symfony · nicolas-grekas · Dec 16, 2021 · Dec 16, 2021
diff --git a/src/Symfony/Component/Cache/CHANGELOG.md b/src/Symfony/Component/Cache/CHANGELOG.md
@@ -4,7 +4,6 @@ CHANGELOG
 5.4
 ---

- * Make `LockRegistry` use semaphores when possible
 * Deprecate `DoctrineProvider` and `DoctrineAdapter` because these classes have been added to the `doctrine/cache` package
 * Add `DoctrineDbalAdapter` identical to `PdoAdapter` for `Doctrine\DBAL\Connection` or DBAL URL
 * Deprecate usage of `PdoAdapter` with `Doctrine\DBAL\Connection` or DBAL URL

diff --git a/src/Symfony/Component/Cache/LockRegistry.php b/src/Symfony/Component/Cache/LockRegistry.php
@@ -27,7 +27,7 @@
 final class LockRegistry
 {
    private static $openedFiles = [];
-    private static $lockedKeys;
+    private static $lockedFiles;

    /**
     * The number of items in this list controls the max number of concurrent processes.
@@ -77,41 +77,33 @@ public static function setFiles(array $files): array
                fclose($file);
            }
        }
-        self::$openedFiles = self::$lockedKeys = [];
+        self::$openedFiles = self::$lockedFiles = [];

        return $previousFiles;
    }

    public static function compute(callable $callback, ItemInterface $item, bool &$save, CacheInterface $pool, \Closure $setMetadata = null, LoggerInterface $logger = null)
    {
-        if ('\\' === \DIRECTORY_SEPARATOR && null === self::$lockedKeys) {
+        if ('\\' === \DIRECTORY_SEPARATOR && null === self::$lockedFiles) {
            // disable locking on Windows by default
-            self::$files = self::$lockedKeys = [];
+            self::$files = self::$lockedFiles = [];
        }

-        $key = unpack('i', md5($item->getKey(), true))[1];
+        $key = self::$files ? abs(crc32($item->getKey())) % \count(self::$files) : -1;

-        if (!\function_exists('sem_get')) {
-            $key = self::$files ? abs($key) % \count(self::$files) : null;
-        }
-
-        if (null === $key || (self::$lockedKeys[$key] ?? false) || !$lock = self::open($key)) {
+        if ($key < 0 || (self::$lockedFiles[$key] ?? false) || !$lock = self::open($key)) {
            return $callback($item, $save);
        }

        while (true) {
            try {
                $locked = false;
                // race to get the lock in non-blocking mode
-                if ($wouldBlock = \function_exists('sem_get')) {
-                    $locked = @sem_acquire($lock, true);
-                } else {
-                    $locked = flock($lock, \LOCK_EX | \LOCK_NB, $wouldBlock);
-                }
+                $locked = flock($lock, \LOCK_EX | \LOCK_NB, $wouldBlock);

                if ($locked || !$wouldBlock) {
                    $logger && $logger->info(sprintf('Lock %s, now computing item "{key}"', $locked ? 'acquired' : 'not supported'), ['key' => $item->getKey()]);
-                    self::$lockedKeys[$key] = true;
+                    self::$lockedFiles[$key] = true;

                    $value = $callback($item, $save);

@@ -126,25 +118,12 @@ public static function compute(callable $callback, ItemInterface $item, bool &$s

                    return $value;
                }
-
                // if we failed the race, retry locking in blocking mode to wait for the winner
                $logger && $logger->info('Item "{key}" is locked, waiting for it to be released', ['key' => $item->getKey()]);
-
-                if (\function_exists('sem_get')) {
-                    $lock = sem_get($key);
-                    @sem_acquire($lock);
-                } else {
-                    flock($lock, \LOCK_SH);
-                }
+                flock($lock, \LOCK_SH);
            } finally {
-                if ($locked) {
-                    if (\function_exists('sem_get')) {
-                        sem_remove($lock);
-                    } else {
-                        flock($lock, \LOCK_UN);
-                    }
-                }
-                unset(self::$lockedKeys[$key]);
+                flock($lock, \LOCK_UN);
+                unset(self::$lockedFiles[$key]);
            }
            static $signalingException, $signalingCallback;
            $signalingException = $signalingException ?? unserialize("O:9:\"Exception\":1:{s:16:\"\0Exception\0trace\";a:0:{}}");
@@ -169,10 +148,6 @@ public static function compute(callable $callback, ItemInterface $item, bool &$s

    private static function open(int $key)
    {
-        if (\function_exists('sem_get')) {
-            return sem_get($key);
-        }
-
        if (null !== $h = self::$openedFiles[$key] ?? null) {
            return $h;
        }