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.

LRU

#define LRU   hashp->bufhead.prev

Definition at line 90 of file hash_buf.c.

LRU_INSERT

#define LRU_INSERT

(

B

)

BUF_INSERT((B), LRU)

Definition at line 93 of file hash_buf.c.

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.

Function Documentation

__buf_free()

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

Definition at line 315 of file hash_buf.c.

{
    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);
}

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().

__buf_init()

void __buf_init	(	HTAB *	hashp,
		int	nbytes
	)

Definition at line 290 of file hash_buf.c.

{
    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;
     */
}

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

Referenced by __hash_open().

__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.

{
    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);
}

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(), hash_access(), hash_seq(), and ugly_split().

__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.

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

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

Referenced by __free_ovflpage().

newbuf()

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

static

Definition at line 160 of file hash_buf.c.

{
    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);
}

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().