/*- * See the file LICENSE for redistribution information. * * Copyright (c) 2000 * Sleepycat Software. All rights reserved. */ #include "htconfig.h" #ifndef lint static const char revid[] = "$Id: db_cam.c,v 1.1.2.2 2000/09/17 01:35:04 ghutchis Exp $"; #endif /* not lint */ #ifndef NO_SYSTEM_INCLUDES #include #include #endif #include "db_int.h" #include "db_page.h" #include "db_shash.h" #include "lock.h" #include "btree.h" #include "hash.h" #include "qam.h" #include "db_ext.h" static int __db_c_cleanup __P((DBC *, DBC *, int)); static int __db_c_idup __P((DBC *, DBC **, u_int32_t)); static int __db_wrlock_err __P((DB_ENV *)); #define LOCKING_INIT(dbp, dbc) \ /* \ * If we are running CDB, this had better be either a write \ * cursor or an immediate writer. If it's a regular writer, \ * that means we have an IWRITE lock and we need to upgrade \ * it to a write lock. \ */ \ if (LOCKING((dbp)->dbenv)) { \ if (!F_ISSET(dbc, DBC_WRITECURSOR | DBC_WRITER)) \ return(__db_wrlock_err(dbp->dbenv)); \ \ if (F_ISSET(dbc, DBC_WRITECURSOR) && \ (ret = CDB_lock_get((dbp)->dbenv, (dbc)->locker, \ DB_LOCK_UPGRADE, &(dbc)->lock_dbt, DB_LOCK_WRITE, \ &(dbc)->mylock)) != 0) \ return (ret); \ } #define LOCKING_DONE(dbp, dbc) \ /* Release the upgraded lock. */ \ if (F_ISSET(dbc, DBC_WRITECURSOR)) \ (void)CDB___lock_downgrade( \ (dbp)->dbenv, &(dbc)->mylock, DB_LOCK_IWRITE, 0); #define IS_INITIALIZED(dbc) ((dbc)->internal->pgno != PGNO_INVALID) /* * CDB___db_c_close -- * Close the cursor. * * PUBLIC: int CDB___db_c_close __P((DBC *)); */ int CDB___db_c_close(dbc) DBC *dbc; { DB *dbp; DBC *opd; DBC_INTERNAL *cp; int ret, t_ret; dbp = dbc->dbp; ret = 0; PANIC_CHECK(dbp->dbenv); /* * If the cursor is already closed we have a serious problem, and we * assume that the cursor isn't on the active queue. Don't do any of * the remaining cursor close processing. */ if (!F_ISSET(dbc, DBC_ACTIVE)) { if (dbp && dbp->dbenv) CDB___db_err(dbp->dbenv, "Closing closed cursor"); DB_ASSERT(0); return (EINVAL); } cp = dbc->internal; opd = cp->opd; /* * Remove the cursor(s) from the active queue. We may be closing two * cursors at once here, a top-level one and a lower-level, off-page * duplicate one. The acess-method specific cursor close routine must * close both of them in a single call. * * !!! * Cursors must be removed from the active queue before calling the * access specific cursor close routine, btree depends on having that * order of operations. It must also happen before any action that * can fail and cause CDB___db_c_close to return an error, or else calls * here from CDB___db_close may loop indefinitely. */ MUTEX_THREAD_LOCK(dbp->mutexp); if (opd != NULL) { F_CLR(opd, DBC_ACTIVE); TAILQ_REMOVE(&dbp->active_queue, opd, links); } F_CLR(dbc, DBC_ACTIVE); TAILQ_REMOVE(&dbp->active_queue, dbc, links); MUTEX_THREAD_UNLOCK(dbp->mutexp); /* Call the access specific cursor close routine. */ if ((t_ret = dbc->c_am_close(dbc, PGNO_INVALID, NULL)) != 0 && ret == 0) ret = t_ret; /* * Release the lock after calling the access method specific close * routine, a Btree cursor may have had pending deletes. */ if (LOCKING(dbc->dbp->dbenv)) { /* * If DBC_WRITEDUP is set, the cursor is an internally * duplicated write