Merge #8694: Basic multiwallet support

c237bd7 wallet: Update formatting (Luke Dashjr)
9cbe8c8 wallet: Forbid -salvagewallet, -zapwallettxes, and -upgradewallet with multiple wallets (Luke Dashjr)
a2a5f3f wallet: Base backup filenames on original wallet filename (Luke Dashjr)
b823a4c wallet: Include actual backup filename in recovery warning message (Luke Dashjr)
84dcb45 Bugfix: wallet: Fix warningStr, errorStr argument order (Luke Dashjr)
008c360 Wallet: Move multiwallet sanity checks to CWallet::Verify, and do other checks on all wallets (Luke Dashjr)
0f08575 Wallet: Support loading multiple wallets if -wallet used more than once (Luke Dashjr)
b124cf0 Wallet: Replace pwalletMain with a vector of wallet pointers (Luke Dashjr)
19b3648 CWalletDB: Store the update counter per wallet (Luke Dashjr)
74e8738 Bugfix: ForceSetArg should replace entr(ies) in mapMultiArgs, not append (Luke Dashjr)
23fb9ad wallet: Move nAccountingEntryNumber from static/global to CWallet (Luke Dashjr)
9d15d55 Bugfix: wallet: Increment "update counter" when modifying account stuff (Luke Dashjr)
f28eb80 Bugfix: wallet: Increment "update counter" only after actually making the applicable db changes to avoid potential races (Luke Dashjr)

Tree-SHA512: 23f5dda58477307bc07997010740f1dc729164cdddefd2f9a2c9c7a877111eb1516d3e2ad4f9b104621f0b7f17369c69fcef13d28b85cb6c01d35f09a8845f23

9 files changed, 180 insertions, 156 deletions

diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index e827825692..74b82a8616 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -142,7 +142,7 @@ void CDBEnv::MakeMock()
     fMockDb = true;
 }
 
-CDBEnv::VerifyResult CDBEnv::Verify(const std::string& strFile, bool (*recoverFunc)(const std::string& strFile))
+CDBEnv::VerifyResult CDBEnv::Verify(const std::string& strFile, recoverFunc_type recoverFunc, std::string& out_backup_filename)
 {
     LOCK(cs_db);
     assert(mapFileUseCount.count(strFile) == 0);
@@ -155,21 +155,21 @@ CDBEnv::VerifyResult CDBEnv::Verify(const std::string& strFile, bool (*recoverFu
         return RECOVER_FAIL;
 
     // Try to recover:
-    bool fRecovered = (*recoverFunc)(strFile);
+    bool fRecovered = (*recoverFunc)(strFile, out_backup_filename);
     return (fRecovered ? RECOVER_OK : RECOVER_FAIL);
 }
 
-bool CDB::Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue))
+bool CDB::Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& newFilename)
 {
     // Recovery procedure:
-    // move wallet file to wallet.timestamp.bak
+    // move wallet file to walletfilename.timestamp.bak
     // Call Salvage with fAggressive=true to
     // get as much data as possible.
     // Rewrite salvaged data to fresh wallet file
     // Set -rescan so any missing transactions will be
     // found.
     int64_t now = GetTime();
-    std::string newFilename = strprintf("wallet.%d.bak", now);
+    newFilename = strprintf("%s.%d.bak", filename, now);
 
     int result = bitdb.dbenv->dbrename(NULL, filename.c_str(), NULL,
                                        newFilename.c_str(), DB_AUTO_COMMIT);
@@ -259,18 +259,19 @@ bool CDB::VerifyEnvironment(const std::string& walletFile, const fs::path& dataD
     return true;
 }
 
-bool CDB::VerifyDatabaseFile(const std::string& walletFile, const fs::path& dataDir, std::string& warningStr, std::string& errorStr, bool (*recoverFunc)(const std::string& strFile))
+bool CDB::VerifyDatabaseFile(const std::string& walletFile, const fs::path& dataDir, std::string& warningStr, std::string& errorStr, CDBEnv::recoverFunc_type recoverFunc)
 {
     if (fs::exists(dataDir / walletFile))
     {
-        CDBEnv::VerifyResult r = bitdb.Verify(walletFile, recoverFunc);
+        std::string backup_filename;
+        CDBEnv::VerifyResult r = bitdb.Verify(walletFile, recoverFunc, backup_filename);
         if (r == CDBEnv::RECOVER_OK)
         {
             warningStr = strprintf(_("Warning: Wallet file corrupt, data salvaged!"
                                      " Original %s saved as %s in %s; if"
                                      " your balance or transactions are incorrect you should"
                                      " restore from a backup."),
-                                   walletFile, "wallet.{timestamp}.bak", dataDir);
+                                   walletFile, backup_filename, dataDir);
         }
         if (r == CDBEnv::RECOVER_FAIL)
         {
@@ -432,6 +433,11 @@ void CDB::Flush()
     env->dbenv->txn_checkpoint(nMinutes ? GetArg("-dblogsize", DEFAULT_WALLET_DBLOGSIZE) * 1024 : 0, nMinutes, 0);
 }
 
