1 files changed, 11 insertions, 2 deletions
diff --git a/src/coins.h b/src/coins.h
index 4774c9f6a6..de3264f46e 100644
--- a/src/coins.h
+++ b/src/coins.h
@@ -155,6 +155,12 @@ public:
     //! Retrieve the block hash whose state this CCoinsView currently represents
     virtual uint256 GetBestBlock() const;
 
+    //! Retrieve the range of blocks that may have been only partially written.
+    //! If the database is in a consistent state, the result is the empty vector.
+    //! Otherwise, a two-element vector is returned consisting of the new and
+    //! the old block hash, in that order.
+    virtual std::vector<uint256> GetHeadBlocks() const;
+
     //! Do a bulk modification (multiple Coin changes + BestBlock change).
     //! The passed mapCoins can be modified.
     virtual bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
@@ -181,6 +187,7 @@ public:
     bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
     bool HaveCoin(const COutPoint &outpoint) const override;
     uint256 GetBestBlock() const override;
+    std::vector<uint256> GetHeadBlocks() const override;
     void SetBackend(CCoinsView &viewIn);
     bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) override;
     CCoinsViewCursor *Cursor() const override;
@@ -289,10 +296,12 @@ private:
 };
 
 //! Utility function to add all of a transaction's outputs to a cache.
-// It assumes that overwrites are only possible for coinbase transactions,
+// When check is false, this assumes that overwrites are only possible for coinbase transactions.
+// When check is true, the underlying view may be queried to determine whether an addition is
+// an overwrite.
 // TODO: pass in a boolean to limit these possible overwrites to known
 // (pre-BIP34) cases.
-void AddCoins(CCoinsViewCache& cache, const CTransaction& tx, int nHeight);
+void AddCoins(CCoinsViewCache& cache, const CTransaction& tx, int nHeight, bool check = false);
 
 //! Utility function to find any unspent output with a given txid.
 const Coin& AccessByTxid(const CCoinsViewCache& cache, const uint256& txid);