os0file.c 45.8 KB
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/******************************************************
The interface to the operating system file i/o primitives

(c) 1995 Innobase Oy

Created 10/21/1995 Heikki Tuuri
*******************************************************/

#include "os0file.h"
#include "os0sync.h"
#include "ut0mem.h"


#ifdef POSIX_ASYNC_IO
/* We assume in this case that the OS has standard Posix aio (at least SunOS
2.6, HP-UX 11i and AIX 4.3 have) */

#undef __USE_FILE_OFFSET64

#include <aio.h>
#endif

/* We use these mutexes to protect lseek + file i/o operation, if the
OS does not provide an atomic pread or pwrite, or similar */
#define OS_FILE_N_SEEK_MUTEXES	16
os_mutex_t	os_file_seek_mutexes[OS_FILE_N_SEEK_MUTEXES];

/* In simulated aio, merge at most this many consecutive i/os */
#define OS_AIO_MERGE_N_CONSECUTIVE	32

/* If this flag is TRUE, then we will use the native aio of the
OS (provided we compiled Innobase with it in), otherwise we will
use simulated aio we build below with threads */

ibool	os_aio_use_native_aio	= FALSE;

/* The aio array slot structure */
typedef struct os_aio_slot_struct	os_aio_slot_t;

struct os_aio_slot_struct{
	ibool		is_read;	/* TRUE if a read operation */
	ulint		pos;		/* index of the slot in the aio
					array */
	ibool		reserved;	/* TRUE if this slot is reserved */
	ulint		len;		/* length of the block to read or
					write */
	byte*		buf;		/* buffer used in i/o */
	ulint		type;		/* OS_FILE_READ or OS_FILE_WRITE */
	ulint		offset;		/* 32 low bits of file offset in
					bytes */
	ulint		offset_high;	/* 32 high bits of file offset */
	os_file_t	file;		/* file where to read or write */
	char*		name;		/* file name or path */
	ibool		io_already_done;/* used only in simulated aio:
					TRUE if the physical i/o already
					made and only the slot message
					needs to be passed to the caller
					of os_aio_simulated_handle */
	void*		message1;	/* message which is given by the */
	void*		message2;	/* the requester of an aio operation
					and which can be used to identify
					which pending aio operation was
					completed */
#ifdef WIN_ASYNC_IO
	OVERLAPPED	control;	/* Windows control block for the
					aio request */
#elif defined(POSIX_ASYNC_IO)
	struct aiocb	control;	/* Posix control block for aio
					request */
#endif
};

/* The aio array structure */
typedef struct os_aio_array_struct	os_aio_array_t;

struct os_aio_array_struct{
	os_mutex_t	mutex;	  /* the mutex protecting the aio array */
	os_event_t	not_full; /* The event which is set to signaled
				  state when there is space in the aio
				  outside the ibuf segment */
	ulint		n_slots;  /* Total number of slots in the aio array.
				  This must be divisible by n_threads. */
	ulint		n_segments;/* Number of segments in the aio array of
				  pending aio requests. A thread can wait
				  separately for any one of the segments. */
	ulint		n_reserved;/* Number of reserved slots in the
				  aio array outside the ibuf segment */
	os_aio_slot_t* 	slots;	  /* Pointer to the slots in the array */
	os_event_t*	events;	  /* Pointer to an array of event handles
				  where we copied the handles from slots,
				  in the same order. This can be used in
				  WaitForMultipleObjects; used only in
				  Windows */
};

/* Array of events used in simulated aio */
os_event_t*	os_aio_segment_wait_events	= NULL;

/* The aio arrays for non-ibuf i/o and ibuf i/o, as well as sync aio. These
are NULL when the module has not yet been initialized. */
os_aio_array_t*	os_aio_read_array	= NULL;
os_aio_array_t*	os_aio_write_array	= NULL;
os_aio_array_t*	os_aio_ibuf_array	= NULL;
os_aio_array_t*	os_aio_log_array	= NULL;
os_aio_array_t*	os_aio_sync_array	= NULL;

ulint	os_aio_n_segments	= ULINT_UNDEFINED;

/***************************************************************************
Retrieves the last error number if an error occurs in a file io function.
The number should be retrieved before any other OS calls (because they may
overwrite the error number). If the number is not known to this program,
the OS error number + 100 is returned. */

ulint
os_file_get_last_error(void)
/*========================*/
		/* out: error number, or OS error number + 100 */
{
	ulint	err;

#ifdef __WIN__

	err = (ulint) GetLastError();

	if (err == ERROR_FILE_NOT_FOUND) {
		return(OS_FILE_NOT_FOUND);
	} else if (err == ERROR_DISK_FULL) {
		return(OS_FILE_DISK_FULL);
	} else if (err == ERROR_FILE_EXISTS) {
		return(OS_FILE_ALREADY_EXISTS);
	} else {
		return(100 + err);
	}
#else
	err = (ulint) errno;

	if (err == ENOSPC ) {
		return(OS_FILE_DISK_FULL);
#ifdef POSIX_ASYNC_IO
	} else if (err == EAGAIN) {
		return(OS_FILE_AIO_RESOURCES_RESERVED);
#endif
	} else if (err == ENOENT) {
		return(OS_FILE_NOT_FOUND);
	} else if (err == EEXIST) {
		return(OS_FILE_ALREADY_EXISTS);
	} else {
		return(100 + err);
	}
#endif
}

/********************************************************************
Does error handling when a file operation fails. If we have run out
of disk space, then the user can clean the disk. If we do not find
a specified file, then the user can copy it to disk. */
static
ibool
os_file_handle_error(
/*=================*/
				/* out: TRUE if we should retry the operation */
	os_file_t	file,	/* in: file pointer */
	char*		name)	/* in: name of a file or NULL */
{
	int	input_char;
	ulint	err;

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	UT_NOT_USED(file);

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	err = os_file_get_last_error();
	
	if (err == OS_FILE_DISK_FULL) {
ask_again:
		printf("\n");
		if (name) {
			printf(
			"Innobase encountered a problem with file %s.\n",
									name);
		}
		printf("Disk is full. Try to clean the disk to free space\n");
		printf("before answering the following: How to continue?\n");
		printf("(Y == freed some space: try again)\n");
		printf("(N == crash the database: will restart it)?\n");
ask_with_no_question:
		input_char = getchar();

		if (input_char == (int) 'N') {
			ut_error;
		
			return(FALSE);
		} else if (input_char == (int) 'Y') {

			return(TRUE);
		} else if (input_char == (int) '\n') {

			goto ask_with_no_question;
		} else {
			goto ask_again;
		}
	} else if (err == OS_FILE_AIO_RESOURCES_RESERVED) {

		return(TRUE);
	} else {
		ut_error;
	}

	return(FALSE);	
}

/********************************************************************
Opens an existing file or creates a new. */

