Stefan Fuhrmann wrote on Tue, Aug 26, 2014 at 17:04:27 +0200: > Here the guarantees and limitations of the new implementation: >
I haven't had a chance to look at the code (sorry), but two quick questions based on this summary: > * No lost updates in revprop file contents even if the > SVN caches should be stale. > * A connection (svn_fs_t) will always see at least all > changes up to and including its own last revprop change. > * A new connection will always see all changes made > up to the point the connection got created. > > * On Windows and Unixoids, readers will always see > the latest data if they are on the same machine as the > writing process. > * Depending on OS read cache configuration and if the > repository is shared between machines, open connections > *might* no see revprop updates or might see them delayed > (the open revprop generation file handle may see a stale > OS file buffer). Is starvation possible? i.e., is it possible for the delay to be indefinite (assume the reader fs_t does no write operations)? I assume the delay would be finite and bounded by a constant if the shared disk's local file handles have this property.? Is linearizability guaranteed? i.e., if the repository is load-balanced across four servers, and I do 'svn ps alpha 1; svn ps beta 2; svn ps gamma 3; svn pl', is it possible for the last process to see beta without seeing alpha? (e.g., if each svn process gets load balanced to a different server.) Would the last scenario work correctly if the second command had been an atomic revprop change of property "alpha" with original_value="1"? (See ORIGINAL_VALUE parameter of svn_client_revprop_set2().) > * Revprop caching may be inefficient if the repository is > shared between machines; again depending on OS config. Cheers, Daniel
