This renames the jealloc_metrics module to allocator_metrics, does
similar for the code inside it. It implements a no-op fetch_stats
method for the system allocator.
It marks the jemalloc-sys and jemalloc-ctl crates as optional,
so that they might not be compiled when jemalloc is disabled.
It's not actually possible disable the jemalloc features in this PR
because there is no way to turn off the default-features of the
tikv_alloc crate. A followup in tikv#4207 will make it possible.
It also moves a `mod` to after some `use` statements.
Signed-off-by: Brian Anderson <andersrb@gmail.com>

* tikv_alloc: abstract some new jemalloc code
This renames the jealloc_metrics module to allocator_metrics, does
similar for the code inside it. It implements a no-op fetch_stats
method for the system allocator.
It marks the jemalloc-sys and jemalloc-ctl crates as optional,
so that they might not be compiled when jemalloc is disabled.
It's not actually possible disable the jemalloc features in this PR
because there is no way to turn off the default-features of the
tikv_alloc crate. A followup in #4207 will make it possible.
It also moves a `mod` to after some `use` statements.
Signed-off-by: Brian Anderson <andersrb@gmail.com>

* tikv_alloc: abstract some new jemalloc code
This renames the jealloc_metrics module to allocator_metrics, does
similar for the code inside it. It implements a no-op fetch_stats
method for the system allocator.
It marks the jemalloc-sys and jemalloc-ctl crates as optional,
so that they might not be compiled when jemalloc is disabled.
It's not actually possible disable the jemalloc features in this PR
because there is no way to turn off the default-features of the
tikv_alloc crate. A followup in tikv#4207 will make it possible.
It also moves a `mod` to after some `use` statements.
Signed-off-by: Brian Anderson <andersrb@gmail.com>