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  • Pierre-Yves David's avatar
    6e559391f96e
    tracked-key: remove the dual write and rename to tracked-hint · 6e559391f96e
    Pierre-Yves David authored
    The dual-write approach was mostly useless. As explained in the previous version
    of the help, the key had to be read twice before we could cache a value.
    
    However this "read twice" limitation actually also apply to any usage of the
    key. If some operation wants to rely of the "same value == same tracked set"
    property it would need to read the value before, and after running that
    operation (or at least, after, in all cases). So it cannot be sure the operation
    it did is "valid" until checking the key after the operation. As a resultat such
    operation can only be read-only or rollbackable.
    
    This reduce the utility of the "same value == same tracked set" a lot.
    
    So it seems simpler to drop the double write and to update the documentation to
    highlight that this file does not garantee race-free operation. As a result the
    "key" is demoted to a "hint".
    
    Documentation is updated accordingly.
    
    Differential Revision: https://phab.mercurial-scm.org/D12201
    6e559391f96e
    History
    tracked-key: remove the dual write and rename to tracked-hint
    Pierre-Yves David authored
    The dual-write approach was mostly useless. As explained in the previous version
    of the help, the key had to be read twice before we could cache a value.
    
    However this "read twice" limitation actually also apply to any usage of the
    key. If some operation wants to rely of the "same value == same tracked set"
    property it would need to read the value before, and after running that
    operation (or at least, after, in all cases). So it cannot be sure the operation
    it did is "valid" until checking the key after the operation. As a resultat such
    operation can only be read-only or rollbackable.
    
    This reduce the utility of the "same value == same tracked set" a lot.
    
    So it seems simpler to drop the double write and to update the documentation to
    highlight that this file does not garantee race-free operation. As a result the
    "key" is demoted to a "hint".
    
    Documentation is updated accordingly.
    
    Differential Revision: https://phab.mercurial-scm.org/D12201