buf0buf.h

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

			
/* The buffer control block structure */

struct buf_block_struct{

	/* 1. General fields */

	ulint		magic_n;	/* magic number to check */
	ulint		state;		/* state of the control block:
					BUF_BLOCK_NOT_USED, ... */
	byte*		frame;		/* pointer to buffer frame which
					is of size UNIV_PAGE_SIZE, and
					aligned to an address divisible by
					UNIV_PAGE_SIZE; if AWE is used, this
					will be NULL for the pages which are
					currently not mapped into the virtual
					address space window of the buffer
					pool */
	os_awe_t*	awe_info;	/* if AWE is used, then an array of
					awe page infos for
					UNIV_PAGE_SIZE / OS_AWE_X86_PAGE_SIZE
					(normally = 4) physical memory
					pages; otherwise NULL */
	ulint		space;		/* space id of the page */
	ulint		offset;		/* page number within the space */
	ulint		lock_hash_val;	/* hashed value of the page address
					in the record lock hash table */
	mutex_t*	lock_mutex;	/* mutex protecting the chain in the
					record lock hash table */
	rw_lock_t	lock;		/* read-write lock of the buffer
					frame */
	buf_block_t*	hash;		/* node used in chaining to the page
					hash table */
	ibool		check_index_page_at_flush;
					/* TRUE if we know that this is
					an index page, and want the database
					to check its consistency before flush;
					note that there may be pages in the
					buffer pool which are index pages,
					but this flag is not set because
					we do not keep track of all pages */
	/* 2. Page flushing fields */

	UT_LIST_NODE_T(buf_block_t) flush_list;
					/* node of the modified, not yet
					flushed blocks list */
	dulint		newest_modification;
					/* log sequence number of the youngest
					modification to this block, zero if
					not modified */
	dulint		oldest_modification;
					/* log sequence number of the START of
					the log entry written of the oldest
					modification to this block which has
					not yet been flushed on disk; zero if
					all modifications are on disk */
	ulint		flush_type;	/* if this block is currently being
					flushed to disk, this tells the
					flush_type: BUF_FLUSH_LRU or
					BUF_FLUSH_LIST */

	/* 3. LRU replacement algorithm fields */

	UT_LIST_NODE_T(buf_block_t) free;
					/* node of the free block list */
	ibool		in_free_list;	/* TRUE if in the free list; used in
					debugging */
	UT_LIST_NODE_T(buf_block_t) LRU;
					/* node of the LRU list */
	UT_LIST_NODE_T(buf_block_t) awe_LRU_free_mapped;
					/* in the AWE version node in the
					list of free and LRU blocks which are
					mapped to a frame */
	ibool		in_LRU_list;	/* TRUE of the page is in the LRU list;
					used in debugging */
	ulint		LRU_position;	/* value which monotonically
					decreases (or may stay constant if
					the block is in the old blocks) toward
					the end of the LRU list, if the pool
					ulint_clock has not wrapped around:
					NOTE that this value can only be used
					in heuristic algorithms, because of
					the possibility of a wrap-around! */
	ulint		freed_page_clock;/* the value of freed_page_clock
					buffer pool when this block was
					last time put to the head of the
					LRU list */
	ibool		old;		/* TRUE if the block is in the old
					blocks in the LRU list */
	ibool		accessed;	/* TRUE if the page has been accessed
					while in the buffer pool: read-ahead
					may read in pages which have not been
					accessed yet */
	ulint		buf_fix_count;	/* count of how manyfold this block
					is currently bufferfixed */
	ulint		io_fix;		/* if a read is pending to the frame,
					io_fix is BUF_IO_READ, in the case
					of a write BUF_IO_WRITE, otherwise 0 */
	/* 4. Optimistic search field */

	dulint		modify_clock;	/* this clock is incremented every
					time a pointer to a record on the
					page may become obsolete; this is
					used in the optimistic cursor
					positioning: if the modify clock has
					not changed, we know that the pointer
					is still valid; this field may be
					changed if the thread (1) owns the
					pool mutex and the page is not
					bufferfixed, or (2) the thread has an
					x-latch on the block */

	/* 5. Hash search fields: NOTE that the first 4 fields are NOT
	protected by any semaphore! */
	
	ulint		n_hash_helps;	/* counter which controls building
					of a new hash index for the page */
	ulint		n_fields;	/* recommended prefix length for hash
					search: number of full fields */
	ulint		n_bytes;	/* recommended prefix: number of bytes
					in an incomplete field */
	ulint		side;		/* BTR_SEARCH_LEFT_SIDE or
					BTR_SEARCH_RIGHT_SIDE, depending on
					whether the leftmost record of several
					records with the same prefix should be
					indexed in the hash index */
					
	/* These 6 fields may only be modified when we have
	an x-latch on btr_search_latch AND
	a) we are holding an s-latch or x-latch on block->lock or
	b) we know that block->buf_fix_count == 0.

