Optimize diffInDays

briannesbitt · Aug 5, 2024 · 0e42f93 · 0e42f93
1 parent 0ea08e9
commit 0e42f93
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Showing 2 changed files with 28 additions and 23 deletions.
diff --git a/src/Carbon/Traits/Difference.php b/src/Carbon/Traits/Difference.php
@@ -185,9 +185,9 @@ public function diffInMonths($date = null, bool $absolute = false, bool $utc = f
     {
         $start = $this;
         $end = $this->resolveCarbon($date);
-        $compareUsingUtc = $utc || ($end->timezoneName !== $start->timezoneName);
 
-        if ($compareUsingUtc) {
+        // Compare using UTC
+        if ($utc || ($end->timezoneName !== $start->timezoneName)) {
             $start = $start->avoidMutation()->utc();
             $end = $end->avoidMutation()->utc();
         }
@@ -255,32 +255,26 @@ public function diffInDays($date = null, bool $absolute = false, bool $utc = fal
     {
         $date = $this->resolveCarbon($date);
         $current = $this;
-        $compareUsingUtc = $utc || ($date->timezoneName !== $current->timezoneName);
 
-        if ($compareUsingUtc) {
+        // Compare using UTC
+        if ($utc || ($date->timezoneName !== $current->timezoneName)) {
             $date = $date->avoidMutation()->utc();
             $current = $current->avoidMutation()->utc();
         }
 
-        $interval = $current->diffAsDateInterval($date, $absolute);
-
-        if (!$compareUsingUtc) {
-            $minutes = $interval->i + ($interval->s + $interval->f) / static::SECONDS_PER_MINUTE;
-            // 24 hours means there is a DST bug
-            $hours = ($interval->h === 24 && $interval->days !== false ? 0 : $interval->h) + $minutes / static::MINUTES_PER_HOUR;
-
-            return $this->getIntervalDayDiff($interval)
-                + ($interval->invert ? -$hours : $hours) / static::HOURS_PER_DAY;
-        }
-
-        $hoursDiff = $current->diffInHours($date, $absolute);
-
-        if ($interval->y === 0 && $interval->m === 0 && $interval->d === 0) {
-            return $hoursDiff / static::HOURS_PER_DAY;
-        }
-
-        return $this->getIntervalDayDiff($interval)
-            + fmod($hoursDiff, static::HOURS_PER_DAY) / static::HOURS_PER_DAY;
+        $negative = ($date < $current);
+        [$start, $end] = $negative ? [$date, $current] : [$current, $date];
+        $interval = $start->diffAsDateInterval($end);
+        $daysA = $this->getIntervalDayDiff($interval);
+        $floorEnd = $start->avoidMutation()->addDays($daysA);
+        $daysB = $daysA + ($floorEnd <= $end ? 1 : -1);
+        $ceilEnd = $start->avoidMutation()->addDays($daysB);
+        $microsecondsBetween = $floorEnd->diffInMicroseconds($ceilEnd);
+        $microsecondsToEnd = $floorEnd->diffInMicroseconds($end);
+
+        return ($negative && !$absolute ? -1 : 1)
+            * ($daysA * ($microsecondsBetween - $microsecondsToEnd) + $daysB * $microsecondsToEnd)
+            / $microsecondsBetween;
     }
 
     /**

diff --git a/tests/Carbon/DiffTest.php b/tests/Carbon/DiffTest.php
@@ -2198,6 +2198,17 @@ public function testBigGapInDays()
         $end = Carbon::parse('2027-05-02 01:24:22.848816', 'America/Toronto');
 
         $this->assertSame(-1281.0, $start->diffInDays($end));
+
+        $start = Carbon::parse('2030-11-03 01:24:22.848811', 'America/Toronto');
+        $end = Carbon::parse('2027-05-02 01:24:22.848816', 'America/Toronto');
+
+        $this->assertVeryClose(-1280.999999999942, $start->diffInDays($end));
+
+        $start = Carbon::parse('2024-11-03 00:24:22.848816', 'America/Toronto');
+        $end = Carbon::parse('2024-11-03 23:24:22.848816', 'America/Toronto');
+
+        // November 3rd is a 25-hours day in Toronto because of the DST
+        $this->assertVeryClose(24 / 25, $start->diffInDays($end));
     }
 
     public function testAFormat()