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mdbx: incremental lazy merge sort for dirty-page list.

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The main change for https://github.com/erthink/libmdbx/issues/132

Change-Id: I9907f6abfcf77bd40c7a263f5adb5274d5445864
This commit is contained in:
Leonid Yuriev
2021-01-31 23:42:20 +03:00
parent 0620ec2f2e
commit 28bd5d81d2
2 changed files with 41 additions and 7 deletions
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47
src/core.c
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@@ -3231,15 +3231,49 @@ static int mdbx_dpl_alloc(MDBX_txn *txn) {
#define DP_SORT_CMP(first, last) ((first).pgno < (last).pgno)
SORT_IMPL(dp_sort, false, MDBX_dp, DP_SORT_CMP)
__hot static MDBX_dpl *mdbx_dpl_sort_slowpath(MDBX_dpl *dl) {
const unsigned unsorted = dl->length - dl->sorted;
if (dl->sorted > unsorted / 4 + 4 &&
dl->length + unsorted < dl->detent + MDBX_DPL_GAP_FOR_MERGESORT) {
MDBX_dp *const sorted_begin = dl->items + 1;
MDBX_dp *const sorted_end = sorted_begin + dl->sorted;
MDBX_dp *const end = dl->items + dl->detent + MDBX_DPL_RESERVE_GAP;
MDBX_dp *const tmp = end - unsorted;
assert(dl->items + dl->length + 1 < tmp);
/* copy unsorted to the end of allocated space and sort it */
memcpy(tmp, sorted_end, unsorted * sizeof(MDBX_dp));
dp_sort(tmp, tmp + unsorted);
/* merge two parts from end to begin */
MDBX_dp *w = dl->items + dl->length;
MDBX_dp *l = dl->items + dl->sorted;
MDBX_dp *r = end - 1;
do {
const bool cmp = l->pgno > r->pgno;
*w = cmp ? *l : *r;
l -= cmp;
r -= !cmp;
} while (likely(--w > l));
assert(r == tmp - 1);
assert(dl->items[0].pgno == 0 &&
dl->items[dl->length + 1].pgno == P_INVALID);
if (mdbx_assert_enabled())
for (unsigned i = 0; i <= dl->length; ++i)
assert(dl->items[i].pgno < dl->items[i + 1].pgno);
} else {
dp_sort(dl->items + 1, dl->items + dl->length + 1);
assert(dl->items[0].pgno == 0 &&
dl->items[dl->length + 1].pgno == P_INVALID);
}
dl->sorted = dl->length;
return dl;
}
static __always_inline MDBX_dpl *mdbx_dpl_sort(MDBX_dpl *dl) {
assert(dl->length <= MDBX_PGL_LIMIT);
assert(dl->sorted <= dl->length);
assert(dl->items[0].pgno == 0 && dl->items[dl->length + 1].pgno == P_INVALID);
if (dl->sorted != dl->length) {
dl->sorted = dl->length;
dp_sort(dl->items + 1, dl->items + dl->length + 1);
}
return dl;
return likely(dl->sorted == dl->length) ? dl : mdbx_dpl_sort_slowpath(dl);
}
/* Returns the index of the first dirty-page whose pgno
@@ -3259,8 +3293,7 @@ static unsigned __hot mdbx_dpl_search(MDBX_dpl *dl, pgno_t pgno) {
switch (dl->length - dl->sorted) {
default:
/* sort a whole */
dl->sorted = dl->length;
dp_sort(dl->items + 1, dl->items + dl->length + 1);
mdbx_dpl_sort_slowpath(dl);
break;
case 0:
/* whole sorted cases */