dashpay · UdjinM6 · Mar 6, 2019 · Mar 6, 2019 · Mar 6, 2019 · Mar 6, 2019
diff --git a/src/dbwrapper.h b/src/dbwrapper.h
@@ -356,14 +356,16 @@ class CDBWrapper
 
 };
 
+template<typename Parent, typename CommitTarget>
 class CDBTransaction {
-private:
-    CDBWrapper &db;
+protected:
+    Parent &parent;
+    CommitTarget &commitTarget;
 
     struct KeyHolder {
         virtual ~KeyHolder() = default;
         virtual bool Less(const KeyHolder &b) const = 0;
-        virtual void Erase(CDBBatch &batch) = 0;
+        virtual void Erase(CommitTarget &commitTarget) = 0;
     };
     typedef std::unique_ptr<KeyHolder> KeyHolderPtr;
 
@@ -376,15 +378,15 @@ class CDBTransaction {
             auto *b2 = dynamic_cast<const KeyHolderImpl<K>*>(&b);
             return key < b2->key;
         }
-        virtual void Erase(CDBBatch &batch) {
-            batch.Erase(key);
+        virtual void Erase(CommitTarget &commitTarget) {
+            commitTarget.Erase(key);
         }
         K key;
     };
 
     struct KeyValueHolder {
         virtual ~KeyValueHolder() = default;
-        virtual void Write(CDBBatch &batch) = 0;
+        virtual void Write(CommitTarget &parent) = 0;
     };
     typedef std::unique_ptr<KeyValueHolder> KeyValueHolderPtr;
 
@@ -393,8 +395,13 @@ class CDBTransaction {
         KeyValueHolderImpl(const KeyHolderImpl<K> &_key, const V &_value)
                 : key(_key),
                   value(_value) { }
-        virtual void Write(CDBBatch &batch) {
-            batch.Write(key.key, value);
+        KeyValueHolderImpl(const KeyHolderImpl<K> &_key, V &&_value)
+                : key(_key),
+                  value(std::forward<V>(_value)) { }
+        virtual void Write(CommitTarget &commitTarget) {
+            // we're moving the value instead of copying it. This means that Write() can only be called once per
+            // KeyValueHolderImpl instance. Commit() clears the write maps, so this ok.
+            commitTarget.Write(key.key, std::move(value));
         }
         const KeyHolderImpl<K> &key;
         V value;
@@ -434,22 +441,34 @@ class CDBTransaction {
         return getMapForType<K>(deletes, create);
     }
 
-public:
-    CDBTransaction(CDBWrapper &_db) : db(_db) {}
-
-    template <typename K, typename V>
-    void Write(const K& key, const V& value) {
-        KeyHolderPtr k(new KeyHolderImpl<K>(key));
-        KeyHolderImpl<K>* k2 = dynamic_cast<KeyHolderImpl<K>*>(k.get());
-        KeyValueHolderPtr kv(new KeyValueHolderImpl<K,V>(*k2, value));
+    template <typename K, typename KV>
+    void writeImpl(KeyHolderImpl<K>* k, KV&& kv) {
+        auto k2 = KeyHolderPtr(k);
 
         KeyValueMap *ds = getDeletesMap<K>(false);
         if (ds)
-            ds->erase(k);
+            ds->erase(k2);
 
         KeyValueMap *ws = getWritesMap<K>(true);
-        ws->erase(k);
-        ws->emplace(std::make_pair(std::move(k), std::move(kv)));
+        ws->erase(k2);
+        ws->emplace(std::make_pair(std::move(k2), std::forward<KV>(kv)));
+    }
+
+public:
+    CDBTransaction(Parent &_parent, CommitTarget &_commitTarget) : parent(_parent), commitTarget(_commitTarget) {}
+
+    template <typename K, typename V>
+    void Write(const K& key, const V& v) {
+        auto k = new KeyHolderImpl<K>(key);
+        auto kv = std::make_unique<KeyValueHolderImpl<K, V>>(*k, v);
+        writeImpl(k, std::move(kv));
+    }
+
+    template <typename K, typename V>
+    void Write(const K& key, V&& v) {
+        auto k = new KeyHolderImpl<K>(key);
+        auto kv = std::make_unique<KeyValueHolderImpl<K, typename std::remove_reference<V>::type>>(*k, std::forward<V>(v));
+        writeImpl(k, std::move(kv));
     }
 
     template <typename K, typename V>
@@ -462,7 +481,7 @@ class CDBTransaction {
 
         KeyValueMap *ws = getWritesMap<K>(false);
         if (ws) {
-            KeyValueMap::iterator it = ws->find(k);
+            auto it = ws->find(k);
             if (it != ws->end()) {
                 auto *impl = dynamic_cast<KeyValueHolderImpl<K, V> *>(it->second.get());
                 if (!impl)
@@ -472,7 +491,7 @@ class CDBTransaction {
             }
         }
 
