glibc/db2/mp/mp_bh.c

593 lines
14 KiB
C

/*-
* 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_bh.c 10.45 (Sleepycat) 11/25/98";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#endif
#include "db_int.h"
#include "shqueue.h"
#include "db_shash.h"
#include "mp.h"
#include "common_ext.h"
static int __memp_upgrade __P((DB_MPOOL *, DB_MPOOLFILE *, MPOOLFILE *));
/*
* __memp_bhwrite --
* Write the page associated with a given bucket header.
*
* PUBLIC: int __memp_bhwrite
* PUBLIC: __P((DB_MPOOL *, MPOOLFILE *, BH *, int *, int *));
*/
int
__memp_bhwrite(dbmp, mfp, bhp, restartp, wrotep)
DB_MPOOL *dbmp;
MPOOLFILE *mfp;
BH *bhp;
int *restartp, *wrotep;
{
DB_MPOOLFILE *dbmfp;
DB_MPREG *mpreg;
int incremented, ret;
if (restartp != NULL)
*restartp = 0;
if (wrotep != NULL)
*wrotep = 0;
incremented = 0;
/*
* Walk the process' DB_MPOOLFILE list and find a file descriptor for
* the file. We also check that the descriptor is open for writing.
* If we find a descriptor on the file that's not open for writing, we
* try and upgrade it to make it writeable. If that fails, we're done.
*/
LOCKHANDLE(dbmp, dbmp->mutexp);
for (dbmfp = TAILQ_FIRST(&dbmp->dbmfq);
dbmfp != NULL; dbmfp = TAILQ_NEXT(dbmfp, q))
if (dbmfp->mfp == mfp) {
if (F_ISSET(dbmfp, MP_READONLY) &&
__memp_upgrade(dbmp, dbmfp, mfp)) {
UNLOCKHANDLE(dbmp, dbmp->mutexp);
return (0);
}
/*
* Increment the reference count -- see the comment in
* memp_fclose().
*/
++dbmfp->ref;
incremented = 1;
break;
}
UNLOCKHANDLE(dbmp, dbmp->mutexp);
if (dbmfp != NULL)
goto found;
/*
* It's not a page from a file we've opened. If the file requires
* input/output processing, see if this process has ever registered
* information as to how to write this type of file. If not, there's
* nothing we can do.
*/
if (mfp->ftype != 0) {
LOCKHANDLE(dbmp, dbmp->mutexp);
for (mpreg = LIST_FIRST(&dbmp->dbregq);
mpreg != NULL; mpreg = LIST_NEXT(mpreg, q))
if (mpreg->ftype == mfp->ftype)
break;
UNLOCKHANDLE(dbmp, dbmp->mutexp);
if (mpreg == NULL)
return (0);
}
/*
* Try and open the file, attaching to the underlying shared area.
*
* XXX
* Don't try to attach to temporary files. There are two problems in
* trying to do that. First, if we have different privileges than the
* process that "owns" the temporary file, we might create the backing
* disk file such that the owning process couldn't read/write its own
* buffers, e.g., memp_trickle() running as root creating a file owned
* as root, mode 600. Second, if the temporary file has already been
* created, we don't have any way of finding out what its real name is,
* and, even if we did, it was already unlinked (so that it won't be
* left if the process dies horribly). This decision causes a problem,
* however: if the temporary file consumes the entire buffer cache,
* and the owner doesn't flush the buffers to disk, we could end up
* with resource starvation, and the memp_trickle() thread couldn't do
* anything about it. That's a pretty unlikely scenario, though.
*
* XXX
* There's no negative cache, so we may repeatedly try and open files
* that we have previously tried (and failed) to open.
*
* Ignore any error, assume it's a permissions problem.
*/
if (F_ISSET(mfp, MP_TEMP))
return (0);
if (__memp_fopen(dbmp, mfp, R_ADDR(dbmp, mfp->path_off),
0, 0, mfp->stat.st_pagesize, 0, NULL, &dbmfp) != 0)
return (0);
found: ret = __memp_pgwrite(dbmfp, bhp, restartp, wrotep);
if (incremented) {
LOCKHANDLE(dbmp, dbmp->mutexp);
--dbmfp->ref;
UNLOCKHANDLE(dbmp, dbmp->mutexp);
}
return (ret);
}
/*
* __memp_pgread --
* Read a page from a file.
