[mythtv-commits] Ticket #7616: Revert settings cache behaviour introduced in [20828]
MythTV
mythtv at cvs.mythtv.org
Thu Nov 19 15:32:37 UTC 2009
#7616: Revert settings cache behaviour introduced in [20828]
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Reporter: danielk | Owner: danielk
Type: patch | Status: new
Priority: minor | Milestone: 0.23
Component: MythTV - General | Version: head
Severity: medium | Mlocked: 0
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We stopped caching default values, which caused a noticeable performance
regression in playback startup. I'm attaching two patches to this ticket,
one for trunk, the other for 0.22-fixes.
I asked Michael T. Dean about this and the main problem this was trying to
address was the caching of defaults when Get{,Num,Float}Setting was called
without a default. Then "", 0, and 0.0 would get cached. To address this
problem without the performance implications of not caching defaults at
all we use a sentinel value of "<settings_sentinel_value>" and never cache
that value. The secondary problem this tried to solve was
Get{,Num,Float}Settings called with different defaults in two or more
places, this coding error should not cause the types of problems that
caching "", 0, and 0.0 can cause since anyone providing a default should
be picking a sane one.
Note: There is a bit of unneeded redundancy in the settings code, I will
be addressing that in trunk in separate patch.
--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7616>
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