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mdbx: рефакторинг node_shrink() для ясности исходного кода.

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Леонид Юрьев (Leonid Yuriev) 2024-02-28 02:21:59 +03:00
parent 2e863cf7e0
commit d53dc4572c
1 changed files with 26 additions and 32 deletions
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58
src/core.c
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@ -3357,7 +3357,7 @@ static int __must_check_result node_add_leaf2(MDBX_cursor *mc, size_t indx,
const MDBX_val *key);
static void node_del(MDBX_cursor *mc, size_t ksize);
static void node_shrink(MDBX_page *mp, size_t indx);
static MDBX_node *node_shrink(MDBX_page *mp, size_t indx, MDBX_node *node);
static int __must_check_result node_move(MDBX_cursor *csrc, MDBX_cursor *cdst,
bool fromleft);
static int __must_check_result node_read(MDBX_cursor *mc, const MDBX_node *leaf,
@ -18766,7 +18766,7 @@ static __hot int cursor_del(MDBX_cursor *mc, MDBX_put_flags_t flags) {
if (!(node_flags(node) & F_SUBDATA))
mc->mc_xcursor->mx_cursor.mc_pg[0] = node_data(node);
rc = cursor_del(&mc->mc_xcursor->mx_cursor, 0);
if (unlikely(rc))
if (unlikely(rc != MDBX_SUCCESS))
return rc;
/* If sub-DB still has entries, we're done */
if (mc->mc_xcursor->mx_db.md_entries) {
@ -18775,11 +18775,10 @@ static __hot int cursor_del(MDBX_cursor *mc, MDBX_put_flags_t flags) {
mc->mc_xcursor->mx_db.md_mod_txnid = mc->mc_txn->mt_txnid;
memcpy(node_data(node), &mc->mc_xcursor->mx_db, sizeof(MDBX_db));
} else {
/* shrink fake page */
node_shrink(mp, mc->mc_ki[mc->mc_top]);
node = page_node(mp, mc->mc_ki[mc->mc_top]);
/* shrink sub-page */
node = node_shrink(mp, mc->mc_ki[mc->mc_top], node);
mc->mc_xcursor->mx_cursor.mc_pg[0] = node_data(node);
/* fix other sub-DB cursors pointed at fake pages on this page */
/* fix other sub-DB cursors pointed at sub-pages on this page */
for (MDBX_cursor *m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2;
m2 = m2->mc_next) {
if (m2 == mc || m2->mc_snum < mc->mc_snum)
@ -19234,35 +19233,28 @@ __hot static void node_del(MDBX_cursor *mc, size_t ksize) {
/* Compact the main page after deleting a node on a subpage.
* [in] mp The main page to operate on.
* [in] indx The index of the subpage on the main page. */
static void node_shrink(MDBX_page *mp, size_t indx) {
MDBX_node *node;
MDBX_page *sp, *xp;
size_t nsize, delta, len, ptr;
intptr_t i;
node = page_node(mp, indx);
sp = (MDBX_page *)node_data(node);
delta = page_room(sp);
assert(delta > 0);
static MDBX_node *node_shrink(MDBX_page *mp, size_t indx, MDBX_node *node) {
assert(node = page_node(mp, indx));
MDBX_page *sp = (MDBX_page *)node_data(node);
assert(IS_SUBP(sp) && page_numkeys(sp) > 0);
const size_t delta =
EVEN_FLOOR(page_room(sp) /* avoid the node uneven-sized */);
if (unlikely(delta) == 0)
return node;
/* Prepare to shift upward, set len = length(subpage part to shift) */
if (IS_LEAF2(sp)) {
delta &= /* do not make the node uneven-sized */ ~(size_t)1;
if (unlikely(delta) == 0)
return;
nsize = node_ds(node) - delta;
assert(nsize % 1 == 0);
len = nsize;
} else {
xp = ptr_disp(sp, delta); /* destination subpage */
for (i = page_numkeys(sp); --i >= 0;) {
size_t nsize = node_ds(node) - delta, len = nsize;
assert(nsize % 1 == 0);
if (!IS_LEAF2(sp)) {
len = PAGEHDRSZ;
MDBX_page *xp = ptr_disp(sp, delta); /* destination subpage */
for (intptr_t i = page_numkeys(sp); --i >= 0;) {
assert(sp->mp_ptrs[i] >= delta);
xp->mp_ptrs[i] = (indx_t)(sp->mp_ptrs[i] - delta);
}
nsize = node_ds(node) - delta;
len = PAGEHDRSZ;
}
sp->mp_upper = sp->mp_lower;
assert(sp->mp_upper >= sp->mp_lower + delta);
sp->mp_upper -= (indx_t)delta;
sp->mp_pgno = mp->mp_pgno;
node_set_ds(node, nsize);
@ -19270,15 +19262,17 @@ static void node_shrink(MDBX_page *mp, size_t indx) {
void *const base = ptr_disp(mp, mp->mp_upper + PAGEHDRSZ);
memmove(ptr_disp(base, delta), base, ptr_dist(sp, base) + len);
ptr = mp->mp_ptrs[indx];
for (i = page_numkeys(mp); --i >= 0;) {
if (mp->mp_ptrs[i] <= ptr) {
const size_t pivot = mp->mp_ptrs[indx];
for (intptr_t i = page_numkeys(mp); --i >= 0;) {
if (mp->mp_ptrs[i] <= pivot) {
assert((size_t)UINT16_MAX - mp->mp_ptrs[i] >= delta);
mp->mp_ptrs[i] += (indx_t)delta;
}
}
assert((size_t)UINT16_MAX - mp->mp_upper >= delta);
mp->mp_upper += (indx_t)delta;
return ptr_disp(node, delta);
}
/* Initial setup of a sorted-dups cursor.