[GitHub] [couchdb] janl opened a new pull request #3728: feat(views): cache function compilation. Closes #3517.

[GitBox <gi...@apache.org>]

janl opened a new pull request #3728:
URL: https://github.com/apache/couchdb/pull/3728


   Since supporting SpiderMonkey versions > 1.8.5 we compile design
   doc functions of the form `function(args) { /* impl */ }` into a
   form that is recognise by newer JS engines.
   
   For reduce views, this means a transpilation happens on each
   reduce call over the couchjs protocol, which is once for every
   level in the b+tree plus one final rereduce across all shards.
   
   down reduce view indexing/querying.
   
   This patch adds caching to the compilation function. This is
   implemented by way of producing a SHA-256 hash of all incoming
   JS functions and caching them in a global object in the memory
   of a `couchjs` process.
   
   The cache is cleared when a `add_fun` message is received, which
   happens before new map functions from a new ddoc are loaded into
   `couchjs`. This ensures that only functions from a single view &
   security context are ever loaded into the cache.
   
   SHA-256 was chosen because it is producing collisions that are
   also valid JS functions is unlikley.
   
   This specific SHA-256 implementation was chosen because:
   - it is favourably licensed (MIT)
   - taken from the Deno (https://deno.land) project, (h/t Martin
     Sonnenholzer for the tip)so we can be reasonably assured this
     has been tested thoroughly.
   
   


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[GitHub] [couchdb] AltenTMAOrion commented on pull request #3728: feat(views): cache function compilation. Closes #3517.

[GitBox <gi...@apache.org>]

AltenTMAOrion commented on pull request #3728:
URL: https://github.com/apache/couchdb/pull/3728#issuecomment-986753552


   Hello, 
   
   Do you have any ideas on a date of integration for this patch? 
   We are stuck on couchdb 2.3.1 because of the performance on the map/ reduce design, as our application is mainly based on this feature 
   
   Thank


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