-        return db.Read(key, value);
+        return parent.Read(key, value);
     }
 
     template <typename K>
@@ -487,7 +506,7 @@ class CDBTransaction {
         if (ws && ws->count(k))
             return true;
 
-        return db.Exists(key);
+        return parent.Exists(key);
     }
 
     template <typename K>
@@ -506,48 +525,48 @@ class CDBTransaction {
         deletes.clear();
     }
 
-    bool Commit() {
-        CDBBatch batch(db);
+    void Commit() {
         for (auto &p : deletes) {
             for (auto &p2 : p.second) {
-                p2.first->Erase(batch);
+                p2.first->Erase(commitTarget);
             }
         }
         for (auto &p : writes) {
             for (auto &p2 : p.second) {
-                p2.second->Write(batch);
+                p2.second->Write(commitTarget);
             }
         }
-        bool ret = db.WriteBatch(batch, true);
         Clear();
-        return ret;
     }
 
     bool IsClean() {
         return writes.empty() && deletes.empty();
     }
 };
 
+template<typename Parent, typename CommitTarget>
 class CScopedDBTransaction {
+public:
+    typedef CDBTransaction<Parent, CommitTarget> Transaction;
+
 private:
-    CDBTransaction &dbTransaction;
+    Transaction &dbTransaction;
     std::function<void ()> commitHandler;
     std::function<void ()> rollbackHandler;
     bool didCommitOrRollback{};
 
 public:
-    CScopedDBTransaction(CDBTransaction &dbTx) : dbTransaction(dbTx) {}
+    CScopedDBTransaction(Transaction &dbTx) : dbTransaction(dbTx) {}
     ~CScopedDBTransaction() {
         if (!didCommitOrRollback)
             Rollback();
     }
-    bool Commit() {
+    void Commit() {
         assert(!didCommitOrRollback);
         didCommitOrRollback = true;
-        bool result = dbTransaction.Commit();
+        dbTransaction.Commit();
         if (commitHandler)
             commitHandler();
-        return result;
     }
     void Rollback() {
         assert(!didCommitOrRollback);
@@ -557,9 +576,9 @@ class CScopedDBTransaction {
             rollbackHandler();
     }
 
-    static std::unique_ptr<CScopedDBTransaction> Begin(CDBTransaction &dbTx) {
+    static std::unique_ptr<CScopedDBTransaction<Parent, CommitTarget>> Begin(Transaction &dbTx) {
         assert(dbTx.IsClean());
-        return std::unique_ptr<CScopedDBTransaction>(new CScopedDBTransaction(dbTx));
+        return std::make_unique<CScopedDBTransaction<Parent, CommitTarget>>(dbTx);
     }
 
     void SetCommitHandler(const std::function<void ()> &h) {

diff --git a/src/evo/evodb.cpp b/src/evo/evodb.cpp
@@ -8,10 +8,21 @@ CEvoDB* evoDb;
 
 CEvoDB::CEvoDB(size_t nCacheSize, bool fMemory, bool fWipe) :
     db(fMemory ? "" : (GetDataDir() / "evodb"), nCacheSize, fMemory, fWipe),
-    dbTransaction(db)
+    rootBatch(db),
+    rootDBTransaction(db, rootBatch),
+    curDBTransaction(rootDBTransaction, rootDBTransaction)
 {
 }
 
+bool CEvoDB::CommitRootTransaction()
+{
+    assert(curDBTransaction.IsClean());
+    rootDBTransaction.Commit();
+    bool ret = db.WriteBatch(rootBatch);
+    rootBatch.Clear();
+    return ret;
+}
+
 bool CEvoDB::VerifyBestBlock(const uint256& hash)
 {
     // Make sure evodb is consistent.

diff --git a/src/evo/evodb.h b/src/evo/evodb.h
@@ -16,51 +16,60 @@ class CEvoDB
 private:
     CCriticalSection cs;
     CDBWrapper db;
-    CDBTransaction dbTransaction;
+
+    typedef CDBTransaction<CDBWrapper, CDBBatch> RootTransaction;
+    typedef CDBTransaction<RootTransaction, RootTransaction> CurTransaction;
+    typedef CScopedDBTransaction<RootTransaction, RootTransaction> ScopedTransaction;
+
+    CDBBatch rootBatch;
+    RootTransaction rootDBTransaction;
+    CurTransaction curDBTransaction;
 
 public:
     CEvoDB(size_t nCacheSize, bool fMemory = false, bool fWipe = false);
 
