Switch CCoinsView and chainstate db from per-txid to per-txout

This patch makes several related changes:
* Changes the CCoinsView virtual methods (GetCoins, HaveCoins, ...)
  to be COutPoint/Coin-based rather than txid/CCoins-based.
* Changes the chainstate db to a new incompatible format that is also
  COutPoint/Coin based.
* Implements reconstruction code for hash_serialized_2.
* Adapts the coins_tests unit tests (thanks to Russell Yanofsky).

A side effect of the new CCoinsView model is that we can no longer
use the (unreliable) test for transaction outputs in the UTXO set
to determine whether we already have a particular transaction.

1 files changed, 8 insertions, 8 deletions

diff --git a/src/txdb.h b/src/txdb.h
index df164cb820..73011fe0f9 100644
--- a/src/txdb.h
+++ b/src/txdb.h
@@ -73,11 +73,11 @@ protected:
 public:
     CCoinsViewDB(size_t nCacheSize, bool fMemory = false, bool fWipe = false);
 
-    bool GetCoins(const uint256 &txid, CCoins &coins) const;
-    bool HaveCoins(const uint256 &txid) const;
-    uint256 GetBestBlock() const;
-    bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock);
-    CCoinsViewCursor *Cursor() const;
+    bool GetCoins(const COutPoint &outpoint, Coin &coin) const override;
+    bool HaveCoins(const COutPoint &outpoint) const override;
+    uint256 GetBestBlock() const override;
+    bool BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) override;
+    CCoinsViewCursor *Cursor() const override;
 
     size_t EstimateSize() const override;
 };
@@ -88,8 +88,8 @@ class CCoinsViewDBCursor: public CCoinsViewCursor
 public:
     ~CCoinsViewDBCursor() {}
 
-    bool GetKey(uint256 &key) const;
-    bool GetValue(CCoins &coins) const;
+    bool GetKey(COutPoint &key) const;
+    bool GetValue(Coin &coin) const;
     unsigned int GetValueSize() const;
 
     bool Valid() const;
@@ -99,7 +99,7 @@ private:
     CCoinsViewDBCursor(CDBIterator* pcursorIn, const uint256 &hashBlockIn):
         CCoinsViewCursor(hashBlockIn), pcursor(pcursorIn) {}
     std::unique_ptr<CDBIterator> pcursor;
-    std::pair<char, uint256> keyTmp;
+    std::pair<char, COutPoint> keyTmp;
 
     friend class CCoinsViewDB;
 };