db_dup.c
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上传日期:2022-05-23
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- /*-
- * See the file LICENSE for redistribution information.
- *
- * Copyright (c) 1996-2002
- * Sleepycat Software. All rights reserved.
- */
- #include "db_config.h"
- #ifndef lint
- static const char revid[] = "$Id: db_dup.c,v 11.32 2002/08/08 03:57:47 bostic Exp $";
- #endif /* not lint */
- #ifndef NO_SYSTEM_INCLUDES
- #include <sys/types.h>
- #include <string.h>
- #endif
- #include "db_int.h"
- #include "dbinc/db_page.h"
- #include "dbinc/db_shash.h"
- #include "dbinc/lock.h"
- #include "dbinc/db_am.h"
- /*
- * __db_ditem --
- * Remove an item from a page.
- *
- * PUBLIC: int __db_ditem __P((DBC *, PAGE *, u_int32_t, u_int32_t));
- */
- int
- __db_ditem(dbc, pagep, indx, nbytes)
- DBC *dbc;
- PAGE *pagep;
- u_int32_t indx, nbytes;
- {
- DB *dbp;
- DBT ldbt;
- db_indx_t cnt, *inp, offset;
- int ret;
- u_int8_t *from;
- dbp = dbc->dbp;
- if (DBC_LOGGING(dbc)) {
- ldbt.data = P_ENTRY(dbp, pagep, indx);
- ldbt.size = nbytes;
- if ((ret = __db_addrem_log(dbp, dbc->txn,
- &LSN(pagep), 0, DB_REM_DUP, PGNO(pagep),
- (u_int32_t)indx, nbytes, &ldbt, NULL, &LSN(pagep))) != 0)
- return (ret);
- } else
- LSN_NOT_LOGGED(LSN(pagep));
- /*
- * If there's only a single item on the page, we don't have to
- * work hard.
- */
- if (NUM_ENT(pagep) == 1) {
- NUM_ENT(pagep) = 0;
- HOFFSET(pagep) = dbp->pgsize;
- return (0);
- }
- inp = P_INP(dbp, pagep);
- /*
- * Pack the remaining key/data items at the end of the page. Use
- * memmove(3), the regions may overlap.
- */
- from = (u_int8_t *)pagep + HOFFSET(pagep);
- DB_ASSERT((int)inp[indx] - HOFFSET(pagep) >= 0);
- memmove(from + nbytes, from, inp[indx] - HOFFSET(pagep));
- HOFFSET(pagep) += nbytes;
- /* Adjust the indices' offsets. */
- offset = inp[indx];
- for (cnt = 0; cnt < NUM_ENT(pagep); ++cnt)
- if (inp[cnt] < offset)
- inp[cnt] += nbytes;
- /* Shift the indices down. */
- --NUM_ENT(pagep);
- if (indx != NUM_ENT(pagep))
- memmove(&inp[indx], &inp[indx + 1],
- sizeof(db_indx_t) * (NUM_ENT(pagep) - indx));
- return (0);
- }
- /*
- * __db_pitem --
- * Put an item on a page.
- *
- * PUBLIC: int __db_pitem
- * PUBLIC: __P((DBC *, PAGE *, u_int32_t, u_int32_t, DBT *, DBT *));
- */
- int
- __db_pitem(dbc, pagep, indx, nbytes, hdr, data)
- DBC *dbc;
- PAGE *pagep;
- u_int32_t indx;
- u_int32_t nbytes;
- DBT *hdr, *data;
- {
- DB *dbp;
- BKEYDATA bk;
- DBT thdr;
- db_indx_t *inp;
- int ret;
- u_int8_t *p;
- dbp = dbc->dbp;
- if (nbytes > P_FREESPACE(dbp, pagep)) {
- DB_ASSERT(nbytes <= P_FREESPACE(dbp, pagep));
- return (EINVAL);
- }
- /*
- * Put a single item onto a page. The logic figuring out where to
- * insert and whether it fits is handled in the caller. All we do
- * here is manage the page shuffling. We cheat a little bit in that
- * we don't want to copy the dbt on a normal put twice. If hdr is
- * NULL, we create a BKEYDATA structure on the page, otherwise, just
- * copy the caller's information onto the page.
- *
- * This routine is also used to put entries onto the page where the
- * entry is pre-built, e.g., during recovery. In this case, the hdr
- * will point to the entry, and the data argument will be NULL.
- *
- * !!!
- * There's a tremendous potential for off-by-one errors here, since
- * the passed in header sizes must be adjusted for the structure's
- * placeholder for the trailing variable-length data field.
