res_pjsip: Always set async_operations to 1.

The async_operations setting on a transport configures how
many simultaneous incoming packets the transport can handle
when multiple threads are polling and waiting on the transport.
As we only use a single thread this was needlessly creating
incoming packets when set to a non-default value, wasting memory.

ASTERISK-30006

Change-Id: I1915973ef352862dc2852a6ba4cfce2ed536e68f

configs/samples/pjsip.conf.sample

@@ -972,8 +972,6 @@
 ;[transport]
 ;  SYNOPSIS: SIP Transport
 ;
-;async_operations=1     ; Number of simultaneous Asynchronous Operations
-                        ; (default: "1")
 ;bind=  ; IP Address and optional port to bind to for this transport (default:
         ; "")
 ; Note that for the Websocket transport the TLS configuration is configured

doc/UPGRADE-staging/res_pjsip_async_operations.txt

@@ -0,0 +1,7 @@
+Subject: res_pjsip
+
+The 'async_operations' setting on transports is no longer
+obeyed and instead is always set to 1. This is due to the
+functionality not being applicable to Asterisk and causing
+excess unnecessary memory usage. This setting will now be
+ignored but can also be removed from the configuration file.

res/res_pjsip/config_transport.c

@@ -489,6 +489,12 @@ static int transport_apply(const struct ast_sorcery *sorcery, void *obj)
 		return -1;
 	}
 
+	if (transport->async_operations != 1) {
+		ast_log(LOG_WARNING, "The async_operations setting on transport '%s' has been set to '%d'. The setting can no longer be set and is always 1.\n",
+			transport_id, transport->async_operations);
+		transport->async_operations = 1;
+	}
+
 	perm_state = find_internal_state_by_transport(transport);
 	if (perm_state) {
 		ast_sorcery_diff(sorcery, perm_state->transport, transport, &changes);

res/res_pjsip/pjsip_config.xml

@@ -1305,7 +1305,7 @@
 						will not suffice.</para></note>
 				</description>
 				<configOption name="async_operations" default="1">
-					<synopsis>Number of simultaneous Asynchronous Operations</synopsis>
+					<synopsis>Number of simultaneous Asynchronous Operations, can no longer be set, always set to 1</synopsis>
 				</configOption>
 				<configOption name="bind">
 					<synopsis>IP Address and optional port to bind to for this transport</synopsis>