/*

 * POSIX library for Lua 5.1, 5.2 & 5.3.

 * (c) Gary V. Vaughan <gary@vaughan.pe>, 2013-2015

 * (c) Reuben Thomas <rrt@sc3d.org> 2010-2013

 * (c) Natanael Copa <natanael.copa@gmail.com> 2008-2010

 * Clean up and bug fixes by Leo Razoumov <slonik.az@gmail.com> 2006-10-11

 * Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br> 07 Apr 2006 23:17:49

 * Based on original by Claudio Terra for Lua 3.x.

 * With contributions by Roberto Ierusalimschy.

 * With documentation from Steve Donovan 2012

 */

/***

 Kernel Thread Scheduling Priority.

 Where supported by the underlying system, functions to discover and

 change the kernel thread scheduling priority.  If the module loads

 successfully, but there is no kernel support, then `posix.sched.version`

 will be set, but the unsupported APIs will be `nil`.

@module posix.sched

*/

#include <config.h>

#include <unistd.h>	/* for _POSIX_PRIORITY_SCHEDULING */

#ifdef _POSIX_PRIORITY_SCHEDULING

#include <sched.h>

#endif

#include "_helpers.c"

/***

get scheduling policy

@function sched_getscheduler

@int[opt=0] pid process to act on, or `0` for caller process

@treturn[1] int scheduling policy `SCHED_FIFO`, `SCHED_RR`, `SCHED_OTHER`,

  if successful

@return[2] nil

@treturn[2] string error message

@treturn[2] int errnum

@see sched_getscheduler(2)

*/

#if HAVE_SCHED_GETSCHEDULER

static int

Psched_getscheduler(lua_State *L)

{

	struct sched_param sched_param  = {0};

	pid_t pid = optint(L, 1, 0);

	checknargs(L, 1);

	return pushresult(L, sched_getscheduler(pid), NULL);

}

#endif

/***

set scheduling policy/priority

@function sched_setscheduler

@see sched_setscheduler(2)

@int[opt=0] pid process to act on, or `0` for caller process

@int[opt=`SCHED_OTHER`] policy one of `SCHED_FIFO`, `SCHED_RR` or

  `SCHED_OTHER`

@int[opt=0] priority must be `0` for `SCHED_OTHER`, or else a positive

  number below 100 for real-time policies

@treturn[1] int `0`, if successful

@return[2] nil

@treturn[2] string error message

@treturn[2] int errnum

*/

#if HAVE_SCHED_SETSCHEDULER

static int

Psched_setscheduler(lua_State *L)

{

	struct sched_param sched_param = {0};

	pid_t pid = optint(L, 1, 0);

	int policy = optint(L, 2, SCHED_OTHER);

	sched_param.sched_priority =  optint (L, 3, 0);

	checknargs(L, 3);

	return pushresult(L, sched_setscheduler(pid, policy, &sched_param), NULL);

}

#endif

static const luaL_Reg posix_sched_fns[] =

{

#if HAVE_SCHED_GETSCHEDULER

	LPOSIX_FUNC( Psched_getscheduler	),

#endif

#if HAVE_SCHED_SETSCHEDULER

	LPOSIX_FUNC( Psched_setscheduler	),

#endif

	{NULL, NULL}

};

/***

Constants.

@section constants

*/

/***

Scheduler constants.

Any constants not available in the underlying system will be `nil` valued.

@table posix.sched

@int SCHED_FIFO  first-in, first-out scheduling policy

@int SCHED_RR round-robin scheduling policy

@int SCHED_OTHER another scheduling policy

@usage

  -- Print scheduler constants supported on this host.

  for name, value in pairs (require "posix.sched") do

    if type (value) == "number" then

      print (name, value)

     end

  end

*/

LUALIB_API int

luaopen_posix_sched(lua_State *L)

{

	luaL_register(L, "posix.sched", posix_sched_fns);

	lua_pushliteral(L, "posix.sched for " LUA_VERSION " / " PACKAGE_STRING);

	lua_setfield(L, -2, "version");

	/* Psched_setscheduler flags */

#ifdef SCHED_FIFO

	LPOSIX_CONST( SCHED_FIFO	);

#endif

#ifdef SCHED_RR

	LPOSIX_CONST( SCHED_RR		);

#endif

#ifdef SCHED_OTHER

	LPOSIX_CONST( SCHED_OTHER	);

#endif

	return 1;

}