FullPrunedBlockChain: add a runScripts property, defaulting to true. Resolves issue 463.

core/src/main/java/com/google/bitcoin/core/FullPrunedBlockChain.java

@@ -45,6 +45,9 @@ public class FullPrunedBlockChain extends AbstractBlockChain {
     /** Keeps a map of block hashes to StoredBlocks. */
     protected final FullPrunedBlockStore blockStore;
 
+    // Whether or not to execute scriptPubKeys before accepting a transaction (i.e. check signatures).
+    private boolean runScripts = true;
+
     /**
      * Constructs a BlockChain connected to the given wallet and store. To obtain a {@link Wallet} you can construct
      * one from scratch, or you can deserialize a saved wallet from disk using {@link Wallet#loadFromFile(java.io.File)}
@@ -95,6 +98,17 @@ public class FullPrunedBlockChain extends AbstractBlockChain {
         return true;
     }
 
+    /**
+     * Whether or not to run scripts whilst accepting blocks (i.e. checking signatures, for most transactions).
+     * If you're accepting data from an untrusted node, such as one found via the P2P network, this should be set
+     * to true (which is the default). If you're downloading a chain from a node you control, script execution
+     * is redundant because you know the connected node won't relay bad data to you. In that case it's safe to set
+     * this to false and obtain a significant speedup.
+     */
+    public void setRunScripts(boolean value) {
+        this.runScripts = value;
+    }
+    
     //TODO: Remove lots of duplicated code in the two connectTransactions
     
     // TODO: execute in order of largest transaction (by input count) first
@@ -218,7 +232,7 @@ public class FullPrunedBlockChain extends AbstractBlockChain {
                     totalFees = totalFees.add(valueIn.subtract(valueOut));
                 }
                 
-                if (!isCoinBase) {
+                if (!isCoinBase && runScripts) {
                     // Because correctlySpends modifies transactions, this must come after we are done with tx
                     FutureTask<VerificationException> future = new FutureTask<VerificationException>(new Verifier(tx, prevOutScripts, enforcePayToScriptHash));
                     scriptVerificationExecutor.execute(future);

core/src/test/java/com/google/bitcoin/core/FullPrunedBlockChainTest.java

@@ -101,6 +101,41 @@ public class FullPrunedBlockChainTest {
         }
     }
 
+    @Test
+    public void skipScripts() throws Exception {
+        store = new MemoryFullPrunedBlockStore(params, 10);
+        chain = new FullPrunedBlockChain(params, store);
+
+        // Check that we aren't accidentally leaving any references
+        // to the full StoredUndoableBlock's lying around (ie memory leaks)
+
+        ECKey outKey = new ECKey();
+
+        // Build some blocks on genesis block to create a spendable output
+        Block rollingBlock = params.getGenesisBlock().createNextBlockWithCoinbase(outKey.getPubKey());
+        chain.add(rollingBlock);
+        TransactionOutput spendableOutput = rollingBlock.getTransactions().get(0).getOutput(0);
+        for (int i = 1; i < params.getSpendableCoinbaseDepth(); i++) {
+            rollingBlock = rollingBlock.createNextBlockWithCoinbase(outKey.getPubKey());
+            chain.add(rollingBlock);
+        }
+
+        rollingBlock = rollingBlock.createNextBlock(null);
+        Transaction t = new Transaction(params);
+        t.addOutput(new TransactionOutput(params, t, Utils.toNanoCoins(50, 0), new byte[] {}));
+        TransactionInput input = t.addInput(spendableOutput);
+        // Invalid script.
+        input.setScriptBytes(new byte[]{});
+        rollingBlock.addTransaction(t);
+        rollingBlock.solve();
+        chain.setRunScripts(false);
+        try {
+            chain.add(rollingBlock);
+        } catch (VerificationException e) {
+            fail();
+        }
+    }
+
     @Test
     public void testFinalizedBlocks() throws Exception {
         final int UNDOABLE_BLOCKS_STORED = 10;