+void CWalletDBWrapper::IncrementUpdateCounter()
+{
+    ++nUpdateCounter;
+}
+
 void CDB::Close()
 {
     if (!pdb)
diff --git a/src/wallet/db.h b/src/wallet/db.h
index 3c6870d169..ba37853572 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -55,7 +55,8 @@ public:
     enum VerifyResult { VERIFY_OK,
                         RECOVER_OK,
                         RECOVER_FAIL };
-    VerifyResult Verify(const std::string& strFile, bool (*recoverFunc)(const std::string& strFile));
+    typedef bool (*recoverFunc_type)(const std::string& strFile, std::string& out_backup_filename);
+    VerifyResult Verify(const std::string& strFile, recoverFunc_type recoverFunc, std::string& out_backup_filename);
     /**
      * Salvage data from a file that Verify says is bad.
      * fAggressive sets the DB_AGGRESSIVE flag (see berkeley DB->verify() method documentation).
@@ -93,13 +94,13 @@ class CWalletDBWrapper
     friend class CDB;
 public:
     /** Create dummy DB handle */
-    CWalletDBWrapper(): env(nullptr)
+    CWalletDBWrapper() : nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0), env(nullptr)
     {
     }
 
     /** Create DB handle to real database */
-    CWalletDBWrapper(CDBEnv *env_in, const std::string &strFile_in):
-        env(env_in), strFile(strFile_in)
+    CWalletDBWrapper(CDBEnv *env_in, const std::string &strFile_in) :
+        nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0), env(env_in), strFile(strFile_in)
     {
     }
 
@@ -119,6 +120,13 @@ public:
      */
     void Flush(bool shutdown);
 
+    void IncrementUpdateCounter();
+
+    std::atomic<unsigned int> nUpdateCounter;
+    unsigned int nLastSeen;
+    unsigned int nLastFlushed;
+    int64_t nLastWalletUpdate;
+
 private:
     /** BerkeleyDB specific */
     CDBEnv *env;
@@ -149,7 +157,7 @@ public:
 
     void Flush();
     void Close();
-    static bool Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue));
+    static bool Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename);
 
     /* flush the wallet passively (TRY_LOCK)
        ideal to be called periodically */
@@ -157,7 +165,7 @@ public:
     /* verifies the database environment */
     static bool VerifyEnvironment(const std::string& walletFile, const fs::path& dataDir, std::string& errorStr);
     /* verifies the database file */
-    static bool VerifyDatabaseFile(const std::string& walletFile, const fs::path& dataDir, std::string& warningStr, std::string& errorStr, bool (*recoverFunc)(const std::string& strFile));
+    static bool VerifyDatabaseFile(const std::string& walletFile, const fs::path& dataDir, std::string& warningStr, std::string& errorStr, CDBEnv::recoverFunc_type recoverFunc);
 
 private:
     CDB(const CDB&);
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 73f22c594e..4b8a8b81e4 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -31,7 +31,8 @@
 
 CWallet *GetWalletForJSONRPCRequest(const JSONRPCRequest& request)
 {
-    return pwalletMain;
+    // TODO: Some way to access secondary wallets
+    return vpwallets.empty() ? nullptr : vpwallets[0];
 }
 
 std::string HelpRequiringPassphrase(CWallet * const pwallet)
diff --git a/src/wallet/test/wallet_test_fixture.cpp b/src/wallet/test/wallet_test_fixture.cpp
index 1989bf8d9b..922fcc8e89 100644
--- a/src/wallet/test/wallet_test_fixture.cpp
+++ b/src/wallet/test/wallet_test_fixture.cpp
@@ -8,6 +8,8 @@
 #include "wallet/db.h"
 #include "wallet/wallet.h"
 
+CWallet *pwalletMain;
+
 WalletTestingSetup::WalletTestingSetup(const std::string& chainName):
     TestingSetup(chainName)
 {
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 1ee2722883..96a1b14b60 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -18,6 +18,8 @@
 #include <boost/test/unit_test.hpp>
 #include <univalue.h>
 
