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Scribe Mail3/Sqlite Folders
Date: 17/11/2009
I don't know about you, but the shine of a different back end to store mail in for Scribe v2 has well and truely worn off for me. By that I mean I expect performance to be considerably better than it is. I can even live with the bad write/commit speed, considering that locks need to be made and there are certain overheads to having atomic changes made to the database. However that said I was expecting positively snappy read/query times and well? Yeah it's not all that. Maybe it's the fact I'm using Sqlite rather than a big iron style SQL server. I regularly see SELECT statements take in order of 15-20 seconds to pull up a simple list of email in a folder, esp when the App is starting. I've added an index of the FolderId field so that in theory doing something like:
select * from Mail where FolderId=[inbox_id]
should be a no brainer super fast query right? Well it seems that it's not, and it takes an awfully long time sometimes.

It's not the end of the world. Now that I have an architecture that is flexible I can experiment with a range of back end storage solutions till I hit on something that meets my fast/powerful/portable/small requirements.

One idea that I've got in the back of my head is generalizing the SQL backend to handle a number of different databases. For install, in the "portable" mode you'll probably be storing reasonably small amounts of mail and the existing Sqlite is most likely enough to do the job, but for desktop installs something with more grunt (and more memory / install footprint) could be used instead, trading portability for speed. And with a decent replication tool you wouldn't be tied to that back end forever, you could migrate easily to the next big thing, or just your DB to a different portable format.

Or... and heres a big idea... I make the back end API open and people can plug their own storage in. Of course thats only open to programmers but if someone can produce a good back end implementation I would seriously consider making it available in the default install. The basic API is very controlled and there is already some documentation in the headers. And the existing back ends could be used as reference, as in you'd get source to them as well. If anyone wants a serious crack at that then email me.
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Scribe Import/Export
Date: 12/11/2009
I rewrote the mail encoder API to handle arbitrary streams of bytes for quoted-printable, plain-text and base64 data. This is now used by the mail export code that directly interfaces with the store3 api that each of the mail store back ends use. This means that you get a fairly exact rfc822 message out of the export process. However these changes were initially buggy, so I'm in the process of verifying the changes with actual email. The way I'm doing this is for a given folder, export all the email to a rfc822 message on disk, immediately re-import it to a new object and then compare the mail objects in memory. This has already highlighted a few bugs in the code. Ideally I should be able to do this with every email in my mail store without any comparison errors. So far I've got it working for about the first 10 messages in my inbox :) To help with the debugging I wrote a small app that loads a mime message into a tree control and lets me look at the formatting of the mime segments.

Then I have to verify that this works with the 3 different back ends. Then I have to check that I can copy mail and folders between the 3 different back ends... then... then...

If you wonder why I go silent for weeks on end? It's because I'm working on the code.

The other thing I'm working on are the strange little bugs that happen in the IMAP back end, like when you run a filter that moves an IMAP email, and then sometimes crashes. Basically a IMAP "move" equates to a "copy" and a "delete". So when the delete event propagates back to the UI sometime after the move it nukes the object while other parts of the app still have a pointer to it. Unsurprisingly this is bad for stability. And I still haven't worked out the best way to deal with this.
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Mpeg2 Parser
Date: 19/10/2009
Last night I got the latest refactor of my mpeg2 parser working on non-trivial amounts of data. I'm working on that with a view towards replacing PVAstrumento in my private stock video re-encoding app that compresses a lot of DTV files down to H264/AAC for semi long term storage. The issue with most demuxers is that they are not good at recovering from errors or keep good sync between the video and audio. PVAStrumento is the best demuxer for damaged and chopped up mpeg2 as it has a raft of error recovery logic. However it's painful to use and is not perfect either. Sometimes there are files that even it can't handle. So for most of this year I've been working on and off on a replacement parser.