cursor and the lock isn't ours to put. */ if (!F_ISSET(dbc, DBC_WRITEDUP) && dbc->mylock.off != LOCK_INVALID) { if ((t_ret = CDB_lock_put(dbc->dbp->dbenv, &dbc->mylock)) != 0 && ret == 0) ret = t_ret; dbc->mylock.off = LOCK_INVALID; } /* For safety's sake, since this is going on the free queue. */ memset(&dbc->mylock, 0, sizeof(dbc->mylock)); F_CLR(dbc, DBC_WRITEDUP); } /* Move the cursor(s) to the free queue. */ MUTEX_THREAD_LOCK(dbp->mutexp); if (opd != NULL) { TAILQ_INSERT_TAIL(&dbp->free_queue, opd, links); opd = NULL; } TAILQ_INSERT_TAIL(&dbp->free_queue, dbc, links); MUTEX_THREAD_UNLOCK(dbp->mutexp); return (ret); } /* * CDB___db_c_destroy -- * Destroy the cursor, called after DBC->c_close. * * PUBLIC: int CDB___db_c_destroy __P((DBC *)); */ int CDB___db_c_destroy(dbc) DBC *dbc; { DB *dbp; DBC_INTERNAL *cp; int ret; dbp = dbc->dbp; cp = dbc->internal; /* Remove the cursor from the free queue. */ MUTEX_THREAD_LOCK(dbp->mutexp); TAILQ_REMOVE(&dbp->free_queue, dbc, links); MUTEX_THREAD_UNLOCK(dbp->mutexp); /* Free up allocated memory. */ if (dbc->rkey.data != NULL) CDB___os_free(dbc->rkey.data, dbc->rkey.ulen); if (dbc->rdata.data != NULL) CDB___os_free(dbc->rdata.data, dbc->rdata.ulen); /* Call the access specific cursor destroy routine. */ ret = dbc->c_am_destroy == NULL ? 0 : dbc->c_am_destroy(dbc); CDB___os_free(dbc, sizeof(*dbc)); return (ret); } /* * CDB___db_c_count -- * Return a count of duplicate data items. * * PUBLIC: int CDB___db_c_count __P((DBC *, db_recno_t *, u_int32_t)); */ int CDB___db_c_count(dbc, recnop, flags) DBC *dbc; db_recno_t *recnop; u_int32_t flags; { DB *dbp; int ret; /* * Cursor Cleanup Note: * All of the cursors passed to the underlying access methods by this * routine are not duplicated and will not be cleaned up on return. * So, pages/locks that the cursor references must be resolved by the * underlying functions. */ dbp = dbc->dbp; PANIC_CHECK(dbp->dbenv); /* Check for invalid flags. */ if ((ret = CDB___db_ccountchk(dbp, flags, IS_INITIALIZED(dbc))) != 0) return (ret); switch (dbc->dbtype) { case DB_QUEUE: case DB_RECNO: *recnop = 1; break; case DB_HASH: if (dbc->internal->opd == NULL) { if ((ret = CDB___ham_c_count(dbc, recnop)) != 0) return (ret); break; } /* FALLTHROUGH */ case DB_BTREE: if ((ret = CDB___bam_c_count(dbc, recnop)) != 0) return (ret); break; default: return (CDB___db_unknown_type(dbp->dbenv, "CDB___db_c_count", dbp->type)); } return (0); } /* * CDB___db_c_del -- * Delete using a cursor. * * PUBLIC: int CDB___db_c_del __P((DBC *, u_int32_t)); */ int CDB___db_c_del(dbc, flags) DBC *dbc; u_int32_t flags; { DB *dbp; DBC *opd; int ret; /* * Cursor Cleanup Note: * All of the cursors passed to the underlying access methods by this * routine are not duplicated and will not be cleaned up on return. * So, pages/locks that the cursor references must be resolved by the * underlying functions. */ dbp = dbc->dbp; PANIC_CHECK(dbp->dbenv); /* Check for invalid flags. */ if ((ret = CDB___db_cdelchk(dbp, flags, F_ISSET(dbp, DB_AM_RDONLY), IS_INITIALIZED(dbc))) != 0) return (ret); DEBUG_LWRITE(dbc, dbc->txn, "db_c_del", NULL, NULL, flags); LOCKING_INIT(dbp, dbc); /* * Off-page duplicate trees are locked in the primary tree, that