os_file_t
os_file_create(
/*===========*/
			/* out, own: handle to the file, not defined if error,
			error number can be retrieved with os_get_last_error */
	char*	name,	/* in: name of the file or path as a null-terminated
			string */
	ulint	create_mode, /* in: OS_FILE_OPEN if an existing file is opened
			(if does not exist, error), or OS_FILE_CREATE if a new
			file is created (if exists, error), OS_FILE_OVERWRITE
			if a new is created or an old overwritten */
	ulint	purpose,/* in: OS_FILE_AIO, if asynchronous, non-buffered i/o
			is desired, OS_FILE_NORMAL, if any normal file */
	ibool*	success)/* out: TRUE if succeed, FALSE if error */
{
#ifdef __WIN__
	os_file_t	file;
	DWORD		create_flag;
	DWORD		attributes;
	ibool		retry;
	
try_again:	
	ut_a(name);

	if (create_mode == OS_FILE_OPEN) {
		create_flag = OPEN_EXISTING;
	} else if (create_mode == OS_FILE_CREATE) {
		create_flag = CREATE_NEW;
	} else if (create_mode == OS_FILE_OVERWRITE) {
		create_flag = CREATE_ALWAYS;
	} else {
		create_flag = 0;
		ut_error;
	}

	if (purpose == OS_FILE_AIO) {
		/* use asynchronous (overlapped) io and no buffering
		of writes in the OS */
		attributes = 0;
#ifdef WIN_ASYNC_IO
		if (os_aio_use_native_aio) {
			attributes = attributes | FILE_FLAG_OVERLAPPED;
		}
#endif			
#ifdef UNIV_NON_BUFFERED_IO
		attributes = attributes | FILE_FLAG_NO_BUFFERING;
#endif
	} else if (purpose == OS_FILE_NORMAL) {
		attributes = 0
#ifdef UNIV_NON_BUFFERED_IO
			 | FILE_FLAG_NO_BUFFERING
#endif
			;
	} else {
		attributes = 0;
		ut_error;
	}

	file = CreateFile(name,
			GENERIC_READ | GENERIC_WRITE, /* read and write
							access */
			FILE_SHARE_READ,/* file can be read by other
					processes */
			NULL,	/* default security attributes */
			create_flag,
			attributes,
			NULL);	/* no template file */

	if (file == INVALID_HANDLE_VALUE) {
		*success = FALSE;

		if (create_mode != OS_FILE_OPEN
		    && os_file_get_last_error() == OS_FILE_DISK_FULL) {

			retry = os_file_handle_error(file, name);

			if (retry) {
				goto try_again;
			}
		}
	} else {
		*success = TRUE;
	}

	return(file);
#else
	os_file_t	file;
	int		create_flag;
	ibool		retry;
	
try_again:	
	ut_a(name);

	if (create_mode == OS_FILE_OPEN) {
		create_flag = O_RDWR;
	} else if (create_mode == OS_FILE_CREATE) {
		create_flag = O_RDWR | O_CREAT | O_EXCL;
	} else if (create_mode == OS_FILE_OVERWRITE) {
		create_flag = O_RDWR | O_CREAT | O_TRUNC;
	} else {
		create_flag = 0;
		ut_error;
	}

	UT_NOT_USED(purpose);

	if (create_mode == OS_FILE_CREATE) {
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#ifndef S_IRWXU
                file = open(name, create_flag);
#else
	        file = open(name, create_flag, S_IRWXU | S_IRWXG | S_IRWXO);
#endif
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        } else {
                file = open(name, create_flag);
        }
	
	if (file == -1) {
		*success = FALSE;

		if (create_mode != OS_FILE_OPEN
		    && errno == ENOSPC) {

			retry = os_file_handle_error(file, name);

			if (retry) {
				goto try_again;
			}
		}
	} else {
		*success = TRUE;
	}

	return(file);	
#endif
}

/***************************************************************************
Closes a file handle. In case of error, error number can be retrieved with
os_file_get_last_error. */

ibool
os_file_close(
/*==========*/
				/* out: TRUE if success */
	os_file_t	file)	/* in, own: handle to a file */
{
#ifdef __WIN__
	BOOL	ret;

	ut_a(file);

	ret = CloseHandle(file);

	if (ret) {
		return(TRUE);
	}

	return(FALSE);
#else
	int	ret;

	ret = close(file);

	if (ret == -1) {
		return(FALSE);
	}

	return(TRUE);
#endif
}

/***************************************************************************
Gets a file size. */

ibool
os_file_get_size(
/*=============*/
				/* out: TRUE if success */
	os_file_t	file,	/* in: handle to a file */
	ulint*		size,	/* out: least significant 32 bits of file
				size */
	ulint*		size_high)/* out: most significant 32 bits of size */
{
#ifdef __WIN__
	DWORD	high;
	DWORD	low;

	low = GetFileSize(file, &high);

	if ((low == 0xFFFFFFFF) && (GetLastError() != NO_ERROR)) {
		return(FALSE);
	}

	*size = low;
	*size_high = high;

	return(TRUE);
#else
	*size = (ulint) lseek(file, 0, SEEK_END);
	*size_high = 0;
	
	return(TRUE);	
#endif
}

/***************************************************************************
Sets a file size. This function can be used to extend or truncate a file. */

ibool
os_file_set_size(
/*=============*/
				/* out: TRUE if success */
	char*		name,	/* in: name of the file or path as a
				null-terminated string */
	os_file_t	file,	/* in: handle to a file */
	ulint		size,	/* in: least significant 32 bits of file
				size */
	ulint		size_high)/* in: most significant 32 bits of size */
{
	ulint   offset;
	ulint   n_bytes;
	ulint	low;
	ibool	ret;
	ibool	retry;
	ulint   i;
	byte*   buf;

try_again:
	buf = ut_malloc(UNIV_PAGE_SIZE * 64);

	/* Write buffer full of zeros */
	for (i = 0; i < UNIV_PAGE_SIZE * 64; i++) {
	        buf[i] = '\0';
	}

	offset = 0;
	low = size;
#if (UNIV_WORD_SIZE == 8)
	low = low + (size_high << 32);
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#else
	UT_NOT_USED(size_high);
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#endif
	while (offset < low) {
	        if (low - offset < UNIV_PAGE_SIZE * 64) {
	                 n_bytes = low - offset;
	        } else {
	                 n_bytes = UNIV_PAGE_SIZE * 64;
	        }
	  
	        ret = os_file_write(name, file, buf, offset, 0, n_bytes);

	        if (!ret) {
			ut_free(buf);
	         	goto error_handling;
	        }
	        offset += n_bytes;
	}

	ut_free(buf);

	ret = os_file_flush(file);

	if (ret) {
	        return(TRUE);
	}

error_handling:
	retry = os_file_handle_error(file, name); 

	if (retry) {
		goto try_again;
	}
	
	ut_error;
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	return(FALSE);
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}

