Validate environment variables prefixed with KOKKOS_

[brian-kelley]

For any environment variables prefixed with KOKKOS_ (case insensitive), check that it is one of the recognized variables that kokkos or kokkos-tools uses. Give a warning if it's unrecognized, or if it's recognized but not in the correct case (all-caps).

This is based off work @cwpearson did for Tpetra in trilinos/Trilinos#12722.
The checking is done once during initialize_internal().

Example usage:

export KOKKOS_NOT_A_VALID_VAR=123
export KOKKOS_device_id=0
./example 10

prints:

Warning: environment variable "KOKKOS_device_id" is
not in all-caps, but is otherwise one of the valid
environment variables used by Kokkos. If you intended
to set "KOKKOS_DEVICE_ID", this variable
will not have the same effect.

Warning: environment variable "KOKKOS_NOT_A_VALID_VAR"
is prefixed like a variable that controls Kokkos,
but is not in the list of valid
Kokkos environment variables.
...

[dalg24]

• We need some way of programmatically of disabling warnings for environment variables that match a user-specified regex like we do for command line arguments
  

  kokkos/core/src/impl/Kokkos_Command_Line_Parsing.cpp

  Lines 243 to 252 in bb73401

  	namespace {
  	std::vector<std::regex> do_not_warn_regular_expressions{
  	std::regex{"--kokkos-tool.*", std::regex::egrep},
  	};
  	}
  	void Kokkos::Impl::do_not_warn_not_recognized_command_line_argument(
  	std::regex ignore) {
  	do_not_warn_regular_expressions.push_back(std::move(ignore));
  	}

• You need to add tests. See examples here
  

  kokkos/core/unit_test/TestParseCmdLineArgsAndEnvVars.cpp

  Lines 327 to 336 in 04a5334

  	TEST(defaultdevicetype, env_vars_device_id) {
  	EnvVarsHelper ev = {{
  	{"KOKKOS_DEVICE_ID", "33"},
  	}};
  	SKIP_IF_ENVIRONMENT_VARIABLE_ALREADY_SET(ev);
  	Kokkos::InitializationSettings settings;
  	Kokkos::Impl::parse_environment_variables(settings);
  	EXPECT_TRUE(settings.has_device_id());
  	EXPECT_EQ(settings.get_device_id(), 33);
  	}

• We need to make sure we don't raise warnings for env variables that are commonly set by modules on leadership computing facilities. I expect things like Kokkos_ROOT, Kokkos_DIR, Kokkos_HOME, etc.

[brian-kelley]

@dalg24 I think I addressed your points. Can you think of other variables that should be ignored (from modules etc.)?

[dalg24]

Forgot to remove

[dalg24]

Let's discuss that list at the next developer meeting.
We need to check with other projects in the Kokkos ecosystem that this works for them.

I purposefully omitted KOKKOS_VARIORUM_FUNC_TYPE, I don't think we should accommodate this one.

[dalg24]

This is kinda awkward. We cannot actually assert that there will be no warnings at all. I am wondering whether we should add a leading char* envp[] argument to Impl::parse_environment_variables() so we can control more fine-grained. What do you think?

[dalg24]

The windows build failed with

[ RUN      ] defaultdevicetype.env_vars_unrecognized
C:\projects\source\core\unit_test\TestParseCmdLineArgsAndEnvVars.cpp(418): error: Value of: captured.find("not recognized") != std::string::npos && captured.find("KOKKOS_device_id=0") != std::string::npos && !settings.has_device_id()
  Actual: false
Expected: true
[  FAILED  ] defaultdevicetype.env_vars_unrecognized (18 ms)

[nliber]

The only variable exported form kokkos modules at ALCF is KOKKOS_HOME

[dalg24]

The only variable exported form kokkos modules at ALCF is KOKKOS_HOME

OLCF prefixed them with OLCF_ so no issue