Try to initialize xmlXPathContext faster #3388
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Revert the pieces of 969bea9 related to re-use of xpath context objects. Leave in these pieces of that commit: - ability to de-register variables and namespaces - XPathContext#node= and backfill explicit test coverage for these features, as well as recursive xpath evaluations.
Copying the struct and the hash tables is slightly faster than calling
xmlXpathNewContext:
Comparison:
large: optimized: 17780.0 i/s
large: main: 15143.4 i/s - same-ish: difference falls within error
Comparison:
small: optimized: 62891.9 i/s
small: main: 49413.5 i/s - 1.27x slower
But still slower than re-using the context object ("edge", v1.18.0.rc1):
Comparison:
large: edge: 22230.9 i/s
large: optimized: 17780.0 i/s - 1.25x slower
large: main: 15143.4 i/s - 1.47x slower
Comparison:
small: edge: 129162.0 i/s
small: optimized: 62891.9 i/s - 2.05x slower
small: main: 49413.5 i/s - 2.61x slower
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What problem is this PR intended to solve?
A variation on solving the "slow xpath context creation" problem described in #3266. See first attempt at #3378.
Copying the struct and the hash tables is slightly faster than calling
xmlXpathNewContext:But still slower than re-using the context object ("edge", v1.18.0.rc1):
I probably won't merge this, but thought it was worth sharing for posterity.
Next I'm going to try an extension of #3378 that will push and pop "eval frames" that include the internal state but also the registered functions/namespaces/lookup handlers.