/***************************************************************************
Flushes the write buffers of a given file to the disk. */

ibool
os_file_flush(
/*==========*/
				/* out: TRUE if success */
	os_file_t	file)	/* in, own: handle to a file */
{
#ifdef __WIN__
	BOOL	ret;

	ut_a(file);

	ret = FlushFileBuffers(file);

	if (ret) {
		return(TRUE);
	}

	return(FALSE);
#else
	int	ret;
	
	ret = fsync(file);

	if (ret == 0) {
		return(TRUE);
	}
	
	return(FALSE);
#endif
}


#ifndef __WIN__
/***********************************************************************
Does a synchronous read operation in Posix. */
static
ssize_t
os_file_pread(
/*==========*/
				/* out: number of bytes read, -1 if error */
	os_file_t	file,	/* in: handle to a file */
	void*		buf,	/* in: buffer where to read */
	ulint		n,	/* in: number of bytes to read */	
	ulint		offset)	/* in: offset from where to read */
{
#ifdef HAVE_PREAD
	return(pread(file, buf, n, (off_t) offset));
#else
	ssize_t	ret;
	ulint	i;

	/* Protect the seek / read operation with a mutex */
	i = ((ulint) file) % OS_FILE_N_SEEK_MUTEXES;
	
	os_mutex_enter(os_file_seek_mutexes[i]);

	ret = lseek(file, (off_t) offset, 0);

	if (ret < 0) {
		os_mutex_exit(os_file_seek_mutexes[i]);

		return(ret);
	}
	
	ret = read(file, buf, n);

	os_mutex_exit(os_file_seek_mutexes[i]);

	return(ret);
#endif
}

/***********************************************************************
Does a synchronous write operation in Posix. */
static
ssize_t
os_file_pwrite(
/*===========*/
				/* out: number of bytes written, -1 if error */
	os_file_t	file,	/* in: handle to a file */
	void*		buf,	/* in: buffer from where to write */
	ulint		n,	/* in: number of bytes to write */	
	ulint		offset)	/* in: offset where to write */
{
#ifdef HAVE_PWRITE
	return(pwrite(file, buf, n, (off_t) offset));
#else
	ssize_t	ret;
	ulint	i;

	/* Protect the seek / write operation with a mutex */
	i = ((ulint) file) % OS_FILE_N_SEEK_MUTEXES;
	
	os_mutex_enter(os_file_seek_mutexes[i]);

	ret = lseek(file, (off_t) offset, 0);

	if (ret < 0) {
		os_mutex_exit(os_file_seek_mutexes[i]);

		return(ret);
	}
	
	ret = write(file, buf, n);

	os_mutex_exit(os_file_seek_mutexes[i]);

	return(ret);
#endif
}
#endif

/***********************************************************************
Requests a synchronous positioned read operation. */

ibool
os_file_read(
/*=========*/
				/* out: TRUE if request was
				successful, FALSE if fail */
	os_file_t	file,	/* in: handle to a file */
	void*		buf,	/* in: buffer where to read */
	ulint		offset,	/* in: least significant 32 bits of file
				offset where to read */
	ulint		offset_high, /* in: most significant 32 bits of
				offset */
	ulint		n)	/* in: number of bytes to read */	
{
#ifdef __WIN__
	BOOL		ret;
	DWORD		len;
	DWORD		ret2;
	DWORD		err;
	DWORD		low;
	DWORD		high;
	ibool		retry;
	ulint		i;
	
try_again:	
	ut_ad(file);
	ut_ad(buf);
	ut_ad(n > 0);

	low = offset;
	high = offset_high;

	/* Protect the seek / read operation with a mutex */
	i = ((ulint) file) % OS_FILE_N_SEEK_MUTEXES;
	
	os_mutex_enter(os_file_seek_mutexes[i]);

	ret2 = SetFilePointer(file, low, &high, FILE_BEGIN);

	if (ret2 == 0xFFFFFFFF && GetLastError() != NO_ERROR) {
		err = GetLastError();

		os_mutex_exit(os_file_seek_mutexes[i]);

		goto error_handling;
	} 
	
	ret = ReadFile(file, buf, n, &len, NULL);

	os_mutex_exit(os_file_seek_mutexes[i]);
	
	if (ret && len == n) {
		return(TRUE);
	}		

	err = GetLastError();
#else
	ibool	retry;
	ssize_t	ret;
	ulint   i;
	
#if (UNIV_WORD_SIZE == 8)
	offset = offset + (offset_high << 32);
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#else
	UT_NOT_USED(offset_high);
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#endif	
try_again:
	/* Protect the seek / read operation with a mutex */
	i = ((ulint) file) % OS_FILE_N_SEEK_MUTEXES;
	
	os_mutex_enter(os_file_seek_mutexes[i]);

	ret = os_file_pread(file, buf, n, (off_t) offset);

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	if ((ulint)ret == n) {
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		os_mutex_exit(os_file_seek_mutexes[i]);

		return(TRUE);
	}
#endif	
error_handling:
	retry = os_file_handle_error(file, NULL); 

	if (retry) {
		goto try_again;
	}
	
	ut_error;

	return(FALSE);
}

/***********************************************************************
Requests a synchronous write operation. */

ibool
os_file_write(
/*==========*/
				/* out: TRUE if request was
				successful, FALSE if fail */
	char*		name,	/* in: name of the file or path as a
				null-terminated string */
	os_file_t	file,	/* in: handle to a file */
	void*		buf,	/* in: buffer from which to write */
	ulint		offset,	/* in: least significant 32 bits of file
				offset where to write */
	ulint		offset_high, /* in: most significant 32 bits of
				offset */
	ulint		n)	/* in: number of bytes to write */	
{
#ifdef __WIN__
	BOOL		ret;
	DWORD		len;
	DWORD		ret2;
	DWORD		err;
	DWORD		low;
	DWORD		high;
	ibool		retry;
	ulint		i;

try_again:	
	ut_ad(file);
	ut_ad(buf);
	ut_ad(n > 0);

	low = offset;
	high = offset_high;
	
	/* Protect the seek / write operation with a mutex */
	i = ((ulint) file) % OS_FILE_N_SEEK_MUTEXES;
	
	os_mutex_enter(os_file_seek_mutexes[i]);

	ret2 = SetFilePointer(file, low, &high, FILE_BEGIN);

	if (ret2 == 0xFFFFFFFF && GetLastError() != NO_ERROR) {
		err = GetLastError();

		os_mutex_exit(os_file_seek_mutexes[i]);
		
		goto error_handling;
	} 

	ret = WriteFile(file, buf, n, &len, NULL);

	os_mutex_exit(os_file_seek_mutexes[i]);
	
	if (ret && len == n) {
		return(TRUE);
	}
#else
	ibool	retry;
	ssize_t	ret;
	
