src: refactor timers to remove TimerWrap

Refactor Timers to behave more similarly to Immediates by having
a single uv_timer_t handle which is stored on the Environment.

No longer expose timers in a public binding and instead make
it part of the internalBinding.

PR-URL: https://github.com/nodejs/node/pull/20894
Fixes: https://github.com/nodejs/node/issues/10154
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>

1 files changed, 25 insertions, 39 deletions

diff --git a/lib/timers.js b/lib/timers.js
index 5ae0e6a5ad..ad2d89d7bf 100644
--- a/lib/timers.js
+++ b/lib/timers.js
@@ -21,10 +21,15 @@
 
 'use strict';
 
+const { internalBinding } = require('internal/bootstrap/loaders');
 const {
-  Timer: TimerWrap,
+  getLibuvNow,
   setupTimers,
-} = process.binding('timer_wrap');
+  scheduleTimer,
+  toggleTimerRef,
+  immediateInfo,
+  toggleImmediateRef
+} = internalBinding('timers');
 const L = require('internal/linkedlist');
 const PriorityQueue = require('internal/priority_queue');
 const {
@@ -53,8 +58,9 @@ const kCount = 0;
 const kRefCount = 1;
 const kHasOutstanding = 2;
 
-const [immediateInfo, toggleImmediateRef] =
-  setupTimers(processImmediate, processTimers);
+// Call into C++ to assign callbacks that are responsible for processing
+// Immediates and TimerLists.
+setupTimers(processImmediate, processTimers);
 
 // HOW and WHY the timers implementation works the way it does.
 //
@@ -156,7 +162,6 @@ function setPosition(node, pos) {
   node.priorityQueuePosition = pos;
 }
 
-let handle = null;
 let nextExpiry = Infinity;
 
 let timerListId = Number.MIN_SAFE_INTEGER;
@@ -164,39 +169,31 @@ let refCount = 0;
 
 function incRefCount() {
   if (refCount++ === 0)
-    handle.ref();
+    toggleTimerRef(true);
 }
 
 function decRefCount() {
   if (--refCount === 0)
-    handle.unref();
-}
-
-function createHandle(refed) {
-  debug('initial run, creating TimerWrap handle');
-  handle = new TimerWrap();
-  if (!refed)
-    handle.unref();
+    toggleTimerRef(false);
 }
 
 // Schedule or re-schedule a timer.
 // The item must have been enroll()'d first.
 const active = exports.active = function(item) {
-  insert(item, true, TimerWrap.now());
+  insert(item, true, getLibuvNow());
 };
 
 // Internal APIs that need timeouts should use `_unrefActive()` instead of
 // `active()` so that they do not unnecessarily keep the process open.
 exports._unrefActive = function(item) {
-  insert(item, false, TimerWrap.now());
+  insert(item, false, getLibuvNow());
 };
 
 
 // The underlying logic for scheduling or re-scheduling a timer.
 //
 // Appends a timer onto the end of an existing timers list, or creates a new
-// TimerWrap backed list if one does not already exist for the specified timeout
-// duration.
+// list if one does not already exist for the specified timeout duration.
 function insert(item, refed, start) {
   const msecs = item._idleTimeout;
   if (msecs < 0 || msecs === undefined)
@@ -213,9 +210,7 @@ function insert(item, refed, start) {
     queue.insert(list);
 
     if (nextExpiry > expiry) {
-      if (handle === null)
-        createHandle(refed);
-      handle.start(msecs);
+      scheduleTimer(msecs);
       nextExpiry = expiry;
     }
   }
@@ -252,32 +247,23 @@ function processTimers(now) {
 
   let list, ran;
   while (list = queue.peek()) {
-    if (list.expiry > now)
-      break;
+    if (list.expiry > now) {
+      nextExpiry = list.expiry;
+      return refCount > 0 ? nextExpiry : -nextExpiry;
+    }
     if (ran)
       runNextTicks();
+    else
+      ran = true;
     listOnTimeout(list, now);
-    ran = true;
   }
-
-  if (refCount > 0)
-    handle.ref();
-  else
-    handle.unref();
-
-  if (list !== undefined) {
-    nextExpiry = list.expiry;
-    handle.start(Math.max(nextExpiry - TimerWrap.now(), 1));
-  }
-
-  return true;
+  return 0;
 }
 
 function listOnTimeout(list, now) {
   const msecs = list.msecs;
 
   debug('timeout callback %d', msecs);
-  debug('now: %d', now);
 
   var diff, timer;
   while (timer = L.peek(list)) {
@@ -336,7 +322,7 @@ function listOnTimeout(list, now) {
 // 4.7) what is in this smaller function.
 function tryOnTimeout(timer, start) {
   if (start === undefined && timer._repeat)
-    start = TimerWrap.now();
+    start = getLibuvNow();
   try {
     ontimeout(timer);
   } finally {
@@ -474,7 +460,7 @@ function ontimeout(timer) {
 }
 
 function rearm(timer, start) {
-  // // Do not re-arm unenroll'd or closed timers.
+  // Do not re-arm unenroll'd or closed timers.
   if (timer._idleTimeout === -1)
     return;