Summary:
This will allow RevLogIndex to answer node -> rev and hex lookup queries.
Also change RevlogIndex::new to take file names so it can write back the
nodemap index when the index is lagging. That part of logic currently exists in
pyindexes + clindex.pyx, which are going to be replaced by revlogindex.
Practically, this will generate a `00changelog.nodemap` file in svfs, which is
temporarily unused, but will be used once clindex.pyx gets replaced.
Reviewed By: sfilipco
Differential Revision: D21626209
fbshipit-source-id: 297d9eff26a73c26558708f7a2290d4d8ba1e777
Any native code (C/C++/Rust) that Mercurial (either core or extensions)
depends on should go here. Python code, or native code that depends on
Python code (e.g. #include <Python.h> or use cpython) is disallowed.
As we start to convert more of Mercurial into Rust, and write new paths
entrirely in native code, we'll want to limit our dependency on Python, which is
why this barrier exists.
See also hgext/extlib/README.md, mercurial/cext/README.mb.
How do I choose between lib and extlib (and cext)?
If your code is native and doesn't depend on Python (awesome!), it goes here.
Otherwise, put it in hgext/extlib (if it's only used by extensions) or
mercurial/cext (if it's used by extensions or core).