Allow disabling array cache to reduce memory usage

Author: danog

src/Psalm/Config.php

@@ -221,6 +221,8 @@ final class Config
      */
     public ?string $cache_directory = null;
 
+    public bool $array_cache = true;
+
     private bool $cache_directory_initialized = false;
 
     /**
@@ -942,6 +944,7 @@ private static function fromXmlAndPaths(
         $config_xml = simplexml_import_dom($dom_document);
 
         $booleanAttributes = [
+            'arrayCache' => 'array_cache',
             'useDocblockTypes' => 'use_docblock_types',
             'useDocblockPropertyTypes' => 'use_docblock_property_types',
             'docblockPropertyTypesSealProperties' => 'docblock_property_types_seal_properties',

src/Psalm/Internal/Cache.php

@@ -58,13 +58,16 @@ final class Cache
     /** @var resource */
     private mixed $lock;
 
+    private readonly bool $arrayCache;
+
     public function __construct(
         Config $config,
         string $subdir,
         array $dependencies = [],
         private readonly bool $persistent = true,
     ) {
         $this->serializer = $config->getCacheSerializer();
+        $this->arrayCache = $config->array_cache;
         if (!$persistent) {
             return;
         }
@@ -104,7 +107,7 @@ public function __construct(
         flock($lock, LOCK_SH);
         $this->lock = $lock;
 
-        if (file_exists($this->dir.'consolidated')) {
+        if (file_exists($this->dir.'consolidated') && $this->arrayCache) {
             /** @var array<string, list{string, T}> */
             $this->cache = $this->serializer->unserialize(Providers::safeFileGetContents($this->dir.'consolidated'));
         }
@@ -226,7 +229,9 @@ public function getItem(string $key, ?string $hash = ''): array|object|string|nu
 
         /** @var T */
         $content = $this->serializer->unserialize($content);
-        $this->cache[$key] = [$hash, $content];
+        if ($this->arrayCache) {
+            $this->cache[$key] = [$hash, $content];
+        }
         return $content;
     }
 

src/Psalm/Internal/Codebase/DataFlowGraph.php

@@ -9,7 +9,6 @@
 
 use function abs;
 use function array_keys;
-use function array_reverse;
 use function array_sum;
 use function count;
 use function str_starts_with;

src/Psalm/Internal/Fork/ForkContext.php

@@ -235,6 +235,9 @@ private function checkExit(bool $wait = false): ?int
             if ($signal === 11) {
                 $signal = "11: THIS IS A PHP BUG, please report this to https://github.com/vimeo/psalm/issues".
                     " AND to https://github.com/php/php-src/issues";
+            } elseif ($signal === 9) {
+                $signal = "9: the process was likely killed by the OOM killer, try increasing the swap space ".
+                    "or use the arrayCache=\"false\" config to reduce memory usage";
             }
             throw new ContextException("Worker exited due to signal $signal!");
         }