static int
mdb_page_alloc(MDB_cursor *mc, int num, MDB_page **mp)
{
+#ifdef MDB_PARANOID /* Seems like we can ignore this now */
+ /* Get at most <Max_retries> more freeDB records once me_pghead
+ * has enough pages. If not enough, use new pages from the map.
+ * If <Paranoid> and mc is updating the freeDB, only get new
+ * records if me_pghead is empty. Then the freelist cannot play
+ * catch-up with itself by growing while trying to save it.
+ */
+ enum { Paranoid = 1, Max_retries = 500 };
+#else
+ enum { Paranoid = 0, Max_retries = INT_MAX /*infinite*/ };
+#endif
+ int rc, n2 = num-1, retry = Max_retries;
MDB_txn *txn = mc->mc_txn;
MDB_env *env = txn->mt_env;
- pgno_t pgno = P_INVALID, *mop = env->me_pghead;
+ pgno_t pgno, *mop = env->me_pghead;
unsigned mop_len = mop ? mop[0] : 0;
MDB_page *np;
MDB_ID2 mid;
txnid_t oldest = 0, last;
- int rc;
+ MDB_cursor_op op;
+ MDB_cursor m2;
*mp = NULL;
if (txn->mt_dirty_room == 0)
return MDB_TXN_FULL;
- /* Pages freed by txn#1 (after allocating but discarding them)
- * are used when txn#1 is unreferenced, i.e. txn#3.
- */
- if (txn->mt_txnid >= 3) {
- if (!mop_len && txn->mt_dbs[FREE_DBI].md_root != P_INVALID) {
- /* See if there's anything in the free DB */
- MDB_cursor m2;
- MDB_node *leaf;
- MDB_val data;
- txnid_t *kptr;
-
- mdb_cursor_init(&m2, txn, FREE_DBI, NULL);
- if (!txn->mt_env->me_pglast) {
- mdb_page_search(&m2, NULL, 0);
- leaf = NODEPTR(m2.mc_pg[m2.mc_top], 0);
- kptr = (txnid_t *)NODEKEY(leaf);
- last = *kptr;
- } else {
- MDB_val key;
-again:
- last = txn->mt_env->me_pglast + 1;
- leaf = NULL;
- key.mv_data = &last;
- key.mv_size = sizeof(last);
- rc = mdb_cursor_set(&m2, &key, &data, MDB_SET_RANGE, NULL);
- if (rc)
- goto none;
- last = *(txnid_t *)key.mv_data;
- }
-
- if (!oldest)
- oldest = mdb_find_oldest(txn);
-
- if (oldest > last) {
- /* It's usable, grab it.
- */
- pgno_t *idl;
+ for (op = MDB_FIRST;; op = MDB_NEXT) {
+ unsigned int i, j, k;
+ MDB_val key, data;
+ MDB_node *leaf;
+ pgno_t *idl, old_id, new_id;
- if (!txn->mt_env->me_pglast) {
- mdb_node_read(txn, leaf, &data);
- }
- idl = (MDB_ID *) data.mv_data;
- mop_len = idl[0];
- if (!mop) {
- if (!(env->me_pghead = mop = mdb_midl_alloc(mop_len)))
- return ENOMEM;
- } else if (mop_len > mop[-1]) {
- if ((rc = mdb_midl_grow(&env->me_pghead, mop_len)) != 0)
- return rc;
- mop = env->me_pghead;
+ /* Seek a big enough contiguous page range. Prefer
+ * pages at the tail, just truncating the list.
