1 files changed, 21 insertions, 4 deletions
diff --git a/src/dbwrapper.h b/src/dbwrapper.h
index 24ef71bfbf..e19fde51c1 100644
--- a/src/dbwrapper.h
+++ b/src/dbwrapper.h
@@ -22,7 +22,7 @@ static const size_t DBWRAPPER_PREALLOC_VALUE_SIZE = 1024;
 class dbwrapper_error : public std::runtime_error
 {
 public:
-    dbwrapper_error(const std::string& msg) : std::runtime_error(msg) {}
+    explicit dbwrapper_error(const std::string& msg) : std::runtime_error(msg) {}
 };
 
 class CDBWrapper;
@@ -61,7 +61,7 @@ public:
     /**
      * @param[in] _parent   CDBWrapper that this batch is to be submitted to
      */
-    CDBBatch(const CDBWrapper &_parent) : parent(_parent), ssKey(SER_DISK, CLIENT_VERSION), ssValue(SER_DISK, CLIENT_VERSION), size_estimate(0) { };
+    explicit CDBBatch(const CDBWrapper &_parent) : parent(_parent), ssKey(SER_DISK, CLIENT_VERSION), ssValue(SER_DISK, CLIENT_VERSION), size_estimate(0) { };
 
     void Clear()
     {
@@ -130,7 +130,7 @@ public:
         parent(_parent), piter(_piter) { };
     ~CDBIterator();
 
-    bool Valid();
+    bool Valid() const;
 
     void SeekToFirst();
 
@@ -177,7 +177,7 @@ class CDBWrapper
 {
     friend const std::vector<unsigned char>& dbwrapper_private::GetObfuscateKey(const CDBWrapper &w);
 private:
-    //! custom environment this database is using (may be NULL in case of default environment)
+    //! custom environment this database is using (may be nullptr in case of default environment)
     leveldb::Env* penv;
 
     //! database options used
@@ -321,6 +321,23 @@ public:
         pdb->GetApproximateSizes(&range, 1, &size);
         return size;
     }
+
+    /**
+     * Compact a certain range of keys in the database.
+     */
+    template<typename K>
+    void CompactRange(const K& key_begin, const K& key_end) const
+    {
+        CDataStream ssKey1(SER_DISK, CLIENT_VERSION), ssKey2(SER_DISK, CLIENT_VERSION);
+        ssKey1.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
+        ssKey2.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
+        ssKey1 << key_begin;
+        ssKey2 << key_end;
+        leveldb::Slice slKey1(ssKey1.data(), ssKey1.size());
+        leveldb::Slice slKey2(ssKey2.data(), ssKey2.size());
+        pdb->CompactRange(&slKey1, &slKey2);
+    }
+
 };
 
 #endif // BITCOIN_DBWRAPPER_H