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Protocol core-core Version 3 » History » Revision 35

Revision 34 (Greg Burri, 07/09/2009 05:23 PM) → Revision 35/73 (Greg Burri, 07/09/2009 05:24 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 : 
       - Ask the hashes to the source (see the message 'GetHashes'). 
    For each chunk not downloaded 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. 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 user when reading or writing a file. | 
 | _TCPSocketBufferSize_ | 33554432 | [Byte] | (32Mo). Used when data are received. See _QAbstractSocket::setReadBufferSize_. | 

 h2. Core <-> GUI