wall time, user time, and system time since a process started.
For walltime, we currently use TimeValue's interface and a global
initializer to compute a close approximation of total process runtime.
For user time, this adds support for an somewhat more precise timing
mechanism -- clock_gettime with the CLOCK_PROCESS_CPUTIME_ID clock
selected.
For system time, we have to do a full getrusage call to extract the
system time from the OS. This is expensive but unavoidable.
In passing, clean up the implementation of the old APIs and fix some
latent bugs in the Windows code. This might have manifested on Windows
ARM systems or other systems with strange 64-bit integer behavior.
The old API for this both user time and system time simultaneously from
a single getrusage call. While this results in fewer system calls, it
also results in a lower precision user time and if only user time is
desired, it introduces a higher overhead. It may be worthwhile to switch
some of the pass timers to not track system time and directly track user
and wall time. The old API also tracked walltime in a confusing way --
it just set it to the current walltime rather than providing any measure
of wall time since the process started the way buth user and system time
are tracked. The new API is more consistent here.
The plan is to eventually implement these methods for a *child* process
by using the wait3(2) system call to populate an rusage struct
representing the whole subprocess execution. That way, after waiting on
a child process its stats will become accurate and cheap to query.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171551 91177308-0d34-0410-b5e6-96231b3b80d8
Implement the old API in terms of the new one. This simplifies the
implementation on Windows which can now re-use the self_process's once
initialization.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171330 91177308-0d34-0410-b5e6-96231b3b80d8
The coding style used here is not LLVM's style because this is modeled
after a Boost interface and thus done in the style of a candidate C++
standard library interface. I'll probably end up proposing it as
a standard C++ library if it proves to be reasonably portable and
useful.
This is just the most basic parts of the interface -- getting the
process ID out of it. However, it helps sketch out some of the boiler
plate such as the base class, derived class, shared code, and static
factory function. It also introduces a unittest so that I can
incrementally ensure this stuff works.
However, I've not even compiled this code for Windows yet. I'll try to
fix any Windows fallout from the bots, and if I can't fix it I'll revert
and get someone on Windows to help out. There isn't a lot more that is
mandatory, so soon I'll switch to just stubbing out the Windows side and
get Michael Spencer to help with implementation as he can test it
directly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171289 91177308-0d34-0410-b5e6-96231b3b80d8
LLVM libraries. Also, clean up the doxygen and formatting of the
existing interfaces.
With this change I'm calling the existing interface "legacy" because I'd
like to replace it with something much better. My end goal is to expose
a common set of interfaces for inspecting various properties of
a process, and implementations to expose those both for the current
process and for child processes. This will also expose more rich
interfaces for spawning and controling a subprocess, notably to use
system calls like wait3 and wait4 where available and gather detailed
resource usage stats about the subprocess.
My plan (discussed with Michael Spencer on IRC) is to base this loosely
around the proposed Boost.Process interface, but to implement
a relatively small subset of that functionality based around the needs
of LLVM, Clang, the Clang driver, etc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171285 91177308-0d34-0410-b5e6-96231b3b80d8
To be used in printing unprintable source in clang diagnostics.
Patch by Seth Cantrell, with a minor fix for mingw by me.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154805 91177308-0d34-0410-b5e6-96231b3b80d8
or Clang is using this, and it would be hard to use it correctly given
the thread hostility of the function. Also, it never checked the return
which is rather dangerous with chdir. If someone was in fact using this,
please let me know, as well as what the usecase actually is so that
I can add it back and make it more correct and secure to use. (That
said, it's never going to be "safe" per-se, but we could at least
document the risks...)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148211 91177308-0d34-0410-b5e6-96231b3b80d8
