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Diffstat (limited to 'db2/mp/mp_sync.c')
-rw-r--r--db2/mp/mp_sync.c393
1 files changed, 320 insertions, 73 deletions
diff --git a/db2/mp/mp_sync.c b/db2/mp/mp_sync.c
index 65b2a18267..2f042df9e1 100644
--- a/db2/mp/mp_sync.c
+++ b/db2/mp/mp_sync.c
@@ -7,13 +7,14 @@
#include "config.h"
#ifndef lint
-static const char sccsid[] = "@(#)mp_sync.c 10.9 (Sleepycat) 8/29/97";
+static const char sccsid[] = "@(#)mp_sync.c 10.15 (Sleepycat) 11/1/97";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <errno.h>
+#include <stdlib.h>
#include <string.h>
#endif
@@ -23,6 +24,8 @@ static const char sccsid[] = "@(#)mp_sync.c 10.9 (Sleepycat) 8/29/97";
#include "mp.h"
#include "common_ext.h"
+static int __bhcmp __P((const void *, const void *));
+
/*
* memp_sync --
* Mpool sync function.
@@ -32,27 +35,40 @@ memp_sync(dbmp, lsnp)
DB_MPOOL *dbmp;
DB_LSN *lsnp;
{
- BH *bhp;
+ BH *bhp, **bharray;
DB_ENV *dbenv;
MPOOL *mp;
MPOOLFILE *mfp;
- int can_write, wrote, lsn_cnt, restart, ret;
+ int ar_cnt, cnt, nalloc, next, notused, ret, wrote;
dbenv = dbmp->dbenv;
- if (dbmp->dbenv->lg_info == NULL) {
- __db_err(dbenv, "memp_sync requires logging");
+ if (dbenv->lg_info == NULL) {
+ __db_err(dbenv, "memp_sync: requires logging");
return (EINVAL);
}
+ /*
+ * We try and write the buffers in page order so that the underlying
+ * filesystem doesn't have to seek and can write contiguous blocks,
+ * plus, we don't want to hold the region lock while we write the
+ * buffers. Get memory to hold the buffer pointers. Get a good-size
+ * block, too, because we realloc while holding the region lock if we
+ * run out.
+ */
+ if ((bharray =
+ (BH **)__db_malloc((nalloc = 1024) * sizeof(BH *))) == NULL)
+ return (ENOMEM);
+
LOCKREGION(dbmp);
/*
- * If the application is asking about a previous call, and we haven't
- * found any buffers that the application holding the pin couldn't
- * write, return yes or no based on the current count. Note, if the
- * application is asking about a LSN *smaller* than one we've already
- * handled, then we return based on the count for that LSN.
+ * If the application is asking about a previous call to memp_sync(),
+ * and we haven't found any buffers that the application holding the
+ * pin couldn't write, return yes or no based on the current count.
+ * Note, if the application is asking about a LSN *smaller* than one
+ * we've already handled or are currently handling, then we return a
+ * result based on the count for the larger LSN.
*/
mp = dbmp->mp;
if (!F_ISSET(mp, MP_LSN_RETRY) && log_compare(lsnp, &mp->lsn) <= 0) {
@@ -61,9 +77,7 @@ memp_sync(dbmp, lsnp)
ret = 0;
} else
ret = DB_INCOMPLETE;
-
- UNLOCKREGION(dbmp);
- return (ret);
+ goto done;
}
/* Else, it's a new checkpoint. */
@@ -74,7 +88,7 @@ memp_sync(dbmp, lsnp)
* for which we were already doing a checkpoint. (BTW, I don't expect
* to see multiple LSN's from the same or multiple processes, but You
* Just Never Know. Responding as if they all called with the largest
- * of the LSNs specified makes everything work.
+ * of the LSNs specified makes everything work.)
*
* We don't currently use the LSN we save. We could potentially save
* the last-written LSN in each buffer header and use it to determine
@@ -93,64 +107,127 @@ memp_sync(dbmp, lsnp)
/*
* Walk the list of buffers and mark all dirty buffers to be written
- * and all pinned buffers to be potentially written. We do this in
- * single fell swoop while holding the region locked so that processes
- * can't make new buffers dirty, causing us to never finish. Since
- * the application may have restarted the sync, clear any BH_WRITE
- * flags that appear to be left over.
+ * and all pinned buffers to be potentially written (we can't know if
+ * we'll need to write them until the holding process returns them to
+ * the cache). We do this in one pass while holding the region locked
+ * so that processes can't make new buffers dirty, causing us to never
+ * finish. Since the application may have restarted the sync, clear
+ * any BH_WRITE flags that appear to be left over from previous calls.
