Protocol core-core Version 3 » History » Revision 38
Revision 37 (Greg Burri, 07/09/2009 10:12 PM) → Revision 38/73 (Greg Burri, 07/09/2009 10:13 PM)
h1. Protocols
This page describes the protocols used by Aybabtu for network communication between cores and between core and GUI.
h2. Core <-> Core
See source:protos/network_protocol.proto for message details.
h3. Downloading threads
There is _NbDownloadThread_ threads. Each thread will choose a free chunk and download it.
There is no more than one downloading from B to A. A peer which a download is active is setted as not free.
<pre>
F : the list of all unfinished download
C : A list of chunk candidates (empty at start)
- Take the first file in F -> f.
Loop :
If the hash chunks of f are unknown :
If there is already a peer asking for hashes :
- Take the next file in F -> f.
- continue
Else
- Ask the hashes to the source (see the message 'GetHashes').
For each chunk not downloaded and or not being downloaded -> c :
If c has a free peer :
- Add c to C
If C isn't empty :
- Take the best chunk in C based on peer.downloadRate.
If there is more than one best chunk then choose one randomly.
- Grab the lock for the peer
- Request the download
- Take the first file in F -> f.
Else :
- Take the next file in F -> f.
</pre>
h3. Updating peer to hash association thread
This thread will periodically grab the _NumberOfChunkToUpdate_ first chunks and request to all other peers what chunk they have.
If there is no chunk available the message will be send without hashes.
<pre>
F : the list of all unfinished download
C : list of latest chunk hashes sent
Loop :
Time.now -> t
Empty C
n : number of chunk = 0
While take the next file in F -> f
If C.count >= 'NumberOfChunkToUpdate' :
- Break
If we know the hashes for f :
For all chunks of f -> c :
- Add c to C
Else :
- Break
- Copy C to C_latest
- Send the list of the chunk to everyone. (The received responses will be compared against C)
- Wait 'TimeBetweenChunksUpdate' - (Time.now - t)
</pre>
h3. Parameters
Most parameters will be stored as constants in their component.
|_.Name|_.Value |_.Unit|_.Explanation/Comments|
| _IMAliveFrequency_ | 0.1 | [Hz] | The message _IMAlive_ is sent each 10s. |
| _ChunkSize_ | 33554432 | [Byte] | (32 MB) |
| _LanSpeed_ | 52428800 | [Byte/s] | (50 MB/s) |
| _TimeRecheckChunkFactor_ | 4 | - | If the time to download a chunk exceeds _TimeRecheckChunkFactor_ * _ChunkSize_ / _LanSpeed_ the peers are rescanned to choose a better one (better download rate). For example : 4 * 32 / 50 = 2.6 second |
| _SwitchToAnotherPeerFactor_ | 1.5 | - | During the recheck of the peers to choose a better one the other download rate must be above the current * 1.5. |
| _DownloadRateValidTime_ | 1500 / _LanSpeed_ = 300 s | [s] | (5 min). The download rate of a peer is only valid during this time after its last update. After that its rate is set to the maximum. |
| _TimeBetweenChunksUpdate_ | 500 / _LanSpeed_ = 10 s | [s] | Each 10 s a daemon will scan the _NumberOfChunkToUpdate_ first chunks from the first queued downloads to know which peer has which chunk. |
| _NumberOfChunkToUpdate_ | 100 * _LanSpeed_ / _ChunkSize_ = 156 | - | The first 156 hash chunks (3 kB) will by send periodically to each peer. See message _HaveChunks_ in the proto file. |
| _FindTimeout_ | 15 | [s] | A search request is abandoned after 15 seconds from the start of the request. See message _Find_. |
| _GetHashesTimeout_ | 200 | [s] | Timeout for the message _GetHashes_. |
| _GetChunkTimeout_ | 10 | [s] | Timeout for the message _GetChunk_. |
| _HaveChunksTimeout_ | _TimeBetweenChunksUpdate_ = 10 | [s] | Timeout for the message _HaveChunks_. |
| _GetEntriesTimeout_ | 10 | [s] | Timeout for the message _GetEntries_. |
| _NbDownloadThread_ | 3 | - | Number of concurrent downloading thread. |
| _BufferSize_ | 1048576 | [Byte] | (1MB). This buffer is used when reading or writing a file. |
| _TCPSocketBufferSize_ | 33554432 | [Byte] | (32Mo). Used when data are received. See _QAbstractSocket::setReadBufferSize_. |
h2. Core <-> GUI