couch-chakra is a (sort of) drop in replacement for the CouchDB Query Server Runtime couchjs build on top of Microsoft's ChakraCore.
- Learning the inner workings of the CouchDB Query Server Subsystem
- Get my C skills back out of the closet
- Have fun working with fancy technology
- ChakraCore is used in Microsoft's DocumentDB
- It currently passes all tests in query_server_spec.rb
- Has proper sandboxing
- Deals with the anonymous function issue, aka COUCHDB-1397
- NO
for each, so you'll have to patch views.js before running the query server tests - NO cURL bindings
- NO
-Tcommand line flag for test suite specific functions - NO
-ucommand line argument - NO
--no-evalcommand line argument
It's not the first alternative suggested to the existing Query Server Runtime. There's at least one based on NodeJS which started an interesting discussion at COUCHDB-1894. A couple of important aspects for a Query Server Runtime can be extracted from it:
- Sandboxing
- The anonymous function issue
- Versioning of the runtime
- Ease of installation
The anonymous function issue, aka COUCHDB-1397
In short, CouchDB makes use of a now disabled feature of the SpiderMonkey runtime which allowed anonymous functions to appear in global scope. This made for a really nice way of declaring view functions in CouchDB, however it was always invalid behavior and no modern runtime is going to add this feature again.
Couch-Chakra has two propositions to work around this issue.
Code written in the old CouchDB style function(doc, view) {...} is considered legacy.
Running Couch-Chakra with the -L flag parses the provided script with a patched
version of esprima, rewrites
the resulting AST and generates a compliant version of the function with the help of escodegen.
This is quite a huge machinery and I do hope that a modern JS runtime can make up for the performance hit, however
I can't provide any figures.
Fortunately ES6 introduced so called arrow functions
which seem to be a perfect fit for CouchDB map functions. Replacing function(doc, view) {...} by
(doc, view) => {} is a rather simple modification, simple to explain and transforms the not-so-valid JavaScript into
perfectly ES6 code which can be run without the legacy mode enabled.
Couch-Chakra builds with current master of ChakraCore (I used cb7817b) which I'm afraid you have to
build from sources. Once built, modify the first two lines of the Makefile of this project
and run make. If you want to run the (two very simplistic) tests, run make check . Everythings
is very early, it builds on my machine™ which runs on MacOS X 10.11.6 with latest xcode.