[abnegate]

Problem

Since #1042, a write fails when the cache cannot confirm its invalidation. During an outage that is the point. But it also turns a single Redis timeout into a failed write.

On Appwrite Cloud fra1 (2026-10-21 03:50:35Z), one unconfirmed purge of a collection definition refused a TablesDB row insert:

Utopia\Cache\Exception\Unavailable: Cache purge of '…:_metadata:database_164328_collection_1' could not be confirmed

The client saw a 500. The next call to the same cache succeeded. The same error hit four unrelated projects in the two hours before, on rows, documents and transaction routes.

Fix

The cache steps a write waits on now go through the existing bounded withRetries(), which purgeCommittedCollection() already uses: three attempts, with a 100 ms backoff that doubles. That covers:

• blockDocumentCacheEpoch(): the tombstone save, the #started purge, the definition purge, and the unreadable-epoch purge
• purgeCachedDocumentInternal(): the document purge

An outage longer than the retries still fails the write exactly as before. A transaction failure is still not retried here, because isRetryable() defers to the transaction.

Tests

CacheUnavailableTest::testAWriteRidesOutAPurgeBlip makes the next two purges fail and then lets the cache recover. It covers a single update, an update in a transaction, and a batch update. Each write must commit, and the cache must not keep serving the old document. On main all three fail with Cache purge could not be confirmed. The existing outage cases still fail the write and roll it back.

UnavailableCache gains failNextPurges() to model the blip.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved reliability for document updates when cache services experience temporary purge failures.
  • Document writes now retry affected cache cleanup operations and continue successfully when the cache recovers.
  • Updated document data remains consistent between stored records and cached results across direct, transactional, and batch updates.

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⚙️ Run configuration

• Configuration used: Repository: utopia-php/database/.coderabbit.yaml
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📥 Commits

Reviewing files that changed from the base of the PR and between 187b979 and b02ac7c.

📒 Files selected for processing: 1

• tests/unit/Documents/DocumentCacheInvalidationTest.php

📝 Walkthrough

Document cache purges and epoch invalidation now retry failures. Tests cover direct, transactional, and batch writes that encounter temporary cache purge failures.

Changes: Cache purge retries

Layer / File(s)	Summary
Retry document cache invalidation src/Database/Trait/Documents.php	Document cache purges and epoch cleanup and invalidation steps now use retries. A failed tombstone save raises a RuntimeException within the retry operation.
Test writes during purge failures tests/unit/Cache/UnavailableCache.php, tests/unit/Documents/CacheUnavailableTest.php	UnavailableCache can simulate a configured number of purge failures. Tests cover direct, transactional, and batch writes that succeed after two failed purge attempts and update stored and cached documents.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: 🔵 Low · up to 187b9

Writes now ride out brief cache purge errors that raise exceptions. However, a purge that fails silently by returning a failure value is still not retried and does not fail the write, which can leave a stale cached collection definition. This gap existed before the change, so the change is mergeable with follow-up to close it.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 54.55% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 11 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly summarizes the main change: retrying cache invalidation before refusing a write.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

---

• 🪄 Fix comments: Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at @src/Database/Trait/Documents.php:
- Line 3578: Update purgeCachedDefinition() and each purge adapter used by
withRetries() so a missing key is treated as a successful no-op, while an actual
filesystem deletion failure throws from the retry operation. Ensure
purgeCachedDefinition() does not discard purge failures, allowing withRetries()
to exhaust retries and propagate the failure before the write proceeds.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Repository: utopia-php/database/.coderabbit.yaml
• Review profile: CHILL
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📥 Commits

Reviewing files that changed from the base of the PR and between 3859954 and 187b979.

📒 Files selected for processing: 3

• src/Database/Trait/Documents.php
• tests/unit/Cache/UnavailableCache.php
• tests/unit/Documents/CacheUnavailableTest.php

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