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Bug:map_view_base Lookup failure case is several orders slower due to C++ exceptions #1511
Description
Activity
Related workaround in Rust to avoid the cost of C++ exceptions: microsoft/windows-rs#3476
thanks for pointing that out. I commented in that completed PR but repeating that here; making 2 calls is fine for in proc, but OOP APIs, where the cost per call is high, that is a problem. Antonio is making progress on a fix for this.
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Version
v2.0.250303.1
Summary
I created a synthetic benchmark to test the perf of the failed case of Lookup(), that generates a C++ exception (impl below hresult_out_of_bounds()), and it reports the following when compared to the OS implementation of ValueSet. Lookup is called in TryLookup to simplify usage.
2021ms vs 2ms
Antonio is working on fixing this in this PR.
... struct map_view_base : iterable_base<D, Windows::Foundation::Collections::IKeyValuePair<K, V>, Version> { V Lookup(K const& key) const { ... if (pair == static_cast<D const&>(*this).get_container().end()) { throw hresult_out_of_bounds(); }Reproducible example
Expected behavior
No response
Actual behavior
No response
Additional comments
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