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Refactor BlockChain to make it more extensible.

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This creates a new AbstractBlockChain abstract class which
BlockChain extends.
It continues to have a createable BlockChain class to avoid
changing the API too much.
This commit is contained in:
Matt Corallo 2012-07-08 05:16:16 +02:00 committed by Mike Hearn
parent 74042b8ca3
commit 548333bc6f
5 changed files with 763 additions and 494 deletions
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678
core/src/main/java/com/google/bitcoin/core/AbstractBlockChain.java Normal file
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/*
* Copyright 2012 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.bitcoin.core;
import com.google.bitcoin.store.BlockStore;
import com.google.bitcoin.store.BlockStoreException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.math.BigInteger;
import java.util.*;
import static com.google.common.base.Preconditions.*;
/**
* A BlockChain holds a series of {@link Block} objects, links them together, and knows how to verify that the
* chain follows the rules of the {@link NetworkParameters} for this chain.<p>
*
* A BlockChain requires a {@link Wallet} to receive transactions that it finds during the initial download. However,
* if you don't care about this, you can just pass in an empty wallet and nothing bad will happen.<p>
*
* A newly constructed BlockChain is empty. To fill it up, use a {@link Peer} object to download the chain from the
* network.<p>
*
* <b>Notes</b><p>
*
* The 'chain' can actually be a tree although in normal operation it can be thought of as a simple list. In such a
* situation there are multiple stories of the economy competing to become the one true consensus. This can happen
* naturally when two miners solve a block within a few seconds of each other, or it can happen when the chain is
* under attack.<p>
*
* A reference to the head block of every chain is stored. If you can reach the genesis block by repeatedly walking
* through the prevBlock pointers, then we say this is a full chain. If you cannot reach the genesis block we say it is
* an orphan chain.<p>
*
* Orphan chains can occur when blocks are solved and received during the initial block chain download,
* or if we connect to a peer that doesn't send us blocks in order.
*
* This class implements an abstract class which makes it simple to create a BlockChain that does/doesn't do full
* verification. It verifies headers and is implements most of what is required to implement a SPV BlockChain, but
* also provides callback hooks which can be used to do full verification.
*/
public abstract class AbstractBlockChain {
private static final Logger log = LoggerFactory.getLogger(AbstractBlockChain.class);
/** Keeps a map of block hashes to StoredBlocks. */
private final BlockStore blockStore;
/**
* Tracks the top of the best known chain.<p>
*
* Following this one down to the genesis block produces the story of the economy from the creation of BitCoin
* until the present day. The chain head can change if a new set of blocks is received that results in a chain of
* greater work than the one obtained by following this one down. In that case a reorganize is triggered,
* potentially invalidating transactions in our wallet.
*/
private StoredBlock chainHead;
// The chainHead field is read/written synchronized with this object rather than BlockChain. However writing is
// also guaranteed to happen whilst BlockChain is synchronized (see setChainHead). The goal of this is to let
// clients quickly access the chain head even whilst the block chain is downloading and thus the BlockChain is
// locked most of the time.
private final Object chainHeadLock = new Object();
protected final NetworkParameters params;
private final List<Wallet> wallets;
// Holds blocks that we have received but can't plug into the chain yet, eg because they were created whilst we
// were downloading the block chain.
private final LinkedHashMap<Sha256Hash, Block> orphanBlocks = new LinkedHashMap<Sha256Hash, Block>();
/**
* Constructs a BlockChain connected to the given list of wallets and a store.
*/
public AbstractBlockChain(NetworkParameters params, List<Wallet> wallets,
BlockStore blockStore) throws BlockStoreException {
this.blockStore = blockStore;
chainHead = blockStore.getChainHead();
log.info("chain head is at height {}:\n{}", chainHead.getHeight(), chainHead.getHeader());
this.params = params;
this.wallets = new ArrayList<Wallet>(wallets);
}
/**
* Add a wallet to the BlockChain. Note that the wallet will be unaffected by any blocks received while it
* was not part of this BlockChain. This method is useful if the wallet has just been created, and its keys
* have never been in use, or if the wallet has been loaded along with the BlockChain
*/
public synchronized void addWallet(Wallet wallet) {
wallets.add(wallet);
}
/**
* Returns the {@link BlockStore} the chain was constructed with. You can use this to iterate over the chain.