- */
- if (DBC_LOGGING(dbc)) {
- if ((ret = __db_addrem_log(dbp, dbc->txn,
- &LSN(pagep), 0, DB_ADD_DUP, PGNO(pagep),
- (u_int32_t)indx, nbytes, hdr, data, &LSN(pagep))) != 0)
- return (ret);
- } else
- LSN_NOT_LOGGED(LSN(pagep));
- if (hdr == NULL) {
- B_TSET(bk.type, B_KEYDATA, 0);
- bk.len = data == NULL ? 0 : data->size;
- thdr.data = &bk;
- thdr.size = SSZA(BKEYDATA, data);
- hdr = &thdr;
- }
- inp = P_INP(dbp, pagep);
- /* Adjust the index table, then put the item on the page. */
- if (indx != NUM_ENT(pagep))
- memmove(&inp[indx + 1], &inp[indx],
- sizeof(db_indx_t) * (NUM_ENT(pagep) - indx));
- HOFFSET(pagep) -= nbytes;
- inp[indx] = HOFFSET(pagep);
- ++NUM_ENT(pagep);
- p = P_ENTRY(dbp, pagep, indx);
- memcpy(p, hdr->data, hdr->size);
- if (data != NULL)
- memcpy(p + hdr->size, data->data, data->size);
- return (0);
- }
- /*
- * __db_relink --
- * Relink around a deleted page.
- *
- * PUBLIC: int __db_relink __P((DBC *, u_int32_t, PAGE *, PAGE **, int));
- */
- int
- __db_relink(dbc, add_rem, pagep, new_next, needlock)
- DBC *dbc;
- u_int32_t add_rem;
- PAGE *pagep, **new_next;
- int needlock;
- {
- DB *dbp;
- PAGE *np, *pp;
- DB_LOCK npl, ppl;
- DB_LSN *nlsnp, *plsnp, ret_lsn;
- DB_MPOOLFILE *mpf;
- int ret;
- dbp = dbc->dbp;
- np = pp = NULL;
- LOCK_INIT(npl);
- LOCK_INIT(ppl);
- nlsnp = plsnp = NULL;
- mpf = dbp->mpf;
- ret = 0;
- /*
- * Retrieve and lock the one/two pages. For a remove, we may need
- * two pages (the before and after). For an add, we only need one
- * because, the split took care of the prev.
- */
- if (pagep->next_pgno != PGNO_INVALID) {
- if (needlock && (ret = __db_lget(dbc,
- 0, pagep->next_pgno, DB_LOCK_WRITE, 0, &npl)) != 0)
- goto err;
- if ((ret = mpf->get(mpf, &pagep->next_pgno, 0, &np)) != 0) {
- __db_pgerr(dbp, pagep->next_pgno, ret);
- goto err;
- }
- nlsnp = &np->lsn;
- }
- if (add_rem == DB_REM_PAGE && pagep->prev_pgno != PGNO_INVALID) {
- if (needlock && (ret = __db_lget(dbc,
- 0, pagep->prev_pgno, DB_LOCK_WRITE, 0, &ppl)) != 0)
- goto err;
- if ((ret = mpf->get(mpf, &pagep->prev_pgno, 0, &pp)) != 0) {
- __db_pgerr(dbp, pagep->next_pgno, ret);
- goto err;
- }
- plsnp = &pp->lsn;
- }
- /* Log the change. */
- if (DBC_LOGGING(dbc)) {
- if ((ret = __db_relink_log(dbp, dbc->txn, &ret_lsn, 0, add_rem,
- pagep->pgno, &pagep->lsn, pagep->prev_pgno, plsnp,
- pagep->next_pgno, nlsnp)) != 0)
- goto err;
- } else
- LSN_NOT_LOGGED(ret_lsn);
- if (np != NULL)
- np->lsn = ret_lsn;
- if (pp != NULL)
- pp->lsn = ret_lsn;
- if (add_rem == DB_REM_PAGE)
- pagep->lsn = ret_lsn;
- /*
- * Modify and release the two pages.
- *
- * !!!
- * The parameter new_next gets set to the page following the page we
- * are removing. If there is no following page, then new_next gets
- * set to NULL.
- */
- if (np != NULL) {
- if (add_rem == DB_ADD_PAGE)
- np->prev_pgno = pagep->pgno;
- else
- np->prev_pgno = pagep->prev_pgno;
- if (new_next == NULL)
- ret = mpf->put(mpf, np, DB_MPOOL_DIRTY);
- else {
- *new_next = np;
- ret = mpf->set(mpf, np, DB_MPOOL_DIRTY);
- }
- if (ret != 0)
- goto err;
- if (needlock)
- (void)__TLPUT(dbc, npl);
- } else if (new_next != NULL)
- *new_next = NULL;
- if (pp != NULL) {
- pp->next_pgno = pagep->next_pgno;
- if ((ret = mpf->put(mpf, pp, DB_MPOOL_DIRTY)) != 0)
- goto err;
- if (needlock)
- (void)__TLPUT(dbc, ppl);
- }
- return (0);
- err: if (np != NULL)
- (void)mpf->put(mpf, np, 0);
- if (needlock)
- (void)__TLPUT(dbc, npl);
- if (pp != NULL)
- (void)mpf->put(mpf, pp, 0);
- if (needlock)
- (void)__TLPUT(dbc, ppl);
- return (ret);
- }