sapi/fpm: fixed fpm status inconsistent issue when using fastcgi_finish_request with keepalive connection

Added new field to represent the number of keepalive connections in fpm status page.
@see php#19191

Author: Appla

sapi/fpm/fpm/fpm_process_ctl.c

@@ -333,6 +333,7 @@ static void fpm_pctl_perform_idle_server_maintenance(struct timeval *now) /* {{{
 		struct fpm_child_s *last_idle_child = NULL;
 		int idle = 0;
 		int active = 0;
+		int reused = 0;
 		int children_to_fork;
 		unsigned cur_lq = 0;
 
@@ -359,7 +360,8 @@ static void fpm_pctl_perform_idle_server_maintenance(struct timeval *now) /* {{{
 		fpm_scoreboard_update_begin(wp->scoreboard);
 
 		for (child = wp->children; child; child = child->next) {
-			if (fpm_request_is_idle(child)) {
+			int reuse_cnt = 0;
+			if (fpm_request_is_idle_with_reuse_count(child, &reuse_cnt)) {
 				if (last_idle_child == NULL) {
 					last_idle_child = child;
 				} else {
@@ -370,10 +372,13 @@ static void fpm_pctl_perform_idle_server_maintenance(struct timeval *now) /* {{{
 				idle++;
 			} else {
 				active++;
+				if (reuse_cnt > 0) {
+					reused--;
+				}
 			}
 		}
 
-		fpm_scoreboard_update_commit(idle, active, cur_lq, -1, -1, -1, 0, FPM_SCOREBOARD_ACTION_SET, wp->scoreboard);
+		fpm_scoreboard_update_commit(idle, active, cur_lq, -1, -1, -1, reused, FPM_SCOREBOARD_ACTION_SET, wp->scoreboard);
 
 		/* this is specific to PM_STYLE_ONDEMAND */
 		if (wp->config->pm == PM_STYLE_ONDEMAND) {

sapi/fpm/fpm/fpm_request.c

@@ -63,6 +63,7 @@ void fpm_request_reading_headers(void)
 	struct fpm_scoreboard_proc_s *proc;
 
 	struct timeval now;
+	int reused_times = 0;
 	clock_t now_epoch;
 #ifdef HAVE_TIMES
 	struct tms cpu;
@@ -96,10 +97,19 @@ void fpm_request_reading_headers(void)
 	proc->query_string[0] = '\0';
 	proc->auth_user[0] = '\0';
 	proc->content_length = 0;
+	// @note reuse this field as keepalive connection reuse counter.
+	// 000
+	reused_times = (proc->used += 8) >> 3;
 	fpm_scoreboard_proc_release(proc);
 
-	/* idle--, active++, request++ */
-	fpm_scoreboard_update_commit(-1, 1, 0, 0, 1, 0, 0, FPM_SCOREBOARD_ACTION_INC, NULL);
+	// means this is used for multiple times
+	if (reused_times > 1) {
+		/* request++, lq_len if reused_times == 2 */
+		fpm_scoreboard_update_commit(0, 0, 0, reused_times == 2 ? 1 : 0, 1, 0, 0, FPM_SCOREBOARD_ACTION_INC, NULL);
+	} else {
+		/* idle--, active++, request++ */
+		fpm_scoreboard_update_commit(-1, 1, 0, 0, 1, 0, 0, FPM_SCOREBOARD_ACTION_INC, NULL);
+	}
 }
 
 void fpm_request_info(void)
@@ -206,6 +216,7 @@ void fpm_request_finished(void)
 {
 	struct fpm_scoreboard_proc_s *proc;
 	struct timeval now;
+	int reused_times;
 
 	fpm_clock_get(&now);
 
@@ -214,10 +225,18 @@ void fpm_request_finished(void)
 		zlog(ZLOG_WARNING, "failed to acquire proc scoreboard");
 		return;
 	}
-
+	reused_times = (proc->used += 8) >> 3;
+	// @note reuse this field as keepalive connection reuse counter, when this function got called, the connection is already closed, so we reset the counter.
+	if (reused_times > 0) {
+		proc->used = proc->used & 0x01;
+	}
 	proc->request_stage = FPM_REQUEST_FINISHED;
 	proc->tv = now;
 	fpm_scoreboard_proc_release(proc);
+	if (reused_times > 1) {
+		/* reused--, via lq_len if reused_times > 1 */
+		fpm_scoreboard_update_commit(0, 0, 0, -1, 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) /* {{{ */
@@ -293,6 +312,20 @@ int fpm_request_is_idle(struct fpm_child_s *child) /* {{{ */
 }
 /* }}} */
 
