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timers: do less work in insert
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Most of the code in insert is only applicable to scheduling
non-timers or re-scheduling timers. We can skip most of it
in the case of setTimeout, setInterval & setUnrefTimeout.

PR-URL: #27345
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Jeremiah Senkpiel <[email protected]>
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: James M Snell <[email protected]>
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apapirovski authored and BridgeAR committed Jan 3, 2020
1 parent 7b2bf20 commit 83330a0
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Showing 2 changed files with 39 additions and 33 deletions.
58 changes: 31 additions & 27 deletions lib/internal/timers.js
Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,7 @@ function initAsyncResource(resource, type) {

// Timer constructor function.
// The entire prototype is defined in lib/timers.js
function Timeout(callback, after, args, isRepeat) {
function Timeout(callback, after, args, isRepeat, isRefed) {
after *= 1; // Coalesce to number or NaN
if (!(after >= 1 && after <= TIMEOUT_MAX)) {
if (after > TIMEOUT_MAX) {
Expand All @@ -179,7 +179,9 @@ function Timeout(callback, after, args, isRepeat) {
this._repeat = isRepeat ? after : null;
this._destroyed = false;

this[kRefed] = null;
if (isRefed)
incRefCount();
this[kRefed] = isRefed;

initAsyncResource(this, 'Timeout');
}
Expand Down Expand Up @@ -295,27 +297,43 @@ function decRefCount() {
// Schedule or re-schedule a timer.
// The item must have been enroll()'d first.
function active(item) {
insert(item, true, getLibuvNow());
insertGuarded(item, true);
}

// Internal APIs that need timeouts should use `unrefActive()` instead of
// `active()` so that they do not unnecessarily keep the process open.
function unrefActive(item) {
insert(item, false, getLibuvNow());
insertGuarded(item, false);
}

// 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
// list if one does not already exist for the specified timeout duration.
function insert(item, refed, start) {
let msecs = item._idleTimeout;
function insertGuarded(item, refed, start) {
const msecs = item._idleTimeout;
if (msecs < 0 || msecs === undefined)
return;

// Truncate so that accuracy of sub-millisecond timers is not assumed.
msecs = MathTrunc(msecs);
insert(item, msecs, start);

if (!item[async_id_symbol] || item._destroyed) {
item._destroyed = false;
initAsyncResource(item, 'Timeout');
}

if (refed === !item[kRefed]) {
if (refed)
incRefCount();
else
decRefCount();
}
item[kRefed] = refed;
}

function insert(item, msecs, start = getLibuvNow()) {
// Truncate so that accuracy of sub-milisecond timers is not assumed.
msecs = MathTrunc(msecs);
item._idleStart = start;

// Use an existing list if there is one, otherwise we need to make a new one.
Expand All @@ -332,19 +350,6 @@ function insert(item, refed, start) {
}
}

if (!item[async_id_symbol] || item._destroyed) {
item._destroyed = false;
initAsyncResource(item, 'Timeout');
}

if (refed === !item[kRefed]) {
if (refed)
incRefCount();
else
decRefCount();
}
item[kRefed] = refed;

L.append(list, item);
}

Expand All @@ -354,8 +359,8 @@ function setUnrefTimeout(callback, after) {
throw new ERR_INVALID_CALLBACK(callback);
}

const timer = new Timeout(callback, after, undefined, false);
unrefActive(timer);
const timer = new Timeout(callback, after, undefined, false, false);
insert(timer, timer._idleTimeout);

return timer;
}
Expand Down Expand Up @@ -540,16 +545,14 @@ function getTimerCallbacks(runNextTicks) {
} finally {
if (timer._repeat && timer._idleTimeout !== -1) {
timer._idleTimeout = timer._repeat;
if (start === undefined)
start = getLibuvNow();
insert(timer, timer[kRefed], start);
insert(timer, timer._idleTimeout, start);
} else if (!timer._idleNext && !timer._idlePrev) {
if (timer[kRefed])
refCount--;
timer[kRefed] = null;

if (destroyHooksExist() && !timer._destroyed) {
emitDestroy(timer[async_id_symbol]);
emitDestroy(asyncId);
}
timer._destroyed = true;
}
Expand Down Expand Up @@ -598,6 +601,7 @@ module.exports = {
},
active,
unrefActive,
insert,
timerListMap,
timerListQueue,
decRefCount,
Expand Down
14 changes: 8 additions & 6 deletions lib/timers.js
Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,8 @@ const {
timerListQueue,
immediateQueue,
active,
unrefActive
unrefActive,
insert
} = require('internal/timers');
const {
promisify: { custom: customPromisify },
Expand Down Expand Up @@ -142,16 +143,17 @@ function setTimeout(callback, after, arg1, arg2, arg3) {
break;
}

const timeout = new Timeout(callback, after, args, false);
active(timeout);
const timeout = new Timeout(callback, after, args, false, true);
insert(timeout, timeout._idleTimeout);

return timeout;
}

setTimeout[customPromisify] = function(after, value) {
const args = value !== undefined ? [value] : value;
return new Promise((resolve) => {
active(new Timeout(resolve, after, args, false));
const timeout = new Timeout(resolve, after, args, false, true);
insert(timeout, timeout._idleTimeout);
});
};

Expand Down Expand Up @@ -188,8 +190,8 @@ function setInterval(callback, repeat, arg1, arg2, arg3) {
break;
}

const timeout = new Timeout(callback, repeat, args, true);
active(timeout);
const timeout = new Timeout(callback, repeat, args, true, true);
insert(timeout, timeout._idleTimeout);

return timeout;
}
Expand Down

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