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  • Hash : 43820f20
    Author : Vicent Marti
    Date : 2015-10-14T19:24:07

    odb: Be smarter when refreshing backends
    
    In the current implementation of ODB backends, each backend is tasked
    with refreshing itself after a failed lookup. This is standard Git
    behavior: we want to e.g. reload the packfiles on disk in case they have
    changed and that's the reason we can't find the object we're looking
    for.
    
    This behavior, however, becomes pathological in repositories where
    multiple alternates have been loaded. Given that each alternate counts
    as a separate backend, a miss in the main repository (which can
    potentially be very frequent in cases where object storage comes from
    the alternate) will result in refreshing all its packfiles before we
    move on to the alternate backend where the object will most likely be
    found.
    
    To fix this, the code in `odb.c` has been refactored as to perform the
    refresh of all the backends externally, once we've verified that the
    object is nowhere to be found.
    
    If the refresh is successful, we then perform the lookup sequentially
    through all the backends, skipping the ones that we know for sure
    weren't refreshed (because they have no refresh API).
    
    The on-disk pack backend has been adjusted accordingly: it no longer
    performs refreshes internally.