#if (UNIV_WORD_SIZE == 8)
	offset = offset + (offset_high << 32);
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#else
	UT_NOT_USED(offset_high);
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#endif	
try_again:
	ret = pwrite(file, buf, n, (off_t) offset);

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	if ((ulint)ret == n) {
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		return(TRUE);
	}
#endif
775
error_handling:		
776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907
	retry = os_file_handle_error(file, name); 

	if (retry) {
		goto try_again;
	}
	
	ut_error;

	return(FALSE);
}

/********************************************************************
Returns a pointer to the nth slot in the aio array. */
static
os_aio_slot_t*
os_aio_array_get_nth_slot(
/*======================*/
					/* out: pointer to slot */
	os_aio_array_t*		array,	/* in: aio array */
	ulint			index)	/* in: index of the slot */
{
	ut_a(index < array->n_slots);

	return((array->slots) + index);
}

/****************************************************************************
Creates an aio wait array. */
static
os_aio_array_t*
os_aio_array_create(
/*================*/
				/* out, own: aio array */
	ulint	n,		/* in: maximum number of pending aio operations
				allowed; n must be divisible by n_segments */
	ulint	n_segments) 	/* in: number of segments in the aio array */
{
	os_aio_array_t*	array;
	ulint		i;
	os_aio_slot_t*	slot;
#ifdef WIN_ASYNC_IO
	OVERLAPPED*	over;
#endif	
	ut_a(n > 0);
	ut_a(n_segments > 0);
	ut_a(n % n_segments == 0);

	array = ut_malloc(sizeof(os_aio_array_t));

	array->mutex 		= os_mutex_create(NULL);
	array->not_full		= os_event_create(NULL);
	array->n_slots  	= n;
	array->n_segments	= n_segments;
	array->n_reserved	= 0;
	array->slots		= ut_malloc(n * sizeof(os_aio_slot_t));
	array->events		= ut_malloc(n * sizeof(os_event_t));
	
	for (i = 0; i < n; i++) {
		slot = os_aio_array_get_nth_slot(array, i);

		slot->pos = i;
		slot->reserved = FALSE;
#ifdef WIN_ASYNC_IO
		over = &(slot->control);

		over->hEvent = os_event_create(NULL);

		*((array->events) + i) = over->hEvent;
#endif
	}
	
	return(array);
}

/****************************************************************************
Initializes the asynchronous io system. Creates separate aio array for
non-ibuf read and write, a third aio array for the ibuf i/o, with just one
segment, two aio arrays for log reads and writes with one segment, and a
synchronous aio array of the specified size. The combined number of segments
in the three first aio arrays is the parameter n_segments given to the
function. The caller must create an i/o handler thread for each segment in
the four first arrays, but not for the sync aio array. */

void
os_aio_init(
/*========*/
	ulint	n,		/* in: maximum number of pending aio operations
				allowed; n must be divisible by n_segments */
	ulint	n_segments,	/* in: combined number of segments in the four
				first aio arrays; must be >= 4 */
	ulint	n_slots_sync)	/* in: number of slots in the sync aio array */
{
	ulint	n_read_segs;
	ulint	n_write_segs;
	ulint	n_per_seg;
	ulint	i;
#ifdef POSIX_ASYNC_IO
	sigset_t   sigset;
#endif
	ut_ad(n % n_segments == 0);
	ut_ad(n_segments >= 4);

	n_per_seg = n / n_segments;
	n_write_segs = (n_segments - 2) / 2;
	n_read_segs = n_segments - 2 - n_write_segs;
	
	/* printf("Array n per seg %lu\n", n_per_seg); */

	os_aio_read_array = os_aio_array_create(n_read_segs * n_per_seg,
							n_read_segs);
	os_aio_write_array = os_aio_array_create(n_write_segs * n_per_seg,
							n_write_segs);
	os_aio_ibuf_array = os_aio_array_create(n_per_seg, 1);

	os_aio_log_array = os_aio_array_create(n_per_seg, 1);

	os_aio_sync_array = os_aio_array_create(n_slots_sync, 1);

	os_aio_n_segments = n_segments;

	os_aio_validate();

	for (i = 0; i < OS_FILE_N_SEEK_MUTEXES; i++) {
		os_file_seek_mutexes[i] = os_mutex_create(NULL);
	}

	os_aio_segment_wait_events = ut_malloc(n_segments * sizeof(void*));

	for (i = 0; i < n_segments; i++) {
		os_aio_segment_wait_events[i] = os_event_create(NULL);
	}

908
#if defined(POSIX_ASYNC_IO) && defined(NOT_USED_WITH_MYSQL)
909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921
	/* Block aio signals from the current thread and its children:
	for this to work, the current thread must be the first created
	in the database, so that all its children will inherit its
	signal mask */
	
        sigemptyset(&sigset);
	sigaddset(&sigset, SIGRTMIN + 1 + 0);
	sigaddset(&sigset, SIGRTMIN + 1 + 1);
	sigaddset(&sigset, SIGRTMIN + 1 + 2);
	sigaddset(&sigset, SIGRTMIN + 1 + 3);

	pthread_sigmask(SIG_BLOCK, &sigset, NULL);
#endif
}
				
/**************************************************************************
Calculates segment number for a slot. */
static
ulint
os_aio_get_segment_no_from_slot(
/*============================*/
				/* out: segment number (which is the number
				used by, for example, i/o-handler threads) */
	os_aio_array_t*	array,	/* in: aio wait array */
	os_aio_slot_t*	slot)	/* in: slot in this array */
{
	ulint	segment;
	ulint	seg_len;

	if (array == os_aio_ibuf_array) {
		segment = 0;

	} else if (array == os_aio_log_array) {
		segment = 1;
		
	} else if (array == os_aio_read_array) {
		seg_len = os_aio_read_array->n_slots /
				os_aio_read_array->n_segments;

		segment = 2 + slot->pos / seg_len;
	} else {
		ut_a(array == os_aio_write_array);
		seg_len = os_aio_write_array->n_slots /
				os_aio_write_array->n_segments;

		segment = os_aio_read_array->n_segments + 2
				+ slot->pos / seg_len;
	}

	return(segment);
}

/**************************************************************************
Calculates local segment number and aio array from global segment number. */
static
ulint
os_aio_get_array_and_local_segment(
/*===============================*/
					/* out: local segment number within
					the aio array */
	os_aio_array_t** array,		/* out: aio wait array */
	ulint		 global_segment)/* in: global segment number */
{
	ulint	segment;

	ut_a(global_segment < os_aio_n_segments);	

	if (global_segment == 0) {
		*array = os_aio_ibuf_array;
		segment = 0;

	} else if (global_segment == 1) {
		*array = os_aio_log_array;
		segment = 0;
		
