Fixed key comparator for kevacache.

src/keva/common.cpp

@@ -127,27 +127,38 @@ bool CCacheKeyIterator::next(valtype& key, CKevaData& data)
 {
   /* Exit early if no more data is available in either the cache
      nor the base iterator.  */
-  if (!baseHasMore && cacheIter == cache.entries.end())
+
+  bool endOfCacheNamespace = false;
+  if (cacheIter != cache.entries.end()) {
+    valtype curNameSpace = std::get<0>(cacheIter->first);
+    if (curNameSpace != nameSpace) {
+      endOfCacheNamespace = true;
+    }
+  }
+  bool noMoreCache = (cacheIter == cache.entries.end()) || endOfCacheNamespace;
+  if (!baseHasMore && noMoreCache) {
     return false;
+  }
 
   /* Determine which source to use for the next.  */
-  bool useBase;
-  if (!baseHasMore)
+  bool useBase = false;
+  if (!baseHasMore) {
     useBase = false;
-  else if (cacheIter == cache.entries.end())
+  } else if (cacheIter == cache.entries.end()) {
     useBase = true;
-  else {
-    /* A special case is when both iterators are equal.  In this case,
+  } else {
+    if (baseKey == std::get<1>(cacheIter->first)) {
+      /* A special case is when both iterators are equal.  In this case,
         we want to use the cached version.  We also have to advance
         the base iterator.  */
-    if (baseKey == std::get<1>(cacheIter->first))
       advanceBaseIterator ();
+    }
 
     /* Due to advancing the base iterator above, it may happen that
         no more base entries are present.  Handle this gracefully.  */
-    if (!baseHasMore)
+    if (!baseHasMore) {
       useBase = false;
-    else {
+    } else {
       assert(baseKey != std::get<1>(cacheIter->first));
 
       CKevaCache::KeyComparator cmp;

src/keva/common.h

@@ -309,12 +309,20 @@ private:
     inline bool operator() (const std::tuple<valtype, valtype> a,
                             const std::tuple<valtype, valtype> b) const
     {
-      unsigned int aSize = std::get<0>(a).size() + std::get<1>(a).size();
-      unsigned int bSize = std::get<0>(b).size() + std::get<1>(b).size();
-      if (aSize != bSize) {
-        return aSize < bSize;
+      // This is how namespace/key pairs are sorted in database.
+      auto nsA = std::get<0>(a);
+      auto nsB = std::get<0>(b);
+      if (nsA == nsB) {
+        auto aKey = std::get<1>(a);
+        auto bKey = std::get<1>(b);
+        uint32_t aKeySize = aKey.size();
+        uint32_t bKeySize = bKey.size();
+        if (aKeySize == bKeySize) {
+          return aKey < bKey;
+        }
+        return aKeySize < bKeySize;
       }
-      return a < b;
+      return nsA < nsB;
     }
   };
 

src/txdb.cpp

@@ -157,36 +157,7 @@ bool CCoinsViewDB::GetName(const valtype &nameSpace, const valtype &key, CKevaDa
 }
 
 bool CCoinsViewDB::GetNamesForHeight(unsigned nHeight, std::set<valtype>& names) const {
-    names.clear();
-#if 0
-    /* It seems that there are no "const iterators" for LevelDB.  Since we
-       only need read operations on it, use a const-cast to get around
-       that restriction.  */
-    boost::scoped_ptr<CDBIterator> pcursor(const_cast<CDBWrapper*>(&db)->NewIterator());
-
-    const CKevaCache::ExpireEntry seekEntry(nHeight, valtype ());
-    pcursor->Seek(std::make_pair(DB_NAME_EXPIRY, seekEntry));
-
-    for (; pcursor->Valid(); pcursor->Next())
-    {
-        std::pair<char, CKevaCache::ExpireEntry> key;
-        if (!pcursor->GetKey(key) || key.first != DB_NAME_EXPIRY)
-            break;
-        const CKevaCache::ExpireEntry& entry = key.second;
-
-        assert (entry.nHeight >= nHeight);
-        if (entry.nHeight > nHeight)
-          break;
-
-        const valtype& name = entry.name;
-        if (names.count(name) > 0) {
-            return error("%s : duplicate name '%s' in expire index",
-                                    __func__, ValtypeToString(name).c_str());
-        }
-        names.insert(name);
-    }
-#endif
-    return true;
+    return false;
 }
 
 bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock, const CKevaCache &names) {