timers: add internal [@@ refresh()] function

Hidden via a symbol because I'm unsure exactly what the API should look
like in the end.

Removes the need to use _unrefActive for efficiently refreshing
timeouts.
It still uses it under the hood but that could be replaced with
insert() directly if it were in the same file.

PR-URL: https://github.com/nodejs/node/pull/18065
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>

1 files changed, 21 insertions, 2 deletions

diff --git a/lib/internal/timers.js b/lib/internal/timers.js
index cd5efb6dbb..aa061be3db 100644
--- a/lib/internal/timers.js
+++ b/lib/internal/timers.js
@@ -19,12 +19,16 @@ const errors = require('internal/errors');
 // Timeout values > TIMEOUT_MAX are set to 1.
 const TIMEOUT_MAX = 2 ** 31 - 1;
 
+const refreshFnSymbol = Symbol('refresh()');
+const unrefedSymbol = Symbol('unrefed');
+
 module.exports = {
   TIMEOUT_MAX,
   kTimeout: Symbol('timeout'), // For hiding Timeouts on other internals.
   async_id_symbol,
   trigger_async_id_symbol,
   Timeout,
+  refreshFnSymbol,
   setUnrefTimeout,
   validateTimerDuration
 };
@@ -39,7 +43,7 @@ function getTimers() {
 
 // Timer constructor function.
 // The entire prototype is defined in lib/timers.js
-function Timeout(callback, after, args, isRepeat) {
+function Timeout(callback, after, args, isRepeat, isUnrefed) {
   after *= 1; // coalesce to number or NaN
   if (!(after >= 1 && after <= TIMEOUT_MAX)) {
     if (after > TIMEOUT_MAX) {
@@ -64,6 +68,8 @@ function Timeout(callback, after, args, isRepeat) {
   this._repeat = isRepeat ? after : null;
   this._destroyed = false;
 
+  this[unrefedSymbol] = isUnrefed;
+
   this[async_id_symbol] = ++async_id_fields[kAsyncIdCounter];
   this[trigger_async_id_symbol] = getDefaultTriggerAsyncId();
   if (async_hook_fields[kInit] > 0) {
@@ -74,6 +80,19 @@ function Timeout(callback, after, args, isRepeat) {
   }
 }
 
+Timeout.prototype[refreshFnSymbol] = function refresh() {
+  if (this._handle) {
+    // Would be more ideal with uv_timer_again(), however that API does not
+    // cause libuv's sorted timers data structure (a binary heap at the time
+    // of writing) to re-sort itself. This causes ordering inconsistencies.
+    this._handle.stop();
+    this._handle.start(this._idleTimeout);
+  } else if (this[unrefedSymbol]) {
+    getTimers()._unrefActive(this);
+  } else {
+    getTimers().active(this);
+  }
+};
 
 function setUnrefTimeout(callback, after, arg1, arg2, arg3) {
   // Type checking identical to setTimeout()
@@ -102,7 +121,7 @@ function setUnrefTimeout(callback, after, arg1, arg2, arg3) {
       break;
   }
 
-  const timer = new Timeout(callback, after, args, false);
+  const timer = new Timeout(callback, after, args, false, true);
   getTimers()._unrefActive(timer);
 
   return timer;