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-rw-r--r--db2/mp/mp_region.c340
1 files changed, 340 insertions, 0 deletions
diff --git a/db2/mp/mp_region.c b/db2/mp/mp_region.c
new file mode 100644
index 0000000000..a5c52123b9
--- /dev/null
+++ b/db2/mp/mp_region.c
@@ -0,0 +1,340 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996, 1997
+ * Sleepycat Software. All rights reserved.
+ */
+#include "config.h"
+
+#ifndef lint
+static const char sccsid[] = "@(#)mp_region.c 10.11 (Sleepycat) 8/2/97";
+#endif /* not lint */
+
+#ifndef NO_SYSTEM_INCLUDES
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.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"
+
+/*
+ * __memp_ralloc --
+ * Allocate some space in the mpool region.
+ *
+ * PUBLIC: int __memp_ralloc __P((DB_MPOOL *, size_t, size_t *, void *));
+ */
+int
+__memp_ralloc(dbmp, len, offsetp, retp)
+ DB_MPOOL *dbmp;
+ size_t len, *offsetp;
+ void *retp;
+{
+ BH *bhp, *nbhp;
+ MPOOL *mp;
+ MPOOLFILE *mfp;
+ size_t fsize, total;
+ int nomore, restart, ret, wrote;
+ void *p;
+
+ mp = dbmp->mp;
+
+ nomore = 0;
+alloc: if ((ret = __db_shalloc(dbmp->addr, len, MUTEX_ALIGNMENT, &p)) == 0) {
+ if (offsetp != NULL)
+ *offsetp = OFFSET(dbmp, p);
+ *(void **)retp = p;
+ return (0);
+ }
+ if (nomore) {
+ __db_err(dbmp->dbenv, "%s", strerror(ret));
+ return (ret);
+ }
+
+ /* Look for a buffer on the free list that's the right size. */
+ for (bhp =
+ SH_TAILQ_FIRST(&mp->bhfq, __bh); bhp != NULL; bhp = nbhp) {
+ nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
+
+ if (__db_shsizeof(bhp) == len) {
+ SH_TAILQ_REMOVE(&mp->bhfq, bhp, q, __bh);
+ if (offsetp != NULL)
+ *offsetp = OFFSET(dbmp, bhp);
+ *(void **)retp = bhp;
+ return (0);
+ }
+ }
+
+ /* Discard from the free list until we've freed enough memory. */
+ total = 0;
+ for (bhp =
+ SH_TAILQ_FIRST(&mp->bhfq, __bh); bhp != NULL; bhp = nbhp) {
+ nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
+
+ SH_TAILQ_REMOVE(&mp->bhfq, bhp, q, __bh);
+ __db_shalloc_free(dbmp->addr, bhp);
+
+ /*
+ * Retry as soon as we've freed up sufficient space. If we
+ * have to coalesce of memory to satisfy the request, don't
+ * try until it's likely (possible?) that we'll succeed.
+ */
+ total += fsize = __db_shsizeof(bhp);
+ if (fsize >= len || total >= 3 * len)
+ goto alloc;
+ }
+
+retry: /* Find a buffer we can flush; pure LRU. */
+ total = 0;
+ for (bhp =
+ SH_TAILQ_FIRST(&mp->bhq, __bh); bhp != NULL; bhp = nbhp) {
+ nbhp = SH_TAILQ_NEXT(bhp, q, __bh);
+
+ /* Ignore pinned or locked (I/O in progress) buffers. */
+ if (bhp->ref != 0 || F_ISSET(bhp, BH_LOCKED))
+ continue;
+
+ /* Find the associated MPOOLFILE. */
+ mfp = ADDR(dbmp, bhp->mf_offset);
+
+ /*
+ * Write the page if it's dirty.
+ *
+ * If we wrote the page, fall through and free the buffer. We
+ * don't have to rewalk the list to acquire the buffer because
+ * it was never available for any other process to modify it.
