feat: new 'db_resurrect_ttl' configuration property + resilient cache callbacks #3579
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This new version adds support for `resurrect_ttl`, which resurrects stale values when the callback fails on soft errors. https://github.com/thibaultcha/lua-resty-mlcache/blob/master/CHANGELOG.md#220
This option is based on thibaultcha/lua-resty-mlcache#52 Documentation for its behaviour can be read in the description test included in kong.conf.default.
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In order for the resurrection of stale cached values to occur when callback I/O fails (see c932dc6), we have to return soft errors from our callbacks, and not throw them via error().
mlcache can cache negative hits (`nil`) values. Historically, this stub cached value was introduced at a time when the cache solution was a homegrown utility which did not support negative caching.
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This fixes unit tests with mlcache 2.2.0 which relies on the `get_stale()` shm function.
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This new version adds support for
resurrect_ttl, which resurrectsstale values when the callback fails on soft errors.
https://github.com/thibaultcha/lua-resty-mlcache/blob/master/CHANGELOG.md#220
Documentation for its behaviour can be read in the description test
included in kong.conf.default.
In order for the resurrection of stale cached values to occur when
callback I/O fails (see c932dc6), we have to return soft errors from our
callbacks, and not throw them via error().
Additionally, we rely on the modern behavior of mlcache with regards to
the caching of cache misses - returning
nilis cached my mlcache.