+extern CWallet* pwalletMain;
+
 extern UniValue importmulti(const JSONRPCRequest& request);
 extern UniValue dumpwallet(const JSONRPCRequest& request);
 extern UniValue importwallet(const JSONRPCRequest& request);
@@ -401,8 +403,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     // after.
     {
         CWallet wallet;
-        CWallet *backup = ::pwalletMain;
-        ::pwalletMain = &wallet;
+        vpwallets.insert(vpwallets.begin(), &wallet);
         UniValue keys;
         keys.setArray();
         UniValue key;
@@ -433,7 +434,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
                       "downloading and rescanning the relevant blocks (see -reindex and -rescan "
                       "options).\"}},{\"success\":true}]",
                               0, oldTip->GetBlockTimeMax(), TIMESTAMP_WINDOW));
-        ::pwalletMain = backup;
+        vpwallets.erase(vpwallets.begin());
     }
 }
 
@@ -443,7 +444,6 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
 // than or equal to key birthday.
 BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
 {
-    CWallet *pwalletMainBackup = ::pwalletMain;
     LOCK(cs_main);
 
     // Create two blocks with same timestamp to verify that importwallet rescan
@@ -469,7 +469,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
         JSONRPCRequest request;
         request.params.setArray();
         request.params.push_back("wallet.backup");
-        ::pwalletMain = &wallet;
+        vpwallets.insert(vpwallets.begin(), &wallet);
         ::dumpwallet(request);
     }
 
@@ -481,7 +481,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
         JSONRPCRequest request;
         request.params.setArray();
         request.params.push_back("wallet.backup");
-        ::pwalletMain = &wallet;
+        vpwallets[0] = &wallet;
         ::importwallet(request);
 
         BOOST_CHECK_EQUAL(wallet.mapWallet.size(), 3);
@@ -494,7 +494,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
     }
 
     SetMockTime(0);
-    ::pwalletMain = pwalletMainBackup;
+    vpwallets.erase(vpwallets.begin());
 }
 
 // Check that GetImmatureCredit() returns a newly calculated value instead of
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index b3fed1c4dc..eb6de4870f 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -35,7 +35,7 @@
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/thread.hpp>
 
-CWallet* pwalletMain = NULL;
+std::vector<CWalletRef> vpwallets;
 /** Transaction fee set by the user */
 CFeeRate payTxFee(DEFAULT_TRANSACTION_FEE);
 unsigned int nTxConfirmTarget = DEFAULT_TX_CONFIRM_TARGET;
@@ -440,30 +440,40 @@ bool CWallet::Verify()
     if (GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET))
         return true;
 
-    uiInterface.InitMessage(_("Verifying wallet..."));
-    std::string walletFile = GetArg("-wallet", DEFAULT_WALLET_DAT);
+    uiInterface.InitMessage(_("Verifying wallet(s)..."));
 
-    std::string strError;
-    if (!CWalletDB::VerifyEnvironment(walletFile, GetDataDir().string(), strError))
-        return InitError(strError);
+    for (const std::string& walletFile : gArgs.GetArgs("-wallet")) {
+        if (boost::filesystem::path(walletFile).filename() != walletFile) {
+            return InitError(_("-wallet parameter must only specify a filename (not a path)"));
+        } else if (SanitizeString(walletFile, SAFE_CHARS_FILENAME) != walletFile) {
+            return InitError(_("Invalid characters in -wallet filename"));
+        }
 
-    if (GetBoolArg("-salvagewallet", false))
-    {
-        // Recover readable keypairs:
-        CWallet dummyWallet;
-        if (!CWalletDB::Recover(walletFile, (void *)&dummyWallet, CWalletDB::RecoverKeysOnlyFilter))
+        std::string strError;
+        if (!CWalletDB::VerifyEnvironment(walletFile, GetDataDir().string(), strError)) {
+            return InitError(strError);
+        }
+
+        if (GetBoolArg("-salvagewallet", false)) {
+            // Recover readable keypairs:
+            CWallet dummyWallet;
+            std::string backup_filename;
+            if (!CWalletDB::Recover(walletFile, (void *)&dummyWallet, CWalletDB::RecoverKeysOnlyFilter, backup_filename)) {
+                return false;
+            }
+        }
+
+        std::string strWarning;
+        bool dbV = CWalletDB::VerifyDatabaseFile(walletFile, GetDataDir().string(), strWarning, strError);
+        if (!strWarning.empty()) {
+            InitWarning(strWarning);
+        }
+        if (!dbV) {
+            InitError(strError);
             return false;
+        }
     }
 
