wallet: Avoid use of Chain::Lock in rescanblockchain

This is a step toward removing the Chain::Lock class and reducing cs_main
locking.

This change only affects behavior in the case where wallet last block processed
falls behind the chain tip. The rescanblockchain error height error checking
will just be stricter in this case and only accept values up to the last
processed height

1 files changed, 9 insertions, 18 deletions

diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 14e2066c90..6bda33c6c9 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -3536,22 +3536,23 @@ UniValue rescanblockchain(const JSONRPCRequest& request)
     }
 
     int start_height = 0;
-    uint256 start_block, stop_block;
+    Optional<int> stop_height;
+    uint256 start_block;
     {
         auto locked_chain = pwallet->chain().lock();
-        Optional<int> tip_height = locked_chain->getHeight();
+        LOCK(pwallet->cs_wallet);
+        int tip_height = pwallet->GetLastBlockHeight();
 
         if (!request.params[0].isNull()) {
             start_height = request.params[0].get_int();
-            if (start_height < 0 || !tip_height || start_height > *tip_height) {
+            if (start_height < 0 || start_height > tip_height) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid start_height");
             }
         }
 
-        Optional<int> stop_height;
         if (!request.params[1].isNull()) {
             stop_height = request.params[1].get_int();
-            if (*stop_height < 0 || !tip_height || *stop_height > *tip_height) {
+            if (*stop_height < 0 || *stop_height > tip_height) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid stop_height");
             }
             else if (*stop_height < start_height) {
@@ -3560,25 +3561,15 @@ UniValue rescanblockchain(const JSONRPCRequest& request)
         }
 
         // We can't rescan beyond non-pruned blocks, stop and throw an error
-        if (locked_chain->findPruned(start_height, stop_height)) {
+        if (!pwallet->chain().hasBlocks(pwallet->GetLastBlockHash(), start_height, stop_height)) {
             throw JSONRPCError(RPC_MISC_ERROR, "Can't rescan beyond pruned data. Use RPC call getblockchaininfo to determine your pruned height.");
         }
 
-        if (tip_height) {
-            start_block = locked_chain->getBlockHash(start_height);
-            // If called with a stop_height, set the stop_height here to
-            // trigger a rescan to that height.
-            // If called without a stop height, leave stop_height as null here
-            // so rescan continues to the tip (even if the tip advances during
-            // rescan).
-            if (stop_height) {
-                stop_block = locked_chain->getBlockHash(*stop_height);
-            }
-        }
+        CHECK_NONFATAL(pwallet->chain().findAncestorByHeight(pwallet->GetLastBlockHash(), start_height, FoundBlock().hash(start_block)));
     }
 
     CWallet::ScanResult result =
-        pwallet->ScanForWalletTransactions(start_block, stop_block, reserver, true /* fUpdate */);
+        pwallet->ScanForWalletTransactions(start_block, stop_height, reserver, true /* fUpdate */);
     switch (result.status) {
     case CWallet::ScanResult::SUCCESS:
         break;