From 1a58418ae76a96c830a0536432e96a9ad051bc58 Mon Sep 17 00:00:00 2001
From: Maxim Dounin <mdounin@mdounin.ru>
Date: Tue, 7 Mar 2017 18:51:15 +0300
Subject: [PATCH] Cancelable timers are now preserved if there are other
 timers.

There is no need to cancel timers early if there are other timers blocking
shutdown anyway.  Preserving such timers allows nginx to continue some
periodic work till the shutdown is actually possible.

With the new approach, timers with ev->cancelable are simply ignored when
checking if there are any timers left during shutdown.
---
 src/event/ngx_event_timer.c      | 42 ++++++++++++--------------------
 src/event/ngx_event_timer.h      |  2 +-
 src/os/unix/ngx_process_cycle.c  |  5 +---
 src/os/win32/ngx_process_cycle.c |  6 +----
 4 files changed, 18 insertions(+), 37 deletions(-)

diff --git a/src/event/ngx_event_timer.c b/src/event/ngx_event_timer.c
index 8f547b215..20e52f45e 100644
--- a/src/event/ngx_event_timer.c
+++ b/src/event/ngx_event_timer.c
@@ -96,43 +96,31 @@ ngx_event_expire_timers(void)
 }
 
 
-void
-ngx_event_cancel_timers(void)
+ngx_int_t
+ngx_event_no_timers_left(void)
 {
     ngx_event_t        *ev;
     ngx_rbtree_node_t  *node, *root, *sentinel;
 
     sentinel = ngx_event_timer_rbtree.sentinel;
+    root = ngx_event_timer_rbtree.root;
 
-    for ( ;; ) {
-        root = ngx_event_timer_rbtree.root;
-
-        if (root == sentinel) {
-            return;
-        }
-
-        node = ngx_rbtree_min(root, sentinel);
+    if (root == sentinel) {
+        return NGX_OK;
+    }
 
+    for (node = ngx_rbtree_min(root, sentinel);
+         node;
+         node = ngx_rbtree_next(&ngx_event_timer_rbtree, node))
+    {
         ev = (ngx_event_t *) ((char *) node - offsetof(ngx_event_t, timer));
 
         if (!ev->cancelable) {
-            return;
+            return NGX_AGAIN;
         }
-
-        ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0,
-                       "event timer cancel: %d: %M",
-                       ngx_event_ident(ev->data), ev->timer.key);
-
-        ngx_rbtree_delete(&ngx_event_timer_rbtree, &ev->timer);
-
-#if (NGX_DEBUG)
-        ev->timer.left = NULL;
-        ev->timer.right = NULL;
-        ev->timer.parent = NULL;
-#endif
-
-        ev->timer_set = 0;
-
-        ev->handler(ev);
     }
+
+    /* only cancelable timers left */
+
+    return NGX_OK;
 }
diff --git a/src/event/ngx_event_timer.h b/src/event/ngx_event_timer.h
index 99f8a48fb..be81b157f 100644
--- a/src/event/ngx_event_timer.h
+++ b/src/event/ngx_event_timer.h
@@ -22,7 +22,7 @@
 ngx_int_t ngx_event_timer_init(ngx_log_t *log);
 ngx_msec_t ngx_event_find_timer(void);
 void ngx_event_expire_timers(void);
-void ngx_event_cancel_timers(void);
+ngx_int_t ngx_event_no_timers_left(void);
 
 
 extern ngx_rbtree_t  ngx_event_timer_rbtree;
diff --git a/src/os/unix/ngx_process_cycle.c b/src/os/unix/ngx_process_cycle.c
index 5c4e21dfd..d0c61143e 100644
--- a/src/os/unix/ngx_process_cycle.c
+++ b/src/os/unix/ngx_process_cycle.c
@@ -738,10 +738,7 @@ ngx_worker_process_cycle(ngx_cycle_t *cycle, void *data)
     for ( ;; ) {
 
         if (ngx_exiting) {
-            ngx_event_cancel_timers();
-
-            if (ngx_event_timer_rbtree.root == ngx_event_timer_rbtree.sentinel)
-            {
+            if (ngx_event_no_timers_left() == NGX_OK) {
                 ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");
 
                 ngx_worker_process_exit(cycle);
diff --git a/src/os/win32/ngx_process_cycle.c b/src/os/win32/ngx_process_cycle.c
index 99fec54e3..5b2df3858 100644
--- a/src/os/win32/ngx_process_cycle.c
+++ b/src/os/win32/ngx_process_cycle.c
@@ -782,11 +782,7 @@ ngx_worker_thread(void *data)
     while (!ngx_quit) {
 
         if (ngx_exiting) {
-            ngx_event_cancel_timers();
-
-            if (ngx_event_timer_rbtree.root
-                == ngx_event_timer_rbtree.sentinel)
-            {
+            if (ngx_event_no_timers_left() == NGX_OK) {
                 break;
             }
         }