hash_buf.c File Reference

#include <sys/param.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include "../include/db.h"
#include "hash.h"
#include "page.h"
#include "extern.h"

Include dependency graph for hash_buf.c:

Go to the source code of this file.

Macros
#define	BUF_INSERT(B, P)
#define	BUF_REMOVE(B)
#define	LRU   hashp->bufhead.prev
#define	LRU_INSERT(B)   BUF_INSERT((B), LRU)
#define	MRU   hashp->bufhead.next
#define	MRU_INSERT(B)   BUF_INSERT((B), &hashp->bufhead)

Functions
int	__buf_free (HTAB *hashp, int do_free, int to_disk)
void	__buf_init (HTAB *hashp, int nbytes)
BUFHEAD *	__get_buf (HTAB *hashp, u_int32_t addr, BUFHEAD *prev_bp, int newpage)
static BUFHEAD *newbuf	__P ((HTAB *, u_int32_t, BUFHEAD *))
void	__reclaim_buf (HTAB *hashp, BUFHEAD *bp)
static BUFHEAD *	newbuf (HTAB *hashp, u_int32_t addr, BUFHEAD *prev_bp)

Macro Definition Documentation

BUF_INSERT

#define BUF_INSERT	(		B,
			P
	)

Definition at line 82 of file hash_buf.c.

BUF_REMOVE

#define BUF_REMOVE

(

B

)

Value:

{ \
 (B)->prev->next = (B)->next; \
 (B)->next->prev = (B)->prev; \
}

Definition at line 76 of file hash_buf.c.

Referenced by __buf_free(), __get_buf(), __reclaim_buf(), and newbuf().

LRU

#define LRU   hashp->bufhead.prev

Definition at line 90 of file hash_buf.c.

Referenced by __buf_free(), and newbuf().

LRU_INSERT

#define LRU_INSERT

(

B

)

BUF_INSERT((B), LRU)

Definition at line 93 of file hash_buf.c.

Referenced by __reclaim_buf(), and newbuf().

MRU

#define MRU   hashp->bufhead.next

Definition at line 89 of file hash_buf.c.

MRU_INSERT

#define MRU_INSERT

(

B

)

BUF_INSERT((B), &hashp->bufhead)

Definition at line 92 of file hash_buf.c.

Referenced by __get_buf(), and newbuf().

Function Documentation

__buf_free()

int __buf_free	(	HTAB *	hashp,
		int	do_free,
		int	to_disk
	)

Definition at line 315 of file hash_buf.c.

References __put_page(), _bufhead::addr, BUF_MOD, BUF_REMOVE, htab::bufhead, _bufhead::flags, free(), IS_BUCKET, LRU, _bufhead::page, and _bufhead::prev.

Referenced by hash_sync(), and hdestroy().

{
 BUFHEAD *bp;

 /* Need to make sure that buffer manager has been initialized */
 if (!LRU)
 return (0);
 for (bp = LRU; bp != &hashp->bufhead;) {
 /* Check that the buffer is valid */
 if (bp->addr || IS_BUCKET(bp->flags)) {
 if (to_disk && (bp->flags & BUF_MOD) &&
 __put_page(hashp, bp->page,
 bp->addr, IS_BUCKET(bp->flags), 0))
 return (-1);
 }
 /* Check if we are freeing stuff */
 if (do_free) {
 if (bp->page)
 free(bp->page);
 BUF_REMOVE(bp);
 free(bp);
 bp = LRU;
 } else
 bp = bp->prev;
 }
 return (0);
}

__buf_init()

void __buf_init	(	HTAB *	hashp,
		int	nbytes
	)

Definition at line 290 of file hash_buf.c.

References htab::bufhead, MAX, MIN_BUFFERS, htab::nbufs, _bufhead::next, and _bufhead::prev.

Referenced by __hash_open().

