fix: MakeIterator takes read latch twice in a thread (#663)

skyzh · web-flow · commit bd470805b88d · 2023-11-16T18:09:44.000-05:00
Signed-off-by: Alex Chi &lt;iskyzh@gmail.com&gt;
diff --git a/src/storage/table/table_heap.cpp b/src/storage/table/table_heap.cpp
@@ -116,7 +116,9 @@ auto TableHeap::MakeIterator() -> TableIterator {
 
   auto page_guard = bpm_->FetchPageRead(last_page_id);
   auto page = page_guard.As<TablePage>();
-  return {this, {first_page_id_, 0}, {last_page_id, page->GetNumTuples()}};
+  auto num_tuples = page->GetNumTuples();
+  page_guard.Drop();
+  return {this, {first_page_id_, 0}, {last_page_id, num_tuples}};
 }
 
 auto TableHeap::MakeEagerIterator() -> TableIterator { return {this, {first_page_id_, 0}, {INVALID_PAGE_ID, 0}}; }

Original file line number	Diff line number	Diff line change
`@@ -116,7 +116,9 @@ auto TableHeap::MakeIterator() -> TableIterator {`
`116`	`116`
`117`	`117`	`auto page_guard = bpm_->FetchPageRead(last_page_id);`
`118`	`118`	`auto page = page_guard.As<TablePage>();`
`119`		`- return {this, {first_page_id_, 0}, {last_page_id, page->GetNumTuples()}};`
	`119`	`+ auto num_tuples = page->GetNumTuples();`
	`120`	`+ page_guard.Drop();`
	`121`	`+ return {this, {first_page_id_, 0}, {last_page_id, num_tuples}};`
`120`	`122`	`}`
`121`	`123`
`122`	`124`	`auto TableHeap::MakeEagerIterator() -> TableIterator { return {this, {first_page_id_, 0}, {INVALID_PAGE_ID, 0}}; }`