	An exception to this is when we init or create a page
	in the buffer pool in buf0buf.c. */

	ibool		is_hashed;	/* TRUE if hash index has already been
					built on this page; note that it does
					not guarantee that the index is
					complete, though: there may have been
					hash collisions, record deletions,
					etc. */
	ulint		n_pointers;	/* used in debugging: the number of
					pointers in the adaptive hash index
					pointing to this frame */
	ulint		curr_n_fields;	/* prefix length for hash indexing:
					number of full fields */
	ulint		curr_n_bytes;	/* number of bytes in hash indexing */
	ulint		curr_side;	/* BTR_SEARCH_LEFT_SIDE or
					BTR_SEARCH_RIGHT_SIDE in hash
					indexing */
	dict_index_t*	index;		/* Index for which the adaptive
					hash index has been created. */
	/* 6. Debug fields */
#ifdef UNIV_SYNC_DEBUG
	rw_lock_t	debug_latch;	/* in the debug version, each thread
					which bufferfixes the block acquires
					an s-latch here; so we can use the
					debug utilities in sync0rw */
#endif
        ibool           file_page_was_freed;
                                        /* this is set to TRUE when fsp
                                        frees a page in buffer pool */
};

#define BUF_BLOCK_MAGIC_N	41526563

/* The buffer pool structure. NOTE! The definition appears here only for
other modules of this directory (buf) to see it. Do not use from outside! */

struct buf_pool_struct{

	/* 1. General fields */

	mutex_t		mutex;		/* mutex protecting the buffer pool
					struct and control blocks, except the
					read-write lock in them */
	byte*		frame_mem;	/* pointer to the memory area which
					was allocated for the frames; in AWE
					this is the virtual address space
					window where we map pages stored
					in physical memory */
	byte*		frame_zero;	/* pointer to the first buffer frame:
					this may differ from frame_mem, because
					this is aligned by the frame size */
	byte*		high_end;	/* pointer to the end of the buffer
					frames */
	ulint		n_frames;	/* number of frames */
	buf_block_t*	blocks;		/* array of buffer control blocks */
	buf_block_t**	blocks_of_frames;/* inverse mapping which can be used
					to retrieve the buffer control block
					of a frame; this is an array which
					lists the blocks of frames in the
					order frame_zero,
					frame_zero + UNIV_PAGE_SIZE, ...
					a control block is always assigned
					for each frame, even if the frame does
					not contain any data; note that in AWE
					there are more control blocks than
					buffer frames */
	os_awe_t*	awe_info;	/* if AWE is used, AWE info for the
					physical 4 kB memory pages associated
					with buffer frames */
	ulint		max_size;	/* number of control blocks ==
					maximum pool size in pages */
	ulint		curr_size;	/* current pool size in pages;
					currently always the same as
					max_size */
	hash_table_t*	page_hash;	/* hash table of the file pages */

	ulint		n_pend_reads;	/* number of pending read operations */

	time_t		last_printout_time; /* when buf_print was last time
					called */
	ulint		n_pages_read;	/* number read operations */
	ulint		n_pages_written;/* number write operations */
	ulint		n_pages_created;/* number of pages created in the pool
					with no read */
	ulint		n_page_gets;	/* number of page gets performed;
					also successful searches through
					the adaptive hash index are
					counted as page gets; this field
					is NOT protected by the buffer
					pool mutex */
	ulint		n_pages_awe_remapped; /* if AWE is enabled, the
					number of remaps of blocks to
					buffer frames */
	ulint		n_page_gets_old;/* n_page_gets when buf_print was
					last time called: used to calculate
					hit rate */
	ulint		n_pages_read_old;/* n_pages_read when buf_print was
					last time called */
	ulint		n_pages_written_old;/* number write operations */
	ulint		n_pages_created_old;/* number of pages created in
					the pool with no read */
	ulint		n_pages_awe_remapped_old;
	/* 2. Page flushing algorithm fields */

