D-LAN

h1. Persistent data

h2. Files cache

This file contains all the shared files and theirs SHA-1 hashes. This file is saved in user space after an update of the file list, it is completely loaded at the start of Aybabtu. If some paths of some files doesn't match the shared directory they are discarded.

This file is saved as a binary file serialized by protocol buffer.

You can see the proto file here : source:/application/Protos/files_cache.proto

h3. Size

Here is a size approximation for 50'000 files stored in 1 TB. The overhead of the file format is not taken in account.

<pre>

Nb of files : 50'0000

Total size : 1 TB

Chunk Size : 32 MB

Average file per directory : 50

Average filename and dirname length : 50 char

Size of a hash : 20B

</pre>

<pre>

AverageFileSize = 1*1024^4 / 50'000 = 21MB

Sha1Size = floor(AverageFileSize / 32MB) * 20 * 50'000 = 1 * 20 * 50'000 = 977kB

FilenameSize = 50'000 * 50 * 2 = 4.8MB (2 bytes per char)

DirnameSize = (50'000 / 50) * 50 * 2 = 97kB

TotalSize = 977kB + 4.8MB + 97kB = 5.9MB

</pre>

h2. Queued files and directories

A file containing the queued files and directories is saved in user space. An item from the list may contains a remote peer id and/or the hashes which identify a file. 

As the file cache file (see above), this file is saved as a binary file serialized by protocol buffer.

For more details see the file : source:/application/Protos/queue.proto

h2. Configuration file

h3. Core side

here are the persisted data :

* The nick

* The peer ID

* The shared folders in read-only 

* The shared folders in read-write

As the other data described above these data are saved as a file serialized by _Protocol Buffer_ but in a human readable form.

For more details see the message _Settings_ in file : source:/application/Protos/common.proto

h3. Client Side

here are the persisted data :

* Core address

* Password for remote core

These data are save using _QSettings_ : http://doc.trolltech.com/4.5/qsettings.html.