*
* PUBLIC: int __memp_pgread __P((DB_MPOOLFILE *, BH *, int));
*/
int
__memp_pgread(dbmfp, bhp, can_create)
DB_MPOOLFILE *dbmfp;
BH *bhp;
int can_create;
{
DB_IO db_io;
DB_MPOOL *dbmp;
MPOOLFILE *mfp;
size_t len, pagesize;
ssize_t nr;
int created, ret;
dbmp = dbmfp->dbmp;
mfp = dbmfp->mfp;
pagesize = mfp->stat.st_pagesize;
F_SET(bhp, BH_LOCKED | BH_TRASH);
LOCKBUFFER(dbmp, bhp);
UNLOCKREGION(dbmp);
/*
* Temporary files may not yet have been created. We don't create
* them now, we create them when the pages have to be flushed.
*/
nr = 0;
if (dbmfp->fd == -1)
ret = 0;
else {
/*
* Ignore read errors if we have permission to create the page.
* Assume that the page doesn't exist, and that we'll create it
* when we write it out.
*/
db_io.fd_io = dbmfp->fd;
db_io.fd_lock = dbmp->reginfo.fd;
db_io.mutexp =
F_ISSET(dbmp, MP_LOCKHANDLE) ? dbmfp->mutexp : NULL;
db_io.pagesize = db_io.bytes = pagesize;
db_io.pgno = bhp->pgno;
db_io.buf = bhp->buf;
ret = __os_io(&db_io, DB_IO_READ, &nr);
}
created = 0;
if (nr < (ssize_t)pagesize) {
if (can_create)
created = 1;
else {
/* If we had a short read, ret may be 0. */
if (ret == 0)
ret = EIO;
__db_err(dbmp->dbenv,
"%s: page %lu doesn't exist, create flag not set",
__memp_fn(dbmfp), (u_long)bhp->pgno);
goto err;
}
}
/*
* Clear any bytes we didn't read that need to be cleared. If we're
* running in diagnostic mode, smash any bytes on the page that are
* unknown quantities for the caller.
*/
if (nr != (ssize_t)pagesize) {
len = mfp->clear_len == 0 ? pagesize : mfp->clear_len;
if (nr < (ssize_t)len)
memset(bhp->buf + nr, 0, len - nr);
#ifdef DIAGNOSTIC
if (nr > (ssize_t)len)
len = nr;
if (len < pagesize)
memset(bhp->buf + len, 0xdb, pagesize - len);
#endif
}
/* Call any pgin function. */
ret = mfp->ftype == 0 ? 0 : __memp_pg(dbmfp, bhp, 1);
/* Unlock the buffer and reacquire the region lock. */
err: UNLOCKBUFFER(dbmp, bhp);
LOCKREGION(dbmp);
/*
* If no errors occurred, the data is now valid, clear the BH_TRASH
* flag; regardless, clear the lock bit and let other threads proceed.
*/
F_CLR(bhp, BH_LOCKED);
if (ret == 0) {
F_CLR(bhp, BH_TRASH);
/* Update the statistics. */
if (created) {
++dbmp->mp->stat.st_page_create;
++mfp->stat.st_page_create;
} else {
++dbmp->mp->stat.st_page_in;
++mfp->stat.st_page_in;
}
}
return (ret);
}
/*
* __memp_pgwrite --
* Write a page to a file.
*
* PUBLIC: int __memp_pgwrite __P((DB_MPOOLFILE *, BH *, int *, int *));
*/
int
__memp_pgwrite(dbmfp, bhp, restartp, wrotep)
DB_MPOOLFILE *dbmfp;
BH *bhp;
int *restartp, *wrotep;
{
DB_ENV *dbenv;
DB_IO db_io;
DB_LOG *lg_info;
DB_LSN lsn;
DB_MPOOL *dbmp;
MPOOL *mp;
MPOOLFILE *mfp;
ssize_t nw;
int callpgin, ret, syncfail;
const char *fail;
dbmp = dbmfp->dbmp;
dbenv = dbmp->dbenv;
mp = dbmp->mp;
mfp = dbmfp->mfp;
if (restartp != NULL)
*restartp = 0;
if (wrotep != NULL)
*wrotep = 0;
callpgin = 0;
/*
* Check the dirty bit -- this buffer may have been written since we
* decided to write it.
*/
if (!F_ISSET(bhp, BH_DIRTY)) {
if (wrotep != NULL)
*wrotep = 1;
return (0);
}
LOCKBUFFER(dbmp, bhp);
/*
* If there were two writers, we may have just been waiting while the
* other writer completed I/O on this buffer. Check the dirty bit one
* more time.
