walletdb: Move PeriodicFlush into WalletDatabase

Make PeriodicFlush a non-static member of WalletDatabase instead of
WalletBatch.

Author: achow101

src/wallet/bdb.cpp

@@ -614,14 +614,12 @@ void BerkeleyEnvironment::Flush(bool fShutdown)
     }
 }
 
-bool BerkeleyBatch::PeriodicFlush(BerkeleyDatabase& database)
+bool BerkeleyDatabase::PeriodicFlush()
 {
-    if (database.IsDummy()) {
+    if (IsDummy()) {
         return true;
     }
     bool ret = false;
-    BerkeleyEnvironment *env = database.env.get();
-    const std::string& strFile = database.strFile;
     TRY_LOCK(cs_db, lockDb);
     if (lockDb)
     {

src/wallet/bdb.h

@@ -131,6 +131,9 @@ class BerkeleyDatabase
     /** Make sure all changes are flushed to disk.
      */
     void Flush(bool shutdown);
+    /* flush the wallet passively (TRY_LOCK)
+       ideal to be called periodically */
+    bool PeriodicFlush();
 
     void IncrementUpdateCounter();
 
@@ -215,10 +218,6 @@ class BerkeleyBatch
     void Flush();
     void Close();
 
-    /* flush the wallet passively (TRY_LOCK)
-       ideal to be called periodically */
-    static bool PeriodicFlush(BerkeleyDatabase& database);
-
     template <typename K, typename T>
     bool Read(const K& key, T& value)
     {

src/wallet/walletdb.cpp

@@ -964,7 +964,7 @@ void MaybeCompactWalletDB()
         }
 
         if (dbh.nLastFlushed != nUpdateCounter && GetTime() - dbh.nLastWalletUpdate >= 2) {
-            if (BerkeleyBatch::PeriodicFlush(dbh)) {
+            if (dbh.PeriodicFlush()) {
                 dbh.nLastFlushed = nUpdateCounter;
             }
         }