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mdbx: alter mdbx_rebalance().

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This commit is contained in:
Leo Yuriev 2018-09-09 21:51:04 +03:00
parent ff738f1512
commit 76f7c118c6
1 changed files with 70 additions and 49 deletions
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97
src/mdbx.c
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@ -10011,12 +10011,14 @@ static void mdbx_cursor_copy(const MDBX_cursor *csrc, MDBX_cursor *cdst) {
* Returns 0 on success, non-zero on failure. */
static int mdbx_rebalance(MDBX_cursor *mc) {
MDBX_node *node;
int rc, fromleft;
unsigned ptop, minkeys, thresh;
MDBX_cursor mn;
indx_t oldki;
int rc;
unsigned minkeys, thresh;
if (IS_BRANCH(mc->mc_pg[mc->mc_top])) {
mdbx_cassert(mc, mc->mc_snum > 0);
mdbx_cassert(mc, mc->mc_snum < mc->mc_db->md_depth ||
IS_LEAF(mc->mc_pg[mc->mc_db->md_depth - 1]));
const int pagetype = PAGETYPE(mc->mc_pg[mc->mc_top]);
if (pagetype == P_BRANCH) {
minkeys = 2;
thresh = 1;
} else {
@ -10024,9 +10026,9 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
thresh = FILL_THRESHOLD;
}
mdbx_debug("rebalancing %s page %" PRIaPGNO " (has %u keys, %.1f%% full)",
IS_LEAF(mc->mc_pg[mc->mc_top]) ? "leaf" : "branch",
(pagetype & P_LEAF) ? "leaf" : "branch",
mc->mc_pg[mc->mc_top]->mp_pgno, NUMKEYS(mc->mc_pg[mc->mc_top]),
(float)PAGEFILL(mc->mc_txn->mt_env, mc->mc_pg[mc->mc_top]) / 10);
PAGEFILL(mc->mc_txn->mt_env, mc->mc_pg[mc->mc_top]) / 10.24);
if (PAGEFILL(mc->mc_txn->mt_env, mc->mc_pg[mc->mc_top]) >= thresh &&
NUMKEYS(mc->mc_pg[mc->mc_top]) >= minkeys) {
@ -10042,6 +10044,7 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
mdbx_cassert(mc, (mc->mc_db->md_entries == 0) == (nkeys == 0));
if (IS_SUBP(mp)) {
mdbx_debug("Can't rebalance a subpage, ignoring");
mdbx_cassert(mc, pagetype & P_LEAF);
return MDBX_SUCCESS;
}
if (nkeys == 0) {
@ -10056,7 +10059,7 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
if (mc->mc_flags & C_SUB)
mdbx_outer_db(mc)->md_leaf_pages -= 1;
rc = mdbx_pnl_append(&mc->mc_txn->mt_befree_pages, mp->mp_pgno);
if (unlikely(rc))
if (unlikely(rc != MDBX_SUCCESS))
return rc;
/* Adjust cursors pointing to mp */
const MDBX_dbi dbi = mc->mc_dbi;
@ -10064,7 +10067,8 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
m2 = m2->mc_next) {
MDBX_cursor *m3 =
(mc->mc_flags & C_SUB) ? &m2->mc_xcursor->mx_cursor : m2;
if (!(m3->mc_flags & C_INITIALIZED) || (m3->mc_snum < mc->mc_snum))
if (m3 == mc || !(m3->mc_flags & C_INITIALIZED) ||
(m3->mc_snum < mc->mc_snum))
continue;
if (m3->mc_pg[0] == mp) {
m3->mc_snum = 0;
@ -10082,7 +10086,7 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
return rc;
mc->mc_db->md_root = NODEPGNO(NODEPTR(mp, 0));
rc = mdbx_page_get(mc, mc->mc_db->md_root, &mc->mc_pg[0], NULL);
if (unlikely(rc))
if (unlikely(rc != MDBX_SUCCESS))
return rc;
mc->mc_db->md_depth--;
mc->mc_db->md_branch_pages--;
@ -10093,19 +10097,14 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
mc->mc_pg[i] = mc->mc_pg[i + 1];
mc->mc_ki[i] = mc->mc_ki[i + 1];
}
{
/* Adjust other cursors pointing to mp */
MDBX_cursor *m2, *m3;
MDBX_dbi dbi = mc->mc_dbi;
for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2 = m2->mc_next) {
if (mc->mc_flags & C_SUB)
m3 = &m2->mc_xcursor->mx_cursor;
else
m3 = m2;
if (m3 == mc)
continue;
if (!(m3->mc_flags & C_INITIALIZED))
m3 = (mc->mc_flags & C_SUB) ? &m2->mc_xcursor->mx_cursor : m2;
if (m3 == mc || !(m3->mc_flags & C_INITIALIZED))
continue;
if (m3->mc_pg[0] == mp) {
for (int i = 0; i < mc->mc_db->md_depth; i++) {
@ -10116,7 +10115,11 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
m3->mc_top--;
}
}
}
mdbx_cassert(mc, IS_LEAF(mc->mc_pg[mc->mc_top]) ||
PAGETYPE(mc->mc_pg[mc->mc_top]) == pagetype);
mdbx_cassert(mc, mc->mc_snum < mc->mc_db->md_depth ||
IS_LEAF(mc->mc_pg[mc->mc_db->md_depth - 1]));
} else {
mdbx_debug("root page %" PRIaPGNO
" doesn't need rebalancing (flags 0x%x)",
@ -10127,50 +10130,53 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
/* The parent (branch page) must have at least 2 pointers,
* otherwise the tree is invalid. */
ptop = mc->mc_top - 1;
mdbx_cassert(mc, IS_BRANCH(mc->mc_pg[ptop]));
mdbx_cassert(mc, NUMKEYS(mc->mc_pg[ptop]) > 1);
const unsigned pre_top = mc->mc_top - 1;
mdbx_cassert(mc, IS_BRANCH(mc->mc_pg[pre_top]));
mdbx_cassert(mc, !IS_SUBP(mc->mc_pg[0]));
mdbx_cassert(mc, NUMKEYS(mc->mc_pg[pre_top]) > 1);
/* Leaf page fill factor is below the threshold.
