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<p style="margin: 10px 0 0 0">Reviewed and applied as 4e832cb.</p>
<p style="margin: 10px 0 0 0">A couple of notes: </p>
<p style="margin: 10px 0 0 0">Firstly: The supplied patch doesn't compile, what's wrong is obvious but if the OP thinks that they are running with this patch, they aren't.</p>
<p style="margin: 10px 0 0 0">Secondly (and longly):<br /> This change moves all the manipulation of <tt>m_filestamp</tt> into the constructor or the worker thread and so throws into sharp contrast the use of the lock in managing it.</p>
<p style="margin: 10px 0 0 0">There is but one setter thread and so we don't actually need to syncrhonize the setting of a 64 bit number (we can trust the hardware these days), but first and foremost <tt>m_filestamp</tt> is a protected field so we should be careful. Fir enough.</p>
<p style="margin: 10px 0 0 0">But even assuming that no-one would party on it there is still a purpose - grabbing the lock before we update causes any read lockers to drain and so it forces the update to wait until activity queisces. Of course we drop the lock again before we do the final update of the cached data, but I cannot but feel that having the write lock pulsed will help pointless cycles as threads look at the value and go "its out of date" and kick the thread. In other words it has no meaning in terms of locking but it helps to serialize.</p>
<p style="margin: 10px 0 0 0">Of course there is still the effect that once the date has been updated the users will continue using out of date data (whilst thinking it to be valid) until such time as we get in and update the data, but that's no change from before. </p>
<p style="margin: 10px 0 0 0">I'm wondering whether we should move the update to after the load (and all the exception handling). I think that would work - m_filestamp is the stat of the file sometime previous to the last attempted load. So it could be too old, but never too young , the loading thread would be work more often but given that it now looks before it leaps there is minimal cost there.</p>
<p style="margin: 10px 0 0 0">I'll leave this open for a couple of days to allow Scott to comment if he wishes, when I come back in 2 days I'll also have a fresh outlook (although the locking in this class and its children does make my head hurt)</p>
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