core: new global parameter log_prefix_mode

- if set to 0 (default), then log_prefix is evaluated when the sip
  message is received and then reused (recommended if the log_prefix has
  only variables that have same value for same message). This is the
  current behaviour of log_prefix evaluation.
- if set to 1, then the log prefix is evaluated before/after each config
  action (needs to be set when the log_prefix has variables that are
  different based on the context of config execution, e.g., $cfg(line))

action.c

@@ -1546,8 +1546,14 @@ int run_actions(struct run_act_ctx* h, struct action* a, struct sip_msg* msg)
 		if(unlikely(cfg_get(core, core_cfg, latency_limit_action)>0))
 			ms = TICKS_TO_MS(get_ticks_raw());
 		_cfg_crt_action = t;
+		if(unlikely(log_prefix_mode==1)) {
+			log_prefix_set(msg);
+		}
 		ret=do_action(h, t, msg);
 		_cfg_crt_action = 0;
+		if(unlikely(log_prefix_mode==1)) {
+			log_prefix_set(msg);
+		}
 		if(unlikely(cfg_get(core, core_cfg, latency_limit_action)>0)) {
 			ms = TICKS_TO_MS(get_ticks_raw()) - ms;
 			if(ms >= cfg_get(core, core_cfg, latency_limit_action)) {

cfg.lex

@@ -290,6 +290,7 @@ LOGFACILITY	log_facility
 LOGNAME		log_name
 LOGCOLOR	log_color
 LOGPREFIX	log_prefix
+LOGPREFIXMODE	log_prefix_mode
 LOGENGINETYPE	log_engine_type
 LOGENGINEDATA	log_engine_data
 LISTEN		listen
@@ -673,6 +674,7 @@ IMPORTFILE      "import_file"
 <INITIAL>{LOGNAME}	{ yylval.strval=yytext; return LOGNAME; }
 <INITIAL>{LOGCOLOR}	{ yylval.strval=yytext; return LOGCOLOR; }
 <INITIAL>{LOGPREFIX}	{ yylval.strval=yytext; return LOGPREFIX; }
+<INITIAL>{LOGPREFIXMODE}	{ yylval.strval=yytext; return LOGPREFIXMODE; }
 <INITIAL>{LOGENGINETYPE}	{ yylval.strval=yytext; return LOGENGINETYPE; }
 <INITIAL>{LOGENGINEDATA}	{ yylval.strval=yytext; return LOGENGINEDATA; }
 <INITIAL>{LISTEN}	{ count(); yylval.strval=yytext; return LISTEN; }

cfg.y

@@ -320,6 +320,7 @@ extern char *default_routename;
 %token LOGNAME
 %token LOGCOLOR
 %token LOGPREFIX
+%token LOGPREFIXMODE
 %token LOGENGINETYPE
 %token LOGENGINEDATA
 %token LISTEN
@@ -777,6 +778,8 @@ assign_stm:
 	| LOGCOLOR EQUAL error { yyerror("boolean value expected"); }
 	| LOGPREFIX EQUAL STRING { log_prefix_fmt=$3; }
 	| LOGPREFIX EQUAL error { yyerror("string value expected"); }
+	| LOGPREFIXMODE EQUAL NUMBER { log_prefix_mode=$3; }
+	| LOGPREFIXMODE EQUAL error { yyerror("number expected"); }
 	| LOGENGINETYPE EQUAL STRING { _km_log_engine_type=$3; }
 	| LOGENGINETYPE EQUAL error { yyerror("string value expected"); }
 	| LOGENGINEDATA EQUAL STRING { _km_log_engine_data=$3; }

dprint.c

@@ -432,6 +432,7 @@ void dprint_color_update(int level, char f, char b)
 
 /* log_prefix functionality */
 str *log_prefix_val = NULL;
+int log_prefix_mode = 0;
 static pv_elem_t *log_prefix_pvs = NULL;
 
 #define LOG_PREFIX_SIZE	1024

dprint.h

@@ -123,6 +123,7 @@ extern int log_stderr;
 extern int log_color;
 extern char *log_prefix_fmt;
 extern str *log_prefix_val;
+extern int log_prefix_mode;
 extern char *_km_log_engine_type;
 extern char *_km_log_engine_data;