Ensure hold lists are empty upon DB destruction

If there was a snapshot reader concurrent with the last modify operation
on the DB, it's possible for the hold list to be non-empty. Explicitly
clean it up now to ensure that we don't try to destroy any data stores
with a non-empty hold list. Failure to do so might trigger an assertion.

2 files changed, 11 insertions, 0 deletions

diff --git a/storage/src/vespa/storage/bucketdb/generic_btree_bucket_database.h b/storage/src/vespa/storage/bucketdb/generic_btree_bucket_database.h
index 5044193ed79..9534b583cd5 100644
--- a/storage/src/vespa/storage/bucketdb/generic_btree_bucket_database.h
+++ b/storage/src/vespa/storage/bucketdb/generic_btree_bucket_database.h
@@ -73,6 +73,8 @@ public:
     GenericBTreeBucketDatabase(GenericBTreeBucketDatabase&&) = delete;
     GenericBTreeBucketDatabase& operator=(GenericBTreeBucketDatabase&&) = delete;
 
+    ~GenericBTreeBucketDatabase();
+
     ValueType entry_from_iterator(const BTreeConstIterator& iter) const;
     ConstValueRef const_value_ref_from_valid_iterator(const BTreeConstIterator& iter) const;
 
diff --git a/storage/src/vespa/storage/bucketdb/generic_btree_bucket_database.hpp b/storage/src/vespa/storage/bucketdb/generic_btree_bucket_database.hpp
index 5fb673a1440..e53fad84db2 100644
--- a/storage/src/vespa/storage/bucketdb/generic_btree_bucket_database.hpp
+++ b/storage/src/vespa/storage/bucketdb/generic_btree_bucket_database.hpp
@@ -17,6 +17,15 @@ namespace storage::bucketdb {
 using document::BucketId;
 
 template <typename DataStoreTraitsT>
+GenericBTreeBucketDatabase<DataStoreTraitsT>::~GenericBTreeBucketDatabase() {
+    // If there was a snapshot reader concurrent with the last modify operation
+    // on the DB, it's possible for the hold list to be non-empty. Explicitly
+    // clean it up now to ensure that we don't try to destroy any data stores
+    // with a non-empty hold list. Failure to do so might trigger an assertion.
+    commit_tree_changes();
+}
+
+template <typename DataStoreTraitsT>
 BucketId GenericBTreeBucketDatabase<DataStoreTraitsT>::bucket_from_valid_iterator(const BTreeConstIterator& iter) {
     return BucketId(BucketId::keyToBucketId(iter.getKey()));
 }