datasette.allowed_many() method and per-request permission check cache#2775
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Adds a per-request cache for permission check results, plus wiring that resolves action permissions in bulk before plugin hooks need them: - New _permission_check_cache contextvar, set to a fresh dict for each request by DatasetteRouter and reset when the request ends. Keys include the full serialized actor, so actors differing in any field (e.g. token restrictions) never share entries. SkipPermissions mode bypasses the cache entirely. - datasette.allowed_many() now consults the cache and stores its results there, so repeated datasette.allowed() checks within one request resolve without further SQL. - Table pages resolve all registered table-level actions against the current table and all database-level actions against its database (database pages likewise) in batched queries before invoking the table_actions/database_actions plugin hooks - allowed() calls made inside those hooks are then served from the cache with no plugin changes required. Actions with no permission rules from any plugin are resolved to False without touching the database. Benchmarks (benchmarks/) with a simulated 12-plugin ecosystem making 18 checks per table page show 34 -> 13 internal-DB queries per page; with 2ms-per-query internal DB latency (modelling Datasette Cloud) table page time drops from 77.9ms to 27.6ms - the caching layer accounts for ~91% of that improvement over allowed_many() alone. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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GPT-5.5 xhigh in Codex spotted this problem and fixed it with a CTE: https://gisthost.github.io/?46076499ee685acddc988ff6b47a74b0
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A code review from GPT-5.5 xhigh spotted an optimization: https://gisthost.github.io/?46076499ee685acddc988ff6b47a74b0 - the big SQL query would crash at over 500 actions because of SQLite compound SELECT limits, but using a CTE instead fixes that. |
simonw
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Jun 13, 2026
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| This hook may be called for many actions in rapid succession - for example | ||
| :ref:`datasette.allowed_many() <datasette_allowed_many>` gathers rules for every action in its batch | ||
| concurrently before table and database pages render their action menus. Hook implementations must not | ||
| assume that checks for different actions arrive one page-render apart, and expensive work (such as | ||
| network calls) should be cached independently of the ``action`` argument where possible. | ||
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I don't think this documentation is useful.
simonw
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Got this out of Fable before they shut it down.
📚 Documentation preview 📚: https://datasette--2775.org.readthedocs.build/en/2775/