[Bug]: Dirty user_status table read

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

user_status table is written and read within the same process.

{
  "reqId": "fxUYHfQwOF9dq7xnFck2",
  "level": 0,
  "time": "2024-01-23T11:06:42+00:00",
  "remoteAddr": "127.0.0.1",
  "user": "admin",
  "app": "no app in context",
  "method": "PUT",
  "url": "/ocs/v2.php/apps/user_status/api/v1/heartbeat?format=json",
  "message": "dirty table reads: SELECT * FROM `*PREFIX*user_status` WHERE `user_id` = :dcValue1",
  "userAgent": "Mozilla/5.0 (X11; Linux x86_64; rv:120.0) Gecko/20100101 Firefox/120.0",
  "version": "29.0.0.4",
  "exception": {
    "Exception": "Exception",
    "Message": "",
    "Code": 0,
    "Trace": [
      {
        "file": "/home/christoph/workspace/nextcloud/3rdparty/doctrine/dbal/src/Query/QueryBuilder.php",
        "line": 337,
        "function": "executeQuery",
        "class": "OC\\DB\\Connection",
        "type": "->",
        "args": [
          "SELECT * FROM `*PREFIX*user_status` WHERE `user_id` = :dcValue1",
          [
            "admin"
          ],
          [
            2
          ],
          null
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/3rdparty/doctrine/dbal/src/Query/QueryBuilder.php",
        "line": 377,
        "function": "executeQuery",
        "class": "Doctrine\\DBAL\\Query\\QueryBuilder",
        "type": "->",
        "args": []
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php",
        "line": 280,
        "function": "execute",
        "class": "Doctrine\\DBAL\\Query\\QueryBuilder",
        "type": "->",
        "args": []
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php",
        "line": 293,
        "function": "execute",
        "class": "OC\\DB\\QueryBuilder\\QueryBuilder",
        "type": "->",
        "args": []
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/public/AppFramework/Db/QBMapper.php",
        "line": 275,
        "function": "executeQuery",
        "class": "OC\\DB\\QueryBuilder\\QueryBuilder",
        "type": "->",
        "args": []
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/public/AppFramework/Db/QBMapper.php",
        "line": 361,
        "function": "findOneQuery",
        "class": "OCP\\AppFramework\\Db\\QBMapper",
        "type": "->",
        "args": [
          [
            "OC\\DB\\QueryBuilder\\QueryBuilder"
          ]
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/apps/user_status/lib/Db/UserStatusMapper.php",
        "line": 112,
        "function": "findEntity",
        "class": "OCP\\AppFramework\\Db\\QBMapper",
        "type": "->",
        "args": [
          [
            "OC\\DB\\QueryBuilder\\QueryBuilder"
          ]
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/apps/user_status/lib/Service/StatusService.php",
        "line": 138,
        "function": "findByUserId",
        "class": "OCA\\UserStatus\\Db\\UserStatusMapper",
        "type": "->",
        "args": [
          "admin"
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/apps/user_status/lib/Listener/UserLiveStatusListener.php",
        "line": 74,
        "function": "findByUserId",
        "class": "OCA\\UserStatus\\Service\\StatusService",
        "type": "->",
        "args": [
          "admin"
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/EventDispatcher/ServiceEventListener.php",
        "line": 86,
        "function": "handle",
        "class": "OCA\\UserStatus\\Listener\\UserLiveStatusListener",
        "type": "->",
        "args": [
          [
            "OCP\\User\\Events\\UserLiveStatusEvent"
          ]
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/3rdparty/symfony/event-dispatcher/EventDispatcher.php",
        "line": 230,
        "function": "__invoke",
        "class": "OC\\EventDispatcher\\ServiceEventListener",
        "type": "->",
        "args": [
          [
            "OCP\\User\\Events\\UserLiveStatusEvent"
          ],
          "OCP\\User\\Events\\UserLiveStatusEvent",
          [
            "Symfony\\Component\\EventDispatcher\\EventDispatcher"
          ]
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/3rdparty/symfony/event-dispatcher/EventDispatcher.php",
        "line": 59,
        "function": "callListeners",
        "class": "Symfony\\Component\\EventDispatcher\\EventDispatcher",
        "type": "->",
        "args": [
          [
            [
              "Closure"
            ]
          ],
          "OCP\\User\\Events\\UserLiveStatusEvent",
