Commit 4a9ee2cb authored by Hallvard Furuseth's avatar Hallvard Furuseth
Browse files

ITS#7620: Keep empty IDLs. Tweak mdb_page_alloc().

MDB_env.me_pghead: Don't free it when empty. mdb_ovpage_free()
needs it, but cannot allocate it.
mdb_midl_alloc(): Fill in length=0.
mdb_page_alloc(): Also Skip freeDB if txnid<3, instead of <4,
and consistently DPRINTF consumed IDLs.
parent 1d94ea5b
......@@ -928,8 +928,8 @@ typedef struct MDB_xcursor {
/** 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. */
......@@ -1341,8 +1341,10 @@ static int
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;
......@@ -1353,13 +1355,11 @@ mdb_page_alloc(MDB_cursor *mc, int num, MDB_page **mp)
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;
......@@ -1391,24 +1391,22 @@ again:
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
......@@ -1420,11 +1418,15 @@ again:
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;
......@@ -1448,7 +1450,7 @@ none:
#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;
......@@ -1473,22 +1475,31 @@ none:
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;
......@@ -1519,10 +1530,6 @@ none:
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;
}
}
}
......@@ -1966,7 +1973,6 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned int flags, MDB_txn **ret)
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;
......@@ -2138,7 +2144,7 @@ mdb_freelist_save(MDB_txn *txn)
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)
......
......@@ -104,8 +104,10 @@ int mdb_midl_insert( MDB_IDL ids, MDB_ID id )
MDB_IDL mdb_midl_alloc(int num)
{
MDB_IDL ids = malloc((num+2) * sizeof(MDB_ID));
if (ids)
if (ids) {
*ids++ = num;
*ids = 0;
}
return ids;
}
......
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