	} else if (global_segment < os_aio_read_array->n_segments + 2) {
		*array = os_aio_read_array;

		segment = global_segment - 2;
	} else {
		*array = os_aio_write_array;

		segment = global_segment - (os_aio_read_array->n_segments + 2);
	}

	return(segment);
}

/***********************************************************************
Gets an integer value designating a specified aio array. This is used
to give numbers to signals in Posix aio. */
static
ulint
os_aio_get_array_no(
/*================*/
	os_aio_array_t*	array)	/* in: aio array */
{	
	if (array == os_aio_ibuf_array) {
	
		return(0);

	} else if (array == os_aio_log_array) {

		return(1);

	} else if (array == os_aio_read_array) {

		return(2);
	} else if (array == os_aio_write_array) {

		return(3);
	} else {
		ut_a(0);

		return(0);
	}
}

/***********************************************************************
Gets the aio array for its number. */
static
os_aio_array_t*
os_aio_get_array_from_no(
/*=====================*/
			/* out: aio array */
	ulint	n)	/* in: array number */
{	
	if (n == 0) {
		return(os_aio_ibuf_array);
	} else if (n == 1) {

		return(os_aio_log_array);
	} else if (n == 2) {

		return(os_aio_read_array);
	} else if (n == 3) {

		return(os_aio_write_array);
	} else {
		ut_a(0);

		return(NULL);
	}
}

/***********************************************************************
Requests for a slot in the aio array. If no slot is available, waits until
not_full-event becomes signaled. */
static
os_aio_slot_t*
os_aio_array_reserve_slot(
/*======================*/
				/* out: pointer to slot */
	ulint		type,	/* in: OS_FILE_READ or OS_FILE_WRITE */
	os_aio_array_t*	array,	/* in: aio array */
	void*		message1,/* in: message to be passed along with
				the aio operation */
	void*		message2,/* in: message to be passed along with
				the aio operation */
	os_file_t	file,	/* in: file handle */
	char*		name,	/* in: name of the file or path as a
				null-terminated string */
	void*		buf,	/* in: buffer where to read or from which
				to write */
	ulint		offset,	/* in: least significant 32 bits of file
				offset */
	ulint		offset_high, /* in: most significant 32 bits of
				offset */
	ulint		len)	/* in: length of the block to read or write */
{
	os_aio_slot_t*	slot;
#ifdef WIN_ASYNC_IO
	OVERLAPPED*	control;

#elif defined(POSIX_ASYNC_IO)

	struct aiocb*	control;
#endif
	ulint		i;
loop:
	os_mutex_enter(array->mutex);

	if (array->n_reserved == array->n_slots) {
		os_mutex_exit(array->mutex);

		if (!os_aio_use_native_aio) {
			/* If the handler threads are suspended, wake them
			so that we get more slots */

			os_aio_simulated_wake_handler_threads();
		}
		
		os_event_wait(array->not_full);

		goto loop;
	}

	for (i = 0;; i++) {
		slot = os_aio_array_get_nth_slot(array, i);

		if (slot->reserved == FALSE) {
			break;
		}
	}

	array->n_reserved++;

	if (array->n_reserved == array->n_slots) {
		os_event_reset(array->not_full);
	}
	
	slot->reserved = TRUE;
	slot->message1 = message1;
	slot->message2 = message2;
	slot->file     = file;
	slot->name     = name;
	slot->len      = len;
	slot->type     = type;
	slot->buf      = buf;
	slot->offset   = offset;
	slot->offset_high = offset_high;
	slot->io_already_done = FALSE;
	
#ifdef WIN_ASYNC_IO		
	control = &(slot->control);
	control->Offset = (DWORD)offset;
	control->OffsetHigh = (DWORD)offset_high;
	os_event_reset(control->hEvent);

#elif defined(POSIX_ASYNC_IO)

#if (UNIV_WORD_SIZE == 8)
	offset = offset + (offset_high << 32);
#else
	ut_a(offset_high == 0);
#endif 
	control = &(slot->control);
	control->aio_fildes = file;
	control->aio_buf = buf;
	control->aio_nbytes = len;
	control->aio_offset = offset;
	control->aio_reqprio = 0;
	control->aio_sigevent.sigev_notify = SIGEV_SIGNAL;
	control->aio_sigevent.sigev_signo =
			SIGRTMIN + 1 + os_aio_get_array_no(array);
			/* TODO: How to choose the signal numbers? */
/*
	printf("AIO signal number %lu\n", (ulint) control->aio_sigevent.sigev_signo);
*/
	control->aio_sigevent.sigev_value.sival_ptr = slot;
#endif
	os_mutex_exit(array->mutex);

	return(slot);
}

/***********************************************************************
Frees a slot in the aio array. */
static
void
os_aio_array_free_slot(
/*===================*/
	os_aio_array_t*	array,	/* in: aio array */
	os_aio_slot_t*	slot)	/* in: pointer to slot */
{
	ut_ad(array);
	ut_ad(slot);

	os_mutex_enter(array->mutex);

	ut_ad(slot->reserved);
	
	slot->reserved = FALSE;

	array->n_reserved--;

	if (array->n_reserved == array->n_slots - 1) {
		os_event_set(array->not_full);
	}

#ifdef WIN_ASYNC_IO		
	os_event_reset(slot->control.hEvent);
#endif
	os_mutex_exit(array->mutex);
}

/**************************************************************************
Wakes up a simulated aio i/o-handler thread if it has something to do. */
static
void
os_aio_simulated_wake_handler_thread(
/*=================================*/
	ulint	global_segment)	/* in: the number of the segment in the aio
				arrays */
{
	os_aio_array_t*	array;
	ulint		segment;
	os_aio_slot_t*	slot;
	ulint		n;
	ulint		i;

	ut_ad(!os_aio_use_native_aio);

	segment = os_aio_get_array_and_local_segment(&array, global_segment);

	n = array->n_slots / array->n_segments;

	/* Look through n slots after the segment * n'th slot */

	os_mutex_enter(array->mutex);

	for (i = 0; i < n; i++) {
		slot = os_aio_array_get_nth_slot(array, i + segment * n);

		if (slot->reserved) {
			/* Found an i/o request */
			
			break;
		}
	}

	os_mutex_exit(array->mutex);

	if (i < n) {
		os_event_set(os_aio_segment_wait_events[global_segment]);
	}
}

/**************************************************************************
Wakes up simulated aio i/o-handler threads if they have something to do. */

void
os_aio_simulated_wake_handler_threads(void)
/*=======================================*/
{
	ulint	i;

	if (os_aio_use_native_aio) {
		/* We do not use simulated aio: do nothing */

		return;
	}

	for (i = 0; i < os_aio_n_segments; i++) {
		os_aio_simulated_wake_handler_thread(i);
	}
}

