txdb: Add Cursor() method to CCoinsView to iterate over UTXO set

Add a method Cursor() to CCoinsView that returns a cursor which can be
used to iterate over the whole UTXO set.

- rpc: Change gettxoutsetinfo to use new Cursor method

- txdb: Remove GetStats method - Now that GetStats is implemented in
  terms of Cursor, remove it.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/coins.cpp b/src/coins.cpp
index 877fb8b26..1c329740b 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -45,7 +45,7 @@ bool CCoinsView::GetCoins(const uint256 &txid, CCoins &coins) const { return fal
 bool CCoinsView::HaveCoins(const uint256 &txid) const { return false; }
 uint256 CCoinsView::GetBestBlock() const { return uint256(); }
 bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
-bool CCoinsView::GetStats(CCoinsStats &stats) const { return false; }
+CCoinsViewCursor *CCoinsView::Cursor() const { return 0; }
 
 
 CCoinsViewBacked::CCoinsViewBacked(CCoinsView *viewIn) : base(viewIn) { }
@@ -54,7 +54,7 @@ bool CCoinsViewBacked::HaveCoins(const uint256 &txid) const { return base->HaveC
 uint256 CCoinsViewBacked::GetBestBlock() const { return base->GetBestBlock(); }
 void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
 bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
-bool CCoinsViewBacked::GetStats(CCoinsStats &stats) const { return base->GetStats(stats); }
+CCoinsViewCursor *CCoinsViewBacked::Cursor() const { return base->Cursor(); }
 
 CCoinsKeyHasher::CCoinsKeyHasher() : salt(GetRandHash()) {}
 
@@ -300,3 +300,7 @@ CCoinsModifier::~CCoinsModifier()
         cache.cachedCoinsUsage += it->second.coins.DynamicMemoryUsage();
     }
 }
+
+CCoinsViewCursor::~CCoinsViewCursor()
+{
+}