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partition_snapshot_row_cursor: Don't carry end iterators

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The btree's iterator can be checked to reach the tree's end
without holding the ending iterator itself. This makes the
whole p_s_r_c 20% smaller (288 bytes -> 224 bytes) since it
now keeps 4 extra iterators on-board -- inside small vectors
for heap and current_row.

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
This commit is contained in:
Pavel Emelyanov
2021-04-08 16:35:33 +03:00
parent 4558eb3afc
commit d891cfe6cd
1 changed files with 8 additions and 10 deletions
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18
partition_snapshot_row_cursor.hh
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@@ -110,7 +110,6 @@ class partition_snapshot_row_cursor final {
friend class partition_snapshot_row_weakref;
struct position_in_version {
mutation_partition::rows_type::iterator it;
mutation_partition::rows_type::iterator end;
int version_no;
bool unique_owner;
@@ -178,12 +177,11 @@ class partition_snapshot_row_cursor final {
unique_owner = unique_owner && (first || !v.is_referenced());
auto& rows = v.partition().clustered_rows();
auto pos = rows.lower_bound(lower_bound, cmp);
auto end = rows.end();
if (first) {
_latest_it = pos;
}
if (pos != end) {
_heap.push_back({pos, end, version_no, unique_owner});
if (pos) {
_heap.push_back({pos, version_no, unique_owner});
}
++version_no;
first = false;
@@ -210,7 +208,7 @@ class partition_snapshot_row_cursor final {
if (curr.version_no == 0) {
_latest_it = curr.it;
}
if (curr.it != curr.end) {
if (curr.it) {
_heap.push_back(curr);
boost::range::push_heap(_heap, heap_less);
}
@@ -277,13 +275,13 @@ public:
auto it = rows.lower_bound(_position, match, cmp);
_latest_it = it;
auto heap_i = boost::find_if(_heap, [](auto&& v) { return v.version_no == 0; });
if (it == rows.end()) {
if (!it) {
if (heap_i != _heap.end()) {
_heap.erase(heap_i);
boost::range::make_heap(_heap, heap_less);
}
} else if (match) {
_current_row.insert(_current_row.begin(), position_in_version{it, rows.end(), 0});
_current_row.insert(_current_row.begin(), position_in_version{it, 0});
if (heap_i != _heap.end()) {
_heap.erase(heap_i);
boost::range::make_heap(_heap, heap_less);
@@ -293,7 +291,7 @@ public:
heap_i->it = it;
boost::range::make_heap(_heap, heap_less);
} else {
_heap.push_back({it, rows.end(), 0});
_heap.push_back({it, 0});
boost::range::push_heap(_heap, heap_less);
}
}
@@ -404,7 +402,7 @@ public:
// Copy row from older version because rows in evictable versions must
// hold values which are independently complete to be consistent on eviction.
auto e = current_allocator().construct<rows_entry>(_schema, *_current_row[0].it);
e->set_continuous(latest_i != rows.end() && latest_i->continuous());
e->set_continuous(latest_i && latest_i->continuous());
_snp.tracker()->insert(*e);
rows.insert_before(latest_i, *e);
return {*e, true};
@@ -440,7 +438,7 @@ public:
auto&& rows = _snp.version()->partition().clustered_rows();
auto latest_i = get_iterator_in_latest_version();
auto e = current_allocator().construct<rows_entry>(_schema, pos, is_dummy(!pos.is_clustering_row()),
is_continuous(latest_i != rows.end() && latest_i->continuous()));
is_continuous(latest_i && latest_i->continuous()));
_snp.tracker()->insert(*e);
rows.insert_before(latest_i, *e);
return ensure_result{*e, true};