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Greg Burri, 08/03/2009 09:25 AM


Algorithms

Searching

For a functional description see here : Functional definition

Peer ID

Each peer owns a peer id which is unique and generated during the first start. This ID is used to identify a peer, it's better than the previous usage of peer IP, considering this situation :

  • A put in queue a file entry f from B, B doesn't know the hashes of this file entry.
  • B change his IP address.
  • A want to download f, it can ask B for the hashes even B's IP changed.

Core threads

There are three kind of threads in the core in addition to the main thread :

Updating the file cache

Here is the algorithm for the thread (FileManager::FileUpdater) which will periodically update the file cache and persist it.

D : The set of shared directories
T : Time during the hashes are computed (for example 30s)
F : A set of file initialy empty

- Add a watcher to the shared directories

// First synchronize (at start)
For each d in D (recursively) :
   - Synchronize physical folders and files whit d content
   - Add in F the files which doesn't have computed hashes

Loop :   
   t : Time.now
   For each f in F :
      - Compute the unknown hash of files f
      - Remove f from F
      If (Time.now - t) > T : break
   - Wait T - (Time.now - t)
   - Wait for changes for a period of P
      - When a modification occurs synchronise the file/folder
      - Add each new file in F
   - Persist the entire cache in a file (only every ~30min)

Downloading

See here : Protocol_core-core

Updated by Greg Burri over 11 years ago · 13 revisions