+ */
+ if (mop_len >= (unsigned)num) {
+ i = mop_len;
+ do {
+ pgno = mop[i];
+ if (mop[i-n2] == pgno+n2) {
+ mop[0] = mop_len -= num;
+ /* Move any stragglers down */
+ for (j = i-n2; j <= mop_len; )
+ mop[j++] = mop[++i];
+ goto search_done;
}
- txn->mt_env->me_pglast = last;
- memcpy(mop, idl, MDB_IDL_SIZEOF(idl));
+ } while (--i >= (unsigned)num);
+ if (Max_retries < INT_MAX && --retry < 0)
+ break;
+ }
-#if MDB_DEBUG > 1
- {
- unsigned int i;
- DPRINTF("IDL read txn %zu root %zu num %zu",
- last, txn->mt_dbs[FREE_DBI].md_root, idl[0]);
- for (i = idl[0]; i; i--)
- DPRINTF("IDL %zu", idl[i]);
- }
-#endif
- /* We might have a zero-length IDL due to freelist growth
- * during a prior commit
- */
- if (!mop_len)
- goto again;
+ if (op == MDB_FIRST) { /* 1st iteration */
+ /* Prepare to fetch more and coalesce */
+ oldest = mdb_find_oldest(txn);
+ last = env->me_pglast;
+ mdb_cursor_init(&m2, txn, FREE_DBI, NULL);
+ if (last) {
+ op = MDB_SET_RANGE;
+ key.mv_data = &last; /* will loop up last+1 */
+ key.mv_size = sizeof(last);
}
+ if (Paranoid && mc->mc_dbi == FREE_DBI)
+ retry = -1;
}
-none:
- if (mop_len) {
- if (num > 1) {
- MDB_cursor m2;
- int retry = 1, readit = 0, n2 = num-1;
- unsigned int i, j, k;
-
- /* If current list is too short, must fetch more and coalesce */
- if (mop[0] < (unsigned)num)
- readit = 1;
-
- mdb_cursor_init(&m2, txn, FREE_DBI, NULL);
- do {
-#ifdef MDB_PARANOID /* Seems like we can ignore this now */
- /* If on freelist, don't try to read more. If what we have
- * right now isn't enough just use new pages.
- * TODO: get all of this working. Many circular dependencies...
- */
- if (mc->mc_dbi == FREE_DBI) {
- retry = 0;
- readit = 0;
- }
-#endif
- if (readit) {
- MDB_val key, data;
- pgno_t *idl, old_id, new_id;
-
- last = txn->mt_env->me_pglast + 1;
-
- /* We haven't hit the readers list yet? */
- if (!oldest) {
- oldest = mdb_find_oldest(txn);
- }
+ if (Paranoid && retry < 0 && mop_len)
+ break;
- /* There's nothing we can use on the freelist */
- if (oldest - last < 1)
- break;
+ last++;
+ /* Do not fetch more if the record will be too recent */
+ if (oldest <= last)
+ break;
+ rc = mdb_cursor_get(&m2, &key, NULL, op);
+ if (rc) {
+ if (rc == MDB_NOTFOUND)
+ break;
+ return rc;
+ }
+ last = *(txnid_t*)key.mv_data;
+ if (oldest <= last)
+ break;
+ np = m2.mc_pg[m2.mc_top];
+ leaf = NODEPTR(np, m2.mc_ki[m2.mc_top]);
+ if ((rc = mdb_node_read(txn, leaf, &data)) != MDB_SUCCESS)
+ return rc;
- key.mv_data = &last;
- key.mv_size = sizeof(last);
- rc = mdb_cursor_set(&m2,&key,&data,MDB_SET_RANGE,NULL);
- if (rc) {
- if (rc == MDB_NOTFOUND)
- break;
- return rc;
- }
- last = *(txnid_t*)key.mv_data;
- if (oldest <= last)
- break;
- idl = (MDB_ID *) data.mv_data;
- i = idl[0];
- if (mop_len+i > mop[-1]) {
- if ((rc = mdb_midl_grow(&env->me_pghead, i)) != 0)
- return rc;
- mop = env->me_pghead;
- }
+ idl = (MDB_ID *) data.mv_data;
+ i = idl[0];
