Logs: a loop's thread does not write a log itself

A logger whose thread could not be started is written by its clients
themselves. A client of a loop, a fiber or a callback on the loop's
thread, would hold the loop while a database or a server takes its
line, so on a loop's thread the line is dropped instead, counted as the
log's lines dropped are.

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

src/common.c

@@ -338,6 +338,8 @@ int
    are told to its loop. errno is left as it was. */
 void (*fiberblockfunc)(SOCKET s, short events) = NULL;
 void (*fiberclosefunc)(SOCKET s) = NULL;
+/* set as well: whether this thread is a loop's, which is not to wait */
+int (*onloopfunc)(void) = NULL;
 #define BLOCKED(s, ev) do { if(fiberblockfunc && (errno == EAGAIN || errno == EWOULDBLOCK)) \
 	fiberblockfunc((s), (ev)); } while(0)
 

src/log.c

@@ -1049,6 +1049,14 @@ static void logdirect(struct logger *lg, struct clientparam *param, const unsign
 	unsigned msec, n = 0, lost = 0;
 	int res = 0, reopened = 0;
 
+	/* a loop's thread does not wait for a log whose thread could not be
+	   started, a database's or a server's: the line is dropped, counted */
+	if(onloopfunc && onloopfunc()){
+		_3proxy_mutex_lock(&lg->mutex);
+		lg->faildropped++;
+		_3proxy_mutex_unlock(&lg->mutex);
+		return;
+	}
 	lognow(&sec, &msec);
 	_3proxy_mutex_lock(&lg->mutex);
 	if(lg->failed && sec - lg->failtime >= LOGRETRY){

src/mainloop.c

@@ -1177,6 +1177,7 @@ static int loopsstart(void){
 		sockmapcbfunc = fibermap;
 #endif
 		fiberpollfunc = fiberpoll;
+		onloopfunc = onlooper;
 	}
 	_3proxy_mutex_unlock(&loops_mutex);
 	return !i;

src/proxy.h

@@ -340,6 +340,7 @@ int sockpoll(struct sockfuncs *sf, void *state, struct pollfd *fds, unsigned nfd
 extern int (*fiberpollfunc)(struct pollfd *fds, unsigned nfds, int timeout);
 extern void (*fiberblockfunc)(SOCKET s, short events);
 extern void (*fiberclosefunc)(SOCKET s);
+extern int (*onloopfunc)(void);
 int sockreadable(SOCKET s);
 #ifndef _WIN32
 int fdclose(int fd);