rust-vfs: add tests to `AtomicFile` This also makes it more usable from Rust by separating `from_file` and `new`.

rust-vfs: delete the temp file and not the target on drop Oops. This never affected anything since `close()` is correct and no code has dropped an `AtomicFile` without a close first yet. Next patch will add tests.

rust: don't star export from the `revlog` module This made a lot of the imports confusing because they didn't make sense at the top level (so, outside of `revlog`), and they hide the more common types when autocompleting.

rust: populate mmaps in a separate thread if possible Same rationale as b619ba39d10a.

rust-revlog: build an in-memory nodemap if a given revlog gets queried a lot This will help with non-persistent nodemap repos that would benefit from one, and mirrors what the C implementation does.

rust-revlog: generalize an error message This is used for more than the nodemap data.

rust-revlog: don't create an in-memory nodemap for filelogs from Python Explanations inline. Benchmarks from this change affect positively the only repo that showed this being a problem: ``` ### data-env-vars.name = mozilla-try-2024-03-26-ds2-pnm # benchmark.name = hg.command.cat # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.files = all-root # benchmark.variants.output = plain # benchmark.variants.rev = tip default: 62.848869 ~~~~~ before-this-patch: 58.113051 (-7.54%, -4.74) this-patch: 57.407533 (-8.66%, -5.44) ### data-env-vars.name = mozilla-try-2024-03-26-ds2-pnm # benchmark.name = hg.command.log # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.limit-rev = 10 # benchmark.variants.patch = yes # benchmark.variants.rev = none default: 3.173532 ~~~~~ before-this-patch: 3.543591 (+11.66%, +0.37) this-patch: 3.297235 (+3.90%, +0.12) ```

rust-revlog: move non-persistent-nodemap rev lookup to the index It only uses index features and does not need to be on the revlog. A later patch will make use of this function from a different context.

revlog: add glue to use a pure-Rust VFS This will save us a lot of calling back into Python, which is always horribly expensive. We are now faster in all benchmarked cases except for `log --patch` specifically on mozilla-try. Fixing this will happen in a later patch. ``` ### data-env-vars.name = mercurial-devel-2024-03-22-ds2-pnm # benchmark.name = hg.command.cat # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.files = all-root # benchmark.variants.output = plain # benchmark.variants.rev = tip e679697a6ca4: 1.760765 ~~~~~ 5559d7e63ec3: 1.555513 (-11.66%, -0.21) ### data-env-vars.name = mozilla-try-2024-03-26-ds2-pnm # benchmark.name = hg.command.cat # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.files = all-root # benchmark.variants.output = plain # benchmark.variants.rev = tip e679697a6ca4: 62.848869 ~~~~~ 5559d7e63ec3: 58.113051 (-7.54%, -4.74) ### data-env-vars.name = mozilla-try-2024-03-26-ds2-pnm # benchmark.name = hg.command.log # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.limit-rev = 10 # benchmark.variants.patch = yes # benchmark.variants.rev = none e679697a6ca4: 3.173532 ~~~~~ 5559d7e63ec3: 3.543591 (+11.66%, +0.37) ### data-env-vars.name = mozilla-try-2024-03-26-ds2-pnm # benchmark.name = hg.command.log # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.limit-rev = 1000 # benchmark.variants.patch = no # benchmark.variants.rev = none e679697a6ca4: 1.214698 ~~~~~ 5559d7e63ec3: 1.192478 (-1.83%, -0.02) ### data-env-vars.name = mozilla-unified-2024-03-22-ds2-pnm # benchmark.name = hg.command.cat # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.files = all-root # benchmark.variants.output = plain # benchmark.variants.rev = tip e679697a6ca4: 56.205474 ~~~~~ 5559d7e63ec3: 51.520074 (-8.34%, -4.69) ### data-env-vars.name = mozilla-unified-2024-03-22-ds2-pnm # benchmark.name = hg.command.log # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.limit-rev = 10 # benchmark.variants.patch = yes # benchmark.variants.rev = none e679697a6ca4: 2.105419 ~~~~~ 5559d7e63ec3: 2.051849 (-2.54%, -0.05) ### data-env-vars.name = mozilla-unified-2024-03-22-ds2-pnm # benchmark.name = hg.command.log # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.limit-rev = 1000 # benchmark.variants.patch = no # benchmark.variants.rev = none e679697a6ca4: 0.309960 ~~~~~ 5559d7e63ec3: 0.299035 (-3.52%, -0.01) ### data-env-vars.name = tryton-public-2024-03-22-ds2-pnm # benchmark.name = hg.command.cat # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.files = all-root # benchmark.variants.output = plain # benchmark.variants.rev = tip e679697a6ca4: 1.849832 ~~~~~ 5559d7e63ec3: 1.805076 (-2.42%, -0.04) ### data-env-vars.name = tryton-public-2024-03-22-ds2-pnm # benchmark.name = hg.command.log # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.limit-rev = 10 # benchmark.variants.patch = yes # benchmark.variants.rev = none e679697a6ca4: 0.289521 ~~~~~ 5559d7e63ec3: 0.279889 (-3.33%, -0.01) ### data-env-vars.name = tryton-public-2024-03-22-ds2-pnm # benchmark.name = hg.command.log # bin-env-vars.hg.flavor = rust # bin-env-vars.hg.py-re2-module = default # benchmark.variants.limit-rev = 1000 # benchmark.variants.patch = no # benchmark.variants.rev = none e679697a6ca4: 0.332270 ~~~~~ 5559d7e63ec3: 0.323324 (-2.69%, -0.01) ```

fncache: add attribute to check whether we're using dotencode This will make it easy to know if we can use the Rust implementation that doesn't support older forms of encoding.