[Dovecot] [Plugin dev] First-time-only cache lock failure

[John G]

Hi

This is a question related to plugin developement on Dovecot 2.1.4.

I'm currently implementing a dovecot plugin that retrieves mails from a corporate server through an internal protocol.
The plugin is very similar to the pop3c storage (lib-storage/index/pop3c).
The plugin has to map original server UIDs to IMAP UIDs, using MAIL_CACHE_POP3_UIDL cache field the same way pop3c does.

So, I've got a function similar to pop3c_sync_messages(), performing several mail_index_append() and mail_cache_add() calls.

The problem is that on the first sync, when the index and cache files don't exist yet, there's a failure writing data in cache.
The call to mail_index_sync_commit()\mail_cache_transaction_commit() fails because of mail_cache_transaction_lock().

The index and cache files are properly created, but the cache doesn't contain the MAIL_CACHE_POP3_UIDL values.
It works properly on the second sync, the MAIL_CACHE_POP3_UIDL field being properly saved.

Would you have some ideas on what could be wrong here?

Thanks,

John