          [
            "OCP\\User\\Events\\UserLiveStatusEvent"
          ]
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/EventDispatcher/EventDispatcher.php",
        "line": 94,
        "function": "dispatch",
        "class": "Symfony\\Component\\EventDispatcher\\EventDispatcher",
        "type": "->",
        "args": [
          [
            "OCP\\User\\Events\\UserLiveStatusEvent"
          ],
          "OCP\\User\\Events\\UserLiveStatusEvent"
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/EventDispatcher/EventDispatcher.php",
        "line": 106,
        "function": "dispatch",
        "class": "OC\\EventDispatcher\\EventDispatcher",
        "type": "->",
        "args": [
          "OCP\\User\\Events\\UserLiveStatusEvent",
          [
            "OCP\\User\\Events\\UserLiveStatusEvent"
          ]
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/apps/user_status/lib/Controller/HeartbeatController.php",
        "line": 100,
        "function": "dispatchTyped",
        "class": "OC\\EventDispatcher\\EventDispatcher",
        "type": "->",
        "args": [
          [
            "OCP\\User\\Events\\UserLiveStatusEvent"
          ]
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",
        "line": 232,
        "function": "heartbeat",
        "class": "OCA\\UserStatus\\Controller\\HeartbeatController",
        "type": "->",
        "args": [
          "online"
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",
        "line": 138,
        "function": "executeController",
        "class": "OC\\AppFramework\\Http\\Dispatcher",
        "type": "->",
        "args": [
          [
            "OCA\\UserStatus\\Controller\\HeartbeatController"
          ],
          "heartbeat"
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/AppFramework/App.php",
        "line": 184,
        "function": "dispatch",
        "class": "OC\\AppFramework\\Http\\Dispatcher",
        "type": "->",
        "args": [
          [
            "OCA\\UserStatus\\Controller\\HeartbeatController"
          ],
          "heartbeat"
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/lib/private/Route/Router.php",
        "line": 315,
        "function": "main",
        "class": "OC\\AppFramework\\App",
        "type": "::",
        "args": [
          "OCA\\UserStatus\\Controller\\HeartbeatController",
          "heartbeat",
          [
            "OC\\AppFramework\\DependencyInjection\\DIContainer"
          ],
          [
            "ocs.user_status.Heartbeat.heartbeat"
          ]
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/ocs/v1.php",
        "line": 65,
        "function": "match",
        "class": "OC\\Route\\Router",
        "type": "->",
        "args": [
          "/ocsapp/apps/user_status/api/v1/heartbeat"
        ]
      },
      {
        "file": "/home/christoph/workspace/nextcloud/ocs/v2.php",
        "line": 23,
        "args": [
          "/home/christoph/workspace/nextcloud/ocs/v1.php"
        ],
        "function": "require_once"
      }
    ],
    "File": "/home/christoph/workspace/nextcloud/lib/private/DB/Connection.php",
    "Line": 284,
    "message": "dirty table reads: SELECT * FROM `*PREFIX*user_status` WHERE `user_id` = :dcValue1",
    "tables": [
      "oc_user_status"
    ],
    "reads": [
      "oc_user_status"
    ],
    "exception": {},
    "CustomMessage": "dirty table reads: SELECT * FROM `*PREFIX*user_status` WHERE `user_id` = :dcValue1"
  }
}

Options:

1. Prevent reading at all by keeping the written data in memory and using that.
2. Wrap write+read in a transaction if the two operations depend on each other.

Steps to reproduce

1. Set log level to debug
2. Load a Nextcloud page

Expected behavior

No dirty read logs

Installation method

None

Nextcloud Server version

master

Operating system

None

PHP engine version

None

Web server

None

Database engine version

None

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

No response

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

Reproduce the debug log by loading a Nextcloud page, then trace the heartbeat path from apps/user_status/lib/Controller/HeartbeatController.php through UserLiveStatusListener.php, StatusService.php, and UserStatusMapper.php. Also inspect lib/private/DB/Connection.php where the dirty-read message is emitted. Done means the user_status write and read no longer produce dirty-read logs, with the intended handling approach decided.