Speed up rbenv by dynamically loading compiled command #528
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On systems that support both C compiling and dynamic loading, we can speed up `realpath()` (where most time in rbenv is spent) by replacing it with a dynamically loaded bash builtin. When `make -C src` is called in the project's root, `libexec/rbenv-realpath.dylib` will be created. If it exists, rbenv will attempt to load it as a builtin command. If it fails, execution will fall back to the old `realpath()` shell function.
With `realpath` extension, hooks tests on OS X will output `/private/tmp` instead of `/tmp` because the latter is an actual symlink to the former. Avoid this mistmach in output assertions by expanding BATS_TMPDIR if `realpath` extension is compiled.
This speeds up every `rbenv` invocation significantly.
It's slow and not necessary since we expect `$0` to already be expanded.
In tests this change forces us to deal with some relative paths, but
it's not a big deal. The `rbenv init -` output in the most common case
will be the same as before:
source '/home/myuser/.rbenv/libexec/../completions/rbenv.bash'
Seems to only work on OS X; fails on Travis https://travis-ci.org/sstephenson/rbenv/jobs/16384866
Given the `-o <HOST-OS>` parameter, the script generates environment variables with information how to compile dynamically loadable libraries for that system. Imported from bash-3.2.48
The `shobj-conf` script imported from bash seems to not support the latest OS X. This makes sure that `SHOBJ_LDFLAG=-dynamiclib` is output for Darwin10+ (latest version is Darwin 13.0).
The previous Makefile only worked on OS X. The dynamically generated Makefile (from `Makefile.in`) should now work on multiple platforms (tested on OS X and Ubuntu).
mislav
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Oct 15, 2014
Speed up rbenv by dynamically loading compiled command
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The most time spent in rbenv execution is resolving paths to their absolute representations without symlinks. Manually doing this in bash is slow.
By dynamically loading a compiled bash builtin, we can access the
realpathPOSIX C function which does exactly what we need and is fast.If dynamic loading fails, rbenv will still continue working as before (will fall back to shell implementation).
If RBENV_NATIVE_EXT environment variable is set, rbenv will abort if it didn't manage to load the builtin. This is primarily useful for testing.
Tested on OS X 10.9 and Ubuntu 12.
/cc @sstephenson