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timers: use Maps for internal duration pooling #11040

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timers: use Maps for internal duration pooling #11040

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30 changes: 15 additions & 15 deletions lib/timers.js
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Original file line number Diff line number Diff line change
Expand Up @@ -37,14 +37,14 @@ const TIMEOUT_MAX = 2147483647; // 2^31-1
// operations as close to constant-time as possible.
// (So that performance is not impacted by the number of scheduled timers.)
//
// Object maps are kept which contain linked lists keyed by their duration in
// Maps are kept which contain linked lists keyed by their duration in
// milliseconds.
// The linked lists within also have some meta-properties, one of which is a
// TimerWrap C++ handle, which makes the call after the duration to process the
// list it is attached to.
//
//
// ╔════ > Object Map
// ╔════ > Map
// ║
// ╠══
// ║ refedLists: { '40': { }, '320': { etc } } (keys of millisecond duration)
Expand Down Expand Up @@ -85,18 +85,17 @@ const TIMEOUT_MAX = 2147483647; // 2^31-1
// other alternative timers architectures.


// Object maps containing linked lists of timers, keyed and sorted by their
// Maps containing linked lists of timers, keyed and sorted by their
// duration in milliseconds.
//
// The difference between these two objects is that the former contains timers
// The difference between these two Maps is that the former contains timers
// that will keep the process open if they are the only thing left, while the
// latter will not.
//
// - key = time in milliseconds
// - value = linked list
const refedLists = Object.create(null);
const unrefedLists = Object.create(null);

const refedLists = new Map();
const unrefedLists = new Map();

// Schedule or re-schedule a timer.
// The item must have been enroll()'d first.
Expand Down Expand Up @@ -125,10 +124,11 @@ function insert(item, unrefed) {
const lists = unrefed === true ? unrefedLists : refedLists;

// Use an existing list if there is one, otherwise we need to make a new one.
var list = lists[msecs];
var list = lists.get(msecs);
if (!list) {
debug('no %d list was found in insert, creating a new one', msecs);
lists[msecs] = list = createTimersList(msecs, unrefed);
list = createTimersList(msecs, unrefed);
lists.set(msecs, list);
}

L.append(list, item);
Expand Down Expand Up @@ -220,10 +220,10 @@ function listOnTimeout() {
// Either refedLists[msecs] or unrefedLists[msecs] may have been removed and
// recreated since the reference to `list` was created. Make sure they're
// the same instance of the list before destroying.
if (list._unrefed === true && list === unrefedLists[msecs]) {
delete unrefedLists[msecs];
} else if (list === refedLists[msecs]) {
delete refedLists[msecs];
if (list._unrefed === true && list === unrefedLists.get(msecs)) {
unrefedLists.delete(msecs);
} else if (list === refedLists.get(msecs)) {
refedLists.delete(msecs);
}
}

Expand Down Expand Up @@ -265,12 +265,12 @@ function listOnTimeoutNT(list) {
function reuse(item) {
L.remove(item);

var list = refedLists[item._idleTimeout];
var list = refedLists.get(item._idleTimeout);
// if empty - reuse the watcher
if (list && L.isEmpty(list)) {
debug('reuse hit');
list._timer.stop();
delete refedLists[item._idleTimeout];
refedLists.delete(item._idleTimeout);
return list._timer;
}

Expand Down