From 9f70b0e4bc774d25e5bcff3de677e35d2808b646 Mon Sep 17 00:00:00 2001
From: Tim Otten <totten@civicrm.org>
Date: Tue, 19 Jun 2018 16:43:21 -0700
Subject: [PATCH] (dev/core#174) CRM_Utils_Cache_Interface - Add `has()`
 (PSR-16)

---
 CRM/Utils/Cache/APCcache.php       |  1 +
 CRM/Utils/Cache/ArrayCache.php     |  1 +
 CRM/Utils/Cache/Interface.php      | 14 +++++++++
 CRM/Utils/Cache/Memcache.php       |  1 +
 CRM/Utils/Cache/Memcached.php      |  1 +
 CRM/Utils/Cache/NaiveHasTrait.php  | 49 ++++++++++++++++++++++++++++++
 CRM/Utils/Cache/NoCache.php        |  1 +
 CRM/Utils/Cache/Redis.php          |  1 +
 CRM/Utils/Cache/SerializeCache.php |  1 +
 CRM/Utils/Cache/SqlGroup.php       |  1 +
 10 files changed, 71 insertions(+)
 create mode 100644 CRM/Utils/Cache/NaiveHasTrait.php

diff --git a/CRM/Utils/Cache/APCcache.php b/CRM/Utils/Cache/APCcache.php
index d0047b857f..a8b4e5cd69 100644
--- a/CRM/Utils/Cache/APCcache.php
+++ b/CRM/Utils/Cache/APCcache.php
@@ -33,6 +33,7 @@
 class CRM_Utils_Cache_APCcache implements CRM_Utils_Cache_Interface {
 
   use CRM_Utils_Cache_NaiveMultipleTrait; // TODO Consider native implementation.
+  use CRM_Utils_Cache_NaiveHasTrait; // TODO Native implementation
 
   const DEFAULT_TIMEOUT = 3600;
   const DEFAULT_PREFIX = '';
diff --git a/CRM/Utils/Cache/ArrayCache.php b/CRM/Utils/Cache/ArrayCache.php
index 47ad9a082d..c74e1900f1 100644
--- a/CRM/Utils/Cache/ArrayCache.php
+++ b/CRM/Utils/Cache/ArrayCache.php
@@ -37,6 +37,7 @@
 class CRM_Utils_Cache_Arraycache implements CRM_Utils_Cache_Interface {
 
   use CRM_Utils_Cache_NaiveMultipleTrait;
+  use CRM_Utils_Cache_NaiveHasTrait; // TODO Native implementation
 
   /**
    * The cache storage container, an in memory array by default
diff --git a/CRM/Utils/Cache/Interface.php b/CRM/Utils/Cache/Interface.php
index 52e4f11412..51158363d4 100644
--- a/CRM/Utils/Cache/Interface.php
+++ b/CRM/Utils/Cache/Interface.php
@@ -108,4 +108,18 @@ interface CRM_Utils_Cache_Interface {
    */
   public function clear();
 
+  /**
+   * Determines whether an item is present in the cache.
+   *
+   * NOTE: It is recommended that has() is only to be used for cache warming type purposes
+   * and not to be used within your live applications operations for get/set, as this method
+   * is subject to a race condition where your has() will return true and immediately after,
+   * another script can remove it making the state of your app out of date.
+   *
+   * @param string $key The cache item key.
+   *
+   * @return bool
+   */
+  public function has($key);
+
 }
diff --git a/CRM/Utils/Cache/Memcache.php b/CRM/Utils/Cache/Memcache.php
index 23889f5fe7..8e6e01dc51 100644
--- a/CRM/Utils/Cache/Memcache.php
+++ b/CRM/Utils/Cache/Memcache.php
@@ -33,6 +33,7 @@
 class CRM_Utils_Cache_Memcache implements CRM_Utils_Cache_Interface {
 
   use CRM_Utils_Cache_NaiveMultipleTrait; // TODO Consider native implementation.
+  use CRM_Utils_Cache_NaiveHasTrait; // TODO Native implementation
 
   const DEFAULT_HOST = 'localhost';
   const DEFAULT_PORT = 11211;
diff --git a/CRM/Utils/Cache/Memcached.php b/CRM/Utils/Cache/Memcached.php
index 7b9bcfeaf5..c1ad9cb75a 100644
--- a/CRM/Utils/Cache/Memcached.php
+++ b/CRM/Utils/Cache/Memcached.php
@@ -33,6 +33,7 @@
 class CRM_Utils_Cache_Memcached implements CRM_Utils_Cache_Interface {
 
   use CRM_Utils_Cache_NaiveMultipleTrait; // TODO Consider native implementation.
+  use CRM_Utils_Cache_NaiveHasTrait; // TODO Native implementation
 
