Encapsulate CLevelDB iterators cleanly

Conflicts:
	src/leveldb.cpp
	src/leveldb.h
	src/txdb.cpp

src/leveldbwrapper.cpp

@@ -131,7 +131,7 @@ std::vector<unsigned char> CLevelDBWrapper::CreateObfuscateKey() const
 
 bool CLevelDBWrapper::IsEmpty()
 {
-    boost::scoped_ptr<leveldb::Iterator> it(NewIterator());
+    boost::scoped_ptr<CLevelDBIterator> it(NewIterator());
     it->SeekToFirst();
     return !(it->Valid());
 }
@@ -145,3 +145,10 @@ std::string CLevelDBWrapper::GetObfuscateKeyHex() const
 { 
     return HexStr(obfuscate_key); 
 }
+ 
+CLevelDBIterator::~CLevelDBIterator() { delete piter; }
+bool CLevelDBIterator::Valid() { return piter->Valid(); }
+void CLevelDBIterator::SeekToFirst() { piter->SeekToFirst(); }
+void CLevelDBIterator::SeekToLast() { piter->SeekToLast(); }
+void CLevelDBIterator::Next() { piter->Next(); }
+void CLevelDBIterator::Prev() { piter->Prev(); }

src/leveldbwrapper.h

@@ -69,6 +69,64 @@ public:
     }
 };
  
+class CLevelDBIterator
+{
+private:
+    leveldb::Iterator *piter;
+
+public:
+    CLevelDBIterator(leveldb::Iterator *piterIn) : piter(piterIn) {}
+    ~CLevelDBIterator();
+
+    bool Valid();
+
+    void SeekToFirst();
+    void SeekToLast();
+
+    template<typename K> void Seek(const K& key) {
+        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+        ssKey.reserve(ssKey.GetSerializeSize(key));
+        ssKey << key;
+        leveldb::Slice slKey(&ssKey[0], ssKey.size());
+        piter->Seek(slKey);
+    }
+
+    void Next();
+    void Prev();
+
+    template<typename K> bool GetKey(K& key) {
+        leveldb::Slice slKey = piter->key();
+        try {
+            CDataStream ssKey(slKey.data(), slKey.data() + slKey.size(), SER_DISK, CLIENT_VERSION);
+            ssKey >> key;
+        } catch(std::exception &e) {
+            return false;
+        }
+        return true;
+    }
+
+    unsigned int GetKeySize() {
+        return piter->key().size();
+    }
+
+    template<typename V> bool GetValue(V& value) {
+        leveldb::Slice slValue = piter->value();
+        try {
+            CDataStream ssValue(slValue.data(), slValue.data() + slValue.size(), SER_DISK, CLIENT_VERSION);
+            ssValue.Xor(db.GetObfuscateKey());
+            ssValue >> value;
+        } catch(std::exception &e) {
+            return false;
+        }
+        return true;
+    }
+
+    unsigned int GetValueSize() {
+        return piter->value().size();
+    }
+
+};
+ 
 class CLevelDBWrapper
 {
 private:
@@ -191,11 +249,10 @@ public:
         return WriteBatch(batch, true);
     }
 
-    // not exactly clean encapsulation, but it's easiest for now
-    leveldb::Iterator* NewIterator()
+    CLevelDBIterator *NewIterator() 
+    {
+        return new CLevelDBIterator(pdb->NewIterator(iteroptions));
     {
-        return pdb->NewIterator(iteroptions);
-    }
 
     /**
      * Return true if the database managed by this class contains no entries.

src/txdb.cpp

@@ -98,8 +98,8 @@ bool CCoinsViewDB::GetStats(CCoinsStats &stats) const {
     /* It seems that there are no "const iterators" for LevelDB.  Since we
        only need read operations on it, use a const-cast to get around
        that restriction.  */
-    boost::scoped_ptr<leveldb::Iterator> pcursor(const_cast<CLevelDBWrapper*>(&db)->NewIterator());
-    pcursor->SeekToFirst();
+    boost::scoped_ptr<CLevelDBWrapper> pcursor(const_cast<CLevelDBWrapper*>(&db)->NewIterator());
+    pcursor->Seek('c');
 
