Fix GH-18956: PHP-FPM Process Count Inconsistencies

This fixes incorrect decrement of the active number of processes. This
was done in accepting stage before incrementing which is problematic if
there are already some running processes as it decrements their number
first and result in incorrect total (lower than the actual number).

In addition it also fixes GH-14212 as accept is done just once for
keepalive connection so in this case the number of active connection
just increasing with each request.

Author: bukka

sapi/fpm/fpm/fpm_main.c

@@ -1973,6 +1973,8 @@ consult the installation file that came with this distribution, or visit \n\
 
 			fpm_stdio_flush_child();
 
+			fpm_request_shutdown();
+
 			requests++;
 			if (UNEXPECTED(max_requests && (requests == max_requests))) {
 				fcgi_request_set_keep(request, 0);

sapi/fpm/fpm/fpm_request.c

@@ -54,8 +54,8 @@ void fpm_request_accepting(void)
 	proc->tv = now;
 	fpm_scoreboard_proc_release(proc);
 
-	/* idle++, active-- */
-	fpm_scoreboard_update_commit(1, -1, 0, 0, 0, 0, 0, FPM_SCOREBOARD_ACTION_INC, NULL);
+	/* idle++ */
+	fpm_scoreboard_update_commit(1, 0, 0, 0, 0, 0, 0, FPM_SCOREBOARD_ACTION_INC, NULL);
 }
 
 void fpm_request_reading_headers(void)
@@ -220,6 +220,12 @@ void fpm_request_finished(void)
 	fpm_scoreboard_proc_release(proc);
 }
 
+void fpm_request_shutdown(void)
+{
+	/* active-- */
+	fpm_scoreboard_update(0, -1, 0, 0, 0, 0, 0, FPM_SCOREBOARD_ACTION_INC, NULL);
+}
+
 void fpm_request_check_timed_out(struct fpm_child_s *child, struct timeval *now, int terminate_timeout, int slowlog_timeout, int track_finished) /* {{{ */
 {
 	struct fpm_scoreboard_proc_s proc, *proc_p;

sapi/fpm/fpm/fpm_request.h

@@ -15,6 +15,8 @@ void fpm_request_executing(void);
 void fpm_request_end(void);
 /* request processed: cleaning current request */
 void fpm_request_finished(void);
+/* request post shutdown: decrement active */
+void fpm_request_shutdown(void);
 
 struct fpm_child_s;
 struct timeval;