/***********************************************************************
Requests an asynchronous i/o operation. */

ibool
os_aio(
/*===*/
				/* out: TRUE if request was queued
				successfully, FALSE if fail */
	ulint		type,	/* in: OS_FILE_READ or OS_FILE_WRITE */
	ulint		mode,	/* in: OS_AIO_NORMAL, ..., possibly ORed
				to OS_AIO_SIMULATED_WAKE_LATER: the
				last flag advises this function not to wake
				i/o-handler threads, but the caller will
				do the waking explicitly later, in this
				way the caller can post several requests in
				a batch; NOTE that the batch must not be
				so big that it exhausts the slots in aio
				arrays! NOTE that a simulated batch
				may introduce hidden chances of deadlocks,
				because i/os are not actually handled until
				all have been posted: use with great
				caution! */
	char*		name,	/* in: name of the file or path as a
				null-terminated string */
	os_file_t	file,	/* in: handle to a file */
	void*		buf,	/* in: buffer where to read or from which
				to write */
	ulint		offset,	/* in: least significant 32 bits of file
				offset where to read or write */
	ulint		offset_high, /* in: most significant 32 bits of
				offset */
	ulint		n,	/* in: number of bytes to read or write */	
	void*		message1,/* in: messages for the aio handler (these
				can be used to identify a completed aio
				operation); if mode is OS_AIO_SYNC, these
				are ignored */
	void*		message2)
{
	os_aio_array_t*	array;
	os_aio_slot_t*	slot;
#ifdef WIN_ASYNC_IO
	BOOL		ret		= TRUE;
	DWORD		len		= n;
	void*		dummy_mess1;
	void*		dummy_mess2;
#endif
	ulint		err		= 0;
	ibool		retry;
	ulint		wake_later;

	ut_ad(file);
	ut_ad(buf);
	ut_ad(n > 0);
	ut_ad(n % OS_FILE_LOG_BLOCK_SIZE == 0);
	ut_ad((ulint)buf % OS_FILE_LOG_BLOCK_SIZE == 0)
	ut_ad(offset % OS_FILE_LOG_BLOCK_SIZE == 0);
	ut_ad(os_aio_validate());

	wake_later = mode & OS_AIO_SIMULATED_WAKE_LATER;
	mode = mode & (~OS_AIO_SIMULATED_WAKE_LATER);
	
	if (mode == OS_AIO_SYNC
#ifdef WIN_ASYNC_IO
				&& !os_aio_use_native_aio
#endif
	) {
		/* This is actually an ordinary synchronous read or write:
		no need to use an i/o-handler thread. NOTE that if we use
		Windows async i/o, Windows does not allow us to use
		ordinary synchronous os_file_read etc. on the same file,
		therefore we have built a special mechanism for synchronous
		wait in the Windows case. */

		if (type == OS_FILE_READ) {
			return(os_file_read(file, buf, offset, offset_high, n));
		}

		ut_a(type == OS_FILE_WRITE);

		return(os_file_write(name, file, buf, offset, offset_high, n));
	}

try_again:
	if (mode == OS_AIO_NORMAL) {
		if (type == OS_FILE_READ) {
			array = os_aio_read_array;
		} else {
			array = os_aio_write_array;
		}
	} else if (mode == OS_AIO_IBUF) {
		ut_ad(type == OS_FILE_READ);

		array = os_aio_ibuf_array;
	} else if (mode == OS_AIO_LOG) {

		array = os_aio_log_array;
	} else if (mode == OS_AIO_SYNC) {
		array = os_aio_sync_array;
	} else {
		ut_error;
	}
	
	slot = os_aio_array_reserve_slot(type, array, message1, message2, file,
					name, buf, offset, offset_high, n);
	if (type == OS_FILE_READ) {
		if (os_aio_use_native_aio) {
#ifdef WIN_ASYNC_IO
			ret = ReadFile(file, buf, (DWORD)n, &len,
							&(slot->control));
#elif defined(POSIX_ASYNC_IO)
			slot->control.aio_lio_opcode = LIO_READ;
			err = (ulint) aio_read(&(slot->control));
			printf("Starting Posix aio read %lu\n", err);
#endif
		} else {
			if (!wake_later) {
				os_aio_simulated_wake_handler_thread(
				 os_aio_get_segment_no_from_slot(array, slot));
			}
		}
	} else if (type == OS_FILE_WRITE) {
		if (os_aio_use_native_aio) {
#ifdef WIN_ASYNC_IO
			ret = WriteFile(file, buf, (DWORD)n, &len,
							&(slot->control));
#elif defined(POSIX_ASYNC_IO)
			slot->control.aio_lio_opcode = LIO_WRITE;
			err = (ulint) aio_write(&(slot->control));
			printf("Starting Posix aio write %lu\n", err);
#endif
		} else {
			if (!wake_later) {
				os_aio_simulated_wake_handler_thread(
				 os_aio_get_segment_no_from_slot(array, slot));
			}
		}
	} else {
		ut_error;
	}

#ifdef WIN_ASYNC_IO
	if (os_aio_use_native_aio) {
		if ((ret && len == n)
			|| (!ret && GetLastError() == ERROR_IO_PENDING)) {	

			/* aio was queued successfully! */
		
	    		if (mode == OS_AIO_SYNC) {
	    		    /* We want a synchronous i/o operation on a file
	    		    where we also use async i/o: in Windows we must
	    		    use the same wait mechanism as for async i/o */
	    		
	    		    return(os_aio_windows_handle(ULINT_UNDEFINED,
						slot->pos,
		    				&dummy_mess1, &dummy_mess2));
	    		}

			return(TRUE);
		}

		goto error_handling;
	}
#endif
	if (err == 0) {
		/* aio was queued successfully! */

		return(TRUE);
	}

	os_aio_array_free_slot(array, slot);

	retry = os_file_handle_error(file, name);

	if (retry) {

		goto try_again;
	}	

	ut_error;
	
	return(FALSE);
}

#ifdef WIN_ASYNC_IO
/**************************************************************************
This function is only used in Windows asynchronous i/o.
Waits for an aio operation to complete. This function is used to wait the
for completed requests. The aio array of pending requests is divided
into segments. The thread specifies which segment or slot it wants to wait
for. NOTE: this function will also take care of freeing the aio slot,
therefore no other thread is allowed to do the freeing! */

ibool
os_aio_windows_handle(
/*==================*/
				/* out: TRUE if the aio operation succeeded */
	ulint	segment,	/* in: the number of the segment in the aio
				arrays to wait for; segment 0 is the ibuf
				i/o thread, segment 1 the log i/o thread,
				then follow the non-ibuf read threads, and as
				the last are the non-ibuf write threads; if
				this is ULINT_UNDEFINED, then it means that
				sync aio is used, and this parameter is
				ignored */
	ulint	pos,		/* this parameter is used only in sync aio:
				wait for the aio slot at this position */  
	void**	message1,	/* out: the messages passed with the aio
				request; note that also in the case where
				the aio operation failed, these output
				parameters are valid and can be used to
				restart the operation, for example */
	void**	message2)
{
	os_aio_array_t*	array;
	os_aio_slot_t*	slot;
	ulint		n;
	ulint		i;
	ibool		ret_val;
	ulint		err;
	BOOL		ret;
	DWORD		len;

	if (segment == ULINT_UNDEFINED) {
		array = os_aio_sync_array;
		segment = 0;
	} else {
		segment = os_aio_get_array_and_local_segment(&array, segment);
	}
	