As of yesterday I have a basic parser working that allows access to the raw streams. No error correcting yet, but it's a great foundation. The trick is mostly in chopping up the audio packets to match the the valid video frames using the PTS (timestamp) values in the program stream packets. At this point I have access to all the PS packets, their PTS values and all the frames of video and audio. So it's just a matter of working out which to keep and which to chuck. And I can use PVAStrumento as a reference as to what I should be doing (it works great 98% of the time) and then move on to the "problem" files and see where PVAStrumento is falling over and make my parser work for those edge cases.

Well thats the theory anyway.

Strangely I was starting with a 2MB memory buffer for the top level program stream. I was getting 15mb/s parse speed which is considerably lower than the HD's maximum transfer rate and I confirmed that the algorithm was CPU bound by checking the CPU usage.. 1 core was maxed. So I experiemented with different buffer sizes, 4mb? speed dropped to 13mb/s, 1mb? Speed up to 20mb/s, hmmmm thats odd. 512kb? 40mb/s wow... thats nice... 256kb? 54mb/s... I ended up settling on 32kb, which tops out about 59mb/s. I think thats largely because the more buffer I keep track of the most PS packets I have to keep track of and I think somewhere I have a non-optimal algorithm working on the list of packets. Anyway, I think it's most HD bound now, which is how is should be.
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Mac Fonts
Date: 15/10/2009
This morning I fixed the issue that has been blocking Mac development for the last 'n' months. Finally the fonts are looking correct and I can get on with other things. Also the advent of valgrind on Mac might make it my preferred platform for dev work. If only the debugger was a bit faster. At least I think the Mac port of Scribe will get a lot more in the way of releases in the coming months, and will definitely by available on v2.00 launch day.

As for the current Linux build, it does work. But it limps along in Ubuntu 8/9 with a host of issues since the rewrite to XCB/Cairo. Drawing is very slow, crashes often, d'n'd is broken, menus have borders when they shouldn't, dialogs can get lost behind their parent window etc etc. *sigh* However on a good note, the current Ubuntu 9 release runs it without having to recompile any of the libraries, unlike Ubuntu 8 where you need to compile support for Cairo into XCB (or something).
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IMAP in Scribe
Date: 14/10/2009
So for the last few weeks I've been using IMAP(full) in Scribe for one of my accounts and it's now getting to the point where it's usable day to day for reading and organizing mail. Which is probably a first. It does cache all the mail locally on disk so it operates offline as well. However in the cold hard light of day I expect there is still a long way to go till it's production ready. In that there are going to be lots of little things that you expect to work but just er... don't.

For instance I'm not allowing you to move folders at the moment, because it's messy and painful code to write. Basically you have to make a new IMAP folder and then copy all the items across and delete the old folder. I don't thing there is such thing as "move" in the IMAP protocol unfortunately. Also copying mail between IMAP folders and Mail2/Mail3 folders is not working at the moment, just because I haven't had time to fix it yet, when I get that sorted out I'll post a release (i.e. in a few days to a week). It also remains to be seen how well it copes with slow connections and lots of emails/folders.

But anyway I feel like I'm really getting somewhere at the moment. So I thought I'd share. Btw it doesn't totally choke on a mailbox of 21,000 email. It's slow but it doesn't die completely. I guess thats a good sign.
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Why There Isn't A New Scribe Release
Date: 25/8/2009
So if you look at the change log you'll see that I'm still making changes and fixes to the code base for v2 but there is no release. This is mainly because I know there are still bugs that I can't release into the wild. For instance, when you close the mail store manage window... it deletes your mail2 folders. Yeah... you don't want that happening to you. I had it happen to me, twice... because I didn't really investigate and fix the bug the first time. Maybe I'm just slow, but a bug that deletes your whole folders is kinda important right? I took the first time as a sign I should be using the mail3 back end (which is of itself was great for the product) but I didn't fix it. So now I've done it to myself again.

Anyway, for the most part I think the show stoppers are dealt with and I'll just sit on it for a week or so and see if it's stable. New build sometime next week.
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