Hi, > I'd like to add > https://github.com/TysonAndre/immutable_cache-pecl#immutable_cache as a PECL. > > This adds functionality similar to https://pecl.php.net/apcu , > but with immutable cache entries of immutable values (either the values > themselves or an immutable serialized copy of mutable values is stored in the > shared memory region) > > - The API is https://github.com/TysonAndre/immutable_cache-pecl#api-reference > - e.g. for a web server with hundreds of worker processes/threads, the entire > pool would have one anonymous singleton shared memory pool only used by > `immutable_cache` > - The mechanism used is pretty much the same as how opcache internally stores > immutable values (non-reference counted scalars, strings, arrays of immutable > values) > > This provides a noticeable performance benefit (e.g. when caching config > arrays or large strings in userland), because: > - There's no copying out of shared memory needed for arrays/strings, unlike > APCu, which has to account for the possibility of full cache clears at any > time. > So it's constant time, and hundreds of times faster than APCu for large > arrays (e.g. 1000+ values) that have immutable representations > - It's easier to adopt fine-grained locks when cache clears are impossible by > design. > - This allows reusing values if they're already found in `immutable_cache` > > This also makes applications easier to reason about, since an end user would > be certain that a value added to the cache (or preloaded) would remain there > (APCu clears the cache when it fills up and on some other errors). > Applications could use immutable_cache for configs that are never meant to > change until a process group restart, static assets, > results of operations on fixed values, etc., and continue to use APCu for > data with a short ttl or for data that frequently changes. > > This has been an open feature request in APCu since 2016 > https://github.com/krakjoe/apcu/issues/175 and I've had that problem (large > configs that needed to be cached locally, that were generated by merging > dozens of config files, plus templating) > > - I asked about interest in PRs to add this a few weeks ago but didn't hear > back > - > https://web.archive.org/web/20170608185145/https://blog.graphiq.com/500x-faster-caching-than-redis-memcache-apc-in-php-hhvm-dcd26e8447ad > describes a similar problem others have had and details about their > workaround that give background knowledge > - This functionality also seems much easier to package and distribute in a > separate package, regardless of which repo it ends up in > (e.g. for end users or server admins to independently choose which of these > to add from public package repositories, PECL DLLs, etc) > > > Symbols, macros, configure options, and ini settings and supported ways of > getting anonymous shared memory > have been changed to avoid any naming conflicts with APCu that I can think of > (immutable_cache and APCu can be installed, configured, and used > independently) > > Any objections?
A reminder: I plan to add https://github.com/TysonAndre/immutable_cache-pecl#immutable_cache as a PECL if there are no objections. I plan to add this in 7 days. Thanks, - Tyson -- PECL development discussion Mailing List (https://pecl.php.net/) To unsubscribe, visit: https://www.php.net/unsub.php
