bug symfony#53282 [RateLimiter] Fix RateLimit->getRetryAfter() return value when consuming 0 or last tokens (wouterj, ERuban)

This PR was merged into the 6.4 branch.

Discussion
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[RateLimiter] Fix RateLimit->getRetryAfter() return value when consuming 0 or last tokens

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

Replaces symfony#52835 Original description:

> Have got some BC after updating the project to Symfony 6.4 (after that PR symfony#51676).
>
> Sometimes I need to get `RateLimit` object without consuming just before consuming a try, in example:
> ```php
> $rateLimit = $limiter->consume(0);
> if ($rateLimit->getRemainingTokens() === 0) {
>    throw new SomeException($rateLimit->getRetryAfter());
> }
> ...
> $limiter->consume(1)
> ...
> ```
> and found that in that case `$rateLimit->getRetryAfter()` always returns `now`.
>
> So this PR fixes it.

Commits
-------

677b8b7 [RateLimit] Allow to get RateLimit without consuming again
169e383 Reintroduce peek consume test for sliding window policy

Author: nicolas-grekas

src/Symfony/Component/RateLimiter/Policy/SlidingWindowLimiter.php

@@ -65,12 +65,18 @@ public function reserve(int $tokens = 1, float $maxTime = null): Reservation
             $now = microtime(true);
             $hitCount = $window->getHitCount();
             $availableTokens = $this->getAvailableTokens($hitCount);
+            if (0 === $tokens) {
+                $resetDuration = $window->calculateTimeForTokens($this->limit, $window->getHitCount());
+                $resetTime = \DateTimeImmutable::createFromFormat('U', $availableTokens ? floor($now) : floor($now + $resetDuration));
+
+                return new Reservation($now, new RateLimit($availableTokens, $resetTime, true, $this->limit));
+            }
             if ($availableTokens >= $tokens) {
                 $window->add($tokens);
 
                 $reservation = new Reservation($now, new RateLimit($this->getAvailableTokens($window->getHitCount()), \DateTimeImmutable::createFromFormat('U', floor($now)), true, $this->limit));
             } else {
-                $waitDuration = $window->calculateTimeForTokens($this->limit, max(1, $tokens));
+                $waitDuration = $window->calculateTimeForTokens($this->limit, $tokens);
 
                 if (null !== $maxTime && $waitDuration > $maxTime) {
                     // process needs to wait longer than set interval

src/Symfony/Component/RateLimiter/Tests/Policy/SlidingWindowLimiterTest.php

@@ -52,6 +52,7 @@ public function testConsume()
         $rateLimit = $limiter->consume(10);
         $this->assertTrue($rateLimit->isAccepted());
         $this->assertSame(10, $rateLimit->getLimit());
+        $this->assertSame(0, $rateLimit->getRemainingTokens());
     }
 
     public function testWaitIntervalOnConsumeOverLimit()
@@ -76,6 +77,37 @@ public function testReserve()
 
         // 2 over the limit, causing the WaitDuration to become 2/10th of the 12s interval
         $this->assertEqualsWithDelta(12 / 5, $limiter->reserve(4)->getWaitDuration(), 1);
+
+        $limiter->reset();
+        $this->assertEquals(0, $limiter->reserve(10)->getWaitDuration());
+    }
+
+    public function testPeekConsume()
+    {
+        $limiter = $this->createLimiter();
+
+        $limiter->consume(9);
+
+        // peek by consuming 0 tokens twice (making sure peeking doesn't claim a token)
+        for ($i = 0; $i < 2; ++$i) {
+            $rateLimit = $limiter->consume(0);
+            $this->assertTrue($rateLimit->isAccepted());
+            $this->assertSame(10, $rateLimit->getLimit());
+            $this->assertEquals(
+                \DateTimeImmutable::createFromFormat('U', (string) floor(microtime(true))),
+                $rateLimit->getRetryAfter()
+            );
+        }
+
+        $limiter->consume();
+
+        $rateLimit = $limiter->consume(0);
+        $this->assertEquals(0, $rateLimit->getRemainingTokens());
+        $this->assertTrue($rateLimit->isAccepted());
+        $this->assertEquals(
+            \DateTimeImmutable::createFromFormat('U', (string) floor(microtime(true) + 12)),
+            $rateLimit->getRetryAfter()
+        );
     }
 
     private function createLimiter(): SlidingWindowLimiter