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StreamSelectLoop: Improve memory consumption and runtime performance for timers #164

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Merged
merged 2 commits into from
Apr 23, 2018
Merged

StreamSelectLoop: Improve memory consumption and runtime performance for timers #164

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efd037c
Use sorted array to store timers and remove cancelled ones
clue Apr 20, 2018
be70d8c
Improve performance by sorting timers only on demand
clue Apr 21, 2018
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77 changes: 34 additions & 43 deletions src/Timer/Timers.php
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,6 @@
namespace React\EventLoop\Timer;

use React\EventLoop\TimerInterface;
use SplObjectStorage;
use SplPriorityQueue;

/**
* A scheduler implementation that can hold multiple timer instances
Expand All @@ -17,14 +15,9 @@
final class Timers
{
private $time;
private $timers;
private $scheduler;

public function __construct()
{
$this->timers = new SplObjectStorage();
$this->scheduler = new SplPriorityQueue();
}
private $timers = array();
private $schedule = array();
private $sorted = true;

public function updateTime()
{
Expand All @@ -38,36 +31,32 @@ public function getTime()

public function add(TimerInterface $timer)
{
$interval = $timer->getInterval();
$scheduledAt = $interval + microtime(true);

$this->timers->attach($timer, $scheduledAt);
$this->scheduler->insert($timer, -$scheduledAt);
$id = spl_object_hash($timer);
$this->timers[$id] = $timer;
$this->schedule[$id] = $timer->getInterval() + microtime(true);
$this->sorted = false;
}

public function contains(TimerInterface $timer)
{
return $this->timers->contains($timer);
return isset($this->timers[spl_oject_hash($timer)]);
}

public function cancel(TimerInterface $timer)
{
$this->timers->detach($timer);
$id = spl_object_hash($timer);
unset($this->timers[$id], $this->schedule[$id]);
}

public function getFirst()
{
while ($this->scheduler->count()) {
$timer = $this->scheduler->top();

if ($this->timers->contains($timer)) {
return $this->timers[$timer];
}

$this->scheduler->extract();
// ensure timers are sorted to simply accessing next (first) one
if (!$this->sorted) {
$this->sorted = true;
asort($this->schedule);
}

return null;
return reset($this->schedule);
}

public function isEmpty()
Expand All @@ -77,32 +66,34 @@ public function isEmpty()

public function tick()
{
$time = $this->updateTime();
$timers = $this->timers;
$scheduler = $this->scheduler;

while (!$scheduler->isEmpty()) {
$timer = $scheduler->top();
// ensure timers are sorted so we can execute in order
if (!$this->sorted) {
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You have the exact same logic at line 54. You could create a private method ensureScheduleIsSorted() or something similar in order to do this checking and perform the sorting operation.

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Fair point! This is the very core of the event loop, so this is the critical code path and I would rather avoid any additional function calls. What do you think about this? 👍

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Interesting to point out. Make sense to me 👍

$this->sorted = true;
asort($this->schedule);
}

if (!isset($timers[$timer])) {
$scheduler->extract();
$timers->detach($timer);
$time = $this->updateTime();

continue;
foreach ($this->schedule as $id => $scheduled) {
// schedule is ordered, so loop until first timer that is not scheduled for execution now
if ($scheduled >= $time) {
break;
}

if ($timers[$timer] >= $time) {
break;
// skip any timers that are removed while we process the current schedule
if (!isset($this->schedule[$id]) || $this->schedule[$id] !== $scheduled) {
continue;
}

$scheduler->extract();
$timer = $this->timers[$id];
call_user_func($timer->getCallback(), $timer);

if ($timer->isPeriodic() && isset($timers[$timer])) {
$timers[$timer] = $scheduledAt = $timer->getInterval() + $time;
$scheduler->insert($timer, -$scheduledAt);
// re-schedule if this is a periodic timer and it has not been cancelled explicitly already
if ($timer->isPeriodic() && isset($this->timers[$id])) {
$this->schedule[$id] = $timer->getInterval() + $time;
$this->sorted = false;
} else {
$timers->detach($timer);
unset($this->timers[$id], $this->schedule[$id]);
}
}
}
Expand Down