+ * If we didn't write the page, but we discarded and reacquired
+ * the region lock, restart the buffer list walk. If we neither
+ * wrote the buffer nor discarded the region lock, continue down
+ * the buffer list.
+ */
+ if (F_ISSET(bhp, BH_DIRTY)) {
+ if ((ret = __memp_bhwrite(dbmp,
+ mfp, bhp, &restart, &wrote)) != 0)
+ return (ret);
+
+ /*
+ * It's possible that another process wants this buffer
+ * and incremented the ref count while we were writing
+ * it.
+ */
+ if (bhp->ref != 0)
+ goto retry;
+
+ if (wrote)
+ ++mp->stat.st_rw_evict;
+ else {
+ if (restart)
+ goto retry;
+ else
+ continue;
+ }
+ } else
+ ++mp->stat.st_ro_evict;
+
+ /*
+ * Check to see if the buffer is the size we're looking for.
+ * If it is, simply reuse it.
+ */
+ total += fsize = __db_shsizeof(bhp);
+ if (fsize == len) {
+ __memp_bhfree(dbmp, mfp, bhp, 0);
+
+ if (offsetp != NULL)
+ *offsetp = OFFSET(dbmp, bhp);
+ *(void **)retp = bhp;
+ return (0);
+ }
+
+ /* Free the buffer. */
+ __memp_bhfree(dbmp, mfp, bhp, 1);
+
+ /*
+ * Retry as soon as we've freed up sufficient space. If we
+ * have to coalesce of memory to satisfy the request, don't
+ * try until it's likely (possible?) that we'll succeed.
+ */
+ if (fsize >= len || total >= 3 * len)
+ goto alloc;
+
+ /* Restart the walk if we discarded the region lock. */
+ if (restart)
+ goto retry;
+ }
+ nomore = 1;
+ goto alloc;
+}
+
+/*
+ * __memp_ropen --
+ * Attach to, and optionally create, the mpool region.
+ *
+ * PUBLIC: int __memp_ropen
+ * PUBLIC: __P((DB_MPOOL *, const char *, size_t, int, int));
+ */
+int
+__memp_ropen(dbmp, path, cachesize, mode, flags)
+ DB_MPOOL *dbmp;
+ const char *path;
+ size_t cachesize;
+ int mode, flags;
+{
+ MPOOL *mp;
+ size_t rlen;
+ int fd, newregion, ret, retry_cnt;
+
+ /*
+ * Unlike other DB subsystems, mpool can't simply grow the region
+ * because it returns pointers into the region to its clients. To
+ * "grow" the region, we'd have to allocate a new region and then
+ * store a region number in the structures that reference regional
+ * objects. It's reasonable that we fail regardless, as clients
+ * shouldn't have every page in the region pinned, so the only
+ * "failure" mode should be a performance penalty because we don't
+ * find a page in the cache that we'd like to have found.
+ *
+ * Up the user's cachesize by 25% to account for our overhead.
+ */
+ if (cachesize < DB_CACHESIZE_MIN)
+ if (cachesize == 0)
+ cachesize = DB_CACHESIZE_DEF;
+ else
+ cachesize = DB_CACHESIZE_MIN;
+ rlen = cachesize + cachesize / 4;
+
+ /* Map in the region. */
+ retry_cnt = newregion = 0;
+retry: if (LF_ISSET(DB_CREATE)) {
+ /*
+ * If it's a private mpool, use malloc, it's a lot faster than
+ * instantiating a region.
+ *
+ * XXX
+ * If we're doing locking and don't have spinlocks for this
+ * architecture, we'd have to instantiate the file, we need
+ * the file descriptor for locking. However, it should not
+ * be possible for DB_THREAD to be set if HAVE_SPINLOCKS aren't
+ * defined.
