file_out: make worker sleep period configurable, to allow to adapt performance parameters

src/modules/file_out/doc/file_out_admin.xml

@@ -135,6 +135,25 @@ modparam("file_out", "extension", ".txt")
 				<programlisting format="linespecific">
 ...
 modparam("file_out", "interval_seconds", "300")
+...
+				</programlisting>
+			</example>
+
+			<title>
+				<varname>worker_usleep</varname> (int)</title>
+			<para>
+		The time in microseconds which worker will sleep for until next iteration.
+			</para>
+			<para>
+				<emphasis>
+		    Default value is <quote>10000</quote> (10 ms).
+				</emphasis>
+			</para>
+			<example>
+				<title>Set <varname>worker_usleep</varname> parameter</title>
+				<programlisting format="linespecific">
+...
+modparam("file_out", "worker_usleep", "1000")
 ...
 				</programlisting>
 			</example>

src/modules/file_out/file_out.c

@@ -61,6 +61,7 @@ char *fo_base_folder = "/var/log/kamailio/file_out/";
 char *fo_base_filename[FO_MAX_FILES] = {""};
 char *fo_extension = ".out";
 int fo_interval_seconds = 10 * 60;
+int fo_worker_usleep = 10000;
 
 /* Shared variables */
 fo_queue_t *fo_queue = NULL;
@@ -78,7 +79,8 @@ static param_export_t params[] = {
 		{"base_folder", PARAM_STRING, &fo_base_folder},
 		{"base_filename", PARAM_STRING | PARAM_USE_FUNC, &fo_add_filename},
 		{"interval_seconds", PARAM_INT, &fo_interval_seconds},
-		{"extension", PARAM_STRING, &fo_extension}, {0, 0, 0}};
+		{"extension", PARAM_STRING, &fo_extension},
+		{"worker_usleep", PARAM_INT, &fo_worker_usleep}, {0, 0, 0}};
 
 struct module_exports exports = {
 		"file_out",		 /* module name */
@@ -139,7 +141,7 @@ static int child_init(int rank)
 		return 0;
 	}
 
-	pid = fork_process(PROC_NOCHLDINIT, "log_writ", 1);
+	pid = fork_process(PROC_NOCHLDINIT, "fo_writer", 1);
 	if(pid < 0) {
 		LM_ERR("fork failed\n");
 		return -1; /* error */
@@ -159,7 +161,7 @@ static int child_init(int rank)
 			/* update the local config framework structures */
 			cfg_update();
 
-			usleep(10000);
+			usleep(fo_worker_usleep);
 			fo_log_writer_process(rank);
 		}
 		// return 0;