+ *
+ * Keep a count of the total number of buffers we need to write in
+ * MPOOL->lsn_cnt, and for each file, in MPOOLFILE->lsn_count.
*/
- can_write = lsn_cnt = 0;
- for (lsn_cnt = 0, bhp = SH_TAILQ_FIRST(&mp->bhq, __bh);
+ ar_cnt = 0;
+ for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh);
bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh))
if (F_ISSET(bhp, BH_DIRTY) || bhp->ref != 0) {
F_SET(bhp, BH_WRITE);
- if (bhp->ref == 0)
- can_write = 1;
+ ++mp->lsn_cnt;
- mfp = ADDR(dbmp, bhp->mf_offset);
+ mfp = R_ADDR(dbmp, bhp->mf_offset);
++mfp->lsn_cnt;
- ++lsn_cnt;
+ /*
+ * If the buffer isn't in use, we should be able to
+ * write it immediately, so save a reference to it.
+ */
+ if (bhp->ref == 0) {
+ if (ar_cnt == nalloc) {
+ nalloc *= 2;
+ if ((bharray =
+ (BH **)__db_realloc(bharray,
+ nalloc * sizeof(BH *))) == NULL) {
+ ret = ENOMEM;
+ goto err;
+ }
+ }
+ bharray[ar_cnt++] = bhp;
+ }
} else
F_CLR(bhp, BH_WRITE);
- mp->lsn_cnt = lsn_cnt;
-
- /* If there no buffers we can write, we're done. */
- if (!can_write) {
- UNLOCKREGION(dbmp);
- return (mp->lsn_cnt ? DB_INCOMPLETE : 0);
+ /* If there no buffers we can write immediately, we're done. */
+ if (ar_cnt == 0) {
+ ret = mp->lsn_cnt ? DB_INCOMPLETE : 0;
+ goto done;
}
- /*
- * Write any buffers that we can. Restart the walk after each write,
- * __memp_pgwrite() discards and reacquires the region lock during I/O.
- */
-retry: for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh);
- bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) {
- /* Ignore pinned or locked buffers. */
- if (!F_ISSET(bhp, BH_WRITE) ||
- bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED))
- continue;
+ /* Lock down the buffers and their contents. */
+ for (cnt = 0; cnt < ar_cnt; ++cnt)
+ ++bharray[cnt]->ref;
- mfp = ADDR(dbmp, bhp->mf_offset);
- if ((ret =
- __memp_bhwrite(dbmp, mfp, bhp, &restart, &wrote)) != 0)
- goto err;
- if (wrote) {
- if (restart)
- goto retry;
+ UNLOCKREGION(dbmp);
+
+ /* Sort the buffers we're going to write. */
+ qsort(bharray, ar_cnt, sizeof(BH *), __bhcmp);
+
+ LOCKREGION(dbmp);
+
+ /* Walk the array, writing buffers. */
+ for (next = 0; next < ar_cnt; ++next) {
+ /*
+ * It's possible for a thread to have gotten the buffer since
+ * we listed it for writing. If the reference count is still
+ * 1, we're the only ones using the buffer, go ahead and write.
+ * If it's >1, then skip the buffer and assume that it will be
+ * written when it's returned to the cache.
+ */
+ if (bharray[next]->ref > 1) {
+ --bharray[next]->ref;
continue;
}
- __db_err(dbenv, "%s: unable to flush page: %lu",
- ADDR(dbmp, mfp->path_off), (u_long)bhp->pgno);
- ret = EPERM;
- goto err;
+
+ /* Write the buffer. */
+ mfp = R_ADDR(dbmp, bharray[next]->mf_offset);
+ ret =
+ __memp_bhwrite(dbmp, mfp, bharray[next], &notused, &wrote);
+
+ /* Release the buffer. */
+ --bharray[next]->ref;
+
+ /* If there's an error, release the rest of the buffers. */
+ if (ret != 0 || !wrote) {
+ while (++next < ar_cnt)
+ --bharray[next]->ref;
+
+ if (ret != 0)
+ goto err;
+
+ /*
+ * Any process syncing the shared memory buffer pool
+ * had better be able to write to any underlying file.
+ * Be understanding, but firm, on this point.