   const DEFAULT_HOST = 'localhost';
   const DEFAULT_PORT = 11211;
diff --git a/CRM/Utils/Cache/NaiveHasTrait.php b/CRM/Utils/Cache/NaiveHasTrait.php
new file mode 100644
index 0000000000..78ecc67887
--- /dev/null
+++ b/CRM/Utils/Cache/NaiveHasTrait.php
@@ -0,0 +1,49 @@
+<?php
+/*
+ +--------------------------------------------------------------------+
+ | CiviCRM version 5                                                  |
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC (c) 2004-2018                                |
+ +--------------------------------------------------------------------+
+ | This file is a part of CiviCRM.                                    |
+ |                                                                    |
+ | CiviCRM is free software; you can copy, modify, and distribute it  |
+ | under the terms of the GNU Affero General Public License           |
+ | Version 3, 19 November 2007 and the CiviCRM Licensing Exception.   |
+ |                                                                    |
+ | CiviCRM is distributed in the hope that it will be useful, but     |
+ | WITHOUT ANY WARRANTY; without even the implied warranty of         |
+ | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.               |
+ | See the GNU Affero General Public License for more details.        |
+ |                                                                    |
+ | You should have received a copy of the GNU Affero General Public   |
+ | License and the CiviCRM Licensing Exception along                  |
+ | with this program; if not, contact CiviCRM LLC                     |
+ | at info[AT]civicrm[DOT]org. If you have questions about the        |
+ | GNU Affero General Public License or the licensing of CiviCRM,     |
+ | see the CiviCRM license FAQ at http://civicrm.org/licensing        |
+ +--------------------------------------------------------------------+
+ */
+
+/**
+ *
+ * @package CRM
+ * @copyright CiviCRM LLC (c) 2004-2018
+ *
+ * The traditional CRM_Utils_Cache_Interface did not support has().
+ * To get drop-in compliance with PSR-16, we use a naive adapter.
+ *
+ * Ideally, these should be replaced with more performant/native versions.
+ */
+trait CRM_Utils_Cache_NaiveHasTrait {
+
+  public function has($key) {
+    // This is crazy-talk. If you've got an environment setup where you might
+    // be investigating this, fix your preferred cache driver by
+    // replacing `NaiveHasTrait` with a decent function.
+    $hasDefaultA = ($this->get($key, NULL) === NULL);
+    $hasDefaultB = ($this->get($key, 123) === 123);
+    return !($hasDefaultA && $hasDefaultB);
+  }
+
+}
diff --git a/CRM/Utils/Cache/NoCache.php b/CRM/Utils/Cache/NoCache.php
index 1fdaef4e99..3c1d9b9445 100644
--- a/CRM/Utils/Cache/NoCache.php
+++ b/CRM/Utils/Cache/NoCache.php
@@ -33,6 +33,7 @@
 class CRM_Utils_Cache_NoCache implements CRM_Utils_Cache_Interface {
 
   use CRM_Utils_Cache_NaiveMultipleTrait; // TODO Consider native implementation.
+  use CRM_Utils_Cache_NaiveHasTrait; // TODO Native implementation
 
   /**
    * We only need one instance of this object. So we use the singleton
diff --git a/CRM/Utils/Cache/Redis.php b/CRM/Utils/Cache/Redis.php
index 0cc979abcc..01fc538c93 100644
--- a/CRM/Utils/Cache/Redis.php
+++ b/CRM/Utils/Cache/Redis.php
@@ -35,6 +35,7 @@
 class CRM_Utils_Cache_Redis implements CRM_Utils_Cache_Interface {
 
   use CRM_Utils_Cache_NaiveMultipleTrait; // TODO Consider native implementation.
+  use CRM_Utils_Cache_NaiveHasTrait; // TODO Native implementation
 
   const DEFAULT_HOST    = 'localhost';
   const DEFAULT_PORT    = 6379;
diff --git a/CRM/Utils/Cache/SerializeCache.php b/CRM/Utils/Cache/SerializeCache.php
index 910fe1bf7e..fdf0eb6d47 100644
--- a/CRM/Utils/Cache/SerializeCache.php
+++ b/CRM/Utils/Cache/SerializeCache.php
@@ -37,6 +37,7 @@
 class CRM_Utils_Cache_SerializeCache implements CRM_Utils_Cache_Interface {
 
   use CRM_Utils_Cache_NaiveMultipleTrait;
+  use CRM_Utils_Cache_NaiveHasTrait; // TODO Native implementation
 
   /**
    * The cache storage container, an array by default, stored in a file under templates
diff --git a/CRM/Utils/Cache/SqlGroup.php b/CRM/Utils/Cache/SqlGroup.php
index 91237b5847..3b983ae106 100644
--- a/CRM/Utils/Cache/SqlGroup.php
+++ b/CRM/Utils/Cache/SqlGroup.php
@@ -39,6 +39,7 @@
 class CRM_Utils_Cache_SqlGroup implements CRM_Utils_Cache_Interface {
 
   use CRM_Utils_Cache_NaiveMultipleTrait; // TODO Consider native implementation.
+  use CRM_Utils_Cache_NaiveHasTrait; // TODO Native implementation
 
   /**
    * The host name of the memcached server.
-- 
2.25.1