SERVER-44101 Add a KeyString::Value::hash method and use it in validation

2 files changed, 8 insertions, 5 deletions

diff --git a/src/mongo/db/catalog/index_consistency.cpp b/src/mongo/db/catalog/index_consistency.cpp
index a9999d0b5ba..83d9d45f19b 100644
--- a/src/mongo/db/catalog/index_consistency.cpp
+++ b/src/mongo/db/catalog/index_consistency.cpp
@@ -307,10 +307,6 @@ BSONObj IndexConsistency::_generateInfo(const IndexInfo& indexInfo,
 
 uint32_t IndexConsistency::_hashKeyString(const KeyString::Value& ks,
                                           uint32_t indexNameHash) const {
-    using namespace absl::hash_internal;
-    uint64_t hash = indexNameHash;
-    hash = CityHash64WithSeed(ks.getTypeBits().getBuffer(), ks.getTypeBits().getSize(), hash);
-    hash = CityHash64WithSeed(ks.getBuffer(), ks.getSize(), hash);
-    return hash % kNumHashBuckets;
+    return ks.hash(indexNameHash) % kNumHashBuckets;
 }
 }  // namespace mongo
diff --git a/src/mongo/db/storage/key_string.h b/src/mongo/db/storage/key_string.h
index 74fb80406e3..5b8d77a11f4 100644
--- a/src/mongo/db/storage/key_string.h
+++ b/src/mongo/db/storage/key_string.h
@@ -31,6 +31,8 @@
 
 #include <limits>
 
+#include <absl/hash/hash.h>
+
 #include "mongo/base/static_assert.h"
 #include "mongo/bson/bsonelement_comparator_interface.h"
 #include "mongo/bson/bsonmisc.h"
@@ -342,6 +344,11 @@ public:
         return TypeBits::fromBuffer(_version, &reader);
     }
 
+    // Compute hash over key
+    uint64_t hash(uint64_t seed = 0) const {
+        return absl::hash_internal::CityHash64WithSeed(_buffer.get(), _bufSize, seed);
+    }
+
     /**
      * Returns a hex encoding of this key.
      */