+ */
+ if (!wrote) {
+ __db_err(dbenv, "%s: unable to flush page: %lu",
+ R_ADDR(dbmp, mfp->path_off),
+ (u_long)bharray[next]->pgno);
+ ret = EPERM;
+ goto err;
+ }
+ }
}
ret = mp->lsn_cnt ? DB_INCOMPLETE : 0;
-err: UNLOCKREGION(dbmp);
+done:
+ if (0) {
+err: /*
+ * On error, clear:
+ * MPOOL->lsn_cnt (the total sync count)
+ * MPOOLFILE->lsn_cnt (the per-file sync count)
+ * BH_WRITE flag (the scheduled for writing flag)
+ */
+ mp->lsn_cnt = 0;
+ for (mfp = SH_TAILQ_FIRST(&dbmp->mp->mpfq, __mpoolfile);
+ mfp != NULL; mfp = SH_TAILQ_NEXT(mfp, q, __mpoolfile))
+ mfp->lsn_cnt = 0;
+ for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh);
+ bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh))
+ F_CLR(bhp, BH_WRITE);
+ }
+ UNLOCKREGION(dbmp);
+ __db_free(bharray);
return (ret);
}
@@ -162,10 +239,10 @@ int
memp_fsync(dbmfp)
DB_MPOOLFILE *dbmfp;
{
- BH *bhp;
+ BH *bhp, **bharray;
DB_MPOOL *dbmp;
size_t mf_offset;
- int pincnt, restart, ret, wrote;
+ int ar_cnt, cnt, nalloc, next, pincnt, notused, ret, wrote;
/*
* If this handle doesn't have a file descriptor that's open for
@@ -175,35 +252,205 @@ memp_fsync(dbmfp)
if (F_ISSET(dbmfp, MP_READONLY | MP_PATH_TEMP))
return (0);
- dbmp = dbmfp->dbmp;
ret = 0;
+ dbmp = dbmfp->dbmp;
+ mf_offset = R_OFFSET(dbmp, dbmfp->mfp);
- mf_offset = OFFSET(dbmp, dbmfp->mfp);
+ /*
+ * We try and write the buffers in page order so that the underlying
+ * filesystem doesn't have to seek and can write contiguous blocks,
+ * plus, we don't want to hold the region lock while we write the
+ * buffers. Get memory to hold the buffer pointers. Get a good-size
+ * block, too, because we realloc while holding the region lock if we
+ * run out.
+ */
+ nalloc = 1024;
+ if ((bharray =
+ (BH **)__db_malloc((size_t)nalloc * sizeof(BH *))) == NULL)
+ return (ENOMEM);
LOCKREGION(dbmp);
/*
- * Walk the list of buffer headers for the MPOOLFILE, and write out any
- * dirty buffers that we can.
+ * Walk the LRU list of buffer headers, and get a list of buffers to
+ * write for this MPOOLFILE.
*/
-retry: pincnt = 0;
+ ar_cnt = pincnt = 0;
for (bhp = SH_TAILQ_FIRST(&dbmp->mp->bhq, __bh);
- bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh))
- if (F_ISSET(bhp, BH_DIRTY) && bhp->mf_offset == mf_offset) {
- if (bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED)) {
- ++pincnt;
- continue;
- }
- if ((ret =
- __memp_pgwrite(dbmfp, bhp, &restart, &wrote)) != 0)
+ bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) {
+ if (!F_ISSET(bhp, BH_DIRTY) || bhp->mf_offset != mf_offset)
+ continue;
+ if (bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED)) {
+ ++pincnt;
+ continue;
+ }
+
+ if (ar_cnt == nalloc) {
+ nalloc *= 2;
+ if ((bharray = (BH **)__db_realloc(bharray,
+ nalloc * sizeof(BH *))) == NULL) {
+ ret = ENOMEM;
goto err;
- if (!wrote)
- ++pincnt;
- if (restart)
- goto retry;
+ }
+ }
+
+ bharray[ar_cnt++] = bhp;
+ }
+
+ /* Lock down the buffers and their contents. */
+ for (cnt = 0; cnt < ar_cnt; ++cnt)
+ ++bharray[cnt]->ref;
+
+ UNLOCKREGION(dbmp);
+
+ /* Sort the buffers we're going to write. */
+ qsort(bharray, ar_cnt, sizeof(BH *), __bhcmp);
+
+ LOCKREGION(dbmp);
+
+ /* Walk the array, writing buffers. */
+ for (next = 0; next < ar_cnt; ++next) {
+ /*
+ * It's possible for a thread to have gotten the buffer since
+ * we listed it for writing. If the reference count is still
+ * 1, we're the only ones using the buffer, go ahead and write.
