/*****************************************************************************

Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA

*****************************************************************************/

/**************************************************//**
@file os/os0thread.cc
The interface to the operating system thread control primitives

Created 9/8/1995 Heikki Tuuri
*******************************************************/

#include "os0thread.h"
#ifdef UNIV_NONINL
#include "os0thread.ic"
#endif

#ifdef __WIN__
#include <windows.h>
#elif UNIV_LINUX
#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>
#endif

#ifndef UNIV_HOTBACKUP
#include "srv0srv.h"
#include "os0sync.h"

/***************************************************************//**
Compares two thread ids for equality.
@return	TRUE if equal */
UNIV_INTERN
ibool
os_thread_eq(
/*=========*/
	os_thread_id_t	a,	/*!< in: OS thread or thread id */
	os_thread_id_t	b)	/*!< in: OS thread or thread id */
{
#ifdef __WIN__
	if (a == b) {
		return(TRUE);
	}

	return(FALSE);
#else
	if (pthread_equal(a, b)) {
		return(TRUE);
	}

	return(FALSE);
#endif
}

/****************************************************************//**
Converts an OS thread id to a ulint. It is NOT guaranteed that the ulint is
unique for the thread though!
@return	thread identifier as a number */
UNIV_INTERN
ulint
os_thread_pf(
/*=========*/
	os_thread_id_t	a)	/*!< in: OS thread identifier */
{
#ifdef UNIV_HPUX10
	/* In HP-UX-10.20 a pthread_t is a struct of 3 fields: field1, field2,
	field3. We do not know if field1 determines the thread uniquely. */

	return((ulint)(a.field1));
#else
	return((ulint) a);
#endif
}

/*****************************************************************//**
Returns the thread identifier of current thread. Currently the thread
identifier in Unix is the thread handle itself. Note that in HP-UX
pthread_t is a struct of 3 fields.
@return	current thread identifier */
UNIV_INTERN
os_thread_id_t
os_thread_get_curr_id(void)
/*=======================*/
{
#ifdef __WIN__
	return(GetCurrentThreadId());
#else
	return(pthread_self());
#endif
}

/*****************************************************************//**
Returns the system-specific thread identifier of current thread.  On Linux,
returns tid.  On other systems currently returns os_thread_get_curr_id().

@return	current thread identifier */
UNIV_INTERN
os_tid_t
os_thread_get_tid(void)
/*===================*/
{
#ifdef UNIV_LINUX
	return((os_tid_t)syscall(SYS_gettid));
#else
	return(os_thread_get_curr_id());
#endif
}


/****************************************************************//**
Creates a new thread of execution. The execution starts from
the function given. The start function takes a void* parameter
and returns an ulint.
@return	handle to the thread */
UNIV_INTERN
os_thread_t
os_thread_create_func(
/*==================*/
	os_thread_func_t	func,		/*!< in: pointer to function
						from which to start */
	void*			arg,		/*!< in: argument to start
						function */
	os_thread_id_t*		thread_id)	/*!< out: id of the created
						thread, or NULL */
{
	/* the new thread should look recent changes up here so far. */
	os_wmb;

#ifdef __WIN__
	os_thread_t	thread;
	DWORD		win_thread_id;

	os_atomic_increment_ulint(&os_thread_count, 1);

	thread = CreateThread(NULL,	/* no security attributes */
			      0,	/* default size stack */
			      func,
			      arg,
			      0,	/* thread runs immediately */
			      &win_thread_id);

	if (thread_id) {
		*thread_id = win_thread_id;
	}

	return((os_thread_t)thread);
#else
	int		ret;
	os_thread_t	pthread;
	pthread_attr_t	attr;

#ifndef UNIV_HPUX10
	pthread_attr_init(&attr);
#endif

#ifdef UNIV_AIX
	/* We must make sure a thread stack is at least 32 kB, otherwise
	InnoDB might crash; we do not know if the default stack size on
	AIX is always big enough. An empirical test on AIX-4.3 suggested
	the size was 96 kB, though. */

	ret = pthread_attr_setstacksize(&attr,
					(size_t)(PTHREAD_STACK_MIN
						 + 32 * 1024));
	if (ret) {
		fprintf(stderr,
			"InnoDB: Error: pthread_attr_setstacksize"
			" returned %d\n", ret);
		exit(1);
	}
#endif
	ulint new_count = os_atomic_increment_ulint(&os_thread_count, 1);
	ut_a(new_count <= OS_THREAD_MAX_N);