-    std::string strWarning;
-    bool dbV = CWalletDB::VerifyDatabaseFile(walletFile, GetDataDir().string(), strWarning, strError);
-    if (!strWarning.empty())
-        InitWarning(strWarning);
-    if (!dbV)
-    {
-        InitError(strError);
-        return false;
-    }
     return true;
 }
 
@@ -2867,8 +2877,9 @@ bool CWallet::AddAccountingEntry(const CAccountingEntry& acentry)
 
 bool CWallet::AddAccountingEntry(const CAccountingEntry& acentry, CWalletDB *pwalletdb)
 {
-    if (!pwalletdb->WriteAccountingEntry_Backend(acentry))
+    if (!pwalletdb->WriteAccountingEntry(++nAccountingEntryNumber, acentry)) {
         return false;
+    }
 
     laccentries.push_back(acentry);
     CAccountingEntry & entry = laccentries.back();
@@ -3880,7 +3891,7 @@ CWallet* CWallet::CreateWalletFromFile(const std::string walletFile)
         walletInstance->ScanForWalletTransactions(pindexRescan, true);
         LogPrintf(" rescan      %15dms\n", GetTimeMillis() - nStart);
         walletInstance->SetBestChain(chainActive.GetLocator());
-        CWalletDB::IncrementUpdateCounter();
+        walletInstance->dbw->IncrementUpdateCounter();
 
         // Restore wallet transaction metadata after -zapwallettxes=1
         if (GetBoolArg("-zapwallettxes", false) && GetArg("-zapwallettxes", "1") != "2")
@@ -3922,24 +3933,17 @@ CWallet* CWallet::CreateWalletFromFile(const std::string walletFile)
 bool CWallet::InitLoadWallet()
 {
     if (GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
-        pwalletMain = NULL;
         LogPrintf("Wallet disabled!\n");
         return true;
     }
 
-    std::string walletFile = GetArg("-wallet", DEFAULT_WALLET_DAT);
-
-    if (boost::filesystem::path(walletFile).filename() != walletFile) {
-        return InitError(_("-wallet parameter must only specify a filename (not a path)"));
-    } else if (SanitizeString(walletFile, SAFE_CHARS_FILENAME) != walletFile) {
-        return InitError(_("Invalid characters in -wallet filename"));
-    }
-
-    CWallet * const pwallet = CreateWalletFromFile(walletFile);
-    if (!pwallet) {
-        return false;
+    for (const std::string& walletFile : gArgs.GetArgs("-wallet")) {
+        CWallet * const pwallet = CreateWalletFromFile(walletFile);
+        if (!pwallet) {
+            return false;
+        }
+        vpwallets.push_back(pwallet);
     }
-    pwalletMain = pwallet;
 
     return true;
 }
@@ -3960,6 +3964,9 @@ void CWallet::postInitProcess(CScheduler& scheduler)
 
 bool CWallet::ParameterInteraction()
 {
+    SoftSetArg("-wallet", DEFAULT_WALLET_DAT);
+    const bool is_multiwallet = gArgs.GetArgs("-wallet").size() > 1;
+
     if (GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET))
         return true;
 
@@ -3968,15 +3975,27 @@ bool CWallet::ParameterInteraction()
     }
 
     if (GetBoolArg("-salvagewallet", false) && SoftSetBoolArg("-rescan", true)) {
+        if (is_multiwallet) {
+            return InitError(strprintf("%s is only allowed with a single wallet file", "-salvagewallet"));
+        }
         // Rewrite just private keys: rescan to find transactions
         LogPrintf("%s: parameter interaction: -salvagewallet=1 -> setting -rescan=1\n", __func__);
     }
 
     // -zapwallettx implies a rescan
     if (GetBoolArg("-zapwallettxes", false) && SoftSetBoolArg("-rescan", true)) {
+        if (is_multiwallet) {
+            return InitError(strprintf("%s is only allowed with a single wallet file", "-zapwallettxes"));
+        }
         LogPrintf("%s: parameter interaction: -zapwallettxes=<mode> -> setting -rescan=1\n", __func__);
     }
 
+    if (is_multiwallet) {
+        if (GetBoolArg("-upgradewallet", false)) {
+            return InitError(strprintf("%s is only allowed with a single wallet file", "-upgradewallet"));
+        }
+    }
+
     if (GetBoolArg("-sysperms", false))
         return InitError("-sysperms is not allowed in combination with enabled wallet functionality");
     if (GetArg("-prune", 0) && GetBoolArg("-rescan", false))
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index a9c50aee4d..6c6eb69180 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -29,7 +29,8 @@
 #include <utility>
 #include <vector>
 
