diff options
Diffstat (limited to 'db2/mp/mp_fget.c')
| -rw-r--r-- | db2/mp/mp_fget.c | 352 |
1 files changed, 0 insertions, 352 deletions
diff --git a/db2/mp/mp_fget.c b/db2/mp/mp_fget.c deleted file mode 100644 index f159dc2d3e..0000000000 --- a/db2/mp/mp_fget.c +++ /dev/null @@ -1,352 +0,0 @@ -/*- - * See the file LICENSE for redistribution information. - * - * Copyright (c) 1996, 1997, 1998 - * Sleepycat Software. All rights reserved. - */ -#include "config.h" - -#ifndef lint -static const char sccsid[] = "@(#)mp_fget.c 10.53 (Sleepycat) 11/16/98"; -#endif /* not lint */ - -#ifndef NO_SYSTEM_INCLUDES -#include <sys/types.h> - -#include <errno.h> -#include <string.h> -#endif - -#include "db_int.h" -#include "shqueue.h" -#include "db_shash.h" -#include "mp.h" -#include "common_ext.h" - -/* - * memp_fget -- - * Get a page from the file. - */ -int -memp_fget(dbmfp, pgnoaddr, flags, addrp) - DB_MPOOLFILE *dbmfp; - db_pgno_t *pgnoaddr; - u_int32_t flags; - void *addrp; -{ - BH *bhp; - DB_MPOOL *dbmp; - MPOOL *mp; - MPOOLFILE *mfp; - size_t bucket, mf_offset; - u_int32_t st_hsearch; - int b_incr, first, ret; - - dbmp = dbmfp->dbmp; - mp = dbmp->mp; - mfp = dbmfp->mfp; - - MP_PANIC_CHECK(dbmp); - - /* - * Validate arguments. - * - * !!! - * Don't test for DB_MPOOL_CREATE and DB_MPOOL_NEW flags for readonly - * files here, and create non-existent pages in readonly files if the - * flags are set, later. The reason is that the hash access method - * wants to get empty pages that don't really exist in readonly files. - * The only alternative is for hash to write the last "bucket" all the - * time, which we don't want to do because one of our big goals in life - * is to keep database files small. It's sleazy as hell, but we catch - * any attempt to actually write the file in memp_fput(). - */ -#define OKFLAGS (DB_MPOOL_CREATE | DB_MPOOL_LAST | DB_MPOOL_NEW) - if (flags != 0) { - if ((ret = - __db_fchk(dbmp->dbenv, "memp_fget", flags, OKFLAGS)) != 0) - return (ret); - - switch (flags) { - case DB_MPOOL_CREATE: - case DB_MPOOL_LAST: - case DB_MPOOL_NEW: - case 0: - break; - default: - return (__db_ferr(dbmp->dbenv, "memp_fget", 1)); - } - } - -#ifdef DIAGNOSTIC - /* - * XXX - * We want to switch threads as often as possible. Yield every time - * we get a new page to ensure contention. - */ - if (DB_GLOBAL(db_pageyield)) - __os_yield(1); -#endif - - /* Initialize remaining local variables. */ - mf_offset = R_OFFSET(dbmp, mfp); - bhp = NULL; - st_hsearch = 0; - b_incr = ret = 0; - - /* Determine the hash bucket where this page will live. */ - bucket = BUCKET(mp, mf_offset, *pgnoaddr); - - LOCKREGION(dbmp); - - /* - * Check for the last or last + 1 page requests. - * - * Examine and update the file's last_pgno value. We don't care if - * the last_pgno value immediately changes due to another thread -- - * at this instant in time, the value is correct. We do increment the - * current last_pgno value if the thread is asking for a new page, - * however, to ensure that two threads creating pages don't get the - * same one. - */ - if (LF_ISSET(DB_MPOOL_LAST | DB_MPOOL_NEW)) { - if (LF_ISSET(DB_MPOOL_NEW)) - ++mfp->last_pgno; - *pgnoaddr = mfp->last_pgno; - bucket = BUCKET(mp, mf_offset, mfp->last_pgno); - - if (LF_ISSET(DB_MPOOL_NEW)) - goto