*/
if (!F_ISSET(bhp, BH_DIRTY)) {
UNLOCKBUFFER(dbmp, bhp);
if (wrotep != NULL)
*wrotep = 1;
return (0);
}
F_SET(bhp, BH_LOCKED);
UNLOCKREGION(dbmp);
if (restartp != NULL)
*restartp = 1;
/* Copy the LSN off the page if we're going to need it. */
lg_info = dbenv->lg_info;
if (lg_info != NULL || F_ISSET(bhp, BH_WRITE))
memcpy(&lsn, bhp->buf + mfp->lsn_off, sizeof(DB_LSN));
/* Ensure the appropriate log records are on disk. */
if (lg_info != NULL && (ret = log_flush(lg_info, &lsn)) != 0)
goto err;
/*
* Call any pgout function. We set the callpgin flag so that we flag
* that the contents of the buffer will need to be passed through pgin
* before they are reused.
*/
if (mfp->ftype == 0)
ret = 0;
else {
callpgin = 1;
if ((ret = __memp_pg(dbmfp, bhp, 0)) != 0)
goto err;
}
/* Temporary files may not yet have been created. */
if (dbmfp->fd == -1) {
LOCKHANDLE(dbmp, dbmfp->mutexp);
if (dbmfp->fd == -1 && ((ret = __db_appname(dbenv,
DB_APP_TMP, NULL, NULL, DB_CREATE | DB_EXCL | DB_TEMPORARY,
&dbmfp->fd, NULL)) != 0 || dbmfp->fd == -1)) {
UNLOCKHANDLE(dbmp, dbmfp->mutexp);
__db_err(dbenv,
"unable to create temporary backing file");
goto err;
}
UNLOCKHANDLE(dbmp, dbmfp->mutexp);
}
/* Write the page. */
db_io.fd_io = dbmfp->fd;
db_io.fd_lock = dbmp->reginfo.fd;
db_io.mutexp = F_ISSET(dbmp, MP_LOCKHANDLE) ? dbmfp->mutexp : NULL;
db_io.pagesize = db_io.bytes = mfp->stat.st_pagesize;
db_io.pgno = bhp->pgno;
db_io.buf = bhp->buf;
if ((ret = __os_io(&db_io, DB_IO_WRITE, &nw)) != 0) {
__db_panic(dbenv, ret);
fail = "write";
goto syserr;
}
if (nw != (ssize_t)mfp->stat.st_pagesize) {
ret = EIO;
fail = "write";
goto syserr;
}
if (wrotep != NULL)
*wrotep = 1;
/* Unlock the buffer and reacquire the region lock. */
UNLOCKBUFFER(dbmp, bhp);
LOCKREGION(dbmp);
/*
* Clean up the flags based on a successful write.
*
* If we rewrote the page, it will need processing by the pgin
* routine before reuse.
*/
if (callpgin)
F_SET(bhp, BH_CALLPGIN);
F_CLR(bhp, BH_DIRTY | BH_LOCKED);
/*
* If we write a buffer for which a checkpoint is waiting, update
* the count of pending buffers (both in the mpool as a whole and
* for this file). If the count for this file goes to zero, flush
* the writes.
*
* XXX:
* Don't lock the region around the sync, fsync(2) has no atomicity
* issues.
*
* XXX:
* We ignore errors from the sync -- it makes no sense to return an
* error to the calling process, so set a flag causing the checkpoint
* to be retried later.
*/
if (F_ISSET(bhp, BH_WRITE)) {
if (mfp->lsn_cnt == 1) {
UNLOCKREGION(dbmp);
syncfail = __os_fsync(dbmfp->fd) != 0;
LOCKREGION(dbmp);
if (syncfail)
F_SET(mp, MP_LSN_RETRY);
}
F_CLR(bhp, BH_WRITE);
/*
* If the buffer just written has a larger LSN than the current
* max LSN written for this checkpoint, update the saved value.
*/
if (log_compare(&lsn, &mp->lsn) > 0)
mp->lsn = lsn;
--mp->lsn_cnt;
--mfp->lsn_cnt;
}
/* Update the page clean/dirty statistics. */
++mp->stat.st_page_clean;
--mp->stat.st_page_dirty;
/* Update I/O statistics. */
++mp->stat.st_page_out;
++mfp->stat.st_page_out;
return (0);
syserr: __db_err(dbenv, "%s: %s failed for page %lu",
__memp_fn(dbmfp), fail, (u_long)bhp->pgno);
err: /* Unlock the buffer and reacquire the region lock. */
UNLOCKBUFFER(dbmp, bhp);
LOCKREGION(dbmp);
/*
* Clean up the flags based on a failure.
*
* The page remains dirty but we remove our lock. If we rewrote the
* page, it will need processing by the pgin routine before reuse.