-extern CWallet* pwalletMain;
+typedef CWallet* CWalletRef;
+extern std::vector<CWalletRef> vpwallets;
 
 /**
  * Settings
@@ -782,6 +783,7 @@ public:
         nMasterKeyMaxID = 0;
         pwalletdbEncryption = NULL;
         nOrderPosNext = 0;
+        nAccountingEntryNumber = 0;
         nNextResend = 0;
         nLastResend = 0;
         nTimeFirstKey = 0;
@@ -799,6 +801,7 @@ public:
     TxItems wtxOrdered;
 
     int64_t nOrderPosNext;
+    uint64_t nAccountingEntryNumber;
     std::map<uint256, int> mapRequestCount;
 
     std::map<CTxDestination, CAddressBookData> mapAddressBook;
diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index eb97f61f5c..7731fa5631 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -21,59 +21,47 @@
 #include <boost/foreach.hpp>
 #include <boost/thread.hpp>
 
-static uint64_t nAccountingEntryNumber = 0;
-
-static std::atomic<unsigned int> nWalletDBUpdateCounter;
-
 //
 // CWalletDB
 //
 
 bool CWalletDB::WriteName(const std::string& strAddress, const std::string& strName)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::make_pair(std::string("name"), strAddress), strName);
+    return WriteIC(std::make_pair(std::string("name"), strAddress), strName);
 }
 
 bool CWalletDB::EraseName(const std::string& strAddress)
 {
     // This should only be used for sending addresses, never for receiving addresses,
     // receiving addresses must always have an address book entry if they're not change return.
-    nWalletDBUpdateCounter++;
-    return batch.Erase(std::make_pair(std::string("name"), strAddress));
+    return EraseIC(std::make_pair(std::string("name"), strAddress));
 }
 
 bool CWalletDB::WritePurpose(const std::string& strAddress, const std::string& strPurpose)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::make_pair(std::string("purpose"), strAddress), strPurpose);
+    return WriteIC(std::make_pair(std::string("purpose"), strAddress), strPurpose);
 }
 
 bool CWalletDB::ErasePurpose(const std::string& strPurpose)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Erase(std::make_pair(std::string("purpose"), strPurpose));
+    return EraseIC(std::make_pair(std::string("purpose"), strPurpose));
 }
 
 bool CWalletDB::WriteTx(const CWalletTx& wtx)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::make_pair(std::string("tx"), wtx.GetHash()), wtx);
+    return WriteIC(std::make_pair(std::string("tx"), wtx.GetHash()), wtx);
 }
 
 bool CWalletDB::EraseTx(uint256 hash)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Erase(std::make_pair(std::string("tx"), hash));
+    return EraseIC(std::make_pair(std::string("tx"), hash));
 }
 
 bool CWalletDB::WriteKey(const CPubKey& vchPubKey, const CPrivKey& vchPrivKey, const CKeyMetadata& keyMeta)
 {
-    nWalletDBUpdateCounter++;
-
-    if (!batch.Write(std::make_pair(std::string("keymeta"), vchPubKey),
-               keyMeta, false))
+    if (!WriteIC(std::make_pair(std::string("keymeta"), vchPubKey), keyMeta, false)) {
         return false;
+    }
 
     // hash pubkey/privkey to accelerate wallet load
     std::vector<unsigned char> vchKey;
@@ -81,7 +69,7 @@ bool CWalletDB::WriteKey(const CPubKey& vchPubKey, const CPrivKey& vchPrivKey, c
     vchKey.insert(vchKey.end(), vchPubKey.begin(), vchPubKey.end());
     vchKey.insert(vchKey.end(), vchPrivKey.begin(), vchPrivKey.end());
 
-    return batch.Write(std::make_pair(std::string("key"), vchPubKey), std::make_pair(vchPrivKey, Hash(vchKey.begin(), vchKey.end())), false);
+    return WriteIC(std::make_pair(std::string("key"), vchPubKey), std::make_pair(vchPrivKey, Hash(vchKey.begin(), vchKey.end())), false);
 }
 
 bool CWalletDB::WriteCryptedKey(const CPubKey& vchPubKey,
@@ -89,55 +77,53 @@ bool CWalletDB::WriteCryptedKey(const CPubKey& vchPubKey,
                                 const CKeyMetadata &keyMeta)
 {
     const bool fEraseUnencryptedKey = true;
-    nWalletDBUpdateCounter++;
 
-    if (!batch.Write(std::make_pair(std::string("keymeta"), vchPubKey),
-            keyMeta))
+    if (!WriteIC(std::make_pair(std::string("keymeta"), vchPubKey), keyMeta)) {
         return false;
+    }
 
