[GitHub] davisp opened a new pull request #495: Couchdb 3288 mixed cluster upgrade

[gi...@git.apache.org]

davisp opened a new pull request #495: Couchdb 3288 mixed cluster upgrade
URL: https://github.com/apache/couchdb/pull/495
 
 
   ## Overview
   
   This is preparatory work for adding pluggable storage engines. The motivation for this ground work is to enable users to perform rolling reboots of clusters. As such there are a few things that need to change to make that happen.
   
   1. Remove the public definition of `#db{}`
   2. Add a new fabric_rpc:create_db/2 that accepts an options list
   3. Create a template of the new `#db{}` for forwards compatibility
   
   The removal of the `#db{}` definition is what's responsible for 99% of these changes. And while there is a decent amount of code churn here its nearly all quite straightforward changes from `Db#db.name` to `couch_db:name(Db)` type changes so theoretically this should be a pretty quick review.
   
   The only somewhat difficult bits are when we were matching a `#db{}` record in a function head. For the most part this was just to extract fields from the record so those are easily reviewed. Though there are a few cases in the replicator that were using it to tell the different between `#db{}` and `#httpd{}`. For those we have to switch the order of clauses to pull out the `#httpd{}` logic first.
   
   
   ## Testing recommendations
   
   There's no behavior changes so the existing test suite covers the existing logic.
   
   ## JIRA issue number
   
   https://issues.apache.org/jira/browse/COUCHDB-3288
   
   ## Related Pull Requests
   
   I'm going to open a PR for COUCHDB-3287 which is the main PSE work that will be asking to merge into this PR. This is purely for the sake of review-ability. When we go to merge these we'll merge this PR first, and then merge 3287 into master. I expect the review of this work to take at least a couple weeks since it is quite a large change to the core bit of the database.
   
   ## Checklist
   
   - [ ] Code is written and works correctly;
   - [ ] Changes are covered by tests;
   - [ ] Documentation reflects the changes;
   
 
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