ensure empty string is always id 0

2 files changed, 11 insertions, 1 deletions

diff --git a/staging_vespalib/src/vespa/vespalib/metrics/name_collection.cpp b/staging_vespalib/src/vespa/vespalib/metrics/name_collection.cpp
index 697d41c4c6b..6683908a9cd 100644
--- a/staging_vespalib/src/vespa/vespalib/metrics/name_collection.cpp
+++ b/staging_vespalib/src/vespa/vespalib/metrics/name_collection.cpp
@@ -7,6 +7,16 @@ namespace metrics {
 
 using Guard = std::lock_guard<std::mutex>;
 
+NameCollection::NameCollection()
+{
+    size_t first = resolve("");
+    assert(first == 0);
+    assert(lookup(first) == "");
+    assert(_names_by_id.size() == 1);
+    assert(_names.size() == 1);
+    (void) first; // in case of NOP asserts
+}
+
 const vespalib::string &
 NameCollection::lookup(size_t id) const
 {
diff --git a/staging_vespalib/src/vespa/vespalib/metrics/name_collection.h b/staging_vespalib/src/vespa/vespalib/metrics/name_collection.h
index 566fd2a3997..6a91c2d4a9d 100644
--- a/staging_vespalib/src/vespa/vespalib/metrics/name_collection.h
+++ b/staging_vespalib/src/vespa/vespalib/metrics/name_collection.h
@@ -21,7 +21,7 @@ public:
     size_t resolve(const vespalib::string& name);
     size_t size() const;
 
-    NameCollection() = default;
+    NameCollection();
     ~NameCollection() {}
 };