Make nWalletDBUpdated atomic to avoid a potential race.

src/wallet/db.cpp

@@ -24,9 +24,6 @@
 using namespace std;
 
 
-unsigned int nWalletDBUpdated;
-
-
 //
 // CDB
 //

src/wallet/db.h

@@ -23,8 +23,6 @@
 static const unsigned int DEFAULT_WALLET_DBLOGSIZE = 100;
 static const bool DEFAULT_WALLET_PRIVDB = true;
 
-extern unsigned int nWalletDBUpdated;
-
 class CDBEnv
 {
 private:

src/wallet/wallet.cpp

@@ -3508,7 +3508,7 @@ bool CWallet::InitLoadWallet()
         walletInstance->ScanForWalletTransactions(pindexRescan, true);
         LogPrintf(" rescan      %15dms\n", GetTimeMillis() - nStart);
         walletInstance->SetBestChain(chainActive.GetLocator());
-        nWalletDBUpdated++;
+        CWalletDB::IncrementUpdateCounter();
 
         // Restore wallet transaction metadata after -zapwallettxes=1
         if (GetBoolArg("-zapwallettxes", false) && GetArg("-zapwallettxes", "1") != "2")

src/wallet/walletdb.cpp

@@ -15,6 +15,8 @@
 #include "utiltime.h"
 #include "wallet/wallet.h"
 
+#include <atomic>
+
 #include <boost/version.hpp>
 #include <boost/filesystem.hpp>
 #include <boost/foreach.hpp>
@@ -24,13 +26,15 @@ using namespace std;
 
 static uint64_t nAccountingEntryNumber = 0;
 
+static std::atomic<unsigned int> nWalletDBUpdateCounter;
+
 //
 // CWalletDB
 //
 
 bool CWalletDB::WriteName(const string& strAddress, const string& strName)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(make_pair(string("name"), strAddress), strName);
 }
 
@@ -38,37 +42,37 @@ bool CWalletDB::EraseName(const 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.
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Erase(make_pair(string("name"), strAddress));
 }
 
 bool CWalletDB::WritePurpose(const string& strAddress, const string& strPurpose)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(make_pair(string("purpose"), strAddress), strPurpose);
 }
 
 bool CWalletDB::ErasePurpose(const string& strPurpose)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Erase(make_pair(string("purpose"), strPurpose));
 }
 
 bool CWalletDB::WriteTx(const CWalletTx& wtx)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::make_pair(std::string("tx"), wtx.GetHash()), wtx);
 }
 
 bool CWalletDB::EraseTx(uint256 hash)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Erase(std::make_pair(std::string("tx"), hash));
 }
 
 bool CWalletDB::WriteKey(const CPubKey& vchPubKey, const CPrivKey& vchPrivKey, const CKeyMetadata& keyMeta)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
 
     if (!Write(std::make_pair(std::string("keymeta"), vchPubKey),
                keyMeta, false))
@@ -88,7 +92,7 @@ bool CWalletDB::WriteCryptedKey(const CPubKey& vchPubKey,
                                 const CKeyMetadata &keyMeta)
 {
     const bool fEraseUnencryptedKey = true;
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
 
     if (!Write(std::make_pair(std::string("keymeta"), vchPubKey),
             keyMeta))
@@ -106,31 +110,31 @@ bool CWalletDB::WriteCryptedKey(const CPubKey& vchPubKey,
 
 bool CWalletDB::WriteMasterKey(unsigned int nID, const CMasterKey& kMasterKey)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::make_pair(std::string("mkey"), nID), kMasterKey, true);
 }
 
 bool CWalletDB::WriteCScript(const uint160& hash, const CScript& redeemScript)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::make_pair(std::string("cscript"), hash), *(const CScriptBase*)(&redeemScript), false);
 }
 
 bool CWalletDB::WriteWatchOnly(const CScript &dest)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::make_pair(std::string("watchs"), *(const CScriptBase*)(&dest)), '1');
 }
 
 bool CWalletDB::EraseWatchOnly(const CScript &dest)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Erase(std::make_pair(std::string("watchs"), *(const CScriptBase*)(&dest)));
 }
 
 bool CWalletDB::WriteBestBlock(const CBlockLocator& locator)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     Write(std::string("bestblock"), CBlockLocator()); // Write empty block locator so versions that require a merkle branch automatically rescan
     return Write(std::string("bestblock_nomerkle"), locator);
 }
@@ -143,13 +147,13 @@ bool CWalletDB::ReadBestBlock(CBlockLocator& locator)
 
 bool CWalletDB::WriteOrderPosNext(int64_t nOrderPosNext)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::string("orderposnext"), nOrderPosNext);
 }
 
 bool CWalletDB::WriteDefaultKey(const CPubKey& vchPubKey)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::string("defaultkey"), vchPubKey);
 }
 
