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ITS#7455 use freelist for overflow pages

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This commit is contained in:
Howard Chu 2012-11-28 17:13:26 -08:00
parent 185136397d
commit f165507199
1 changed files with 113 additions and 28 deletions
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141
libraries/libmdb/mdb.c
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@ -1242,6 +1242,7 @@ mdb_page_alloc(MDB_cursor *mc, int num, MDB_page **mp)
MDB_page *np;
pgno_t pgno = P_INVALID;
MDB_ID2 mid;
txnid_t oldest = 0, last;
int rc;
*mp = NULL;
@ -1254,12 +1255,11 @@ mdb_page_alloc(MDB_cursor *mc, int num, MDB_page **mp)
if (!txn->mt_env->me_pghead &&
txn->mt_dbs[FREE_DBI].md_root != P_INVALID) {
/* See if there's anything in the free DB */
int j;
MDB_reader *r;
MDB_cursor m2;
MDB_node *leaf;
MDB_val data;
txnid_t *kptr, last;
txnid_t *kptr;
mdb_cursor_init(&m2, txn, FREE_DBI, NULL);
if (!txn->mt_env->me_pgfirst) {
@ -1282,15 +1282,21 @@ again:
last = *(txnid_t *)key.mv_data;
}
/* Unusable if referred by a meta page or reader... */
j = 1;
if (last < txn->mt_txnid-1) {
j = txn->mt_env->me_txns->mti_numreaders;
r = txn->mt_env->me_txns->mti_readers + j;
for (j = -j; j && (last<r[j].mr_txnid || !r[j].mr_pid); j++) ;
{
unsigned int i, nr;
txnid_t mr;
oldest = txn->mt_txnid - 1;
nr = txn->mt_env->me_txns->mti_numreaders;
r = txn->mt_env->me_txns->mti_readers;
for (i=0; i<nr; i++) {
if (!r[i].mr_pid) continue;
mr = r[i].mr_txnid;
if (mr < oldest)
oldest = mr;
}
}
if (!j) {
if (oldest > last) {
/* It's usable, grab it.
*/
MDB_oldpages *mop;
@ -1331,29 +1337,108 @@ none:
if (txn->mt_env->me_pghead) {
MDB_oldpages *mop = txn->mt_env->me_pghead;
if (num > 1) {
/* FIXME: For now, always use fresh pages. We
* really ought to search the free list for a
* contiguous range.
*/
;
MDB_cursor m2;
int retry = 2, readit = 0, n2 = num-1;
unsigned int i, j, k;
/* If current list is too short, must fetch more and coalesce */
if (mop->mo_pages[0] < (unsigned)num)
readit = 1;
mdb_cursor_init(&m2, txn, FREE_DBI, NULL);
do {
if (readit) {
MDB_val key, data;
MDB_oldpages *mop2;
pgno_t *idl;
int exact;
last = mop->mo_txnid + 1;
/* We haven't hit the readers list yet? */
if (!oldest) {
MDB_reader *r;
unsigned int nr;
txnid_t mr;
oldest = txn->mt_txnid - 1;
nr = txn->mt_env->me_txns->mti_numreaders;
r = txn->mt_env->me_txns->mti_readers;
for (i=0; i<nr; i++) {
if (!r[i].mr_pid) continue;
mr = r[i].mr_txnid;
if (mr < oldest)
oldest = mr;
}
}
/* There's nothing we can use on the freelist */
if (oldest - last < 1)
break;
exact = 0;
key.mv_data = &last;
key.mv_size = sizeof(last);
rc = mdb_cursor_set(&m2, &key, &data, MDB_SET, &exact);
if (rc)
return rc;
idl = (MDB_ID *) data.mv_data;
mop2 = malloc(sizeof(MDB_oldpages) + MDB_IDL_SIZEOF(idl) - 2*sizeof(pgno_t) + MDB_IDL_SIZEOF(mop->mo_pages));
if (!mop2)
return ENOMEM;
/* merge in sorted order */
i = idl[0]; j = mop->mo_pages[0]; mop2->mo_pages[0] = k = i+j;
mop->mo_pages[0] = P_INVALID;
while (i>0 || j>0) {
if (i && idl[i] < mop->mo_pages[j])
mop2->mo_pages[k--] = idl[i--];
else
mop2->mo_pages[k--] = mop->mo_pages[j--];
}
txn->mt_env->me_pglast = last;
mop2->mo_txnid = last;
mop2->mo_next = mop->mo_next;
txn->mt_env->me_pghead = mop2;
free(mop);
mop = mop2;
/* Keep trying to read until we have enough */
if (mop->mo_pages[0] < (unsigned)num) {
continue;
}
}
/* current list has enough pages, but are they contiguous? */
for (i=mop->mo_pages[0]; i>=(unsigned)num; i--) {
if (mop->mo_pages[i-n2] == mop->mo_pages[i] + n2) {
pgno = mop->mo_pages[i];
i -= n2;
/* move any stragglers down */
for (j=i+num; j<=mop->mo_pages[0]; j++)
mop->mo_pages[i++] = mop->mo_pages[j];
mop->mo_pages[0] -= num;
break;
}
}
/* Stop if we succeeded, or no more retries */
if (!retry || pgno != P_INVALID)
break;
readit = 1;
retry--;
} while (1);
} else {
/* peel pages off tail, so we only have to truncate the list */
pgno = MDB_IDL_LAST(mop->mo_pages);
if (MDB_IDL_IS_RANGE(mop->mo_pages)) {
mop->mo_pages[2]++;
if (mop->mo_pages[2] > mop->mo_pages[1])
mop->mo_pages[0] = 0;
mop->mo_pages[0]--;
}
if (MDB_IDL_IS_ZERO(mop->mo_pages)) {
txn->mt_env->me_pghead = mop->mo_next;
if (mc->mc_dbi == FREE_DBI) {
mop->mo_next = txn->mt_env->me_pgfree;
txn->mt_env->me_pgfree = mop;
} else {
mop->mo_pages[0]--;
}
if (MDB_IDL_IS_ZERO(mop->mo_pages)) {
txn->mt_env->me_pghead = mop->mo_next;
if (mc->mc_dbi == FREE_DBI) {
mop->mo_next = txn->mt_env->me_pgfree;
txn->mt_env->me_pgfree = mop;
} else {
free(mop);
}
free(mop);
}
}
}