Add function comment.

2 files changed, 10 insertions, 2 deletions

diff --git a/searchlib/src/vespa/searchlib/attribute/save_utils.cpp b/searchlib/src/vespa/searchlib/attribute/save_utils.cpp
index 1d2fabf33d2..b433197b23e 100644
--- a/searchlib/src/vespa/searchlib/attribute/save_utils.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/save_utils.cpp
@@ -8,8 +8,8 @@ namespace search::attribute {
 EntryRefVector
 make_entry_ref_vector_snapshot(const vespalib::RcuVectorBase<vespalib::datastore::AtomicEntryRef>& ref_vector, uint32_t size)
 {
-    assert(size <= ref_vector.get_size());      // Called from writer only
-    auto* source = &ref_vector.get_elem_ref(0); // Called from writer only
+    assert(size <= ref_vector.get_size());
+    auto* source = &ref_vector.get_elem_ref(0);
     EntryRefVector result;
     result.reserve(size);
     for (uint32_t lid = 0; lid < size; ++lid) {
diff --git a/searchlib/src/vespa/searchlib/attribute/save_utils.h b/searchlib/src/vespa/searchlib/attribute/save_utils.h
index bd27a0e130c..56c953fc1c4 100644
--- a/searchlib/src/vespa/searchlib/attribute/save_utils.h
+++ b/searchlib/src/vespa/searchlib/attribute/save_utils.h
@@ -12,6 +12,14 @@ namespace search::attribute {
 
 using EntryRefVector = std::vector<vespalib::datastore::EntryRef, vespalib::allocator_large<vespalib::datastore::EntryRef>>;
 
+/*
+ * Create a vector of entry refs from an rcu vector containing atomic
+ * entry refs. The new vector can be used by a flush thread while
+ * saving an attribute vector as long as the proper generation guard
+ * is also held.
+ *
+ * The function must be called from the attribute write thread.
+ */
 EntryRefVector make_entry_ref_vector_snapshot(const vespalib::RcuVectorBase<vespalib::datastore::AtomicEntryRef>& ref_vector, uint32_t size);
 
 }