is, * we acquire a write lock in the primary tree and no locks in the * off-page dup tree. If the del operation is done in an off-page * duplicate tree, call the primary cursor's upgrade routine first. */ opd = dbc->internal->opd; if (opd == NULL) ret = dbc->c_am_del(dbc); else if ((ret = dbc->c_am_writelock(dbc)) == 0) ret = opd->c_am_del(opd); LOCKING_DONE(dbp, dbc); return (ret); } /* * CDB___db_c_dup -- * Duplicate a cursor * * PUBLIC: int CDB___db_c_dup __P((DBC *, DBC **, u_int32_t)); */ int CDB___db_c_dup(dbc_orig, dbcp, flags) DBC *dbc_orig; DBC **dbcp; u_int32_t flags; { DB_ENV *dbenv; DB *dbp; DBC *dbc_n, *dbc_nopd; int ret; dbp = dbc_orig->dbp; dbenv = dbp->dbenv; dbc_n = dbc_nopd = NULL; PANIC_CHECK(dbp->dbenv); /* * We can never have two write cursors open in CDB, so do not * allow duplication of a write cursor. */ if (flags != DB_POSITIONI && F_ISSET(dbc_orig, DBC_WRITER | DBC_WRITECURSOR)) { CDB___db_err(dbenv, "Cannot duplicate writeable cursor"); return (EINVAL); } /* Allocate a new cursor and initialize it. */ if ((ret = __db_c_idup(dbc_orig, &dbc_n, flags)) != 0) goto err; *dbcp = dbc_n; /* * If we're in CDB, and this isn't an internal duplication (in which * case we're explicitly overriding CDB locking), the duplicated * cursor needs its own read lock. (We know it's not a write cursor * because we wouldn't have made it this far; you can't dup them.) */ if (LOCKING(dbenv) && flags != DB_POSITIONI) { DB_ASSERT(!F_ISSET(dbc_orig, DBC_WRITER | DBC_WRITECURSOR)); if ((ret = CDB_lock_get(dbenv, dbc_n->locker, 0, &dbc_n->lock_dbt, DB_LOCK_READ, &dbc_n->mylock)) != 0) { (void)CDB___db_c_close(dbc_n); return (ret); } } /* * If the cursor references an off-page duplicate tree, allocate a * new cursor for that tree and initialize it. */ if (dbc_orig->internal->opd != NULL) { if ((ret = __db_c_idup(dbc_orig->internal->opd, &dbc_nopd, flags)) != 0) goto err; dbc_n->internal->opd = dbc_nopd; } return (0); err: if (dbc_n != NULL) (void)dbc_n->c_close(dbc_n); if (dbc_nopd != NULL) (void)dbc_nopd->c_close(dbc_nopd); return (ret); } /* * __db_c_idup -- * Internal version of CDB___db_c_dup. */ static int __db_c_idup(dbc_orig, dbcp, flags) DBC *dbc_orig, **dbcp; u_int32_t flags; { DB *dbp; DBC *dbc_n; DBC_INTERNAL *int_n, *int_orig; int ret; dbp = dbc_orig->dbp; dbc_n = *dbcp; if ((ret = CDB___db_icursor(dbp, dbc_orig->txn, dbc_orig->dbtype, dbc_orig->internal->root, F_ISSET(dbc_orig, DBC_OPD), &dbc_n)) != 0) return (ret); dbc_n->locker = dbc_orig->locker; /* If the user wants the cursor positioned, do it here. */ if (flags == DB_POSITION || flags == DB_POSITIONI) { int_n = dbc_n->internal; int_orig = dbc_orig->internal; dbc_n->flags = dbc_orig->flags; int_n->indx = int_orig->indx; int_n->pgno = int_orig->pgno; int_n->root = int_orig->root; switch (dbc_orig->dbtype) { case DB_QUEUE: if ((ret = CDB___qam_c_dup(dbc_orig, dbc_n)) != 0) goto err; break; case DB_BTREE: case DB_RECNO: if ((ret = CDB___bam_c_dup(dbc_orig, dbc_n)) != 0) goto err; break; case DB_HASH: if ((ret = CDB___ham_c_dup(dbc_orig, dbc_n)) != 0) goto err; break; default: ret = CDB___db_unknown_type(dbp->dbenv, "__db_c_idup", dbc_orig->dbtype); goto err; } } *dbcp = dbc_n; return (0); err: (void)dbc_n->c_close(dbc_n); return (ret); } /* * CDB___db_c_get -- * Get using a cursor. * * PUBLIC: int CDB___db_c_get __P((DBC *, DBT *, DBT *, u_int32_t)); */ int CDB___db_c_get(dbc_arg, key, data, flags) DBC *dbc_arg; DBT *key, *data; u_int32_t flags; { DB *dbp; DBC *dbc, *dbc_n, *opd; DBC_INTERNAL *cp, *cp_n; db_pgno_t pgno; u_int32_t tmp_flags, tmp_rmw; u_int8_t type; int ret, t_ret; /* * Cursor Cleanup Note: * All of the cursors passed to the underlying access methods by this * routine are duplicated cursors. On return, any referenced pages * will be discarded, and, if the cursor is not intended to be used * again, the close function will be called. So, pages/locks that * the cursor references do not need to be resolved by the underlying * functions. */ dbp = dbc_arg->dbp; dbc_n = NULL; opd = NULL; PANIC_CHECK(dbp->dbenv); /* Check for invalid flags. */ if ((ret = CDB___db_cgetchk(dbp, key, data, flags, IS_INITIALIZED(dbc_arg))) != 0) return (ret); /* Clear OR'd in additional bits so we can check for flag equality. */ tmp_rmw = LF_ISSET(DB_RMW); LF_CLR(DB_RMW); DEBUG_LREAD(dbc_arg, dbc_arg->txn, "db_c_get", flags == DB_SET || flags == DB_SET_RANGE ? key : NULL, NULL, flags); /* * Return a cursor's record number. It has nothing to do with the * cursor get code except that it was put into the interface. */ if (flags == DB_GET_RECNO) return (CDB___bam_c_rget(dbc_arg, data, flags | tmp_rmw)); /* * If we have an off-page duplicates cursor, and the operation applies * to it, perform the operation. Duplicate the cursor and call the * underlying function. * * Off-page duplicate trees are locked in the primary tree, that is, * we acquire a write lock in the primary tree and no locks in the * off-page dup tree. If the DB_RMW flag was specified and the get * operation is done in an off-page duplicate tree, call the primary * cursor's upgrade routine first. */ cp = dbc_arg->internal; if (cp->opd != NULL && (flags == DB_CURRENT || flags == DB_GET_BOTHC || flags == DB_NEXT || flags == DB_NEXT_DUP || flags == DB_PREV)) { if (tmp_rmw && (ret = dbc_arg->c_am_writelock(dbc_arg)) != 0) return (ret); if ((ret = __db_c_idup(cp->opd, &opd, DB_POSITIONI)) != 0) return (ret); /* * If we're in CDB, the newly dup'ed off-page dup cursor * may need the original outer cursor's locking info. */ if (LOCKING(dbp->dbenv)) (void)CDB___db_cdb_cdup(dbc_arg, opd); switch (ret = opd->c_am_get( opd, key, data, flags, NULL)) { case 0: goto done; case DB_NOTFOUND: /* * Translate DB_NOTFOUND failures for the DB_NEXT and * DB_PREV operations into a subsequent operation on * the parent cursor. */ if (flags == DB_NEXT || flags == DB_PREV) { if ((ret = opd->c_close(opd)) != 0) goto err; opd = NULL; break; } goto err; default: goto err; } } /* * Perform an operation on the CDB_main cursor. Duplicate the cursor, * upgrade the lock as required, and call the underlying function. */ switch (flags) { case DB_CURRENT: case DB_GET_BOTHC: case DB_NEXT: case DB_NEXT_DUP: case DB_NEXT_NODUP: case DB_PREV: case DB_PREV_NODUP: tmp_flags = DB_POSITIONI; break; default: tmp_flags = 0; break; } if ((ret = __db_c_idup(dbc_arg, &dbc_n, tmp_flags)) != 0) goto err; /* * If we're in CDB, the new cursor may need the old cursor's locking * info. */ if (LOCKING(dbp->dbenv)) (void)CDB___db_cdb_cdup(dbc_arg, dbc_n); if (tmp_rmw) F_SET(dbc_n, DBC_RMW); pgno = PGNO_INVALID; ret = dbc_n->c_am_get(dbc_n, key, data, flags, &pgno); if (tmp_rmw) F_CLR(dbc_n, DBC_RMW); if (ret != 0) goto err; cp_n = dbc_n->internal; /* * We may be referencing a new off-page duplicates tree. Acquire * a new cursor and call the underlying function. */ if (pgno != PGNO_INVALID) { if ((ret = CDB___db_icursor(dbp, dbc_arg->txn, dbp->dup_compare == NULL ? DB_RECNO : DB_BTREE, pgno, 1, &cp_n->opd)) != 0) goto err; switch (flags) { case DB_FIRST: case DB_NEXT: case DB_NEXT_NODUP: case DB_SET: case DB_SET_RECNO: case DB_SET_RANGE: tmp_flags = DB_FIRST; break; case DB_LAST: case DB_PREV: case DB_PREV_NODUP: tmp_flags = DB_LAST; break; case DB_GET_BOTH: tmp_flags = DB_GET_BOTH; break; case DB_GET_BOTHC: tmp_flags = DB_GET_BOTHC; break; default: ret = CDB___db_unknown_flag(dbp->dbenv, "CDB___db_c_get", flags); goto err; } if ((ret = cp_n->opd->c_am_get( cp_n->opd, key, data, tmp_flags, NULL)) != 0) goto err; } done: /* * Return a key/data item. The only exception is that we don't return * a key if the user already gave us one, that is, if the DB_SET flag * was set. The DB_SET flag is necessary. In a Btree, the user's key * doesn't have to be the same as the key stored the tree, depending on * the magic performed by the comparison function. As we may not have * done any key-oriented operation here, the page reference may not be * valid. Fill it in as necessary. We don't have to worry about any * locks, the cursor must already be holding appropriate locks. * * XXX * If not a Btree and DB_SET_RANGE is set, we shouldn't return a key * either, should we? */ cp_n = dbc_n == NULL ? dbc_arg->internal : dbc_n->internal; if (!F_ISSET(key, DB_DBT_ISSET)) { if (cp_n->page == NULL && (ret = CDB_memp_fget(dbp->mpf, &cp_n->pgno, 0, &cp_n->page)) != 0) goto err; if ((ret = CDB___db_ret(dbp, cp_n->page, cp_n->indx, key, &dbc_arg->rkey.data, &dbc_arg->rkey.ulen)) != 0) goto err; } dbc = opd != NULL ? opd : cp_n->opd != NULL ? cp_n->opd : dbc_n; if (!F_ISSET(data, DB_DBT_ISSET)) { type = TYPE(dbc->internal->page); ret = CDB___db_ret(dbp, dbc->internal->page, dbc->internal->indx + (type == P_LBTREE || type == P_HASH ? O_INDX : 0), data, &dbc_arg->rdata.data, &dbc_arg->rdata.ulen); } err: /* Don't pass DB_DBT_ISSET back to application level, error or no. */ F_CLR(key, DB_DBT_ISSET); F_CLR(data, DB_DBT_ISSET); /* Cleanup and cursor resolution. */ if (opd != NULL) { if ((t_ret = __db_c_cleanup(dbc_arg->internal->opd, opd, ret)) != 0 && ret == 0) ret = t_ret; } if ((t_ret = __db_c_cleanup(dbc_arg, dbc_n, ret)) != 0 && ret == 0) ret = t_ret; return (ret); } /* * CDB___db_c_put -- * Put using a cursor. * * PUBLIC: int CDB___db_c_put __P((DBC *, DBT *, DBT *, u_int32_t)); */ int CDB___db_c_put(dbc_arg, key, data, flags) DBC *dbc_arg; DBT *key, *data; u_int32_t flags; { DB *dbp; DBC *dbc_n, *opd; db_pgno_t pgno; u_int32_t tmp_flags; int ret, t_ret; /* * Cursor Cleanup Note: * All of the cursors passed to the underlying access methods by this * routine are duplicated cursors. On return, any referenced pages * will be discarded, and, if the cursor is not intended to be used * again, the close function will be called. So, pages/locks that * the cursor references do not need to be resolved by the underlying * functions. */ dbp = dbc_arg->dbp; dbc_n = NULL; PANIC_CHECK(dbp->dbenv); /* Check for invalid flags. */ if ((ret = CDB___db_cputchk(dbp, key, data, flags, F_ISSET(dbp, DB_AM_RDONLY), IS_INITIALIZED(dbc_arg))) != 0) return (ret); DEBUG_LWRITE(dbc_arg, dbc_arg->txn, "db_c_put", flags == DB_KEYFIRST || flags == DB_KEYLAST || flags == DB_NODUPDATA ? key : NULL, data, flags); LOCKING_INIT(dbp, dbc_arg); /* * If we have an off-page duplicates cursor, and the operation applies * to it, perform the operation. Duplicate the cursor and call the * underlying function. * * Off-page duplicate trees are locked in the primary tree, that is, * we acquire a write lock in the primary tree and no locks in the * off-page dup tree. If the put operation is done in an off-page * duplicate tree, call the primary cursor's upgrade routine first. */ if (dbc_arg->internal->opd != NULL && (flags == DB_AFTER || flags == DB_BEFORE || flags == DB_CURRENT)) { if ((ret = dbc_arg->c_am_writelock(dbc_arg)) != 0) return (ret); if ((ret = CDB___db_c_dup(dbc_arg, &dbc_n, DB_POSITIONI)) != 0) goto err; opd = dbc_n->internal->opd; if ((ret = opd->c_am_put( opd, key, data, flags, NULL)) != 0) goto err; goto done; } /* * Perform an operation on the CDB_main cursor. Duplicate the cursor, * and call the underlying function. * * XXX: MARGO * tmp_flags = flags == DB_AFTER || flags == DB_BEFORE || flags == DB_CURRENT ? DB_POSITIONI : 0; */ tmp_flags = DB_POSITIONI; if ((ret = __db_c_idup(dbc_arg, &dbc_n, tmp_flags)) != 0) goto err; pgno = PGNO_INVALID; if ((ret = dbc_n->c_am_put(dbc_n, key, data, flags, &pgno)) != 0) goto err; /* * We may be referencing a new off-page duplicates tree. Acquire * a new cursor and call the underlying function. */ if (pgno != PGNO_INVALID) { if ((ret = CDB___db_icursor(dbp, dbc_arg->txn, dbp->dup_compare == NULL ? DB_RECNO : DB_BTREE, pgno, 1, &dbc_n->internal->opd)) != 0) goto err; opd = dbc_n->internal->opd; if ((ret = opd->c_am_put( opd, key, data, flags, NULL)) != 0) goto err; } done: err: /* Cleanup and cursor resolution. */ if ((t_ret = __db_c_cleanup(dbc_arg, dbc_n, ret)) != 0 && ret == 0) ret = t_ret; LOCKING_DONE(dbp, dbc_arg); return (ret); } /* * CDB___db_duperr() * Error message: we don't currently support sorted duplicate duplicates. * PUBLIC: int CDB___db_duperr __P((DB *, u_int32_t)); */ int CDB___db_duperr(dbp, flags) DB *dbp; u_int32_t flags; { if (flags != DB_NODUPDATA) CDB___db_err(dbp->dbenv, "Duplicate data items are not supported with sorted data"); return (DB_KEYEXIST); } /* * __db_c_cleanup -- * Clean up duplicate cursors. */ static int __db_c_cleanup(dbc, dbc_n, failed) DBC *dbc, *dbc_n; int failed; { DB *dbp; DBC *opd; DBC_INTERNAL *internal; int ret, t_ret; dbp = dbc->dbp; internal = dbc->internal; ret = 0; /* Discard any pages we're holding. */ if (internal->page != NULL) { if ((t_ret = CDB_memp_fput(dbp->mpf, internal->page, 0)) != 0 && ret == 0) ret = t_ret; internal->page = NULL; } opd = internal->opd; if (opd != NULL && opd->internal->page != NULL) { if ((t_ret = CDB_memp_fput(dbp->mpf, opd->internal->page, 0)) != 0 && ret == 0) ret = t_ret; opd->internal->page = NULL; } if (dbc_n == NULL) return (ret); if (dbc_n->internal->page != NULL) { if ((t_ret = CDB_memp_fput(dbp->mpf, dbc_n->internal->page, 0)) != 0 && ret == 0) ret = t_ret; dbc_n->internal->page = NULL; } opd = dbc_n->internal->opd; if (opd != NULL && opd->internal->page != NULL) { if ((t_ret = CDB_memp_fput(dbp->mpf, opd->internal->page, 0)) != 0 && ret == 0) ret = t_ret; opd->internal->page = NULL; } /* * If we didn't fail before entering this routine or just now when * freeing pages, swap the interesting contents of the old and new * cursors. */ if (!failed && ret == 0) { dbc->internal = dbc_n->internal; dbc_n->internal = internal; } /* * Close the cursor we don't care about anymore. The close can fail, * but we only expect DB_LOCK_DEADLOCK failures. This violates our * "the cursor is unchanged on error" semantics, but since all you can * do with a DB_LOCK_DEADLOCK failure is close the cursor, I believe * that's OK. * * XXX * There's no way to recover from failure to close the old cursor. * All we can do is move to the new position and return an error. * * XXX * We might want to consider adding a flag to the cursor, so that any * subsequent operations other than close just return an error? */ if ((t_ret = dbc_n->c_close(dbc_n)) != 0 && ret == 0) ret = t_ret; return (ret); } /* * CDB___db_cdb_cdup -- * Duplicate the internal lock of a CDB write cursor. The method- * independent cursor get and put code duplicate the cursor before * performing operations on it, using the internal cursor interface, which * does no CDB locking. Under normal circumstances this is desirable; * there's no need for an additional lock, as the original cursor * is extant--and its lock is held--throughout, and there's never a * need to perform locking operations on the new cursor. * * The sole exception to this is in the case of a DBC->c_get with a * write cursor. Here, the cursor holds only an IWRITE lock when it * is duplicated; in the common case, there's never a need to * perform a write. If, however, the cursor moves away from a * deleted item in a btree, the btree close method will attempt to * upgrade the lock to a WRITE. This close happens on the _duplicated_ * cursor, so we use this function to provide it with a copy of the * lock. (The lock structure itself doesn't change on an * upgrade/downgrade, so simply copying and later discarding is * sufficient.) * * PUBLIC: int CDB___db_cdb_cdup __P((DBC *, DBC *)); */ int CDB___db_cdb_cdup(dbc_orig, dbc_n) DBC *dbc_orig, *dbc_n; { if (F_ISSET(dbc_orig, DBC_WRITECURSOR | DBC_WRITEDUP)) { memcpy(&dbc_n->mylock, &dbc_orig->mylock, sizeof(dbc_orig->mylock)); /* * dbc_n's locker may be different, since if it's an off-page * duplicate it may not be an idup'ed copy of dbc_orig. It's * not meaningful, though, so overwrite it with dbc_orig's so * we don't self-deadlock. */ dbc_n->locker = dbc_orig->locker; /* * Flag that this lock isn't ours to put; just discard it * in c_close. */ F_SET(dbc_n, DBC_WRITEDUP); } return (0); } /* * __db_wrlock_err -- do not have a write lock. */ static int __db_wrlock_err(dbenv) DB_ENV *dbenv; { CDB___db_err(dbenv, "Write attempted on read-only cursor"); return (EPERM); }