+int fpm_request_is_idle_with_reuse_count(struct fpm_child_s *child, int *reuse_cnt) /* {{{ */
+{
+	struct fpm_scoreboard_proc_s *proc;
+
+	/* no need in atomicity here */
+	proc = fpm_scoreboard_proc_get_from_child(child);
+	if (!proc) {
+		return 0;
+	}
+	*reuse_cnt = proc->used >> 3;
+	return proc->request_stage == FPM_REQUEST_ACCEPTING;
+}
+/* }}} */
+
 int fpm_request_last_activity(struct fpm_child_s *child, struct timeval *tv) /* {{{ */
 {
 	struct fpm_scoreboard_proc_s *proc;

sapi/fpm/fpm/fpm_request.h

@@ -21,6 +21,7 @@ struct timeval;
 
 void fpm_request_check_timed_out(struct fpm_child_s *child, struct timeval *tv, int terminate_timeout, int slowlog_timeout, int track_finished);
 int fpm_request_is_idle(struct fpm_child_s *child);
+int fpm_request_is_idle_with_reuse_count(struct fpm_child_s *child, int *reuse_cnt);
 const char *fpm_request_get_stage_name(int stage);
 int fpm_request_last_activity(struct fpm_child_s *child, struct timeval *tv);
 

sapi/fpm/fpm/fpm_scoreboard.c

@@ -175,6 +175,9 @@ void fpm_scoreboard_update_commit(
 		}
 		if (slow_rq > 0) {
 			scoreboard->slow_rq = slow_rq;
+		} else if (slow_rq < 0) {
+			// we reuse this as a reused connections counter.
+			scoreboard->reused = -slow_rq;
 		}
 	} else {
 		if (scoreboard->idle + idle > 0) {
@@ -183,6 +186,15 @@ void fpm_scoreboard_update_commit(
 			scoreboard->idle = 0;
 		}
 
+		// we use this to record the currently keepalive/reused connections.
+		if (lq_len != 0) {
+			if (scoreboard->reused + lq_len > 0) {
+				scoreboard->reused += lq_len;
+			} else {
+				scoreboard->reused = 0;
+			}
+		}
+
 		if (scoreboard->active + active > 0) {
 			scoreboard->active += active;
 		} else {

sapi/fpm/fpm/fpm_scoreboard.h

@@ -61,6 +61,7 @@ struct fpm_scoreboard_s {
 	time_t start_epoch;
 	int idle;
 	int active;
+	int reused;
 	int active_max;
 	unsigned long int requests;
 	unsigned int max_children_reached;

