/** State of FreeDB old pages, stored in the MDB_env */
typedef struct MDB_pgstate {
- txnid_t mf_pglast; /**< ID of last old page record we used */
- pgno_t *mf_pghead; /**< old pages reclaimed from freelist */
+ pgno_t *mf_pghead; /**< Reclaimed freeDB pages, or NULL before use */
+ txnid_t mf_pglast; /**< ID of last used record, or 0 if !mf_pghead */
} MDB_pgstate;
/** The database environment. */
mdb_page_alloc(MDB_cursor *mc, int num, MDB_page **mp)
{
MDB_txn *txn = mc->mc_txn;
+ MDB_env *env = txn->mt_env;
+ pgno_t pgno = P_INVALID, *mop = env->me_pghead;
+ unsigned mop_len = mop ? mop[0] : 0;
MDB_page *np;
- pgno_t pgno = P_INVALID;
MDB_ID2 mid;
txnid_t oldest = 0, last;
int rc;
if (txn->mt_dirty_room == 0)
return MDB_TXN_FULL;
- /* The free list won't have any content at all until txn 2 has
- * committed. The pages freed by txn 2 will be unreferenced
- * after txn 3 commits, and so will be safe to re-use in txn 4.
+ /* 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 (!txn->mt_env->me_pghead &&
- txn->mt_dbs[FREE_DBI].md_root != P_INVALID) {
+ 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;
if (oldest > last) {
/* It's usable, grab it.
*/
- pgno_t *idl, *mop;
+ pgno_t *idl;
if (!txn->mt_env->me_pglast) {
mdb_node_read(txn, leaf, &data);
}
idl = (MDB_ID *) data.mv_data;
- /* We might have a zero-length IDL due to freelist growth
- * during a prior commit
- */
- if (!idl[0]) {
- txn->mt_env->me_pglast = last;
- goto again;
+ 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;
}
- mop = mdb_midl_alloc(idl[0]);
- if (!mop)
- return ENOMEM;
txn->mt_env->me_pglast = last;
- txn->mt_env->me_pghead = mop;
memcpy(mop, idl, MDB_IDL_SIZEOF(idl));
#if MDB_DEBUG > 1
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;
}
}
none:
- if (txn->mt_env->me_pghead) {
- pgno_t *mop = txn->mt_env->me_pghead;
+ if (mop_len) {
if (num > 1) {
MDB_cursor m2;
int retry = 1, readit = 0, n2 = num-1;
#endif
if (readit) {
MDB_val key, data;
- pgno_t *idl, *mop2;
+ pgno_t *idl, old_id, new_id;
last = txn->mt_env->me_pglast + 1;
if (oldest <= last)
break;
idl = (MDB_ID *) data.mv_data;
- mop2 = mdb_midl_alloc(idl[0] + mop[0]);
- if (!mop2)
- return ENOMEM;
+ 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;
+ }
+#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]);
+#endif
/* merge in sorted order */
- i = idl[0]; j = mop[0]; mop2[0] = k = i+j;
+ j = mop_len;
+ k = mop_len += i;
mop[0] = P_INVALID;
- while (i>0 || j>0) {
- if (i && idl[i] < mop[j])
- mop2[k--] = idl[i--];
- else
- mop2[k--] = mop[j--];
+ 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;
- mdb_midl_free(txn->mt_env->me_pghead);
- txn->mt_env->me_pghead = mop2;
- mop = mop2;
/* Keep trying to read until we have enough */
if (mop[0] < (unsigned)num) {
continue;
pgno = MDB_IDL_LAST(mop);
mop[0]--;
}
- if (MDB_IDL_IS_ZERO(mop)) {
- mdb_midl_free(txn->mt_env->me_pghead);
- txn->mt_env->me_pghead = NULL;
- }
}
}
txn->mt_toggle = parent->mt_toggle;
txn->mt_dirty_room = parent->mt_dirty_room;
txn->mt_u.dirty_list[0].mid = 0;
- txn->mt_free_pgs[0] = 0;
txn->mt_next_pgno = parent->mt_next_pgno;
parent->mt_child = txn;
txn->mt_parent = parent;
mdb_cursor_init(&mc, txn, FREE_DBI, NULL);
- if (env->me_pghead || env->me_pglast) {
+ if (env->me_pghead) {
/* Make sure first page of freeDB is touched and on freelist */
rc = mdb_page_search(&mc, NULL, MDB_PS_MODIFY);
if (rc && rc != MDB_NOTFOUND)
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