+ if (!mop) {
+ if (!(env->me_pghead = mop = mdb_midl_alloc(i)))
+ return ENOMEM;
+ } else if (mop_len+i > mop[-1]) {
+ if ((rc = mdb_midl_grow(&env->me_pghead, i)) != 0)
+ return rc;
+ mop = env->me_pghead;
+ }
+ env->me_pglast = last;
#if MDB_DEBUG > 1
- DPRINTF("IDL read txn %zu root %zu num %u",
- last, txn->mt_dbs[FREE_DBI].md_root, i);
- for (k = i; k; k--)
- DPRINTF("IDL %zu", idl[k]);
+ DPRINTF("IDL read txn %zu root %zu num %u",
+ last, txn->mt_dbs[FREE_DBI].md_root, i);
+ for (k = i; k; k--)
+ DPRINTF("IDL %zu", idl[k]);
#endif
- /* merge in sorted order */
- j = mop_len;
- k = mop_len += i;
- mop[0] = P_INVALID;
- old_id = mop[j];
- while (i) {
- new_id = idl[i--];
- for (; old_id < new_id; old_id = mop[--j])
- mop[k--] = old_id;
- mop[k--] = new_id;
- }
- mop[0] = mop_len;
- txn->mt_env->me_pglast = last;
- /* Keep trying to read until we have enough */
- if (mop[0] < (unsigned)num) {
- continue;
- }
- }
-
- /* current list has enough pages, but are they contiguous? */
- for (i=mop[0]; i>=(unsigned)num; i--) {
- if (mop[i-n2] == mop[i] + n2) {
- pgno = mop[i];
- i -= n2;
- /* move any stragglers down */
- for (j=i+num; j<=mop[0]; j++)
- mop[i++] = mop[j];
- mop[0] -= num;
- break;
- }
- }
-
- /* Stop if we succeeded, or no retries */
- if (!retry || pgno != P_INVALID)
- break;
- readit = 1;
-
- } while (1);
- } else {
- /* peel pages off tail, so we only have to truncate the list */
- pgno = MDB_IDL_LAST(mop);
- mop[0]--;
- }
- }
- }
-
- if (pgno == P_INVALID) {
- /* DB size is maxed out */
- if (txn->mt_next_pgno + num >= txn->mt_env->me_maxpg) {
+ /* Merge in descending sorted order */
+ j = mop_len;
+ k = mop_len += i;
+ mop[0] = (pgno_t)-1;
+ old_id = mop[j];
+ while (i) {
+ new_id = idl[i--];
+ for (; old_id < new_id; old_id = mop[--j])
+ mop[k--] = old_id;
+ mop[k--] = new_id;
+ }
+ mop[0] = mop_len;
+ }
+
+ /* Use new pages from the map when nothing suitable in the freeDB */
+ pgno = P_INVALID;
+ if (txn->mt_next_pgno + num >= env->me_maxpg) {
DPUTS("DB size maxed out");
return MDB_MAP_FULL;
- }
}
- if (txn->mt_env->me_flags & MDB_WRITEMAP) {
+
+search_done:
+ if (env->me_flags & MDB_WRITEMAP) {
if (pgno == P_INVALID) {
pgno = txn->mt_next_pgno;
txn->mt_next_pgno += num;
}
- np = (MDB_page *)(txn->mt_env->me_map + txn->mt_env->me_psize * pgno);
- np->mp_pgno = pgno;
+ np = (MDB_page *)(env->me_map + env->me_psize * pgno);
} else {
if (!(np = mdb_page_malloc(mc, num)))
return ENOMEM;
if (pgno == P_INVALID) {
- np->mp_pgno = txn->mt_next_pgno;
+ pgno = txn->mt_next_pgno;
txn->mt_next_pgno += num;
- } else {
- np->mp_pgno = pgno;
}
}
- mid.mid = np->mp_pgno;
+ mid.mid = np->mp_pgno = pgno;
mid.mptr = np;
- if (txn->mt_env->me_flags & MDB_WRITEMAP) {
+ if (env->me_flags & MDB_WRITEMAP) {
mdb_mid2l_append(txn->mt_u.dirty_list, &mid);
} else {
mdb_mid2l_insert(txn->mt_u.dirty_list, &mid);
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