_info, NULL))) {
 		if (!(varstore = ast_datastore_alloc(&shared_variable_info, NULL))) {
 			ast_log(LOG_ERROR, "Unable to allocate new datastore.  Shared variable not set.\n");
 			ast_channel_unlock(chan);
+			if (c_ref) {
+				c_ref = ast_channel_unref(c_ref);
+			}
 			return -1;
 		}
 
@@ -211,6 +227,9 @@ static int shared_write(struct ast_channel *chan, const char *cmd, char *data, c
 			ast_log(LOG_ERROR, "Unable to allocate variable structure.  Shared variable not set.\n");
 			ast_datastore_free(varstore);
 			ast_channel_unlock(chan);
+			if (c_ref) {
+				c_ref = ast_channel_unref(c_ref);
+			}
 			return -1;
 		}
 
@@ -241,6 +260,10 @@ static int shared_write(struct ast_channel *chan, const char *cmd, char *data, c
 
 	ast_channel_unlock(chan);
 
+	if (c_ref) {
+		c_ref = ast_channel_unref(c_ref);
+	}
+
 	return 0;
 }
 
diff --git a/funcs/func_logic.c b/funcs/func_logic.c
index cd4f18e9b..6ec3a0847 100644
--- a/funcs/func_logic.c
+++ b/funcs/func_logic.c
@@ -230,18 +230,22 @@ static int acf_import(struct ast_channel *chan, const char *cmd, char *data, cha
 		AST_APP_ARG(varname);
 	);
 	AST_STANDARD_APP_ARGS(args, data);
-	buf[0] = 0;
+
+	buf[0] = '\0';
+
 	if (!ast_strlen_zero(args.varname)) {
-		struct ast_channel *chan2 = ast_get_channel_by_name_locked(args.channel);
-		if (chan2) {
+		struct ast_channel *chan2;
+
+		if ((chan2 = ast_channel_get_by_name(args.channel))) {
 			char *s = alloca(strlen(args.varname) + 4);
-			if (s) {
-				sprintf(s, "${%s}", args.varname);
-				pbx_substitute_variables_helper(chan2, s, buf, len);
-			}
+			sprintf(s, "${%s}", args.varname);
+			ast_channel_lock(chan2);
+			pbx_substitute_variables_helper(chan2, s, buf, len);
 			ast_channel_unlock(chan2);
+			chan2 = ast_channel_unref(chan2);
 		}
 	}
+
 	return 0;
 }
 
diff --git a/funcs/func_odbc.c b/funcs/func_odbc.c
index 385144e86..b754d3b7f 100644
--- a/funcs/func_odbc.c
+++ b/funcs/func_odbc.c
@@ -257,7 +257,7 @@ static int acf_odbc_write(struct ast_channel *chan, const char *cmd, char *s, co
 		if (chan)
 			ast_autoservice_stop(chan);
 		if (bogus_chan) {
-			ast_channel_free(chan);
+			ast_channel_release(chan);
 		} else {
 			pbx_builtin_setvar_helper(chan, "ODBCSTATUS", status);
 		}
@@ -367,7 +367,7 @@ static int acf_odbc_write(struct ast_channel *chan, const char *cmd, char *s, co
 	if (chan)
 		ast_autoservice_stop(chan);
 	if (bogus_chan)
-		ast_channel_free(chan);
+		ast_channel_release(chan);
 
 	return 0;
 }
@@ -473,7 +473,7 @@ static int acf_odbc_read(struct ast_channel *chan, const char *cmd, char *s, cha
 			ast_autoservice_stop(chan);
 		}
 		if (bogus_chan) {
-			ast_channel_free(chan);
+			ast_channel_release(chan);
 		}
 		return -1;
 	}
@@ -490,7 +490,7 @@ static int acf_odbc_read(struct ast_channel *chan, const char *cmd, char *s, cha
 			ast_autoservice_stop(chan);
 		}
 		if (bogus_chan) {
-			ast_channel_free(chan);
+			ast_channel_release(chan);
 		}
 		return -1;
 	}
@@ -517,7 +517,7 @@ static int acf_odbc_read(struct ast_channel *chan, const char *cmd, char *s, cha
 		if (chan)
 			ast_autoservice_stop(chan);
 		if (bogus_chan)
-			ast_channel_free(chan);
+			ast_channel_release(chan);
 		return res1;
 	}
 
@@ -560,7 +560,7 @@ static int acf_odbc_read(struct ast_channel *chan, const char *cmd, char *s, cha
 						if (chan)
 							ast_autoservice_stop(chan);
 						if (bogus_chan)
-							ast_channel_free(chan);
+							ast_channel_release(chan);
 						return -1;
 					}
 					resultset = tmp;
@@ -656,7 +656,7 @@ end_acf_read:
 			if (chan)
 				ast_autoservice_stop(chan);
 			if (bogus_chan)
-				ast_channel_free(chan);
+				ast_channel_release(chan);
 			return -1;
 		}
 		odbc_store->data = resultset;
@@ -669,7 +669,7 @@ end_acf_read:
 	if (chan)
 		ast_autoservice_stop(chan);
 	if (bogus_chan)
-		ast_channel_free(chan);
+		ast_channel_release(chan);
 	return 0;
 }
 
@@ -1059,7 +1059,7 @@ static char *cli_odbc_read(struct ast_cli_entry *e, int cmd, struct ast_cli_args
 	}
 
 	ast_str_substitute_variables(&sql, 0, chan, query->sql_read);
-	ast_channel_free(chan);
+	chan = ast_channel_release(chan);
 
 	if (a->argc == 5 && !strcmp(a->argv[4], "exec")) {
 		/* Execute the query */
@@ -1272,7 +1272,7 @@ static char *cli_odbc_write(struct ast_cli_entry *e, int cmd, struct ast_cli_arg
 	pbx_builtin_pushvar_helper(chan, "VALUE", S_OR(a->argv[4], ""));
 	ast_str_substitute_variables(&sql, 0, chan, query->sql_write);
 	ast_debug(1, "SQL is %s\n", ast_str_buffer(sql));
-	ast_channel_free(chan);
+	chan = ast_channel_release(chan);
 
 	if (a->argc == 6 && !strcmp(a->argv[5], "exec")) {
 		/* Execute the query */