Remove unused nested BDB transaction support

src/db.cpp

@@ -170,9 +170,9 @@ void CDB::Close()
 {
     if (!pdb)
         return;
-    if (!vTxn.empty())
-        vTxn.front()->abort();
-    vTxn.clear();
+    if (activeTxn)
+        activeTxn->abort();
+    activeTxn = NULL;
     pdb = NULL;
 
     // Flush database activity from memory pool to disk log

src/db.h

@@ -51,10 +51,10 @@ public:
     void CheckpointLSN(std::string strFile);
     void SetDetach(bool fDetachDB_) { fDetachDB = fDetachDB_; }
 
-    DbTxn *TxnBegin(DbTxn *baseTxn, int flags=DB_TXN_WRITE_NOSYNC)
+    DbTxn *TxnBegin(int flags=DB_TXN_WRITE_NOSYNC)
     {
         DbTxn* ptxn = NULL;
-        int ret = dbenv.txn_begin(baseTxn, &ptxn, flags);
+        int ret = dbenv.txn_begin(NULL, &ptxn, flags);
         if (!ptxn || ret != 0)
             return NULL;
         return ptxn;
@@ -70,7 +70,7 @@ class CDB
 protected:
     Db* pdb;
     std::string strFile;
-    std::vector<DbTxn*> vTxn;
+    DbTxn *activeTxn;
     bool fReadOnly;
 
     explicit CDB(const char* pszFile, const char* pszMode="r+");
@@ -97,7 +97,7 @@ protected:
         // Read
         Dbt datValue;
         datValue.set_flags(DB_DBT_MALLOC);
-        int ret = pdb->get(GetTxn(), &datKey, &datValue, 0);
+        int ret = pdb->get(activeTxn, &datKey, &datValue, 0);
         memset(datKey.get_data(), 0, datKey.get_size());
         if (datValue.get_data() == NULL)
             return false;
@@ -133,7 +133,7 @@ protected:
         Dbt datValue(&ssValue[0], ssValue.size());
 
         // Write
-        int ret = pdb->put(GetTxn(), &datKey, &datValue, (fOverwrite ? 0 : DB_NOOVERWRITE));
+        int ret = pdb->put(activeTxn, &datKey, &datValue, (fOverwrite ? 0 : DB_NOOVERWRITE));
 
         // Clear memory in case it was a private key
         memset(datKey.get_data(), 0, datKey.get_size());
@@ -156,7 +156,7 @@ protected:
         Dbt datKey(&ssKey[0], ssKey.size());
 
         // Erase
-        int ret = pdb->del(GetTxn(), &datKey, 0);
+        int ret = pdb->del(activeTxn, &datKey, 0);
 
         // Clear memory
         memset(datKey.get_data(), 0, datKey.get_size());
@@ -176,7 +176,7 @@ protected:
         Dbt datKey(&ssKey[0], ssKey.size());
 
         // Exists
-        int ret = pdb->exists(GetTxn(), &datKey, 0);
+        int ret = pdb->exists(activeTxn, &datKey, 0);
 
         // Clear memory
         memset(datKey.get_data(), 0, datKey.get_size());
@@ -233,45 +233,33 @@ protected:
         return 0;
     }
 
-    DbTxn* GetTxn()
-    {
-        if (!vTxn.empty())
-            return vTxn.back();
-        else
-            return NULL;
-    }
-
 public:
     bool TxnBegin()
     {
-        if (!pdb)
+        if (!pdb || activeTxn)
             return false;
-        DbTxn* ptxn = bitdb.TxnBegin(GetTxn());
+        DbTxn* ptxn = bitdb.TxnBegin();
         if (!ptxn)
             return false;
-        vTxn.push_back(ptxn);
+        activeTxn = ptxn;
         return true;
     }
 
     bool TxnCommit()
     {
-        if (!pdb)
-            return false;
-        if (vTxn.empty())
+        if (!pdb || !activeTxn)
             return false;
-        int ret = vTxn.back()->commit(0);
-        vTxn.pop_back();
+        int ret = activeTxn->commit(0);
+        activeTxn = NULL;
         return (ret == 0);
     }
 
     bool TxnAbort()
     {
-        if (!pdb)
-            return false;
-        if (vTxn.empty())
+        if (!pdb || !activeTxn)
             return false;
-        int ret = vTxn.back()->abort();
-        vTxn.pop_back();
+        int ret = activeTxn->abort();
+        activeTxn = NULL;
         return (ret == 0);
     }