	UT_LIST_BASE_NODE_T(buf_block_t) flush_list;
					/* base node of the modified block
					list */
	ibool		init_flush[BUF_FLUSH_LIST + 1];
					/* this is TRUE when a flush of the
					given type is being initialized */
	ulint		n_flush[BUF_FLUSH_LIST + 1];
					/* this is the number of pending
					writes in the given flush type */
	os_event_t	no_flush[BUF_FLUSH_LIST + 1];
					/* this is in the set state when there
					is no flush batch of the given type
					running */
	ulint		ulint_clock;	/* a sequence number used to count
					time. NOTE! This counter wraps
					around at 4 billion (if ulint ==
					32 bits)! */
	ulint		freed_page_clock;/* a sequence number used to count the
					number of buffer blocks removed from
					the end of the LRU list; NOTE that
					this counter may wrap around at 4
					billion! */
	ulint		LRU_flush_ended;/* when an LRU flush ends for a page,
					this is incremented by one; this is
					set to zero when a buffer block is
					allocated */

	/* 3. LRU replacement algorithm fields */

	UT_LIST_BASE_NODE_T(buf_block_t) free;
					/* base node of the free block list;
					in the case of AWE, at the start are
					always free blocks for which the
					physical memory is mapped to a frame */
	UT_LIST_BASE_NODE_T(buf_block_t) LRU;
					/* base node of the LRU list */
	buf_block_t*	LRU_old; 	/* pointer to the about 3/8 oldest
					blocks in the LRU list; NULL if LRU
					length less than BUF_LRU_OLD_MIN_LEN */
	ulint		LRU_old_len;	/* length of the LRU list from
					the block to which LRU_old points
					onward, including that block;
					see buf0lru.c for the restrictions
					on this value; not defined if
					LRU_old == NULL */
	UT_LIST_BASE_NODE_T(buf_block_t) awe_LRU_free_mapped;
					/* list of those blocks which are
					in the LRU list or the free list, and
					where the page is mapped to a frame;
					thus, frames allocated, e.g., to the
					locki table, are not in this list */
};

/* States of a control block */
#define	BUF_BLOCK_NOT_USED	211	/* is in the free list */
#define BUF_BLOCK_READY_FOR_USE	212	/* when buf_get_free_block returns
					a block, it is in this state */
#define	BUF_BLOCK_FILE_PAGE	213	/* contains a buffered file page */
#define	BUF_BLOCK_MEMORY	214	/* contains some main memory object */
#define BUF_BLOCK_REMOVE_HASH	215	/* hash index should be removed
					before putting to the free list */

/* Io_fix states of a control block; these must be != 0 */
#define BUF_IO_READ		561
#define BUF_IO_WRITE		562

/************************************************************************
Let us list the consistency conditions for different control block states.

NOT_USED:	is in free list, not in LRU list, not in flush list, nor
		page hash table
READY_FOR_USE:	is not in free list, LRU list, or flush list, nor page
		hash table
MEMORY:		is not in free list, LRU list, or flush list, nor page
		hash table
FILE_PAGE:	space and offset are defined, is in page hash table
		if io_fix == BUF_IO_WRITE,
			pool: no_flush[block->flush_type] is in reset state,
			pool: n_flush[block->flush_type] > 0			
		
		(1) if buf_fix_count == 0, then
			is in LRU list, not in free list
			is in flush list,
				if and only if oldest_modification > 0
			is x-locked,
				if and only if io_fix == BUF_IO_READ
			is s-locked,
				if and only if io_fix == BUF_IO_WRITE
						
		(2) if buf_fix_count > 0, then
			is not in LRU list, not in free list
			is in flush list,
				if and only if oldest_modification > 0
			if io_fix == BUF_IO_READ,		
				is x-locked
			if io_fix == BUF_IO_WRITE,
				is s-locked
			
State transitions:

NOT_USED => READY_FOR_USE
READY_FOR_USE => MEMORY
READY_FOR_USE => FILE_PAGE
MEMORY => NOT_USED
FILE_PAGE => NOT_USED	NOTE: This transition is allowed if and only if 
				(1) buf_fix_count == 0,
				(2) oldest_modification == 0, and
				(3) io_fix == 0.
*/

#ifndef UNIV_NONINL
#include "buf0buf.ic"
#endif

#endif