-    if (!batch.Write(std::make_pair(std::string("ckey"), vchPubKey), vchCryptedSecret, false))
+    if (!WriteIC(std::make_pair(std::string("ckey"), vchPubKey), vchCryptedSecret, false)) {
         return false;
+    }
     if (fEraseUnencryptedKey)
     {
-        batch.Erase(std::make_pair(std::string("key"), vchPubKey));
-        batch.Erase(std::make_pair(std::string("wkey"), vchPubKey));
+        EraseIC(std::make_pair(std::string("key"), vchPubKey));
+        EraseIC(std::make_pair(std::string("wkey"), vchPubKey));
     }
+
     return true;
 }
 
 bool CWalletDB::WriteMasterKey(unsigned int nID, const CMasterKey& kMasterKey)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::make_pair(std::string("mkey"), nID), kMasterKey, true);
+    return WriteIC(std::make_pair(std::string("mkey"), nID), kMasterKey, true);
 }
 
 bool CWalletDB::WriteCScript(const uint160& hash, const CScript& redeemScript)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::make_pair(std::string("cscript"), hash), *(const CScriptBase*)(&redeemScript), false);
+    return WriteIC(std::make_pair(std::string("cscript"), hash), *(const CScriptBase*)(&redeemScript), false);
 }
 
 bool CWalletDB::WriteWatchOnly(const CScript &dest, const CKeyMetadata& keyMeta)
 {
-    nWalletDBUpdateCounter++;
-    if (!batch.Write(std::make_pair(std::string("watchmeta"), *(const CScriptBase*)(&dest)), keyMeta))
+    if (!WriteIC(std::make_pair(std::string("watchmeta"), *(const CScriptBase*)(&dest)), keyMeta)) {
         return false;
-    return batch.Write(std::make_pair(std::string("watchs"), *(const CScriptBase*)(&dest)), '1');
+    }
+    return WriteIC(std::make_pair(std::string("watchs"), *(const CScriptBase*)(&dest)), '1');
 }
 
 bool CWalletDB::EraseWatchOnly(const CScript &dest)
 {
-    nWalletDBUpdateCounter++;
-    if (!batch.Erase(std::make_pair(std::string("watchmeta"), *(const CScriptBase*)(&dest))))
+    if (!EraseIC(std::make_pair(std::string("watchmeta"), *(const CScriptBase*)(&dest)))) {
         return false;
-    return batch.Erase(std::make_pair(std::string("watchs"), *(const CScriptBase*)(&dest)));
+    }
+    return EraseIC(std::make_pair(std::string("watchs"), *(const CScriptBase*)(&dest)));
 }
 
 bool CWalletDB::WriteBestBlock(const CBlockLocator& locator)
 {
-    nWalletDBUpdateCounter++;
-    batch.Write(std::string("bestblock"), CBlockLocator()); // Write empty block locator so versions that require a merkle branch automatically rescan
-    return batch.Write(std::string("bestblock_nomerkle"), locator);
+    WriteIC(std::string("bestblock"), CBlockLocator()); // Write empty block locator so versions that require a merkle branch automatically rescan
+    return WriteIC(std::string("bestblock_nomerkle"), locator);
 }
 
 bool CWalletDB::ReadBestBlock(CBlockLocator& locator)
@@ -148,14 +134,12 @@ bool CWalletDB::ReadBestBlock(CBlockLocator& locator)
 
 bool CWalletDB::WriteOrderPosNext(int64_t nOrderPosNext)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::string("orderposnext"), nOrderPosNext);
+    return WriteIC(std::string("orderposnext"), nOrderPosNext);
 }
 
 bool CWalletDB::WriteDefaultKey(const CPubKey& vchPubKey)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::string("defaultkey"), vchPubKey);
+    return WriteIC(std::string("defaultkey"), vchPubKey);
 }
 
 bool CWalletDB::ReadPool(int64_t nPool, CKeyPool& keypool)
@@ -165,19 +149,17 @@ bool CWalletDB::ReadPool(int64_t nPool, CKeyPool& keypool)
 
 bool CWalletDB::WritePool(int64_t nPool, const CKeyPool& keypool)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::make_pair(std::string("pool"), nPool), keypool);
+    return WriteIC(std::make_pair(std::string("pool"), nPool), keypool);
 }
 
 bool CWalletDB::ErasePool(int64_t nPool)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Erase(std::make_pair(std::string("pool"), nPool));
+    return EraseIC(std::make_pair(std::string("pool"), nPool));
 }
 
