MDL-85336 redis: Split connection and read timeouts

.upgradenotes/MDL-85336-2025112802512668.yml

@@ -0,0 +1,8 @@
+issueNumber: MDL-85336
+notes:
+  core:
+    - message: >-
+        Redis connection timeout settings for cachestores and sessions have been
+        split into connection timeout and read timeout to allow for finer
+        control. These settings now also accept floats.
+      type: improved

config-dist.php

@@ -382,6 +382,7 @@ $CFG->admin = 'admin';
 //                                                           // After 5 seconds it will throttle down to once per second.
 //      $CFG->session_redis_connection_timeout = 3.0;        // Optional, default is 3.0.
 //      $CFG->session_redis_maxretries = 3;                  // Optional, default is 3.
+//      $CFG->session_redis_read_timeout = 3.0;              // Optional, default is 3.0.
 //
 //      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!

public/lib/classes/session/redis.php

@@ -114,9 +114,12 @@ class redis extends handler implements SessionHandlerInterface {
     /** @var clock A clock instance */
     protected clock $clock;
 
-    /** @var float $connectiontimeout The number of seconds to wait for a connection or response from the Redis server. */
+    /** @var float $connectiontimeout The number of seconds to wait for a connection response from the Redis server. */
     protected float $connectiontimeout = 3.0;
 
+    /** @var float $readtimeout The number of seconds to wait for a read from the Redis server. */
+    protected float $readtimeout = 3.0;
+
     /**
      * Create new instance of handler.
      */
@@ -212,6 +215,10 @@ class redis extends handler implements SessionHandlerInterface {
             $this->maxretries = (int)$CFG->session_redis_max_retries;
         }
 
+        if (isset($CFG->session_redis_read_timeout)) {
+            $this->readtimeout = (float)$CFG->session_redis_read_timeout;
+        }
+
         $this->clock = di::get(clock::class);
     }
 
@@ -316,7 +323,7 @@ class redis extends handler implements SessionHandlerInterface {
                             name: null,
                             seeds: $trimmedservers,
                             timeout: $this->connectiontimeout, // Timeout.
-                            read_timeout: $this->connectiontimeout, // Read timeout.
+                            read_timeout: $this->readtimeout, // Read timeout.
                             persistent: true,
                             auth: $this->auth,
                             context: !empty($opts) ? $opts : null,
@@ -326,7 +333,7 @@ class redis extends handler implements SessionHandlerInterface {
                             null,
                             $trimmedservers,
                             $this->connectiontimeout,
-                            $this->connectiontimeout,
+                            $this->readtimeout,
                             true,
                             $this->auth,
                             !empty($opts) ? $opts : null
@@ -342,7 +349,7 @@ class redis extends handler implements SessionHandlerInterface {
                             port: $port,
                             timeout: $this->connectiontimeout, // Timeout.
                             retry_interval: $delay,
-                            read_timeout: $this->connectiontimeout, // Read timeout.
+                            read_timeout: $this->readtimeout, // Read timeout.
                             context: $opts,
                         );
                     } else {
@@ -352,7 +359,7 @@ class redis extends handler implements SessionHandlerInterface {
                             $this->connectiontimeout,
                             null,
                             $delay,
-                            $this->connectiontimeout,
+                            $this->readtimeout,
                             $opts
                         );
                     }