Feature/eip 1283

ethereumj-core/src/main/java/org/ethereum/config/BlockchainConfig.java

@@ -175,4 +175,10 @@ String validateTransactionChanges(BlockStore blockStore, Block curBlock, Transac
      * EXTCODEHASH opcode
      */
     boolean eip1052();
+
+    /**
+     * EIP 1283: https://eips.ethereum.org/EIPS/eip-1283
+     * Net gas metering for SSTORE without dirty maps
+     */
+    boolean eip1283();
 }

ethereumj-core/src/main/java/org/ethereum/config/blockchain/AbstractConfig.java

@@ -203,6 +203,11 @@ public boolean eip145() {
         return false;
     }
 
+    @Override
+    public boolean eip1283() {
+        return false;
+    }
+
     @Override
     public String toString() {
         return getClass().getSimpleName();

ethereumj-core/src/main/java/org/ethereum/config/blockchain/ConstantinopleConfig.java

@@ -43,4 +43,9 @@ public boolean eip1052() {
     public boolean eip145() {
         return true;
     }
+
+    @Override
+    public boolean eip1283() {
+        return true;
+    }
 }

ethereumj-core/src/main/java/org/ethereum/config/blockchain/Eip150HFConfig.java

@@ -191,4 +191,9 @@ public boolean eip145() {
     public boolean eip1052() {
         return false;
     }
+
+    @Override
+    public boolean eip1283() {
+        return false;
+    }
 }

ethereumj-core/src/main/java/org/ethereum/core/Repository.java

@@ -235,4 +235,6 @@ void loadAccount(byte[] addr, HashMap<ByteArrayWrapper, AccountState> cacheAccou
                      HashMap<ByteArrayWrapper, ContractDetails> cacheDetails);
 
     Repository getSnapshotTo(byte[] root);
+
+    Repository clone();
 }

ethereumj-core/src/main/java/org/ethereum/core/TransactionExecutor.java

@@ -396,7 +396,7 @@ public TransactionExecutionSummary finalization() {
             // Accumulate refunds for suicides
             result.addFutureRefund(result.getDeleteAccounts().size() * config.getBlockchainConfig().
                     getConfigForBlock(currentBlock.getNumber()).getGasCost().getSUICIDE_REFUND());
-            long gasRefund = Math.min(result.getFutureRefund(), getGasUsed() / 2);
+            long gasRefund = Math.min(Math.max(0, result.getFutureRefund()), getGasUsed() / 2);
             byte[] addr = tx.isContractCreation() ? tx.getContractAddress() : tx.getReceiveAddress();
             m_endGas = m_endGas.add(BigInteger.valueOf(gasRefund));
 

ethereumj-core/src/main/java/org/ethereum/db/RepositoryImpl.java

@@ -230,6 +230,14 @@ public String dumpStateTrie() {
         throw new RuntimeException("Not supported");
     }
 
+    /**
+     * As tests only implementation this hack is pretty sufficient
+     */
+    @Override
+    public Repository clone() {
+        return startTracking();
+    }
+
     class ContractDetailsImpl implements ContractDetails {
         private byte[] address;
 

ethereumj-core/src/main/java/org/ethereum/db/RepositoryRoot.java

@@ -134,6 +134,11 @@ public Repository getSnapshotTo(byte[] root) {
         return new RepositoryRoot(stateDS, root);
     }
 
+    @Override
+    public Repository clone() {
+        return getSnapshotTo(getRoot());
+    }
+
     @Override
     public synchronized String dumpStateTrie() {
         return ((TrieImpl) stateTrie).dumpTrie();

ethereumj-core/src/main/java/org/ethereum/db/RepositoryWrapper.java

@@ -201,6 +201,11 @@ public Repository getSnapshotTo(byte[] root) {
         return blockchain.getRepository().getSnapshotTo(root);
     }
 
+    @Override
+    public Repository clone() {
+        return getSnapshotTo(getRoot());
+    }
+
     @Override
     public int getStorageSize(byte[] addr) {
         return blockchain.getRepository().getStorageSize(addr);

ethereumj-core/src/main/java/org/ethereum/vm/GasCost.java

@@ -51,6 +51,7 @@ public class GasCost {
     private final int SET_SSTORE = 20000;
     private final int RESET_SSTORE = 5000;
     private final int REFUND_SSTORE = 15000;
+    private final int REUSE_SSTORE = 200;
     private final int CREATE = 32000;
 
     private final int JUMPDEST = 1;
@@ -169,6 +170,10 @@ public int getREFUND_SSTORE() {
         return REFUND_SSTORE;
     }
 
+    public int getREUSE_SSTORE() {
+        return REUSE_SSTORE;
+    }
+
     public int getCREATE() {
         return CREATE;
     }

