Add `ProfError` and `ProfResult<T>` type for profile related functions
to return.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Add `activate_prof` and `deactivate_prof` functions to start and stop
jemalloc mem profiling.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Add new entry "/jeprof" to status_server and start jemalloc profiler for
several seconds (according to `seconds` in query), and return the profile.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

1. Modify entry for profile from `/jeprof` to `/pprof/profile`

2. Abstract the dumping process to two functions. Maybe `dump_prof`
function can be added to `tikv_alloc` crates ( but a global timer is
needed )

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

… one profiler is running

Add ProfilerLock to guarantee only one profiler is running. Actually jemalloc
has only one global profiler so I cannot handle several requests at the same
time.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Impl drop for ProfilerGuard to deactivate_prof, but not use Drop for ProfilerLock.
With this approach once we drop the guard, the lock was released.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Change name of several structs and functions from `Profiler*` to `Prof*`
to keep the same as `ProfResult`

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Move profiler_guard from tikv_alloc/profiler_guard to
server/status_server to remove Futures from tikv_alloc dependencies.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Return `MemProfilingNotEnabled` error but not `JemallocNotEnabled` error
because tcmalloc profiling may alse be supported in the future.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Remove JemallocNotEnabled error. It's not used in this crate.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

impl std::error::Error for ProfError (with default implementation)

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Use lower-case rather than upper-case in several info log to keep
consistent with other logs in tikv

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

For impl `std::error::Error` for ProfError, impl `Display` for ProfError

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

TempDir::new() may return io::Error. Handle this error by returning out.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

OsString.into_string() may cause error when directory path contains
non-unicode letter.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Parse query part in URI in a better way. The previous method is too
hacky :(

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Add `X-Content-Type-Options`, `Content-Disposition`, `Content-Type` and
`Content-Length` to keep the same with net/http/pprof in golang.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Return Error in one closure without use `then` several times.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Return the description of error as HTTP response

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Remove existing code of handling `SIGUSR2`. It's no longer needed with
support of dumping profile with HTTP request.

Remove Option in `dump_prof` arguments because all usage of it is pass a
`Some`.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Handle error in dump_prof function by returning it.

Signed-off-by: Yang Keao <keao.yang@yahoo.com>

Set default value of `seconds` parameter according to TiDB
status_server. (10 seconds)

Signed-off-by: Yang Keao <keao.yang@yahoo.com>