@@ -160,13 +164,13 @@ bool CWalletDB::ReadPool(int64_t nPool, CKeyPool& keypool)
 
 bool CWalletDB::WritePool(int64_t nPool, const CKeyPool& keypool)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::make_pair(std::string("pool"), nPool), keypool);
 }
 
 bool CWalletDB::ErasePool(int64_t nPool)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Erase(std::make_pair(std::string("pool"), nPool));
 }
 
@@ -780,20 +784,20 @@ void ThreadFlushWalletDB(const string& strFile)
     if (!GetBoolArg("-flushwallet", DEFAULT_FLUSHWALLET))
         return;
 
-    unsigned int nLastSeen = nWalletDBUpdated;
-    unsigned int nLastFlushed = nWalletDBUpdated;
+    unsigned int nLastSeen = CWalletDB::GetUpdateCounter();
+    unsigned int nLastFlushed = CWalletDB::GetUpdateCounter();
     int64_t nLastWalletUpdate = GetTime();
     while (true)
     {
         MilliSleep(500);
 
-        if (nLastSeen != nWalletDBUpdated)
+        if (nLastSeen != CWalletDB::GetUpdateCounter())
         {
-            nLastSeen = nWalletDBUpdated;
+            nLastSeen = CWalletDB::GetUpdateCounter();
             nLastWalletUpdate = GetTime();
         }
 
-        if (nLastFlushed != nWalletDBUpdated && GetTime() - nLastWalletUpdate >= 2)
+        if (nLastFlushed != CWalletDB::GetUpdateCounter() && GetTime() - nLastWalletUpdate >= 2)
         {
             TRY_LOCK(bitdb.cs_db,lockDb);
             if (lockDb)
@@ -814,7 +818,7 @@ void ThreadFlushWalletDB(const string& strFile)
                     if (_mi != bitdb.mapFileUseCount.end())
                     {
                         LogPrint("db", "Flushing %s\n", strFile);
-                        nLastFlushed = nWalletDBUpdated;
+                        nLastFlushed = CWalletDB::GetUpdateCounter();
                         int64_t nStart = GetTimeMillis();
 
                         // Flush wallet file so it's self contained
@@ -921,19 +925,29 @@ bool CWalletDB::Recover(CDBEnv& dbenv, const std::string& filename)
 
 bool CWalletDB::WriteDestData(const std::string &address, const std::string &key, const std::string &value)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::make_pair(std::string("destdata"), std::make_pair(address, key)), value);
 }
 
 bool CWalletDB::EraseDestData(const std::string &address, const std::string &key)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Erase(std::make_pair(std::string("destdata"), std::make_pair(address, key)));
 }
 
 
 bool CWalletDB::WriteHDChain(const CHDChain& chain)
 {
-    nWalletDBUpdated++;
+    nWalletDBUpdateCounter++;
     return Write(std::string("hdchain"), chain);
 }
+
+void CWalletDB::IncrementUpdateCounter()
+{
+    nWalletDBUpdateCounter++;
+}
+
+unsigned int CWalletDB::GetUpdateCounter()
+{
+    return nWalletDBUpdateCounter;
+}

src/wallet/walletdb.h

@@ -176,10 +176,11 @@ public:
     //! write the hdchain model (external chain child index counter)
     bool WriteHDChain(const CHDChain& chain);
 
+    static void IncrementUpdateCounter();
+    static unsigned int GetUpdateCounter();
 private:
     CWalletDB(const CWalletDB&);
     void operator=(const CWalletDB&);
-
 };
 
 void ThreadFlushWalletDB(const std::string& strFile);