[GitHub] [couchdb] davisp commented on a change in pull request #2051: CouchDB background jobs

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

davisp commented on a change in pull request #2051: CouchDB background jobs
URL: https://github.com/apache/couchdb/pull/2051#discussion_r299543874
 
 

 ##########
 File path: src/couch_jobs/README.md
 ##########
 @@ -0,0 +1,62 @@
+CouchDB Jobs Application
+========================
+
+Run background jobs in CouchDB
+
+Design (RFC) discussion: https://github.com/apache/couchdb-documentation/pull/409/files
+
+This is a description of some of the modules:
+
+ * `couch_jobs`: The main API module. It contains functions for creating,
+   accepting, executing, and monitoring jobs. A common pattern in this module
+   is to get a jobs transaction object (named `JTx` throughout the code), then
+   start a transaction and call a bunch of functions from `couch_jobs_fdb` in
+   that transaction.
+
+ * `couch_jobs_fdb`: This is a layer that talks to FDB. There is a lot of tuple
+   packing and unpacking, reading ranges and also managing transaction objects.
+
+ * `couch_jobs_pending`: This module implements the pending jobs queue. These
+   functions could all go in `couch_jobs_fdb` but the implemention was fairly
+   self-contained, with its own private helper functions, so it made sense to
+   move to a separate module.
+
+ * `couch_jobs_activity_monitor`: Here is where the "activity monitor"
+   functionality is implemented. That's done with a `gen_server` instance
+   running for each type. This `gen_server` periodically check if there are
+   inactive jobs for its type, and if they are, it re-enqueues them. If the
+   timeout value changes, then it skips the pending check, until the new
+   timeout expires.
+
+ * `couch_jobs_activity_monitor_sup` : This is a simple one-for-one supervisor
+   to spawn `couch_job_activity_monitor` instances for each type.
 
 Review comment:
   Typo. Should be `couch_jobs_activity_monitor`.

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services