* Try to move keys from left or right neighbor, or
* merge with a neighbor page. */
/* Find neighbors. */
MDBX_cursor mn;
mdbx_cursor_copy(mc, &mn);
mn.mc_xcursor = NULL;
oldki = mc->mc_ki[mc->mc_top];
if (mc->mc_ki[ptop] == 0) {
indx_t oldki = mc->mc_ki[mc->mc_top];
bool fromleft;
if (mc->mc_ki[pre_top] == 0) {
/* We're the leftmost leaf in our parent. */
mdbx_debug("reading right neighbor");
mn.mc_ki[ptop]++;
node = NODEPTR(mc->mc_pg[ptop], mn.mc_ki[ptop]);
mn.mc_ki[pre_top]++;
node = NODEPTR(mc->mc_pg[pre_top], mn.mc_ki[pre_top]);
rc = mdbx_page_get(mc, NODEPGNO(node), &mn.mc_pg[mn.mc_top], NULL);
if (unlikely(rc))
if (unlikely(rc != MDBX_SUCCESS))
return rc;
mdbx_cassert(mc, PAGETYPE(mn.mc_pg[mn.mc_top]) ==
PAGETYPE(mc->mc_pg[mc->mc_top]));
mn.mc_ki[mn.mc_top] = 0;
mc->mc_ki[mc->mc_top] = NUMKEYS(mc->mc_pg[mc->mc_top]);
fromleft = 0;
fromleft = false;
} else {
/* There is at least one neighbor to the left. */
mdbx_debug("reading left neighbor");
mn.mc_ki[ptop]--;
node = NODEPTR(mc->mc_pg[ptop], mn.mc_ki[ptop]);
mn.mc_ki[pre_top]--;
node = NODEPTR(mc->mc_pg[pre_top], mn.mc_ki[pre_top]);
rc = mdbx_page_get(mc, NODEPGNO(node), &mn.mc_pg[mn.mc_top], NULL);
if (unlikely(rc))
if (unlikely(rc != MDBX_SUCCESS))
return rc;
mdbx_cassert(mc, PAGETYPE(mn.mc_pg[mn.mc_top]) ==
PAGETYPE(mc->mc_pg[mc->mc_top]));
mn.mc_ki[mn.mc_top] = NUMKEYS(mn.mc_pg[mn.mc_top]) - 1;
mc->mc_ki[mc->mc_top] = 0;
fromleft = 1;
fromleft = true;
}
mdbx_debug("found neighbor page %" PRIaPGNO " (%u keys, %.1f%% full)",
mn.mc_pg[mn.mc_top]->mp_pgno, NUMKEYS(mn.mc_pg[mn.mc_top]),
(float)PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) / 10);
PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) / 10.24);
/* If the neighbor page is above threshold and has enough keys,
* move one key from it. Otherwise we should try to merge them.
@ -10178,24 +10184,39 @@ static int mdbx_rebalance(MDBX_cursor *mc) {
if (PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) >= thresh &&
NUMKEYS(mn.mc_pg[mn.mc_top]) > minkeys) {
rc = mdbx_node_move(&mn, mc, fromleft);
if (fromleft) {
/* if we inserted on left, bump position up */
oldki++;
}
if (unlikely(rc != MDBX_SUCCESS))
return rc;
oldki += fromleft /* if we inserted on left, bump position up */;
mdbx_cassert(mc, IS_LEAF(mc->mc_pg[mc->mc_top]) ||
PAGETYPE(mc->mc_pg[mc->mc_top]) == pagetype);
mdbx_cassert(mc, mc->mc_snum < mc->mc_db->md_depth ||
IS_LEAF(mc->mc_pg[mc->mc_db->md_depth - 1]));
} else {
if (!fromleft) {
rc = mdbx_page_merge(&mn, mc);
if (unlikely(rc != MDBX_SUCCESS))
return rc;
mdbx_cassert(mc, IS_LEAF(mc->mc_pg[mc->mc_top]) ||
PAGETYPE(mc->mc_pg[mc->mc_top]) == pagetype);
mdbx_cassert(mc, mc->mc_snum < mc->mc_db->md_depth ||
IS_LEAF(mc->mc_pg[mc->mc_db->md_depth - 1]));
} else {
oldki += NUMKEYS(mn.mc_pg[mn.mc_top]);
mn.mc_ki[mn.mc_top] += mc->mc_ki[mn.mc_top] + 1;
/* We want mdbx_rebalance to find mn when doing fixups */
WITH_CURSOR_TRACKING(mn, rc = mdbx_page_merge(mc, &mn));
if (unlikely(rc != MDBX_SUCCESS))
return rc;
mdbx_cursor_copy(&mn, mc);
mdbx_cassert(mc, IS_LEAF(mc->mc_pg[mc->mc_top]) ||
PAGETYPE(mc->mc_pg[mc->mc_top]) == pagetype);
mdbx_cassert(mc, mc->mc_snum < mc->mc_db->md_depth ||
IS_LEAF(mc->mc_pg[mc->mc_db->md_depth - 1]));
}
mc->mc_flags &= ~C_EOF;
}
mc->mc_ki[mc->mc_top] = oldki;
return rc;
return MDBX_SUCCESS;
}
/* Complete a delete operation started by mdbx_cursor_del(). */