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);
}