ethereumj-core/src/main/java/org/ethereum/vm/VM.java

@@ -241,18 +241,54 @@ public void step(Program program) {
                     }
                     break;
                 case SSTORE:
+                    DataWord currentValue = program.getCurrentValue(stack.peek());
+                    if (currentValue == null) currentValue = DataWord.ZERO;
                     DataWord newValue = stack.get(stack.size() - 2);
-                    DataWord oldValue = program.storageLoad(stack.peek());
-                    if (oldValue == null && !newValue.isZero())
-                        gasCost = gasCosts.getSET_SSTORE();
-                    else if (oldValue != null && newValue.isZero()) {
-                        // todo: GASREFUND counter policy
-
-                        // refund step cost policy.
-                        program.futureRefundGas(gasCosts.getREFUND_SSTORE());
-                        gasCost = gasCosts.getCLEAR_SSTORE();
-                    } else
-                        gasCost = gasCosts.getRESET_SSTORE();
+
+                    if (blockchainConfig.eip1283()) { // Net gas metering for SSTORE
+                        if (newValue.equals(currentValue)) {
+                            gasCost = gasCosts.getREUSE_SSTORE();
+                        } else {
+                            DataWord origValue = program.getOriginalValue(stack.peek());
+                            if (origValue == null) origValue = DataWord.ZERO;
+                            if (currentValue.equals(origValue)) {
+                                if (origValue.isZero()) {
+                                    gasCost = gasCosts.getSET_SSTORE();
+                                } else {
+                                    gasCost = gasCosts.getCLEAR_SSTORE();
+                                    if (newValue.isZero()) {
+                                        program.futureRefundGas(gasCosts.getREFUND_SSTORE());
+                                    }
+                                }
+                            } else {
+                                gasCost = gasCosts.getREUSE_SSTORE();
+                                if (!origValue.isZero()) {
+                                    if (currentValue.isZero()) {
+                                        program.futureRefundGas(-gasCosts.getREFUND_SSTORE());
+                                    } else if (newValue.isZero()) {
+                                        program.futureRefundGas(gasCosts.getREFUND_SSTORE());
+                                    }
+                                }
+                                if (origValue.equals(newValue)) {
+                                    if (origValue.isZero()) {
+                                        program.futureRefundGas(gasCosts.getSET_SSTORE() - gasCosts.getREUSE_SSTORE());
+                                    } else {
+                                        program.futureRefundGas(gasCosts.getCLEAR_SSTORE() - gasCosts.getREUSE_SSTORE());
+                                    }
+                                }
+                            }
+                        }
+                    } else { // Before EIP-1283 cost calculation
+                        if (currentValue.isZero() && !newValue.isZero())
+                            gasCost = gasCosts.getSET_SSTORE();
+                        else if (!currentValue.isZero() && newValue.isZero()) {
+                            // refund step cost policy.
+                            program.futureRefundGas(gasCosts.getREFUND_SSTORE());
+                            gasCost = gasCosts.getCLEAR_SSTORE();
+                        } else {
+                            gasCost = gasCosts.getRESET_SSTORE();
+                        }
+                    }
                     break;
                 case SLOAD:
                     gasCost = gasCosts.getSLOAD();

ethereumj-core/src/main/java/org/ethereum/vm/program/Program.java

@@ -88,6 +88,7 @@ public class Program {
     private Stack stack;
     private Memory memory;
     private Storage storage;
+    private Repository originalRepo;
     private byte[] returnDataBuffer;
 
     private ProgramResult result = new ProgramResult();
@@ -136,6 +137,7 @@ public Program(byte[] codeHash, byte[] ops, ProgramInvoke programInvoke, Transac
         traceListener = new ProgramTraceListener(config.vmTrace());
         this.memory = setupProgramListener(new Memory());
         this.stack = setupProgramListener(new Stack());
+        this.originalRepo = programInvoke.getRepository().clone();
         this.storage = setupProgramListener(new Storage(programInvoke));
         this.trace = new ProgramTrace(config, programInvoke);
         this.blockchainConfig = config.getBlockchainConfig().getConfigForBlock(programInvoke.getNumber().longValue());
@@ -793,6 +795,22 @@ public DataWord storageLoad(DataWord key) {
         return getStorage().getStorageValue(getOwnerAddress().getLast20Bytes(), key);
     }
 
+    /**
+     * @return current Storage data for key
+     */
+    public DataWord getCurrentValue(DataWord key) {
+        return getStorage().getStorageValue(getOwnerAddress().getLast20Bytes(), key);
+    }
+
+    /*
+     * Original storage value at the beginning of current frame execution
+     * For more info check EIP-1283 https://eips.ethereum.org/EIPS/eip-1283
+     * @return Storage data at the beginning of Program execution
+     */
+    public DataWord getOriginalValue(DataWord key) {
+        return originalRepo.getStorageValue(getOwnerAddress().getLast20Bytes(), key);
+    }
+
     public DataWord getPrevHash() {
         return invoke.getPrevHash();
     }

ethereumj-core/src/main/java/org/ethereum/vm/program/Storage.java

@@ -45,6 +45,11 @@ public Storage(ProgramInvoke programInvoke) {
         this.repository = programInvoke.getRepository();
     }
 
+    private Storage(Repository repository, DataWord address) {
+        this.repository = repository;
+        this.address = address;
+    }
+
     @Override
     public void setProgramListener(ProgramListener listener) {
         this.programListener = listener;
@@ -224,6 +229,11 @@ public Repository getSnapshotTo(byte[] root) {
         throw new UnsupportedOperationException();
     }
 
+    @Override
+    public Repository clone() {
+        return new Storage(repository.getSnapshotTo(getRoot()), address);
+    }
+
     @Override
     public int getStorageSize(byte[] addr) {
         return repository.getStorageSize(addr);

ethereumj-core/src/test/java/org/ethereum/jsontestsuite/suite/IterableTestRepository.java

@@ -77,6 +77,11 @@ public Repository getSnapshotTo(byte[] root) {
         return new IterableTestRepository(src.getSnapshotTo(root), this);
     }
 
+    @Override
+    public Repository clone() {
+        return new IterableTestRepository(src.clone(), this);
+    }
+
     @Override
     public AccountState createAccount(byte[] addr) {
         addAccount(addr);