The list of last requests hashes from thGetLastRequestsHashes and stubGetLastRequestsHashes can miss some requests because of the race condition

Created on 26 February 2025, 2 months ago

Problem/Motivation

The module uses Drupal State API to store the list of the last requests hashes, and simply appends the last request to the stored list.

But in some cases when we have multiple parallel requests to Drupal, we can face the race condition and the values can be overwritten by another parallel request between "get" and "set" here:

  protected function stubStoreRequestHash(string $hash): void {
    parent::stubStoreRequestHash($hash);
    $lastHashes = $this->state->get(self::STATE_KEY_LAST_REQUESTS_HASHES, []);
    array_unshift($lastHashes, $hash);
    $lastHashes = array_slice($lastHashes, 0, self::LAST_REQUESTS_HASHES_STORE_LIMIT);
    $this->state->set(self::STATE_KEY_LAST_REQUESTS_HASHES, $lastHashes);
  }

Steps to reproduce

Run a test that executes multiple parallel requests to Drupal.

See that the tests are not stable and sometimes miss the stored response hashes.

Proposed resolution

Use a locking mechanism to prevent overwriting the values.

Remaining tasks

User interface changes

API changes

Data model changes

🐛 Bug report

Status

Active

Version

1.5

Component

Code

Created by

🇦🇲Armenia murz Yerevan, Armenia

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Merge Requests

!136The list of last requests hashes from thGetLastRequestsHashes and stubGetLastRequestsHashes can miss some requests because of the race condition
Merged
🇦🇲Armenia murz
updated 2 months ago

Comments & Activities

Issue created by @murz
Merge request !136Issue #3509060: Lock the State while updating the list of the last requests hashes → (Merged) created by murz
Pipeline finished with Skipped
2 months ago
#436851
Comment 2 months ago →
System Message

murz → committed faa69870 on 1.5.x
Issue #3509060: The list of last requests hashes from...
Comment 2 months ago →
🇦🇲Armenia murz Yerevan, Armenia
The issue was in the static cache of the State API, so when we call $this->stateService->get('some_key') more than one time, all next calls return statically cached value for the current request, not the actual value from the database.

So, another parallel request can update the value, and it will be overwritten by the current request. That causes the issue.

The solution is to force clear the static cache before each call of the $this->stateService->get('some_key').
Comment 2 months ago →
🇦🇲Armenia murz Yerevan, Armenia

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