     CHashWriter ss(SER_GETHASH, PROTOCOL_VERSION);
     stats.hashBlock = GetBestBlock();
@@ -107,22 +107,10 @@ bool CCoinsViewDB::GetStats(CCoinsStats &stats) const {
     CAmount nTotalAmount = 0;
     while (pcursor->Valid()) {
         boost::this_thread::interruption_point();
-        try {
-            leveldb::Slice slKey = pcursor->key();
-            CDataStream ssKey(slKey.data(), slKey.data()+slKey.size(), SER_DISK, CLIENT_VERSION);
-            char chType;
-            ssKey >> chType;
-            if (chType == DB_COINS) {
-                leveldb::Slice slValue = pcursor->value();
-                CDataStream ssValue(slValue.data(), slValue.data()+slValue.size(), SER_DISK, CLIENT_VERSION);
+        std::pair<char, uint256> key;
         CCoins coins;
-                ssValue >> coins;
-                uint256 txhash;
-                ssKey >> txhash;
-                ss << txhash;
-                ss << VARINT(coins.nVersion);
-                ss << (coins.fCoinBase ? 'c' : 'n');
-                ss << VARINT(coins.nHeight);
+        if (pcursor->GetKey(key) && key.first == 'c') {
+            if (pcursor->GetValue(coins)) {
                 stats.nTransactions++;
                 for (unsigned int i=0; i<coins.vout.size(); i++) {
                     const CTxOut &out = coins.vout[i];
@@ -133,13 +121,15 @@ bool CCoinsViewDB::GetStats(CCoinsStats &stats) const {
                         nTotalAmount += out.nValue;
                     }
                 }
-                stats.nSerializedSize += 32 + slValue.size();
+                stats.nSerializedSize += 32 + pcursor->GetKeySize();
                 ss << VARINT(0);
+            } else {
+                return error("CCoinsViewDB::GetStats() : unable to read value");
             }
-            pcursor->Next();
-        } catch (const std::exception& e) {
-            return error("%s: Deserialize or I/O error - %s", __func__, e.what());
+        } else {
+            break;
         }
+        pcursor->Next();
     }
     {
         LOCK(cs_main);
@@ -189,24 +179,15 @@ bool CBlockTreeDB::LoadBlockIndexGuts()
 {
     boost::scoped_ptr<leveldb::Iterator> pcursor(NewIterator());
 
-    CDataStream ssKeySet(SER_DISK, CLIENT_VERSION);
-    ssKeySet << make_pair(DB_BLOCK_INDEX, uint256());
-    pcursor->Seek(ssKeySet.str());
+    pcursor->Seek(make_pair('b', uint256(0)));
 
     // Load mapBlockIndex
     while (pcursor->Valid()) {
         boost::this_thread::interruption_point();
-        try {
-            leveldb::Slice slKey = pcursor->key();
-            CDataStream ssKey(slKey.data(), slKey.data()+slKey.size(), SER_DISK, CLIENT_VERSION);
-            char chType;
-            ssKey >> chType;
-            if (chType == DB_BLOCK_INDEX) {
-                leveldb::Slice slValue = pcursor->value();
-                CDataStream ssValue(slValue.data(), slValue.data()+slValue.size(), SER_DISK, CLIENT_VERSION);
+        std::pair<char, uint256> key;
+        if (pcursor->GetKey(key) && key.first == 'b') {
             CDiskBlockIndex diskindex;
-                ssValue >> diskindex;
-
+            if (pcursor->GetValue(diskindex)) {
                 // Construct block index object
                 CBlockIndex* pindexNew = InsertBlockIndex(diskindex.GetBlockHash());
                 pindexNew->pprev          = InsertBlockIndex(diskindex.hashPrev);
@@ -227,10 +208,10 @@ bool CBlockTreeDB::LoadBlockIndexGuts()
 
                 pcursor->Next();
             } else {
-                break; // if shutdown requested or finished loading block index
+                return error("LoadBlockIndex() : failed to read value");
             }
-        } catch (const std::exception& e) {
-            return error("%s: Deserialize or I/O error - %s", __func__, e.what());
+        } else {
+            break;
         }
     }