	/* NOTE! We only access constant fields in os_aio_array. Therefore
	we do not have to acquire the protecting mutex yet */

	ut_ad(os_aio_validate());
	ut_ad(segment < array->n_segments);

	n = array->n_slots / array->n_segments;

	if (array == os_aio_sync_array) {
		ut_ad(pos < array->n_slots); 
		os_event_wait(array->events[pos]);
		i = pos;
	} else {
		i = os_event_wait_multiple(n, (array->events) + segment * n);
	}

	os_mutex_enter(array->mutex);

	slot = os_aio_array_get_nth_slot(array, i + segment * n);

	ut_a(slot->reserved);

	ret = GetOverlappedResult(slot->file, &(slot->control), &len, TRUE);

	*message1 = slot->message1;
	*message2 = slot->message2;

	if (ret && len == slot->len) {
		ret_val = TRUE;
	} else {
		err = GetLastError();
		ut_error;

		ret_val = FALSE;
	}		  

	os_mutex_exit(array->mutex);

	os_aio_array_free_slot(array, slot);
	
	return(ret_val);
}
#endif

#ifdef POSIX_ASYNC_IO

/**************************************************************************
This function is only used in Posix asynchronous i/o. Waits for an aio
operation to complete. */

ibool
os_aio_posix_handle(
/*================*/
				/* out: TRUE if the aio operation succeeded */
	ulint	array_no,	/* in: array number 0 - 3 */
	void**	message1,	/* out: the messages passed with the aio
				request; note that also in the case where
				the aio operation failed, these output
				parameters are valid and can be used to
				restart the operation, for example */
	void**	message2)
{
	os_aio_array_t*	array;
	os_aio_slot_t*	slot;
	siginfo_t	info;
	sigset_t	sigset;
	sigset_t        proc_sigset;
	sigset_t        thr_sigset;
	int		ret;
	int             i;
	int             sig;
	
        sigemptyset(&sigset);
	sigaddset(&sigset, SIGRTMIN + 1 + array_no);

	pthread_sigmask(SIG_UNBLOCK, &sigset, NULL);

	/*
	sigprocmask(0, NULL, &proc_sigset);
	pthread_sigmask(0, NULL, &thr_sigset);

	for (i = 32 ; i < 40; i++) {
	  printf("%lu : %lu %lu\n", (ulint)i,
		 (ulint)sigismember(&proc_sigset, i),
		 (ulint)sigismember(&thr_sigset, i));
	}
	*/

	ret = sigwaitinfo(&sigset, &info);

	if (sig != SIGRTMIN + 1 + array_no) {

		ut_a(0);
	
		return(FALSE);
	}
	
	printf("Handling Posix aio\n");

	array = os_aio_get_array_from_no(array_no);

	os_mutex_enter(array->mutex);

	slot = info.si_value.sival_ptr;

	ut_a(slot->reserved);

	*message1 = slot->message1;
	*message2 = slot->message2;

	os_mutex_exit(array->mutex);

	os_aio_array_free_slot(array, slot);
	
	return(TRUE);
}
#endif

/**************************************************************************
Does simulated aio. This function should be called by an i/o-handler
thread. */

ibool
os_aio_simulated_handle(
/*====================*/
				/* out: TRUE if the aio operation succeeded */
	ulint	global_segment,	/* in: the number of the segment in the aio
				arrays to wait for; segment 0 is the ibuf
				i/o thread, segment 1 the log i/o thread,
				then follow the non-ibuf read threads, and as
				the last are the non-ibuf write threads */
	void**	message1,	/* out: the messages passed with the aio
				request; note that also in the case where
				the aio operation failed, these output
				parameters are valid and can be used to
				restart the operation, for example */
	void**	message2)
{
	os_aio_array_t*	array;
	ulint		segment;
	os_aio_slot_t*	slot;
	os_aio_slot_t*	slot2;
	os_aio_slot_t*	consecutive_ios[OS_AIO_MERGE_N_CONSECUTIVE];
	ulint		n_consecutive;
	ulint		total_len;
	ulint		offs;
	ulint		lowest_offset;
	byte*		combined_buf;
	ibool		ret;
	ulint		n;
	ulint		i;

	segment = os_aio_get_array_and_local_segment(&array, global_segment);
	
restart:
	/* Give other threads chance to add several i/os to the array
	at once */
	
	os_thread_yield();

	/* NOTE! We only access constant fields in os_aio_array. Therefore
	we do not have to acquire the protecting mutex yet */

	ut_ad(os_aio_validate());
	ut_ad(segment < array->n_segments);

	n = array->n_slots / array->n_segments;

	/* Look through n slots after the segment * n'th slot */

	os_mutex_enter(array->mutex);

	/* Check if there is a slot for which the i/o has already been
	done */
	
	for (i = 0; i < n; i++) {
		slot = os_aio_array_get_nth_slot(array, i + segment * n);

		if (slot->reserved && slot->io_already_done) {

			ret = TRUE;
			
			goto slot_io_done;
		}
	}

	n_consecutive = 0;

	/* Look for an i/o request at the lowest offset in the array */

	lowest_offset = ULINT_MAX;
	
	for (i = 0; i < n; i++) {
		slot = os_aio_array_get_nth_slot(array, i + segment * n);

		if (slot->reserved && slot->offset < lowest_offset) {

			/* Found an i/o request */
			consecutive_ios[0] = slot;

			n_consecutive = 1;

			lowest_offset = slot->offset;
		}
	}

	if (n_consecutive == 0) {

		/* No i/o requested at the moment */

		goto wait_for_io;
	}

	slot = consecutive_ios[0];

	/* Check if there are several consecutive blocks to read or write */

consecutive_loop:	
	for (i = 0; i < n; i++) {
		slot2 = os_aio_array_get_nth_slot(array, i + segment * n);

		if (slot2->reserved && slot2 != slot
		    && slot2->offset == slot->offset + slot->len
		    && slot->offset + slot->len > slot->offset /* check that
						sum does not wrap over */
		    && slot2->offset_high == slot->offset_high
		    && slot2->type == slot->type
		    && slot2->file == slot->file) {