-    std::unique_ptr<CScopedDBTransaction> BeginTransaction()
+    std::unique_ptr<ScopedTransaction> BeginTransaction()
     {
         LOCK(cs);
-        auto t = CScopedDBTransaction::Begin(dbTransaction);
+        auto t = ScopedTransaction::Begin(curDBTransaction);
         return t;
     }
 
     template <typename K, typename V>
     bool Read(const K& key, V& value)
     {
         LOCK(cs);
-        return dbTransaction.Read(key, value);
+        return curDBTransaction.Read(key, value);
     }
 
     template <typename K, typename V>
     void Write(const K& key, const V& value)
     {
         LOCK(cs);
-        dbTransaction.Write(key, value);
+        curDBTransaction.Write(key, value);
     }
 
     template <typename K>
     bool Exists(const K& key)
     {
         LOCK(cs);
-        return dbTransaction.Exists(key);
+        return curDBTransaction.Exists(key);
     }
 
     template <typename K>
     void Erase(const K& key)
     {
         LOCK(cs);
-        dbTransaction.Erase(key);
+        curDBTransaction.Erase(key);
     }
 
     CDBWrapper& GetRawDB()
     {
         return db;
     }
 
+    bool CommitRootTransaction();
+
     bool VerifyBestBlock(const uint256& hash);
     void WriteBestBlock(const uint256& hash);
 };

diff --git a/src/validation.cpp b/src/validation.cpp
@@ -2394,6 +2394,9 @@ bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode, int n
         // Flush the chainstate (which may refer to block index entries).
         if (!pcoinsTip->Flush())
             return AbortNode(state, "Failed to write to coin database");
+        if (!evoDb->CommitRootTransaction()) {
+            return AbortNode(state, "Failed to commit EvoDB");
+        }
         nLastFlush = nNow;
     }
     if (fDoFullFlush || ((mode == FLUSH_STATE_ALWAYS || mode == FLUSH_STATE_PERIODIC) && nNow > nLastSetChain + (int64_t)DATABASE_WRITE_INTERVAL * 1000000)) {
@@ -2499,12 +2502,11 @@ bool static DisconnectTip(CValidationState& state, const CChainParams& chainpara
             return error("DisconnectTip(): DisconnectBlock %s failed", pindexDelete->GetBlockHash().ToString());
         bool flushed = view.Flush();
         assert(flushed);
-        bool committed = dbTx->Commit();
-        assert(committed);
+        dbTx->Commit();
     }
     LogPrint("bench", "- Disconnect block: %.2fms\n", (GetTimeMicros() - nStart) * 0.001);
     // Write the chain state to disk, if necessary.
-    if (!FlushStateToDisk(state, IsInitialBlockDownload() ? FLUSH_STATE_IF_NEEDED : FLUSH_STATE_ALWAYS))
+    if (!FlushStateToDisk(state, FLUSH_STATE_IF_NEEDED))
         return false;
     // Resurrect mempool transactions from the disconnected block.
     std::vector<uint256> vHashUpdate;
@@ -2589,13 +2591,12 @@ bool static ConnectTip(CValidationState& state, const CChainParams& chainparams,
         LogPrint("bench", "  - Connect total: %.2fms [%.2fs]\n", (nTime3 - nTime2) * 0.001, nTimeConnectTotal * 0.000001);
         bool flushed = view.Flush();
         assert(flushed);
-        bool committed = dbTx->Commit();
-        assert(committed);
+        dbTx->Commit();
     }
     int64_t nTime4 = GetTimeMicros(); nTimeFlush += nTime4 - nTime3;
     LogPrint("bench", "  - Flush: %.2fms [%.2fs]\n", (nTime4 - nTime3) * 0.001, nTimeFlush * 0.000001);
     // Write the chain state to disk, if necessary.
-    if (!FlushStateToDisk(state, IsInitialBlockDownload() ? FLUSH_STATE_IF_NEEDED : FLUSH_STATE_ALWAYS))
+    if (!FlushStateToDisk(state, FLUSH_STATE_IF_NEEDED))
         return false;
     int64_t nTime5 = GetTimeMicros(); nTimeChainState += nTime5 - nTime4;
     LogPrint("bench", "  - Writing chainstate: %.2fms [%.2fs]\n", (nTime5 - nTime4) * 0.001, nTimeChainState * 0.000001);