core: new parameter async_usleep

- add option to do usleep() before processing async tasks
- could help saving cpu usage on vms with immediate interruptions
  triggered to recvfrom()

async_task.c

@@ -46,6 +46,7 @@
 
 static int _async_task_workers = 0;
 static int _async_task_sockets[2];
+static int _async_task_usleep = 0;
 
 int async_task_run(int idx);
 
@@ -174,6 +175,19 @@ int async_task_set_workers(int n)
 	return 0;
 }
 
+/**
+ *
+ */
+int async_task_set_usleep(int n)
+{
+	int v;
+
+	v = _async_task_usleep;
+	_async_task_usleep = n;
+
+	return v;
+}
+
 /**
  *
  */
@@ -204,6 +218,7 @@ int async_task_run(int idx)
 	LM_DBG("async task worker %d ready\n", idx);
 
 	for( ; ; ) {
+		if(unlikely(_async_task_usleep)) sleep_us(_async_task_usleep);
 		if ((received = recvfrom(_async_task_sockets[0],
 							&ptask, sizeof(async_task_t*),
 							0, NULL, 0)) < 0) {

async_task.h

@@ -36,5 +36,6 @@ int async_task_child_init(int rank);
 int async_task_initialized(void);
 int async_task_set_workers(int n);
 int async_task_push(async_task_t *task);
+int async_task_set_usleep(int n);
 
 #endif

cfg.lex

@@ -400,6 +400,7 @@ SQL_BUFFER_SIZE sql_buffer_size
 CHILDREN children
 SOCKET_WORKERS socket_workers
 ASYNC_WORKERS async_workers
+ASYNC_USLEEP async_usleep
 CHECK_VIA	check_via
 PHONE2TEL	phone2tel
 MEMLOG		"memlog"|"mem_log"
@@ -810,6 +811,7 @@ IMPORTFILE      "import_file"
 <INITIAL>{CHILDREN}	{ count(); yylval.strval=yytext; return CHILDREN; }
 <INITIAL>{SOCKET_WORKERS}	{ count(); yylval.strval=yytext; return SOCKET_WORKERS; }
 <INITIAL>{ASYNC_WORKERS}	{ count(); yylval.strval=yytext; return ASYNC_WORKERS; }
+<INITIAL>{ASYNC_USLEEP}	{ count(); yylval.strval=yytext; return ASYNC_USLEEP; }
 <INITIAL>{CHECK_VIA}	{ count(); yylval.strval=yytext; return CHECK_VIA; }
 <INITIAL>{PHONE2TEL}	{ count(); yylval.strval=yytext; return PHONE2TEL; }
 <INITIAL>{MEMLOG}	{ count(); yylval.strval=yytext; return MEMLOG; }

cfg.y

@@ -446,6 +446,7 @@ extern char *default_routename;
 %token CHILDREN
 %token SOCKET_WORKERS
 %token ASYNC_WORKERS
+%token ASYNC_USLEEP
 %token CHECK_VIA
 %token PHONE2TEL
 %token MEMLOG
@@ -954,6 +955,8 @@ assign_stm:
 	| SOCKET_WORKERS EQUAL error { yyerror("number expected"); }
 	| ASYNC_WORKERS EQUAL NUMBER { async_task_set_workers($3); }
 	| ASYNC_WORKERS EQUAL error { yyerror("number expected"); }
+	| ASYNC_USLEEP EQUAL NUMBER { async_task_set_usleep($3); }
+	| ASYNC_USLEEP EQUAL error { yyerror("number expected"); }
 	| CHECK_VIA EQUAL NUMBER { check_via=$3; }
 	| CHECK_VIA EQUAL error { yyerror("boolean value expected"); }
 	| PHONE2TEL EQUAL NUMBER { phone2tel=$3; }