			/* Found a consecutive i/o request */

			consecutive_ios[n_consecutive] = slot2;
			n_consecutive++;

			slot = slot2;

			if (n_consecutive < OS_AIO_MERGE_N_CONSECUTIVE) {
			
				goto consecutive_loop;
			} else {
				break;
			}
		}
	}

	/* We have now collected n_consecutive i/o requests in the array;
	allocate a single buffer which can hold all data, and perform the
	i/o */

	total_len = 0;
	slot = consecutive_ios[0];
	
	for (i = 0; i < n_consecutive; i++) {
		total_len += consecutive_ios[i]->len;
	}

	if (n_consecutive == 1) {
		/* We can use the buffer of the i/o request */
		combined_buf = slot->buf;
	} else {
		combined_buf = ut_malloc(total_len);

		ut_a(combined_buf);
	}
	
	/* We release the array mutex for the time of the i/o: NOTE that
	this assumes that there is just one i/o-handler thread serving
	a single segment of slots! */

	os_mutex_exit(array->mutex);

	if (slot->type == OS_FILE_WRITE && n_consecutive > 1) {
		/* Copy the buffers to the combined buffer */
		offs = 0;
		
		for (i = 0; i < n_consecutive; i++) {

			ut_memcpy(combined_buf + offs, consecutive_ios[i]->buf,
						consecutive_ios[i]->len);
			offs += consecutive_ios[i]->len;
		}
	}

	/* Do the i/o with ordinary, synchronous i/o functions: */
	if (slot->type == OS_FILE_WRITE) {
		ret = os_file_write(slot->name, slot->file, combined_buf,
				slot->offset, slot->offset_high, total_len);
	} else {
		ret = os_file_read(slot->file, combined_buf,
				slot->offset, slot->offset_high, total_len);
	}

	ut_a(ret);
	
/* printf("aio: %lu consecutive %lu:th segment, first offs %lu blocks\n",
			n_consecutive, global_segment, slot->offset
					/ UNIV_PAGE_SIZE); */

	if (slot->type == OS_FILE_READ && n_consecutive > 1) {
		/* Copy the combined buffer to individual buffers */
		offs = 0;
		
		for (i = 0; i < n_consecutive; i++) {

			ut_memcpy(consecutive_ios[i]->buf, combined_buf + offs, 
						consecutive_ios[i]->len);
			offs += consecutive_ios[i]->len;
		}
	}

	if (n_consecutive > 1) {
		ut_free(combined_buf);
	}

	os_mutex_enter(array->mutex);

	/* Mark the i/os done in slots */

	for (i = 0; i < n_consecutive; i++) {
		consecutive_ios[i]->io_already_done = TRUE;
	}

	/* We return the messages for the first slot now, and if there were
	several slots, the messages will be returned with subsequent calls
	of this function */
	
slot_io_done:

	ut_a(slot->reserved);

	*message1 = slot->message1;
	*message2 = slot->message2;

	os_mutex_exit(array->mutex);

	os_aio_array_free_slot(array, slot);
	
	return(ret);

wait_for_io:
	/* We wait here until there again can be i/os in the segment
	of this thread */
	
	os_event_reset(os_aio_segment_wait_events[global_segment]);

	os_mutex_exit(array->mutex);

	os_event_wait(os_aio_segment_wait_events[global_segment]);

	goto restart;
}

/**************************************************************************
Validates the consistency of an aio array. */
static
ibool
os_aio_array_validate(
/*==================*/
				/* out: TRUE if ok */
	os_aio_array_t*	array)	/* in: aio wait array */
{
	os_aio_slot_t*	slot;
	ulint		n_reserved	= 0;
	ulint		i;
	
	ut_a(array);

	os_mutex_enter(array->mutex);

	ut_a(array->n_slots > 0);
	ut_a(array->n_segments > 0);
	
	for (i = 0; i < array->n_slots; i++) {
		slot = os_aio_array_get_nth_slot(array, i);
	
		if (slot->reserved) {
			n_reserved++;
			ut_a(slot->len > 0);
		}
	}

	ut_a(array->n_reserved == n_reserved);

	os_mutex_exit(array->mutex);

	return(TRUE);
}

/**************************************************************************
Validates the consistency the aio system. */

ibool
os_aio_validate(void)
/*=================*/
				/* out: TRUE if ok */
{
	os_aio_array_validate(os_aio_read_array);
	os_aio_array_validate(os_aio_write_array);
	os_aio_array_validate(os_aio_ibuf_array);
	os_aio_array_validate(os_aio_log_array);
	os_aio_array_validate(os_aio_sync_array);

	return(TRUE);
}

/**************************************************************************
Prints info of the aio arrays. */

void
os_aio_print(void)
/*==============*/
{
	os_aio_array_t*	array;
	os_aio_slot_t*	slot;
	ulint		n_reserved;
	ulint		i;
	
	array = os_aio_read_array;
loop:
	ut_a(array);
	
	printf("INFO OF AN AIO ARRAY\n");

	os_mutex_enter(array->mutex);

	ut_a(array->n_slots > 0);
	ut_a(array->n_segments > 0);
	
	n_reserved = 0;

	for (i = 0; i < array->n_slots; i++) {
		slot = os_aio_array_get_nth_slot(array, i);
	
		if (slot->reserved) {
			n_reserved++;
			printf("Reserved slot, messages %lx %lx\n",
1922 1923
					(ulint)slot->message1,
					(ulint)slot->message2);
1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
			ut_a(slot->len > 0);
		}
	}

	ut_a(array->n_reserved == n_reserved);

	printf("Total of %lu reserved aio slots\n", n_reserved);
	
	os_mutex_exit(array->mutex);

	if (array == os_aio_read_array) {
		array = os_aio_write_array;

		goto loop;
	}

	if (array == os_aio_write_array) {
		array = os_aio_ibuf_array;

		goto loop;
	}

	if (array == os_aio_ibuf_array) {
		array = os_aio_log_array;

		goto loop;
	}

	if (array == os_aio_log_array) {
		array = os_aio_sync_array;

		goto loop;
	}
}

/**************************************************************************
Checks that all slots in the system have been freed, that is, there are
no pending io operations. */

ibool
os_aio_all_slots_free(void)
/*=======================*/
				/* out: TRUE if all free */
{
	os_aio_array_t*	array;
	ulint		n_res	= 0;
	
	array = os_aio_read_array;

	os_mutex_enter(array->mutex);

	n_res += array->n_reserved; 
	
	os_mutex_exit(array->mutex);

	array = os_aio_write_array;

	os_mutex_enter(array->mutex);

	n_res += array->n_reserved; 
	
	os_mutex_exit(array->mutex);

	array = os_aio_ibuf_array;

	os_mutex_enter(array->mutex);

	n_res += array->n_reserved; 
	
	os_mutex_exit(array->mutex);

	array = os_aio_log_array;

	os_mutex_enter(array->mutex);

	n_res += array->n_reserved; 
	
	os_mutex_exit(array->mutex);

	array = os_aio_sync_array;

	os_mutex_enter(array->mutex);

	n_res += array->n_reserved; 
	
	os_mutex_exit(array->mutex);

	if (n_res == 0) {

		return(TRUE);
	}

	return(FALSE);
}