Thunderbird:Pluggable Store Migration: Difference between revisions

Migration is conceptually fairly easy. We iterate over the folders in the source store, create the folder in the target store, and then stream each message in the source folder to target folder. In order to avoid file collisions, especially for file based stores like berkeley mailbox and maildir, we'll need to write to a different directory and then either point the account at the new directory, or delete the original folders from the directory. But we also have to worry about other files stored in the profile directory (msgFilterRules.dat, popstate.dat, feeds.rdf, hostinfo.dat and the like). Either we hardcode the knowledge of those files, or we clone the whole directory, delete the folders from the clone, and then stream the folders into the clone, and then change the server to point at the new clone directory. Or temporarily point the server at the clone directory, delete the folders from the original, and stream from the clone to the original, and then point the server back at the original directory. I want to be very cautious about deleting the original store, since for the pop3 case, that's the user's mail. But we have to give the user some way of deleting the original store. And I want to make unwinding from errors in the migration easier. That all points to a strategy of leaving the original server directory alone, and writing into a new directory, and then switching the server directory at the very end.