On Wed, 2008-07-23 at 12:07 -0400, Daniel Brosseau wrote:

Hi,

I am new to the dovecot source and would like to know why the mailbox_module_context has a pointer to the mail_storage_module_register and not to a mailbox_module_register.

Hmm. I don't actually remember anymore all that much about why I did it that way. :) Just using it is a bit too complex sometimes.. Anyway the idea was something like:

Module context registers should provide some kind of type checking, so that you don't accidentally use wrong type of context structures. Why there's no mailbox_module_register I'm not sure.. I think it's because of 1) less registers -> less complex and 2) if you're going to set mailbox contexts, you're very likely to set mail storage contexts as well.

From what I have understood, if a context is first added to the mailbox.module_contexts array using the mail_storage_module_register and then a context is added to the mail_storage.module_contexts and then a third context is again added to the mailbox.module_contexts the mail_storage_module_register.id will be 3 and the second element in the mailbox.module_context will be unused and the first and third elements of the mail_storage.module_contexts are unused.

It depends on the callers. Each module (plugin, whatever) allocates its own unique ID from register(s) and uses it for all context structures using the same register. So a typical usage would be like:

• plugin1: id=0, use mail_storage.module_contexts[0] and mailbox.module_contexts[0]
• plugin2: id=1, use mail_storage.module_contexts[1] and mailbox.module_contexts[1]
• etc.

The situation you describe could happen if the plugins did something like:

• plugin1: id=0, use ONLY mail_storage.module_contexts[0]
• plugin2: id=1, use ONLY mailbox.module_contexts[1]
• plugin3: id=2, use ONLY mail_storage.module_contexts[2]
• etc.

But that kind of usage should be rare.