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

Copyright (c) 1995, 2023, Oracle and/or its affiliates.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.

This program is also distributed with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation.  The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have included with MySQL.

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, version 2.0, 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, Suite 500, Boston, MA 02110-1335 USA

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

/**************************************************//**
@file os/os0proc.cc
The interface to the operating system
process control primitives

Created 9/30/1995 Heikki Tuuri
*******************************************************/

#include "ha_prototypes.h"

#include "os0proc.h"
#ifdef UNIV_NONINL
#include "os0proc.ic"
#endif

#include "srv0srv.h"
#include "ut0mem.h"
#include "ut0byte.h"

/* FreeBSD for example has only MAP_ANON, Linux has MAP_ANONYMOUS and
MAP_ANON but MAP_ANON is marked as deprecated */
#if defined(MAP_ANONYMOUS)
#define OS_MAP_ANON	MAP_ANONYMOUS
#elif defined(MAP_ANON)
#define OS_MAP_ANON	MAP_ANON
#endif

/** The total amount of memory currently allocated from the operating
system with os_mem_alloc_large(). */
ulint	os_total_large_mem_allocated = 0;

/** Whether to use large pages in the buffer pool */
my_bool	os_use_large_pages;

/** Large page size. This may be a boot-time option on some platforms */
uint	os_large_page_size;

/** Converts the current process id to a number.
@return process id as a number */
ulint
os_proc_get_number(void)
/*====================*/
{
#ifdef _WIN32
	return(static_cast<ulint>(GetCurrentProcessId()));
#else
	return(static_cast<ulint>(getpid()));
#endif
}

/** Allocates large pages memory.
@param[in,out]	n	Number of bytes to allocate
@return allocated memory */
void*
os_mem_alloc_large(
	ulint*	n)
{
	void*	ptr;
	ulint	size;
#if defined HAVE_LINUX_LARGE_PAGES && defined UNIV_LINUX
	int shmid;
	struct shmid_ds buf;

	if (!os_use_large_pages || !os_large_page_size) {
		goto skip;
	}

	/* Align block size to os_large_page_size */
	ut_ad(ut_is_2pow(os_large_page_size));
	size = ut_2pow_round(*n + (os_large_page_size - 1),
			     os_large_page_size);

	shmid = shmget(IPC_PRIVATE, (size_t) size, SHM_HUGETLB | SHM_R | SHM_W);
	if (shmid < 0) {
		ib::warn() << "Failed to allocate " << size
			<< " bytes. errno " << errno;
		ptr = NULL;
	} else {
		ptr = shmat(shmid, NULL, 0);
		if (ptr == (void*)-1) {
			ib::warn() << "Failed to attach shared memory segment,"
				" errno " << errno;
			ptr = NULL;
		}

		/* Remove the shared memory segment so that it will be
		automatically freed after memory is detached or
		process exits */
		shmctl(shmid, IPC_RMID, &buf);
	}

	if (ptr) {
		*n = size;
		os_atomic_increment_ulint(
			&os_total_large_mem_allocated, size);

		UNIV_MEM_ALLOC(ptr, size);
		return(ptr);
	}

	ib::warn() << "Using conventional memory pool";
skip:
#endif /* HAVE_LINUX_LARGE_PAGES && UNIV_LINUX */

#ifdef _WIN32
	SYSTEM_INFO	system_info;
	GetSystemInfo(&system_info);

	/* Align block size to system page size */
	ut_ad(ut_is_2pow(system_info.dwPageSize));
	/* system_info.dwPageSize is only 32-bit. Casting to ulint is required
	on 64-bit Windows. */
	size = *n = ut_2pow_round(*n + (system_info.dwPageSize - 1),
				  (ulint) system_info.dwPageSize);
	ptr = VirtualAlloc(NULL, size, MEM_COMMIT | MEM_RESERVE,
			   PAGE_READWRITE);
	if (!ptr) {
		ib::info() << "VirtualAlloc(" << size << " bytes) failed;"
			" Windows error " << GetLastError();
	} else {
		os_atomic_increment_ulint(
			&os_total_large_mem_allocated, size);
		UNIV_MEM_ALLOC(ptr, size);
	}
#else
	size = getpagesize();
	/* Align block size to system page size */
	ut_ad(ut_is_2pow(size));
	size = *n = ut_2pow_round(*n + (size - 1), size);
	ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
		   MAP_PRIVATE | OS_MAP_ANON, -1, 0);
	if (UNIV_UNLIKELY(ptr == (void*) -1)) {
		ib::error() << "mmap(" << size << " bytes) failed;"
			" errno " << errno;
		ptr = NULL;
	} else {
		os_atomic_increment_ulint(
			&os_total_large_mem_allocated, size);
		UNIV_MEM_ALLOC(ptr, size);
	}
#endif
	return(ptr);
}

/** Frees large pages memory.
@param[in]	ptr	pointer returned by os_mem_alloc_large()
@param[in]	size	size returned by os_mem_alloc_large() */
void
os_mem_free_large(
	void	*ptr,
	ulint	size)
{
	ut_a(os_total_large_mem_allocated >= size);

#if defined HAVE_LINUX_LARGE_PAGES && defined UNIV_LINUX
	if (os_use_large_pages && os_large_page_size && !shmdt(ptr)) {
		os_atomic_decrement_ulint(
			&os_total_large_mem_allocated, size);
		UNIV_MEM_FREE(ptr, size);
		return;
	}
#endif /* HAVE_LINUX_LARGE_PAGES && UNIV_LINUX */
#ifdef _WIN32
	/* When RELEASE memory, the size parameter must be 0.
	Do not use MEM_RELEASE with MEM_DECOMMIT. */
	if (!VirtualFree(ptr, 0, MEM_RELEASE)) {
		ib::error() << "VirtualFree(" << ptr << ", " << size
			<< ") failed; Windows error " << GetLastError();
	} else {
		os_atomic_decrement_ulint(
			&os_total_large_mem_allocated, size);
		UNIV_MEM_FREE(ptr, size);
	}
#elif !defined OS_MAP_ANON
	ut_free(ptr);
#else
# if defined(UNIV_SOLARIS)
	if (munmap(static_cast<caddr_t>(ptr), size)) {
# else
	if (munmap(ptr, size)) {
# endif /* UNIV_SOLARIS */
		ib::error() << "munmap(" << ptr << ", " << size << ") failed;"
			" errno " << errno;
	} else {
		os_atomic_decrement_ulint(
			&os_total_large_mem_allocated, size);
		UNIV_MEM_FREE(ptr, size);
	}
#endif
}