 bool CWalletDB::WriteMinVersion(int nVersion)
 {
-    return batch.Write(std::string("minversion"), nVersion);
+    return WriteIC(std::string("minversion"), nVersion);
 }
 
 bool CWalletDB::ReadAccount(const std::string& strAccount, CAccount& account)
@@ -188,17 +170,12 @@ bool CWalletDB::ReadAccount(const std::string& strAccount, CAccount& account)
 
 bool CWalletDB::WriteAccount(const std::string& strAccount, const CAccount& account)
 {
-    return batch.Write(std::make_pair(std::string("acc"), strAccount), account);
+    return WriteIC(std::make_pair(std::string("acc"), strAccount), account);
 }
 
 bool CWalletDB::WriteAccountingEntry(const uint64_t nAccEntryNum, const CAccountingEntry& acentry)
 {
-    return batch.Write(std::make_pair(std::string("acentry"), std::make_pair(acentry.strAccount, nAccEntryNum)), acentry);
-}
-
-bool CWalletDB::WriteAccountingEntry_Backend(const CAccountingEntry& acentry)
-{
-    return WriteAccountingEntry(++nAccountingEntryNumber, acentry);
+    return WriteIC(std::make_pair(std::string("acentry"), std::make_pair(acentry.strAccount, nAccEntryNum)), acentry);
 }
 
 CAmount CWalletDB::GetAccountCreditDebit(const std::string& strAccount)
@@ -337,8 +314,9 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
             ssKey >> strAccount;
             uint64_t nNumber;
             ssKey >> nNumber;
-            if (nNumber > nAccountingEntryNumber)
-                nAccountingEntryNumber = nNumber;
+            if (nNumber > pwallet->nAccountingEntryNumber) {
+                pwallet->nAccountingEntryNumber = nNumber;
+            }
 
             if (!wss.fAnyUnordered)
             {
@@ -784,38 +762,39 @@ void MaybeCompactWalletDB()
         return;
     }
 
-    static unsigned int nLastSeen = CWalletDB::GetUpdateCounter();
-    static unsigned int nLastFlushed = CWalletDB::GetUpdateCounter();
-    static int64_t nLastWalletUpdate = GetTime();
+    for (CWalletRef pwallet : vpwallets) {
+        CWalletDBWrapper& dbh = pwallet->GetDBHandle();
 
-    if (nLastSeen != CWalletDB::GetUpdateCounter())
-    {
-        nLastSeen = CWalletDB::GetUpdateCounter();
-        nLastWalletUpdate = GetTime();
-    }
+        unsigned int nUpdateCounter = dbh.nUpdateCounter;
 
-    if (nLastFlushed != CWalletDB::GetUpdateCounter() && GetTime() - nLastWalletUpdate >= 2)
-    {
-        if (CDB::PeriodicFlush(pwalletMain->GetDBHandle())) {
-            nLastFlushed = CWalletDB::GetUpdateCounter();
+        if (dbh.nLastSeen != nUpdateCounter) {
+            dbh.nLastSeen = nUpdateCounter;
+            dbh.nLastWalletUpdate = GetTime();
+        }
+
+        if (dbh.nLastFlushed != nUpdateCounter && GetTime() - dbh.nLastWalletUpdate >= 2) {
+            if (CDB::PeriodicFlush(dbh)) {
+                dbh.nLastFlushed = nUpdateCounter;
+            }
         }
     }
+
     fOneThread = false;
 }
 
 //
 // Try to (very carefully!) recover wallet file if there is a problem.
 //
-bool CWalletDB::Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue))
+bool CWalletDB::Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename)
 {
-    return CDB::Recover(filename, callbackDataIn, recoverKVcallback);
+    return CDB::Recover(filename, callbackDataIn, recoverKVcallback, out_backup_filename);
 }
 
-bool CWalletDB::Recover(const std::string& filename)
+bool CWalletDB::Recover(const std::string& filename, std::string& out_backup_filename)
 {
     // recover without a key filter callback
     // results in recovering all record types
-    return CWalletDB::Recover(filename, NULL, NULL);
+    return CWalletDB::Recover(filename, NULL, NULL, out_backup_filename);
 }
 
 bool CWalletDB::RecoverKeysOnlyFilter(void *callbackData, CDataStream ssKey, CDataStream ssValue)
@@ -848,36 +827,23 @@ bool CWalletDB::VerifyEnvironment(const std::string& walletFile, const fs::path&
 