sapi/fpm/fpm/fpm_status.c

@@ -243,6 +243,7 @@ int fpm_status_handle_request(void) /* {{{ */
 					"<tr><th>listen queue len</th><td>%u</td></tr>\n"
 					"<tr><th>idle processes</th><td>%d</td></tr>\n"
 					"<tr><th>active processes</th><td>%d</td></tr>\n"
+					"<tr><th>reused processes</th><td>%d</td></tr>\n"
 					"<tr><th>total processes</th><td>%d</td></tr>\n"
 					"<tr><th>max active processes</th><td>%d</td></tr>\n"
 					"<tr><th>max children reached</th><td>%u</td></tr>\n"
@@ -260,6 +261,7 @@ int fpm_status_handle_request(void) /* {{{ */
 						"<th>start time</th>"
 						"<th>start since</th>"
 						"<th>requests</th>"
+						"<th>rused</th>"
 						"<th>request duration</th>"
 						"<th>request method</th>"
 						"<th>request uri</th>"
@@ -278,6 +280,7 @@ int fpm_status_handle_request(void) /* {{{ */
 						"<td>%lu</td>"
 						"<td>%lu</td>"
 						"<td>%lu</td>"
+						"<td>%lu</td>"
 						"<td>%s</td>"
 						"<td>%s%s%s</td>"
 						"<td>%zu</td>"
@@ -309,6 +312,7 @@ int fpm_status_handle_request(void) /* {{{ */
 				"<listen-queue-len>%u</listen-queue-len>\n"
 				"<idle-processes>%d</idle-processes>\n"
 				"<active-processes>%d</active-processes>\n"
+				"<reused-processes>%d</reused-processes>\n"
 				"<total-processes>%d</total-processes>\n"
 				"<max-active-processes>%d</max-active-processes>\n"
 				"<max-children-reached>%u</max-children-reached>\n"
@@ -325,6 +329,7 @@ int fpm_status_handle_request(void) /* {{{ */
 							"<start-time>%s</start-time>"
 							"<start-since>%lu</start-since>"
 							"<requests>%lu</requests>"
+							"<reused>%lu</reused>"
 							"<request-duration>%lu</request-duration>"
 							"<request-method>%s</request-method>"
 							"<request-uri>%s%s%s</request-uri>"
@@ -357,6 +362,7 @@ int fpm_status_handle_request(void) /* {{{ */
 				"\"listen queue len\":%u,"
 				"\"idle processes\":%d,"
 				"\"active processes\":%d,"
+				"\"reused processes\":%d,"
 				"\"total processes\":%d,"
 				"\"max active processes\":%d,"
 				"\"max children reached\":%u,"
@@ -374,6 +380,7 @@ int fpm_status_handle_request(void) /* {{{ */
 					"\"start time\":%s,"
 					"\"start since\":%lu,"
 					"\"requests\":%lu,"
+					"\"reused\":%lu,"
 					"\"request duration\":%lu,"
 					"\"request method\":\"%s\","
 					"\"request uri\":\"%s%s%s\","
@@ -417,6 +424,9 @@ int fpm_status_handle_request(void) /* {{{ */
 				"# HELP phpfpm_active_processes The number of active processes.\n"
 				"# TYPE phpfpm_active_processes gauge\n"
 				"phpfpm_active_processes %d\n"
+				"# HELP phpfpm_reused_active_processes The number of reused active processes.\n"
+				"# TYPE phpfpm_reused_active_processes gauge\n"
+				"phpfpm_reused_active_processes %d\n"
 				"# HELP phpfpm_total_processes The number of idle + active processes.\n"
 				"# TYPE phpfpm_total_processes gauge\n"
 				"phpfpm_total_processes %d\n"
@@ -457,6 +467,7 @@ int fpm_status_handle_request(void) /* {{{ */
 				"listen queue len:     %u\n"
 				"idle processes:       %d\n"
 				"active processes:     %d\n"
+				"reused processes:     %d\n"
 				"total processes:      %d\n"
 				"max active processes: %d\n"
 				"max children reached: %u\n"
@@ -471,6 +482,7 @@ int fpm_status_handle_request(void) /* {{{ */
 						"start time:           %s\n"
 						"start since:          %lu\n"
 						"requests:             %lu\n"
+						"reused:               %lu\n"
 						"request duration:     %lu\n"
 						"request method:       %s\n"
 						"request URI:          %s%s%s\n"
@@ -496,6 +508,7 @@ int fpm_status_handle_request(void) /* {{{ */
 					scoreboard_p->lq_len,
 					scoreboard_p->idle,
 					scoreboard_p->active,
+					scoreboard_p->reused,
 					scoreboard_p->idle + scoreboard_p->active,
 					scoreboard_p->active_max,
 					scoreboard_p->max_children_reached,
@@ -511,6 +524,7 @@ int fpm_status_handle_request(void) /* {{{ */
 					scoreboard_p->lq_len,
 					scoreboard_p->idle,
 					scoreboard_p->active,
+					scoreboard_p->reused,
 					scoreboard_p->idle + scoreboard_p->active,
 					scoreboard_p->active_max,
 					scoreboard_p->max_children_reached,
@@ -598,6 +612,7 @@ int fpm_status_handle_request(void) /* {{{ */
 					time_buffer,
 					(unsigned long) (now_epoch - proc->start_epoch),
 					proc->requests,
+					proc->used >> 3,
 					(unsigned long) (duration.tv_sec * 1000000UL + duration.tv_usec),
 					proc->request_method[0] != '\0' ? proc->request_method : "-",
 					proc->request_uri[0] != '\0' ? proc->request_uri : "-",