TSFC: cache the kernel by the repo state, not just the form signature - #5346
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TSFC: cache the kernel by the repo state, not just the form signature#5346pbrubeck wants to merge 8 commits into
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TSFC indexes its kernel caches by the form being compiled, not by the compiler that lowered it, so an editable install serves a stale kernel after tsfc/, finat/FIAT/gem, ufl or loopy changes -- silently, as a wrong answer rather than a cache miss. Add tsfc.caching.codegen_key(), fixed at import, and fold it into the three cache keys that index a kernel by its form (tsfc_interface, interpolation) plus Slate's own (which also stamps firedrake/slate/slac/, the generator that it owns outside TSFC). Also point setup_cache_dirs() at sys.prefix instead of $VIRTUAL_ENV, so an activated shell and a bare venv/bin/python share one cache. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Neither is obvious from the code alone: why stat a file instead of reading it, and why a value with no cache of its own still lets a kernel cache on disk survive across separate runs.
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"Keyed" is this codebase's own term for this (see hashkey, tsfc_compile_form_hashkey); "indexed" was a synonym substituted in without checking, not the vocabulary the caches actually use.
"On" is the codebase's own preposition for this ("TSFC's kernel cache
keys on the form..."); "by" was substituted in with the previous fix
and changed the idiom without needing to.
The opening sentence described the pre-codegen_key() behavior ("an
edit... leaves a stale kernel in place") without a past-tense marker,
so it read as still true. That is the "Documenting Code That Is Not
There" anti-pattern this same file's own AGENTS.md entry warns
against. The bug belongs in the commit message and PR description,
not in a docstring for code that fixes it.
…key in "Caller" described the code that uses codegen_key() in the abstract instead of naming it: Firedrake's kernel caches.
Lead with what this module does, then why it matters, then the mechanism -- instead of opening on a bare noun phrase that named the output without naming the action.
"Fold" names a functional-programming operation this module does not perform; the caches append codegen_key() as one more tuple element in their own hashkey, which "add" says plainly.
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TSFC originally indexed its kernel caches by the form being compiled, not by the compiler that lowered it, so an editable was retrieving a stale kernel after tsfc, finat/FIAT/gem, ufl or loopy changes -- silently, as a wrong answer rather than a cache miss.
Add
tsfc.caching.codegen_key(), fixed at import, and fold it into the three cache keys that index a kernel by its form signature (tsfc_interface, interpolation) plus Slate's own (which also stamps firedrake/slate/slac/, the generator that it owns outside TSFC). Also pointsetup_cache_dirs()atsys.prefixinstead of$VIRTUAL_ENV, so an activated shell and a barevenv/bin/pythonshare one cache.Description