 bool CWalletDB::VerifyDatabaseFile(const std::string& walletFile, const fs::path& dataDir, std::string& warningStr, std::string& errorStr)
 {
-    return CDB::VerifyDatabaseFile(walletFile, dataDir, errorStr, warningStr, CWalletDB::Recover);
+    return CDB::VerifyDatabaseFile(walletFile, dataDir, warningStr, errorStr, CWalletDB::Recover);
 }
 
 bool CWalletDB::WriteDestData(const std::string &address, const std::string &key, const std::string &value)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::make_pair(std::string("destdata"), std::make_pair(address, key)), value);
+    return WriteIC(std::make_pair(std::string("destdata"), std::make_pair(address, key)), value);
 }
 
 bool CWalletDB::EraseDestData(const std::string &address, const std::string &key)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Erase(std::make_pair(std::string("destdata"), std::make_pair(address, key)));
+    return EraseIC(std::make_pair(std::string("destdata"), std::make_pair(address, key)));
 }
 
 
 bool CWalletDB::WriteHDChain(const CHDChain& chain)
 {
-    nWalletDBUpdateCounter++;
-    return batch.Write(std::string("hdchain"), chain);
-}
-
-void CWalletDB::IncrementUpdateCounter()
-{
-    nWalletDBUpdateCounter++;
-}
-
-unsigned int CWalletDB::GetUpdateCounter()
-{
-    return nWalletDBUpdateCounter;
+    return WriteIC(std::string("hdchain"), chain);
 }
 
 bool CWalletDB::TxnBegin()
diff --git a/src/wallet/walletdb.h b/src/wallet/walletdb.h
index cd9fe279c5..d78f143ebd 100644
--- a/src/wallet/walletdb.h
+++ b/src/wallet/walletdb.h
@@ -140,9 +140,31 @@ public:
  */
 class CWalletDB
 {
+private:
+    template <typename K, typename T>
+    bool WriteIC(const K& key, const T& value, bool fOverwrite = true)
+    {
+        if (!batch.Write(key, value, fOverwrite)) {
+            return false;
+        }
+        m_dbw.IncrementUpdateCounter();
+        return true;
+    }
+
+    template <typename K>
+    bool EraseIC(const K& key)
+    {
+        if (!batch.Erase(key)) {
+            return false;
+        }
+        m_dbw.IncrementUpdateCounter();
+        return true;
+    }
+
 public:
     CWalletDB(CWalletDBWrapper& dbw, const char* pszMode = "r+", bool _fFlushOnClose = true) :
-        batch(dbw, pszMode, _fFlushOnClose)
+        batch(dbw, pszMode, _fFlushOnClose),
+        m_dbw(dbw)
     {
     }
 
@@ -180,7 +202,6 @@ public:
     /// This writes directly to the database, and will not update the CWallet's cached accounting entries!
     /// Use wallet.AddAccountingEntry instead, to write *and* update its caches.
     bool WriteAccountingEntry(const uint64_t nAccEntryNum, const CAccountingEntry& acentry);
-    bool WriteAccountingEntry_Backend(const CAccountingEntry& acentry);
     bool ReadAccount(const std::string& strAccount, CAccount& account);
     bool WriteAccount(const std::string& strAccount, const CAccount& account);
 
@@ -197,9 +218,9 @@ public:
     DBErrors ZapWalletTx(std::vector<CWalletTx>& vWtx);
     DBErrors ZapSelectTx(std::vector<uint256>& vHashIn, std::vector<uint256>& vHashOut);
     /* Try to (very carefully!) recover wallet database (with a possible key type filter) */
-    static bool Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue));
+    static bool Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename);
     /* Recover convenience-function to bypass the key filter callback, called when verify fails, recovers everything */
-    static bool Recover(const std::string& filename);
+    static bool Recover(const std::string& filename, std::string& out_backup_filename);
     /* Recover filter (used as callback), will only let keys (cryptographical keys) as KV/key-type pass through */
     static bool RecoverKeysOnlyFilter(void *callbackData, CDataStream ssKey, CDataStream ssValue);
     /* Function to determine if a certain KV/key-type is a key (cryptographical key) type */
@@ -212,9 +233,6 @@ public:
     //! write the hdchain model (external chain child index counter)
     bool WriteHDChain(const CHDChain& chain);
 
-    static void IncrementUpdateCounter();
-    static unsigned int GetUpdateCounter();
-
     //! Begin a new transaction
     bool TxnBegin();
     //! Commit current transaction
@@ -227,6 +245,7 @@ public:
     bool WriteVersion(int nVersion);
 private:
     CDB batch;
+    CWalletDBWrapper& m_dbw;
 
     CWalletDB(const CWalletDB&);
     void operator=(const CWalletDB&);