Updating a document using Update() unexpectedly results in a conflict

[zgramana]

From @jonlipsky:

For each user that has had this problem, it only occurs after they make a change to an existing document, and when it happens, I get hundreds of error reports about the issue, which leads me to believe this is getting caused during executing the puller.

If they restart the app, the exceptions go away; however the users lose their latest changes and they get replaced by a previous revision.

Description: [Database] Couchbase.Lite.CouchbaseLiteException: Conflicts not allowed and there is already an existing doc with id: f4fe2fb4-e8fe-4fc1-a4b0-82ae1a3726de
at Couchbase.Lite.Database+c_AnonStorey5.<>m_0 () [0x00000] in :0
at Couchbase.Lite.Database+c_AnonStorey0.<>m_0 () [0x00000] in :0

[zgramana]

The large number of counts of exceptions likely happens because Update runs the delegate inside of a do...while loop. If another process is simultaneously updating that doc, then a conflict is raised. This is caught, and the loop will abandon that failed revision and start over again. Consider this example, where foo is the document Id:

                       foo 1-aaaaaaaaaaa
                          /        \
                         /          \
Update > Create new rev: 'foo 2-'    \
                      /        Puller > Insert 'foo 2-bbbbbbbbbbb'
                     /
         Save > Insert 'foo 2-ccccccccccccc'
                    |
                 Conflict!
                    |
Update > Create new rev: 'foo 3-'
                    |
         Save > Insert 'foo 3-ccccccccccccc'
                    |
                 Success!

What's puzzling in this case is that the call to Save is always throwing an exception.

I believe I found the issue. The Java version of Update is missing a critical line from the iOS version which forces the current revision to be reloaded from disk before any subsequent iteration of the loop. I'll commit this fix in a minute.