MDL-83753 redis: Allow for configurable max retries setting

config-dist.php

@@ -361,6 +361,7 @@
 //      $CFG->session_redis_lock_retry = 100;                // Optional wait between lock attempts in ms, default is 100.
 //                                                           // After 5 seconds it will throttle down to once per second.
 //      $CFG->session_redis_connection_timeout = 3;          // Optional, default is 3.
+//      $CFG->session_redis_maxretries = 3;                  // Optional, default is 3.
 //
 //      Use the igbinary serializer instead of the php default one. Note that phpredis must be compiled with
 //      igbinary support to make the setting to work. Also, if you change the serializer you have to flush the database!

lib/classes/session/redis.php

@@ -102,6 +102,9 @@ class redis extends handler {
     /** @var int $timeout How long sessions live before expiring. */
     protected $timeout;
 
+    /** @var int Maximum number of retries for cache store operations. */
+    protected int $maxretries = 3;
+
     /** @var int $connectiontimeout The number of seconds to wait for a connection or response from the Redis server. */
     protected int $connectiontimeout = 3;
 
@@ -199,6 +202,10 @@ public function __construct() {
         if (isset($CFG->session_redis_connection_timeout)) {
             $this->connectiontimeout = (int)$CFG->session_redis_connection_timeout;
         }
+
+        if (isset($CFG->session_redis_max_retries)) {
+            $this->maxretries = (int)$CFG->session_redis_max_retries;
+        }
     }
 
     /**
@@ -246,7 +253,7 @@ public function init() {
 
         // MDL-59866: Add retries for connections (up to 5 times) to make sure it goes through.
         $counter = 1;
-        $maxnumberofretries = 5;
+        $maxnumberofretries = $this->maxretries;
         $opts = [];
         if ($this->sslopts) {
             // Do not set $opts['stream'] = [], breaks connect().