Auto merge of #1486 - str4d:1456-writewitnesscache-exception-safety, r=bitcartel

WriteWitnessCache: Catch errors and abort transaction

Closes #1452

src/wallet/wallet.cpp

@@ -15,7 +15,6 @@
 #include "script/script.h"
 #include "script/sign.h"
 #include "timedata.h"
-#include "util.h"
 #include "utilmoneystr.h"
 #include "zcash/Note.hpp"
 #include "crypter.h"
@@ -697,7 +696,8 @@ void CWallet::IncrementNoteWitnesses(const CBlockIndex* pindex,
             nWitnessCacheSize += 1;
         }
         if (fFileBacked) {
-            WriteWitnessCache();
+            CWalletDB walletdb(strWalletFile);
+            WriteWitnessCache(walletdb);
         }
     }
 }
@@ -718,37 +718,12 @@ void CWallet::DecrementNoteWitnesses()
         // TODO: If nWitnessCache is zero, we need to regenerate the caches (#1302)
         assert(nWitnessCacheSize > 0);
         if (fFileBacked) {
-            WriteWitnessCache();
+            CWalletDB walletdb(strWalletFile);
+            WriteWitnessCache(walletdb);
         }
     }
 }
 
-void CWallet::WriteWitnessCache() {
-    CWalletDB walletdb(strWalletFile);
-    if (!walletdb.TxnBegin()) {
-        // This needs to be done atomically, so don't do it at all
-        LogPrintf("WriteWitnessCache(): Couldn't start atomic write\n");
-        return;
-    }
-    for (std::pair<const uint256, CWalletTx>& wtxItem : mapWallet) {
-        if (!walletdb.WriteTx(wtxItem.first, wtxItem.second)) {
-            LogPrintf("WriteWitnessCache(): Failed to write CWalletTx, aborting atomic write\n");
-            walletdb.TxnAbort();
-            return;
-        }
-    }
-    if (!walletdb.WriteWitnessCacheSize(nWitnessCacheSize)) {
-        LogPrintf("WriteWitnessCache(): Failed to write nWitnessCacheSize, aborting atomic write\n");
-        walletdb.TxnAbort();
-        return;
-    }
-    if (!walletdb.TxnCommit()) {
-        // Couldn't commit all to db, but in-memory state is fine
-        LogPrintf("WriteWitnessCache(): Couldn't commit atomic write\n");
-        return;
-    }
-}
-
 bool CWallet::EncryptWallet(const SecureString& strWalletPassphrase)
 {
     if (IsCrypted())