#ifdef UNIV_HPUX10
	ret = pthread_create(&pthread, pthread_attr_default, func, arg);
#else
	ret = pthread_create(&pthread, &attr, func, arg);
#endif
	ut_a(ret == 0);

#ifndef UNIV_HPUX10
	pthread_attr_destroy(&attr);
#endif

	if (thread_id) {
		*thread_id = pthread;
	}

	return(pthread);
#endif
}

/** Waits until the specified thread completes and joins it.
Its return value is ignored.
@param[in,out]	thread	thread to join */
UNIV_INTERN
void
os_thread_join(
	os_thread_t	thread)
{
	/* This function is currently only used to workaround glibc bug
	described in http://bugs.mysql.com/bug.php?id=82886

	On Windows, no workarounds are necessary, all threads
	are "detached" upon thread exit (handle is closed), so we do
	nothing.
	*/
#ifdef __WIN__
	/* Do nothing. */
#else
#ifdef UNIV_DEBUG
	const int	ret MY_ATTRIBUTE((unused)) =
#endif /* UNIV_DEBUG */
	pthread_join(thread, NULL);

	/* Waiting on already-quit threads is allowed. */
	ut_ad(ret == 0 || ret == ESRCH);
#endif /* __WIN__ */
}

/*****************************************************************//**
Exits the current thread. */
UNIV_INTERN
void
os_thread_exit(
/*===========*/
	void*	exit_value,	/*!< in: exit value; in Windows this void*
				is cast as a DWORD */
	bool	detach)		/*!< in: if true, the thread will be detached
				right before exiting. If false, another thread
				is responsible for joining this thread. */
{
#ifdef UNIV_DEBUG_THREAD_CREATION
	fprintf(stderr, "Thread exits, id %lu\n",
		os_thread_pf(os_thread_get_curr_id()));
#endif

#ifdef UNIV_PFS_THREAD
	pfs_delete_thread();
#endif

	os_atomic_decrement_ulint(&os_thread_count, 1);

#ifdef __WIN__
	ExitThread((DWORD) exit_value);
#else
	if (detach) {
		pthread_detach(pthread_self());
	}
	pthread_exit(exit_value);
#endif
}

/*****************************************************************//**
Advises the os to give up remainder of the thread's time slice. */
UNIV_INTERN
void
os_thread_yield(void)
/*=================*/
{
#if defined(__WIN__)
	SwitchToThread();
#elif (defined(HAVE_SCHED_YIELD) && defined(HAVE_SCHED_H))
	sched_yield();
#elif defined(HAVE_PTHREAD_YIELD_ZERO_ARG)
	pthread_yield();
#elif defined(HAVE_PTHREAD_YIELD_ONE_ARG)
	pthread_yield(0);
#else
	os_thread_sleep(0);
#endif
}
#endif /* !UNIV_HOTBACKUP */

/*****************************************************************//**
The thread sleeps at least the time given in microseconds. */
UNIV_INTERN
void
os_thread_sleep(
/*============*/
	ulint	tm)	/*!< in: time in microseconds */
{
#ifdef __WIN__
	Sleep((DWORD) tm / 1000);
#else
	struct timeval	t;

	t.tv_sec = tm / 1000000;
	t.tv_usec = tm % 1000000;

	select(0, NULL, NULL, NULL, &t);
#endif
}

/*****************************************************************//**
Set relative scheduling priority for a given thread on Linux.  Currently a
no-op on other systems.

@return An actual thread priority after the update */
UNIV_INTERN
ulint
os_thread_set_priority(
/*===================*/
	os_tid_t	thread_id,		/*!< in: thread id */
	ulint		relative_priority)	/*!< in: system-specific
						priority value */
{
#ifdef UNIV_LINUX
	lint	thread_nice = 19 - relative_priority;
	if (setpriority(PRIO_PROCESS, thread_id, thread_nice) == -1) {
		ib_logf(IB_LOG_LEVEL_WARN,
			"Setting thread %lu nice to %ld failed, "
			"current nice %d, errno %d",
			os_thread_pf(thread_id), thread_nice,
			getpriority(PRIO_PROCESS, thread_id), errno);
	}
	return(19 - getpriority(PRIO_PROCESS, thread_id));
#else
	return(relative_priority);
#endif
}

/*****************************************************************//**
Get priority for a given thread on Linux.  Currently a
no-op on other systems.

@return An actual thread priority */
UNIV_INTERN
ulint
os_thread_get_priority(
/*===================*/
	os_tid_t	thread_id)		/*!< in: thread id */
{
#ifdef UNIV_LINUX
	return (getpriority(PRIO_PROCESS, thread_id));
#else
	return (0);
#endif
}