alloc; - } - - /* - * If mmap'ing the file and the page is not past the end of the file, - * just return a pointer. - * - * The page may be past the end of the file, so check the page number - * argument against the original length of the file. If we previously - * returned pages past the original end of the file, last_pgno will - * have been updated to match the "new" end of the file, and checking - * against it would return pointers past the end of the mmap'd region. - * - * If another process has opened the file for writing since we mmap'd - * it, we will start playing the game by their rules, i.e. everything - * goes through the cache. All pages previously returned will be safe, - * as long as the correct locking protocol was observed. - * - * XXX - * We don't discard the map because we don't know when all of the - * pages will have been discarded from the process' address space. - * It would be possible to do so by reference counting the open - * pages from the mmap, but it's unclear to me that it's worth it. - */ - if (dbmfp->addr != NULL && F_ISSET(mfp, MP_CAN_MMAP)) { - if (*pgnoaddr > mfp->orig_last_pgno) { - /* - * !!! - * See the comment above about non-existent pages and - * the hash access method. - */ - if (!LF_ISSET(DB_MPOOL_CREATE)) { - __db_err(dbmp->dbenv, - "%s: page %lu doesn't exist", - __memp_fn(dbmfp), (u_long)*pgnoaddr); - ret = EINVAL; - goto err; - } - } else { - *(void **)addrp = - R_ADDR(dbmfp, *pgnoaddr * mfp->stat.st_pagesize); - ++mp->stat.st_map; - ++mfp->stat.st_map; - goto done; - } - } - - /* Search the hash chain for the page. */ - for (bhp = SH_TAILQ_FIRST(&dbmp->htab[bucket], __bh); - bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, hq, __bh)) { - ++st_hsearch; - if (bhp->pgno != *pgnoaddr || bhp->mf_offset != mf_offset) - continue; - - /* Increment the reference count. */ - if (bhp->ref == UINT16_T_MAX) { - __db_err(dbmp->dbenv, - "%s: page %lu: reference count overflow", - __memp_fn(dbmfp), (u_long)bhp->pgno); - ret = EINVAL; - goto err; - } - - /* - * Increment the reference count. We may discard the region - * lock as we evaluate and/or read the buffer, so we need to - * ensure that it doesn't move and that its contents remain - * unchanged. - */ - ++bhp->ref; - b_incr = 1; - - /* - * Any buffer we find might be trouble. - * - * BH_LOCKED -- - * I/O is in progress. Because we've incremented the buffer - * reference count, we know the buffer can't move. Unlock - * the region lock, wait for the I/O to complete, and reacquire - * the region. - */ - for (first = 1; F_ISSET(bhp, BH_LOCKED); first = 0) { - UNLOCKREGION(dbmp); - - /* - * Explicitly yield the processor if it's not the first - * pass through this loop -- if we don't, we might end - * up running to the end of our CPU quantum as we will - * simply be swapping between the two locks. - */ - if (!first) - __os_yield(1); - - LOCKBUFFER(dbmp, bhp); - /* Wait for I/O to finish... */ - UNLOCKBUFFER(dbmp, bhp); - LOCKREGION(dbmp); - } - - /* - * BH_TRASH -- - * The contents of the buffer are garbage. Shouldn't happen, - * and this read is likely to fail, but might as well try. - */ - if (F_ISSET(bhp, BH_TRASH)) - goto reread; - - /* - * BH_CALLPGIN -- - * The buffer was converted so it could be written, and the - * contents need to be converted again. - */ - if (F_ISSET(bhp, BH_CALLPGIN)) { - if ((ret = __memp_pg(dbmfp, bhp, 1)) != 0) - goto err; - F_CLR(bhp, BH_CALLPGIN); - } - - ++mp->stat.st_cache_hit; - ++mfp->stat.st_cache_hit; - *(void **)addrp = bhp->buf; - goto done; - } - -alloc: /* Allocate new buffer header and data space. */ - if ((ret = __memp_alloc(dbmp, sizeof(BH) - - sizeof(u_int8_t) + mfp->stat.st_pagesize, NULL, &bhp)) != 0) - goto err; - -#ifdef DIAGNOSTIC - if ((ALIGNTYPE)bhp->buf & (sizeof(size_t) - 1)) { - __db_err(dbmp->dbenv, - "Internal error: BH data NOT size_t aligned."); - ret = EINVAL; - goto err; - } -#endif - /* Initialize the BH fields. */ - memset(bhp, 0, sizeof(BH)); - LOCKINIT(dbmp, &bhp->mutex); - bhp->ref = 1; - bhp->pgno = *pgnoaddr; - bhp->mf_offset = mf_offset; - - /* - * Prepend the bucket header to the head of the appropriate MPOOL - * bucket hash list. Append the bucket header to the tail of the - * MPOOL LRU chain. - */ - SH_TAILQ_INSERT_HEAD(&dbmp->htab[bucket], bhp, hq, __bh); - SH_TAILQ_INSERT_TAIL(&mp->bhq, bhp, q); - - /* - * If we created the page, zero it out and continue. - * - * !!! - * Note: DB_MPOOL_NEW specifically doesn't call the pgin function. - * If DB_MPOOL_CREATE is used, then the application's pgin function - * has to be able to handle pages of 0's -- if it uses DB_MPOOL_NEW, - * it can detect all of its page creates, and not bother. - * - * Otherwise, read the page into memory, optionally creating it if - * DB_MPOOL_CREATE is set. - */ - if (LF_ISSET(DB_MPOOL_NEW)) { - if (mfp->clear_len == 0) - memset(bhp->buf, 0, mfp->stat.st_pagesize); - else { - memset(bhp->buf, 0, mfp->clear_len); -#ifdef DIAGNOSTIC - memset(bhp->buf + mfp->clear_len, 0xdb, - mfp->stat.st_pagesize - mfp->clear_len); -#endif - } - - ++mp->stat.st_page_create; - ++mfp->stat.st_page_create; - } else { - /* - * It's possible for the read function to fail, which means - * that we fail as well. Note, the __memp_pgread() function - * discards the region lock, so the buffer must be pinned - * down so that it cannot move and its contents are unchanged. - */ -reread: if ((ret = __memp_pgread(dbmfp, - bhp, LF_ISSET(DB_MPOOL_CREATE))) != 0) { - /* - * !!! - * Discard the buffer unless another thread is waiting - * on our I/O to complete. Regardless, the header has - * the BH_TRASH flag set. - */ - if (bhp->ref == 1) - __memp_bhfree(dbmp, mfp, bhp, 1); - goto err; - } - - ++mp->stat.st_cache_miss; - ++mfp->stat.st_cache_miss; - } - - /* - * If we're returning a page after our current notion of the last-page, - * update our information. Note, there's no way to un-instantiate this - * page, it's going to exist whether it's returned to us dirty or not. - */ - if (bhp->pgno > mfp->last_pgno) - mfp->last_pgno = bhp->pgno; - - ++mp->stat.st_page_clean; - *(void **)addrp = bhp->buf; - -done: /* Update the chain search statistics. */ - if (st_hsearch) { - ++mp->stat.st_hash_searches; - if (st_hsearch > mp->stat.st_hash_longest) - mp->stat.st_hash_longest = st_hsearch; - mp->stat.st_hash_examined += st_hsearch; - } - - ++dbmfp->pinref; - - UNLOCKREGION(dbmp); - - return (0); - -err: /* Discard our reference. */ - if (b_incr) - --bhp->ref; - UNLOCKREGION(dbmp); - - *(void **)addrp = NULL; - return (ret); -} |