Event loops: started once when services' first clients come at once

loopsstart() runs on the thread of the service whose client is the first
one to be served on a loop, not on the configuration's thread: two
services given their first clients at the same time could each initialize
its mutex, take it, and start loops of their own. A loop of the second
array was then given to a thread of the first one as well: two threads
ran one loop, and its timers and fibers were taken by both (crashes in
the timers' heap, seen on Windows under load).

The mutex is a global one now, made at startup with the others.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/3proxy.c

@@ -491,6 +491,7 @@ int WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int
   _3proxy_mutex_init(&bandlim_mutex);
   _3proxy_mutex_init(&connlim_mutex);
   _3proxy_mutex_init(&tc_mutex);
+  _3proxy_mutex_init(&loops_mutex);
   _3proxy_mutex_init(&tpool.mutex);
 #ifndef NORADIUS
   _3proxy_mutex_init(&rad_mutex);

src/conf.c

@@ -37,6 +37,8 @@ void transparent_install(void);
 _3proxy_mutex_t bandlim_mutex;
 _3proxy_mutex_t connlim_mutex;
 _3proxy_mutex_t tc_mutex;
+/* the event loops, started by the first client served on one */
+_3proxy_mutex_t loops_mutex;
 _3proxy_mutex_t config_mutex;
 int runningservices = 0;
 _3proxy_mutex_t runningservices_mutex;

src/mainloop.c

@@ -85,8 +85,6 @@ struct loopjob {
 static struct looper *loopers;
 static unsigned nloopers, nextlooper;
 static int loopsfailed;
-static _3proxy_mutex_t loopers_mutex;
-static int loopers_mutex_init;
 
 /* the loop of this thread, NULL but in a loop's thread */
 static LTLS struct looper *curlooper;
@@ -1111,20 +1109,17 @@ static int loopsstart(void){
 
 	if(nloopers) return 0;
 	if(loopsfailed) return 1;
-	if(!loopers_mutex_init){
-		/* the first services start from the configuration's thread */
-		_3proxy_mutex_init(&loopers_mutex);
-		loopers_mutex_init = 1;
-	}
-	_3proxy_mutex_lock(&loopers_mutex);
+	/* the first clients of services may come at once, each from the
+	   thread of its service */
+	_3proxy_mutex_lock(&loops_mutex);
 	if(nloopers || loopsfailed){
-		_3proxy_mutex_unlock(&loopers_mutex);
+		_3proxy_mutex_unlock(&loops_mutex);
 		return loopsfailed;
 	}
 	n = runconf->loops? (unsigned)runconf->loops : ncpus();
 	if(!fiberusable() || !(loopers = calloc(n, sizeof(*loopers)))){
 		loopsfailed = 1;
-		_3proxy_mutex_unlock(&loopers_mutex);
+		_3proxy_mutex_unlock(&loops_mutex);
 		return 1;
 	}
 	for(i = 0; i < n; i++){
@@ -1166,7 +1161,7 @@ static int loopsstart(void){
 #endif
 		fiberpollfunc = fiberpoll;
 	}
-	_3proxy_mutex_unlock(&loopers_mutex);
+	_3proxy_mutex_unlock(&loops_mutex);
 	return !i;
 }
 
@@ -1196,9 +1191,9 @@ static struct loopjob *loopjobnew(size_t stacksize){
 static void loopspawn(struct loopjob *job, struct clientparam *param){
 	struct looper *lp;
 
-	_3proxy_mutex_lock(&loopers_mutex);
+	_3proxy_mutex_lock(&loops_mutex);
 	lp = loopers + (nextlooper++ % nloopers);
-	_3proxy_mutex_unlock(&loopers_mutex);
+	_3proxy_mutex_unlock(&loops_mutex);
 	job->param = param;
 	looppost(&lp->l, &job->m);
 }

src/proxy.h

@@ -611,6 +611,7 @@ extern _3proxy_sem_t serviceexited;
 extern _3proxy_mutex_t bandlim_mutex;
 extern _3proxy_mutex_t connlim_mutex;
 extern _3proxy_mutex_t tc_mutex;
+extern _3proxy_mutex_t loops_mutex;
 extern _3proxy_mutex_t log_mutex;
 extern _3proxy_mutex_t rad_mutex;
 extern struct datatype datatypes[64];