Configure memory eviction factor

tedious · May 19, 2020 · 98b9e68 · 98b9e68
1 parent 9e0b5f2
commit 98b9e68
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Showing 2 changed files with 49 additions and 5 deletions.
diff --git a/src/Stash/Driver/Ephemeral.php b/src/Stash/Driver/Ephemeral.php
@@ -43,9 +43,21 @@ class Ephemeral extends AbstractDriver
      */
     protected $memoryLimit = 0;
 
+    /**
+     * How aggressive to perform eviction in case of memory limit violation.
+     * Should be positive float less than 1.
+     *
+     * @var float
+     */
+    private $memoryLimitEvictionFactor;
+
     public function getDefaultOptions()
     {
-        return ['maxItems' => 0, 'memoryLimit' => 0];
+        return [
+            'maxItems' => 0,
+            'memoryLimit' => 0,
+            'memoryLimitEvictionFactor' => 0.25,
+        ];
     }
 
     /**
@@ -60,6 +72,7 @@ protected function setOptions(array $options = array())
 
         $this->maxItems = self::positiveIntegerOption($options, 'maxItems');
         $this->memoryLimit = self::positiveIntegerOption($options, 'memoryLimit');
+        $this->memoryLimitEvictionFactor = self::factorOption($options, 'memoryLimitEvictionFactor');
 
         if ($this->maxItems > 0 && count($this->store) > $this->maxItems) {
             $this->evict(count($this->store) - $this->maxItems);
@@ -121,10 +134,12 @@ public function storeData($key, $data, $expiration)
 
         if ($this->memoryLimit > 0) {
             while (count($this->store) && memory_get_usage() > $this->memoryLimit) {
-                $numItemsToKeep = count($this->store) * .25;
-                $this->store = $numItemsToKeep > 10
-                    ? array_slice($this->store, $numItemsToKeep, null, true)
-                    : [];
+                $offset = max(
+                    ceil(count($this->store) * $this->memoryLimitEvictionFactor),
+                    1
+                );
+
+                $this->store = array_slice($this->store, $offset, null, true);
             }
         }
 
@@ -183,4 +198,23 @@ protected static function positiveIntegerOption(array $options, $optionName)
 
         return $optionValue;
     }
+
+    /**
+     * @param array $options
+     * @param string $optionName
+     * @return int
+     * @throws Stash\Exception\InvalidArgumentException
+     */
+    protected static function factorOption(array $options, $optionName)
+    {
+        $optionValue = $options[$optionName];
+
+        if (!is_float($optionValue) || $optionValue < 0 || $optionValue > 1) {
+            throw new Stash\Exception\InvalidArgumentException(
+                $optionName . ' must be a factor 0..1'
+            );
+        }
+
+        return $optionValue;
+    }
 }
diff --git a/tests/Stash/Test/Driver/EphemeralTest.php b/tests/Stash/Test/Driver/EphemeralTest.php
@@ -157,6 +157,16 @@ public function testSettingInvalidMemoryLimitThrows()
         ]);
     }
 
+    /**
+     * @expectedException \Stash\Exception\InvalidArgumentException
+     */
+    public function testSettingInvalidMemoryLimitEvictionFactorThrows()
+    {
+        new $this->driverClass([
+            'memoryLimitEvictionFactor' => 98,
+        ]);
+    }
+
     public function testEvictionCausedByMemoryLimit()
     {
         $expire = time() + 100;