*/
if (callpgin)
F_SET(bhp, BH_CALLPGIN);
F_CLR(bhp, BH_LOCKED);
return (ret);
}
/*
* __memp_pg --
* Call the pgin/pgout routine.
*
* PUBLIC: int __memp_pg __P((DB_MPOOLFILE *, BH *, int));
*/
int
__memp_pg(dbmfp, bhp, is_pgin)
DB_MPOOLFILE *dbmfp;
BH *bhp;
int is_pgin;
{
DBT dbt, *dbtp;
DB_MPOOL *dbmp;
DB_MPREG *mpreg;
MPOOLFILE *mfp;
int ftype, ret;
dbmp = dbmfp->dbmp;
mfp = dbmfp->mfp;
LOCKHANDLE(dbmp, dbmp->mutexp);
ftype = mfp->ftype;
for (mpreg = LIST_FIRST(&dbmp->dbregq);
mpreg != NULL; mpreg = LIST_NEXT(mpreg, q)) {
if (ftype != mpreg->ftype)
continue;
if (mfp->pgcookie_len == 0)
dbtp = NULL;
else {
dbt.size = mfp->pgcookie_len;
dbt.data = R_ADDR(dbmp, mfp->pgcookie_off);
dbtp = &dbt;
}
UNLOCKHANDLE(dbmp, dbmp->mutexp);
if (is_pgin) {
if (mpreg->pgin != NULL && (ret =
mpreg->pgin(bhp->pgno, bhp->buf, dbtp)) != 0)
goto err;
} else
if (mpreg->pgout != NULL && (ret =
mpreg->pgout(bhp->pgno, bhp->buf, dbtp)) != 0)
goto err;
break;
}
if (mpreg == NULL)
UNLOCKHANDLE(dbmp, dbmp->mutexp);
return (0);
err: UNLOCKHANDLE(dbmp, dbmp->mutexp);
__db_err(dbmp->dbenv, "%s: %s failed for page %lu",
__memp_fn(dbmfp), is_pgin ? "pgin" : "pgout", (u_long)bhp->pgno);
return (ret);
}
/*
* __memp_bhfree --
* Free a bucket header and its referenced data.
*
* PUBLIC: void __memp_bhfree __P((DB_MPOOL *, MPOOLFILE *, BH *, int));
*/
void
__memp_bhfree(dbmp, mfp, bhp, free_mem)
DB_MPOOL *dbmp;
MPOOLFILE *mfp;
BH *bhp;
int free_mem;
{
size_t off;
/* Delete the buffer header from the hash bucket queue. */
off = BUCKET(dbmp->mp, R_OFFSET(dbmp, mfp), bhp->pgno);
SH_TAILQ_REMOVE(&dbmp->htab[off], bhp, hq, __bh);
/* Delete the buffer header from the LRU queue. */
SH_TAILQ_REMOVE(&dbmp->mp->bhq, bhp, q, __bh);
/*
* If we're not reusing it immediately, free the buffer header
* and data for real.
*/
if (free_mem) {
__db_shalloc_free(dbmp->addr, bhp);
--dbmp->mp->stat.st_page_clean;
}
}
/*
* __memp_upgrade --
* Upgrade a file descriptor from readonly to readwrite.
*/
static int
__memp_upgrade(dbmp, dbmfp, mfp)
DB_MPOOL *dbmp;
DB_MPOOLFILE *dbmfp;
MPOOLFILE *mfp;
{
int fd, ret;
char *rpath;
/*
* !!!
* We expect the handle to already be locked.
*/
/* Check to see if we've already upgraded. */
if (F_ISSET(dbmfp, MP_UPGRADE))
return (0);
/* Check to see if we've already failed. */
if (F_ISSET(dbmfp, MP_UPGRADE_FAIL))
return (1);
/*
* Calculate the real name for this file and try to open it read/write.
* We know we have a valid pathname for the file because it's the only
* way we could have gotten a file descriptor of any kind.
*/
if ((ret = __db_appname(dbmp->dbenv, DB_APP_DATA,
NULL, R_ADDR(dbmp, mfp->path_off), 0, NULL, &rpath)) != 0)
return (ret);
if (__db_open(rpath, 0, 0, 0, &fd) != 0) {
F_SET(dbmfp, MP_UPGRADE_FAIL);
ret = 1;
} else {
/* Swap the descriptors and set the upgrade flag. */
(void)__os_close(dbmfp->fd);
dbmfp->fd = fd;
F_SET(dbmfp, MP_UPGRADE);
ret = 0;
}
__os_freestr(rpath);
return (ret);
}