Add height, depth, and hash methods to the Chain interface

And use them to remove uses of chainActive and mapBlockIndex in wallet code

This commit does not change behavior.

Co-authored-by: Ben Woosley <ben.woosley@gmail.com>

src/interfaces/chain.cpp

@@ -4,7 +4,9 @@
 
 #include <interfaces/chain.h>
 
+#include <chain.h>
 #include <sync.h>
+#include <uint256.h>
 #include <util/system.h>
 #include <validation.h>
 
@@ -16,6 +18,34 @@ namespace {
 
 class LockImpl : public Chain::Lock
 {
+    Optional<int> getHeight() override
+    {
+        int height = ::chainActive.Height();
+        if (height >= 0) {
+            return height;
+        }
+        return nullopt;
+    }
+    Optional<int> getBlockHeight(const uint256& hash) override
+    {
+        CBlockIndex* block = LookupBlockIndex(hash);
+        if (block && ::chainActive.Contains(block)) {
+            return block->nHeight;
+        }
+        return nullopt;
+    }
+    int getBlockDepth(const uint256& hash) override
+    {
+        const Optional<int> tip_height = getHeight();
+        const Optional<int> height = getBlockHeight(hash);
+        return tip_height && height ? *tip_height - *height + 1 : 0;
+    }
+    uint256 getBlockHash(int height) override
+    {
+        CBlockIndex* block = ::chainActive[height];
+        assert(block != nullptr);
+        return block->GetBlockHash();
+    }
 };
 
 class LockingStateImpl : public LockImpl, public UniqueLock<CCriticalSection>

src/interfaces/chain.h

@@ -5,11 +5,14 @@
 #ifndef BITCOIN_INTERFACES_CHAIN_H
 #define BITCOIN_INTERFACES_CHAIN_H
 
+#include <optional.h>
+
 #include <memory>
 #include <string>
 #include <vector>
 
 class CScheduler;
+class uint256;
 
 namespace interfaces {
 
@@ -28,6 +31,23 @@ public:
     {
     public:
         virtual ~Lock() {}
+
+        //! Get current chain height, not including genesis block (returns 0 if
+        //! chain only contains genesis block, nullopt if chain does not contain
+        //! any blocks).
+        virtual Optional<int> getHeight() = 0;
+
+        //! Get block height above genesis block. Returns 0 for genesis block,
+        //! 1 for following block, and so on. Returns nullopt for a block not
+        //! included in the current chain.
+        virtual Optional<int> getBlockHeight(const uint256& hash) = 0;
+
+        //! Get block depth. Returns 1 for chain tip, 2 for preceding block, and
+        //! so on. Returns 0 for a block not included in the current chain.
+        virtual int getBlockDepth(const uint256& hash) = 0;
+
+        //! Get block hash. Height must be valid or this function will abort.
+        virtual uint256 getBlockHash(int height) = 0;
     };
 
     //! Return Lock interface. Chain is locked when this is called, and

src/interfaces/wallet.cpp

@@ -333,7 +333,7 @@ public:
         if (mi == m_wallet.mapWallet.end()) {
             return false;
         }
-        num_blocks = ::chainActive.Height();
+        num_blocks = locked_chain->getHeight().value_or(-1);
         block_time = ::chainActive.Tip()->GetBlockTime();
         tx_status = MakeWalletTxStatus(*locked_chain, mi->second);
         return true;
@@ -348,7 +348,7 @@ public:
         LOCK(m_wallet.cs_wallet);
         auto mi = m_wallet.mapWallet.find(txid);
         if (mi != m_wallet.mapWallet.end()) {
-            num_blocks = ::chainActive.Height();
+            num_blocks = locked_chain->getHeight().value_or(-1);
             in_mempool = mi->second.InMempool();
             order_form = mi->second.vOrderForm;
             tx_status = MakeWalletTxStatus(*locked_chain, mi->second);
@@ -379,7 +379,7 @@ public:
             return false;
         }
         balances = getBalances();
-        num_blocks = ::chainActive.Height();
+        num_blocks = locked_chain->getHeight().value_or(-1);
         return true;
     }
     CAmount getBalance() override { return m_wallet.GetBalance(); }