{
 BUFHEAD *bfp;
 int npages;

 bfp = &(hashp->bufhead);
 npages = (nbytes + hashp->BSIZE - 1) >> hashp->BSHIFT;
 npages = MAX(npages, MIN_BUFFERS);

 hashp->nbufs = npages;
 bfp->next = bfp;
 bfp->prev = bfp;
 /*
 * This space is calloc'd so these are already null.
 *
 * bfp->ovfl = NULL;
 * bfp->flags = 0;
 * bfp->page = NULL;
 * bfp->addr = 0;
 */
}

__get_buf()

BUFHEAD* __get_buf	(	HTAB *	hashp,
		u_int32_t	addr,
		BUFHEAD *	prev_bp,
		int	newpage
	)

Definition at line 105 of file hash_buf.c.

References __get_page(), _bufhead::addr, BUF_DISK, BUF_REMOVE, htab::dir, ISDISK, MRU_INSERT, htab::new_file, newbuf(), NULL, _bufhead::ovfl, _bufhead::page, and PTROF.

Referenced by __add_ovflpage(), __addel(), __big_delete(), __big_return(), __big_split(), __find_bigpair(), __find_last_page(), __split_page(), collect_data(), collect_key(), fetch_bitmap(), hash_access(), hash_seq(), and ugly_split().

{
 register BUFHEAD *bp;
 register u_int32_t is_disk_mask;
 register int is_disk, segment_ndx = 0;
 SEGMENT segp = 0;

 is_disk = 0;
 is_disk_mask = 0;
 if (prev_bp) {
 bp = prev_bp->ovfl;
 if (!bp || (bp->addr != addr))
 bp = NULL;
 if (!newpage)
 is_disk = BUF_DISK;
 } else {
 /* Grab buffer out of directory */
 segment_ndx = addr & (hashp->SGSIZE - 1);

 /* valid segment ensured by __call_hash() */
 segp = hashp->dir[addr >> hashp->SSHIFT];
#ifdef DEBUG
 assert(segp != NULL);
#endif
 bp = PTROF(segp[segment_ndx]);
 is_disk_mask = ISDISK(segp[segment_ndx]);
 is_disk = is_disk_mask || !hashp->new_file;
 }

 if (!bp) {
 bp = newbuf(hashp, addr, prev_bp);
 if (!bp ||
 __get_page(hashp, bp->page, addr, !prev_bp, is_disk, 0))
 return (NULL);
 if (!prev_bp)
 segp[segment_ndx] =
 (BUFHEAD *)((ptrdiff_t)bp | is_disk_mask);
 } else {
 BUF_REMOVE(bp);
 MRU_INSERT(bp);
 }
 return (bp);
}

__P()

static BUFHEAD* newbuf __P ( (HTAB *, u_int32_t, BUFHEAD *)  )

static

__reclaim_buf()

void __reclaim_buf	(	HTAB *	hashp,
		BUFHEAD *	bp
	)

Definition at line 346 of file hash_buf.c.

References _bufhead::addr, BUF_REMOVE, _bufhead::flags, LRU_INSERT, and _bufhead::ovfl.

Referenced by __free_ovflpage().

{
 bp->ovfl = 0;
 bp->addr = 0;
 bp->flags = 0;
 BUF_REMOVE(bp);
 LRU_INSERT(bp);
}

newbuf()

static BUFHEAD* newbuf ( HTAB *  hashp, u_int32_t  addr, BUFHEAD *  prev_bp  )

static

Definition at line 160 of file hash_buf.c.

References __put_page(), _bufhead::addr, BUF_BUCKET, BUF_DISK, BUF_MOD, BUF_PIN, BUF_REMOVE, htab::dir, _bufhead::flags, free(), if(), IS_BUCKET, ISDISK, LRU, LRU_INSERT, malloc(), MRU_INSERT, htab::nbufs, htab::new_file, NULL, _bufhead::ovfl, and _bufhead::page.

Referenced by __get_buf(), and xmpp_client_receive().

