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 D-LAN. 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 : 64 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 / 64MB) * 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

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