+ */
+ if (F_ISSET(dbmp, MP_ISPRIVATE))
+ ret = (dbmp->maddr = malloc(rlen)) == NULL ? ENOMEM : 0;
+ else
+ ret = __db_rcreate(dbmp->dbenv, DB_APP_NONE, path,
+ DB_DEFAULT_MPOOL_FILE, mode, rlen, &fd,
+ &dbmp->maddr);
+ if (ret == 0) {
+ /* Put the MPOOL structure first in the region. */
+ mp = dbmp->maddr;
+
+ SH_TAILQ_INIT(&mp->bhq);
+ SH_TAILQ_INIT(&mp->bhfq);
+ SH_TAILQ_INIT(&mp->mpfq);
+
+ /* Initialize the rest of the region as free space. */
+ dbmp->addr = (u_int8_t *)dbmp->maddr + sizeof(MPOOL);
+ __db_shalloc_init(dbmp->addr, rlen - sizeof(MPOOL));
+
+ /*
+ *
+ * Pretend that the cache will be broken up into 4K
+ * pages, and that we want to keep it under, say, 10
+ * pages on each chain. This means a 256MB cache will
+ * allocate ~6500 offset pairs.
+ */
+ mp->htab_buckets =
+ __db_tablesize((cachesize / (4 * 1024)) / 10);
+
+ /* Allocate hash table space and initialize it. */
+ if ((ret = __db_shalloc(dbmp->addr,
+ mp->htab_buckets * sizeof(DB_HASHTAB),
+ 0, &dbmp->htab)) != 0)
+ goto err;
+ __db_hashinit(dbmp->htab, mp->htab_buckets);
+ mp->htab = OFFSET(dbmp, dbmp->htab);
+
+ memset(&mp->stat, 0, sizeof(mp->stat));
+ mp->stat.st_cachesize = cachesize;
+
+ mp->flags = 0;
+
+ newregion = 1;
+ } else if (ret != EEXIST)
+ return (ret);
+ }
+
+ /* If we didn't or couldn't create the region, try and join it. */
+ if (!newregion &&
+ (ret = __db_ropen(dbmp->dbenv, DB_APP_NONE,
+ path, DB_DEFAULT_MPOOL_FILE, 0, &fd, &dbmp->maddr)) != 0) {
+ /*
+ * If we failed because the file wasn't available, wait a
+ * second and try again.
+ */
+ if (ret == EAGAIN && ++retry_cnt < 3) {
+ (void)__db_sleep(1, 0);
+ goto retry;
+ }
+ return (ret);
+ }
+
+ /* Set up the common pointers. */
+ dbmp->mp = dbmp->maddr;
+ dbmp->addr = (u_int8_t *)dbmp->maddr + sizeof(MPOOL);
+
+ /*
+ * If not already locked, lock the region -- if it's a new region,
+ * then either __db_rcreate() locked it for us or we malloc'd it
+ * instead of creating a region, neither of which requires locking
+ * here.
+ */
+ if (!newregion)
+ LOCKREGION(dbmp);
+
+ /*
+ * Get the hash table address; it's on the shared page, so we have
+ * to lock first.
+ */
+ dbmp->htab = ADDR(dbmp, dbmp->mp->htab);
+
+ dbmp->fd = fd;
+
+ /* If we locked the region, release it now. */
+ if (!F_ISSET(dbmp, MP_ISPRIVATE))
+ UNLOCKREGION(dbmp);
+ return (0);
+
+err: if (fd != -1) {
+ dbmp->fd = fd;
+ (void)__memp_rclose(dbmp);
+ }
+
+ if (newregion)
+ (void)memp_unlink(path, 1, dbmp->dbenv);
+ return (ret);
+}
+
+/*
+ * __memp_rclose --
+ * Close the mpool region.
+ *
+ * PUBLIC: int __memp_rclose __P((DB_MPOOL *));
+ */
+int
+__memp_rclose(dbmp)
+ DB_MPOOL *dbmp;
+{
+ if (F_ISSET(dbmp, MP_ISPRIVATE)) {
+ free(dbmp->maddr);
+ return (0);
+ }
+ return (__db_rclose(dbmp->dbenv, dbmp->fd, dbmp->maddr));
+}
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