CODEWITHSUNDEEP
emailjakarta-mailimapfetchuid
benchpresser
benchpresser

Reputation: 2188

java imap, performance issues, fetching all mails

I will use java mail api to handle mails like thunderbird etc. I have to fetch mails having 1000 messages. My design will be: When user performs a synch on a folder, i will get all uids of the messages in the folder:

Message[] msgs = ufolder.getMessagesByUID(1, UIDFolder.LASTUID);
// Use a suitable FetchProfile
FetchProfile fp = new FetchProfile();
fp.add(FetchProfile.Item.ENVELOPE);
fp.add(FetchProfile.Item.FLAGS);

I wil then compare the list of uids with the list stored in my db. For the deleted ones, for example a message is not in the folder but in the db, i will mark it as deleted. For the new ones, for example a message is in the folder but not in the db, i will mark as possible new. But, because messageuids are not safe (can be changed by the mail server on some cases), for the new mails, i will use additioanlly a custom hash value build from message id in the header + subject + receivedate and build a md5 hash. Only for the possible new mails i will use this hash and catch new mails. For the moved messages, because their uids will be changed in the new folder, it will be flagged as deleted in the first and will be a new message in new folder, but the message will have same custom hash value becaue message id in the header and other properties will remain same duing the movement.

Question about performance issue: On each click on folder (folder synch) i will do the compare operation of all uids in the folder with the local uid list stored in the db to learn the deleted ones. I could not find another better way to accomplish this. As you know, thunderbird catches immediately a deleted message without relogin, even if the folder is large and the deleted message is very old (5 years). I think thunderbird also compares all message uids in that folder with a list stored locally.

How can i implement a better mechanism for the synch for a better performance? Does thunderbird apply a different approach? How can thunderbird accomplish it so quickly?

If we were interested only for the new messages, i could have kept last stored uid and only compare the new messages later than that, but for the deleted ones, i already have to compare full folder. Additionally, UIDNEXT value is always -1 in my mail server, if it were set correctly, it will not help to get deleted ones again, a full compare is a must i think, am I wrong?

Note: I canot not use or add message listeners because the appliaction is server-client based and the mail handling task is on the server side and we do not support threads listeners etc. The events should be triggered from the client and the request is being processed on ther server and a response is returned and client handles the response on the gui.

Upvotes: 2

Views: 842

Answers (2)

arnt
arnt

Reputation: 9685

What you want is called condstore or quick resync, RFC7162 in both cases. That's what Thunderbird uses.

That's a pair of extensions support commands like "give me all the UIDs that have changed since last time I connected", "tell me what's been deleted" and so on.

Upvotes: 3

Bill Shannon
Bill Shannon

Reputation: 29971

If you can't use threads to listen for these events from the mail server, your options are very limited. Probably the best thing you can do is limit the resynchronization to the messages that are visible to the client.

Upvotes: 0

Related Questions