added redis module

sites/all/modules/contrib/dev/redis/example.services.yml

@@ -0,0 +1,33 @@
+# This file contains example services overrides.
+#
+# Enable with this line in settings.php
+#   $settings['container_yamls'][] = 'modules/redis/example.services.yml';
+#
+# Or copy & paste the desired services into sites/default/services.yml.
+#
+# Note that the redis module must be enabled for this to work.
+
+services:
+  # Cache tag checksum backend. Used by redis and most other cache backend
+  # to deal with cache tag invalidations.
+  cache_tags.invalidator.checksum:
+   class: Drupal\redis\Cache\RedisCacheTagsChecksum
+   arguments: ['@redis.factory']
+   tags:
+     - { name: cache_tags_invalidator }
+
+  # Replaces the default lock backend with a redis implementation.
+  lock:
+    class: Drupal\Core\Lock\LockBackendInterface
+    factory: ['@redis.lock.factory', get]
+
+  # Replaces the default persistent lock backend with a redis implementation.
+  lock.persistent:
+    class: Drupal\Core\Lock\LockBackendInterface
+    factory: ['@redis.lock.factory', get]
+    arguments: [true]
+
+  # Replaces the default flood backend with a redis implementation.
+  flood:
+    class: Drupal\Core\Flood\FloodInterface
+    factory: ['@redis.flood.factory', get]