{
 register BUFHEAD *bp; /* The buffer we're going to use */
 register BUFHEAD *xbp; /* Temp pointer */
 register BUFHEAD *next_xbp;
 SEGMENT segp;
 int segment_ndx;
 u_int16_t oaddr, *shortp;

 oaddr = 0;
 bp = LRU;
 /*
 * If LRU buffer is pinned, the buffer pool is too small. We need to
 * allocate more buffers.
 */
 if (hashp->nbufs || (bp->flags & BUF_PIN)) {
 /* Allocate a new one */
 if ((bp = (BUFHEAD *)malloc(sizeof(BUFHEAD))) == NULL)
 return (NULL);
#ifdef PURIFY
 memset(bp, 0xff, sizeof(BUFHEAD));
#endif
 if ((bp->page = (char *)malloc(hashp->BSIZE)) == NULL) {
 free(bp);
 return (NULL);
 }
#ifdef PURIFY
 memset(bp->page, 0xff, hashp->BSIZE);
#endif
 if (hashp->nbufs)
 hashp->nbufs--;
 } else {
 /* Kick someone out */
 BUF_REMOVE(bp);
 /*
 * If this is an overflow page with addr 0, it's already been
 * flushed back in an overflow chain and initialized.
 */
 if ((bp->addr != 0) || (bp->flags & BUF_BUCKET)) {
 /*
 * Set oaddr before __put_page so that you get it
 * before bytes are swapped.
 */
 shortp = (u_int16_t *)bp->page;
 if (shortp[0])
 oaddr = shortp[shortp[0] - 1];
 if ((bp->flags & BUF_MOD) && __put_page(hashp, bp->page,
 bp->addr, (int)IS_BUCKET(bp->flags), 0))
 return (NULL);
 /*
 * Update the pointer to this page (i.e. invalidate it).
 *
 * If this is a new file (i.e. we created it at open
 * time), make sure that we mark pages which have been
 * written to disk so we retrieve them from disk later,
 * rather than allocating new pages.
 */
 if (IS_BUCKET(bp->flags)) {
 segment_ndx = bp->addr & (hashp->SGSIZE - 1);
 segp = hashp->dir[bp->addr >> hashp->SSHIFT];
#ifdef DEBUG
 assert(segp != NULL);
#endif

 if (hashp->new_file &&
 ((bp->flags & BUF_MOD) ||
 ISDISK(segp[segment_ndx])))
 segp[segment_ndx] = (BUFHEAD *)BUF_DISK;
 else
 segp[segment_ndx] = NULL;
 }
 /*
 * Since overflow pages can only be access by means of
 * their bucket, free overflow pages associated with
 * this bucket.
 */
 for (xbp = bp; xbp->ovfl;) {
 next_xbp = xbp->ovfl;
 xbp->ovfl = 0;
 xbp = next_xbp;

 /* Check that ovfl pointer is up date. */
 if (IS_BUCKET(xbp->flags) ||
 (oaddr != xbp->addr))
 break;

 shortp = (u_int16_t *)xbp->page;
 if (shortp[0])
 /* set before __put_page */
 oaddr = shortp[shortp[0] - 1];
 if ((xbp->flags & BUF_MOD) && __put_page(hashp,
 xbp->page, xbp->addr, 0, 0))
 return (NULL);
 xbp->addr = 0;
 xbp->flags = 0;
 BUF_REMOVE(xbp);
 LRU_INSERT(xbp);
 }
 }
 }

 /* Now assign this buffer */
 bp->addr = addr;
#ifdef DEBUG1
 (void)fprintf(stderr, "NEWBUF1: %d->ovfl was %d is now %d\n",
 bp->addr, (bp->ovfl ? bp->ovfl->addr : 0), 0);
#endif
 bp->ovfl = NULL;
 if (prev_bp) {
 /*
 * If prev_bp is set, this is an overflow page, hook it in to
 * the buffer overflow links.
 */
#ifdef DEBUG1
 (void)fprintf(stderr, "NEWBUF2: %d->ovfl was %d is now %d\n",
 prev_bp->addr, (prev_bp->ovfl ? bp->ovfl->addr : 0),
 (bp ? bp->addr : 0));
#endif
 prev_bp->ovfl = bp;
 bp->flags = 0;
 } else
 bp->flags = BUF_BUCKET;
 MRU_INSERT(bp);
 return (bp);
}