= Combine the puller and scanner =

https://bugs.edge.launchpad.net/launchpad-bazaar/+bug/280578

== Why ==

 * Simplify
 * Avoid double handling
 * Reduce latency


== Gunk ==

 * What to call it?
  * synchronizing
  * publishing
  * bazaar2db
  * branchpopulater
  * on the UI vs internally (operationally vs code)

 * Error handling / OOPSes?
  * Just call mirrorFailed for scanner errors.
  * Traceback will make errors from the scanner part obviously distinct from
    the puller part.

 * How do we talk to the database?
  * puller uses xmlrpc
  * scanner uses direct database access -- and transfers large amounts of  data, would likely be painful and inefficient to serialize it for eg.  XMLRPC
  * if we keep as-is, maximum of 12 database connections to the MASTER db.

 * Separate packages still?
  * To start with, yes.

 * Before combining
  * Tweak the puller to parametrize the number of parallel workers by branch type. https://bugs.edge.launchpad.net/launchpad-bazaar/+bug/153779
  * Talk to spm / mthaddon / stub see if it's ok to have more connections.

 * Combining process
  * Branch to call the scanner from the puller worker
    * Should update the xmlrpc puller methods to update scanner fields
    * Any testing tweaks
      * Combine integration tests
      * Make the worker take a 'scanner' object so we don't have to make puller tests use the database.
  * Make another branch that removes last_scanned & last_scanned_id "calls".

 * Operational issues
  * Stop running the scanner cronjob
  * Kill the scanner OOPS report / combine with puller.

 * After combining
  * Kill IBranchScanner.
  * Delete Branch.last_scanned and Branch.last_scanned_id from the database.
  * Code re-organization: combine the packages.

 * Orthogonal
  * Extract the puller / scanner methods on IBranch to a separate *interface*.
  * De-ick the scanner

== Related but out of scope ==

 * Calling puller/scanner from codehosting
   https://bugs.edge.launchpad.net/launchpad-bazaar/+bug/85326  

 * Splitting out puller / scanner columns to other table
 * Changing puller to job-based system
 * Making puller more like code imports (same as above, really)