+ * If it's >1, then skip the buffer and assume that it will be
+ * written when it's returned to the cache.
+ */
+ if (bharray[next]->ref > 1) {
+ ++pincnt;
+
+ --bharray[next]->ref;
+ continue;
}
+ /* Write the buffer. */
+ ret = __memp_pgwrite(dbmfp, bharray[next], &notused, &wrote);
+
+ /* Release the buffer. */
+ --bharray[next]->ref;
+
+ /* If there's an error, release the rest of the buffers. */
+ if (ret != 0) {
+ while (++next < ar_cnt)
+ --bharray[next]->ref;
+ goto err;
+ }
+ if (!wrote)
+ ++pincnt;
+ }
+
+err: UNLOCKREGION(dbmp);
+
+ __db_free(bharray);
+
+ /*
+ * Sync the underlying file as the last thing we do, so that the OS
+ * has maximal opportunity to flush buffers before we request it.
+ *
+ * XXX:
+ * Don't lock the region around the sync, fsync(2) has no atomicity
+ * issues.
+ */
+ if (ret == 0)
+ return (pincnt == 0 ? __db_fsync(dbmfp->fd) : DB_INCOMPLETE);
+ return (ret);
+
+}
+
+/*
+ * memp_trickle --
+ * Keep a specified percentage of the buffers clean.
+ */
+int
+memp_trickle(dbmp, pct, nwrotep)
+ DB_MPOOL *dbmp;
+ int pct, *nwrotep;
+{
+ BH *bhp;
+ MPOOL *mp;
+ MPOOLFILE *mfp;
+ u_long total;
+ int notused, ret, wrote;
+
+ mp = dbmp->mp;
+ if (nwrotep != NULL)
+ *nwrotep = 0;
+
+ if (pct < 1 || pct > 100)
+ return (EINVAL);
+
+ LOCKREGION(dbmp);
+
+ /*
+ * If there are sufficient clean buffers, or no buffers or no dirty
+ * buffers, we're done.
+ *
+ * XXX
+ * Using st_page_clean and st_page_dirty is our only choice at the
+ * moment, but it's not as correct as we might like in the presence
+ * of pools with more than one buffer size, as a free 512-byte buffer
+ * isn't the same as a free 8K buffer.
+ */
+loop: total = mp->stat.st_page_clean + mp->stat.st_page_dirty;
+ if (total == 0 || mp->stat.st_page_dirty == 0 ||
+ (mp->stat.st_page_clean * 100) / total >= (u_long)pct) {
+ UNLOCKREGION(dbmp);
+ return (0);
+ }
+
+ /* Loop until we write a buffer. */
+ for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh);
+ bhp != NULL; bhp = SH_TAILQ_NEXT(bhp, q, __bh)) {
+ if (bhp->ref != 0 ||
+ !F_ISSET(bhp, BH_DIRTY) || F_ISSET(bhp, BH_LOCKED))
+ continue;
+
+ mfp = R_ADDR(dbmp, bhp->mf_offset);
+ if ((ret =
+ __memp_bhwrite(dbmp, mfp, bhp, &notused, &wrote)) != 0)
+ goto err;
+
+ /*
+ * Any process syncing the shared memory buffer pool
+ * had better be able to write to any underlying file.
+ * Be understanding, but firm, on this point.
+ */
+ if (!wrote) {
+ __db_err(dbmp->dbenv, "%s: unable to flush page: %lu",
+ R_ADDR(dbmp, mfp->path_off), (u_long)bhp->pgno);
+ ret = EPERM;
+ goto err;
+ }
+
+ ++mp->stat.st_page_trickle;
+ if (nwrotep != NULL)
+ ++*nwrotep;
+ goto loop;
+ }
+
+ /* No more buffers to write. */
+ return (0);
+
err: UNLOCKREGION(dbmp);
+ return (ret);
+}
+
+static int
+__bhcmp(p1, p2)
+ const void *p1, *p2;
+{
+ BH *bhp1, *bhp2;
+
+ bhp1 = *(BH **)p1;
+ bhp2 = *(BH **)p2;
+
+ /* Sort by file (shared memory pool offset). */
+ if (bhp1->mf_offset < bhp2->mf_offset)
+ return (-1);
+ if (bhp1->mf_offset > bhp2->mf_offset)
+ return (1);
- return (ret == 0 ? (pincnt ? DB_INCOMPLETE : 0) : ret);
+ /* Sort by page in file. */
+ return (bhp1->pgno < bhp2->pgno ? -1 : 1);
}
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