Merge pull request #13514 from totten/master-nack-rev

(dev/core#635) CRM_Utils_Cache::nack() - Fix format

CRM/Utils/Cache.php

@@ -285,19 +285,20 @@ public static function getCacheDriver() {
    *   $value = $cache->get('foo', $nack);
    *   echo ($value === $nack) ? "Cache has a value, and we got it" : "Cache has no value".
    *
-   * The value should be unique to avoid accidental matches. As a performance
-   * tweak, we may reuse the NACK a few times within the current page-view.
+   * The value should be unique to avoid accidental matches.
    *
    * @return string
    *   Unique nonce value indicating a "negative acknowledgement" (failed read).
    *   If we need to accurately perform has($key)+get($key), we can
    *   use `get($key,$nack)`.
    */
   public static function nack() {
-    if (!isset(Civi::$statics[__CLASS__]['nack'])) {
-      Civi::$statics[__CLASS__]['nack'] = 'NACK:' . md5(CRM_Utils_Request::id() . CIVICRM_SITE_KEY . CIVICRM_DSN . mt_rand(0, 10000));
+    $st =& Civi::$statics[__CLASS__];
+    if (!isset($st['nack-c'])) {
+      $st['nack-c'] = md5(CRM_Utils_Request::id() . CIVICRM_SITE_KEY . CIVICRM_DSN . mt_rand(0, 10000));
+      $st['nack-i'] = 0;
     }
-    return Civi::$statics[__CLASS__];
+    return 'NACK:' . $st['nack-c'] . $st['nack-i']++;
   }
 
 }

CRM/Utils/Cache/NaiveHasTrait.php

@@ -38,7 +38,7 @@
 trait CRM_Utils_Cache_NaiveHasTrait {
 
   public function has($key) {
-    $nack = CRM_Utils_Cache::nack() . 'ht';
+    $nack = CRM_Utils_Cache::nack();
     $value = $this->get($key, $nack);
     return ($value !== $nack);
   }

tests/phpunit/CRM/Utils/CacheTest.php

@@ -0,0 +1,24 @@
+<?php
+
+/**
+ * Class CRM_Utils_CacheTest
+ * @group headless
+ */
+class CRM_Utils_CacheTest extends CiviUnitTestCase {
+
+  public function testNack() {
+    $values = [];
+    for ($i = 0; $i < 5; $i++) {
+      $nack = CRM_Utils_Cache::nack();
+      $this->assertRegExp('/^NACK:[a-z0-9]+$/', $nack);
+      $values[] = $nack;
+    }
+    sort($values);
+    $this->assertEquals($values, array_unique($values));
+
+    // The random token should at the start should same -- because we don't
+    // the overhead of re-generating it frequently.
+    $this->assertEquals(substr($values[0], 0, 37), substr($values[1], 0, 37));
+  }
+
+}