*/
public BlockStore getBlockStore() {
return blockStore;
}
/**
* Adds/updates the given {@link Block} with the block store.
* This version is used when the transactions have not been verified.
* @param storedPrev The {@link StoredBlock} which immediately precedes block.
* @param block The {@link Block} to add/update.
* @returns the newly created {@link StoredBlock}
*/
protected abstract StoredBlock addToBlockStore(StoredBlock storedPrev, Block block)
throws BlockStoreException, VerificationException;
/**
* Adds/updates the given {@link StoredBlock} with the block store.
* This version is used when the transactions have already been verified to properly spend txOutputChanges.
* @param storedPrev The {@link StoredBlock} which immediately precedes block.
* @param header The {@link StoredBlock} to add/update.
* @param txOutputChanges The total sum of all changes made by this block to the set of open transaction outputs (from a call to connectTransactions)
* @returns the newly created {@link StoredBlock}
*/
protected abstract StoredBlock addToBlockStore(StoredBlock storedPrev, Block header,
TransactionOutputChanges txOutputChanges)
throws BlockStoreException, VerificationException;
/**
* Called before setting chain head in memory, but after writing the blockstore to disk.
* Can be used to commit database transactions that were started by
* disconnectTransactions/connectTransactions.
*/
protected abstract void preSetChainHead() throws BlockStoreException;
/**
* Called if we (possibly) previously called disconnectTransaction/connectTransactions,
* but will not be calling preSetChainHead as a block failed verification.
* Can be used to abort database transactions that were started by
* disconnectTransactions/connectTransactions.
*/
protected abstract void notSettingChainHead() throws BlockStoreException;
/**
* Processes a received block and tries to add it to the chain. If there's something wrong with the block an
* exception is thrown. If the block is OK but cannot be connected to the chain at this time, returns false.
* If the block can be connected to the chain, returns true.
*/
public synchronized boolean add(Block block) throws VerificationException, ScriptException, PrunedException {
try {
return add(block, true);
} catch (BlockStoreException e) {
// TODO: Figure out a better way to propagate this exception to the user.
throw new RuntimeException(e);
} catch (ScriptException e) {
// TODO: ScriptException should extend VerificationException.
try {
notSettingChainHead();
} catch (BlockStoreException e1) {
throw new RuntimeException(e1);
}
throw e;
} catch (VerificationException e) {
try {
notSettingChainHead();
} catch (BlockStoreException e1) {
throw new RuntimeException(e1);
}
throw e;
}
}
/**
* Whether or not we are maintaining a set of unspent outputs and are verifying all transactions.
* Also indicates that all calls to add() should provide a block containing transactions
*/
protected abstract boolean shouldVerifyTransactions();
/**
* Connect each transaction in block.transactions, verifying them as we go and removing spent outputs
* If an error is encountered in a transaction, no changes should be made to the underlying BlockStore.
* and a VerificationException should be thrown.
* Only called if(shouldVerifyTransactions())
* @throws VerificationException if an attempt was made to spend an already-spent output, or if a transaction incorrectly solved an output script.
* @throws BlockStoreException if the block store had an underlying error.
* @return The full set of all changes made to the set of open transaction outputs.
*/
protected abstract TransactionOutputChanges connectTransactions(int height, Block block) throws VerificationException, BlockStoreException;
/**
* Load newBlock from BlockStore and connect its transactions, returning changes to the set of unspent transactions.
* If an error is encountered in a transaction, no changes should be made to the underlying BlockStore.
* Only called if(shouldVerifyTransactions())
* @throws PrunedException if newBlock does not exist as a {@link StoredUndoableBlock} in the block store.
* @throws VerificationException if an attempt was made to spend an already-spent output, or if a transaction incorrectly solved an output script.
* @throws BlockStoreException if the block store had an underlying error or newBlock does not exist in the block store at all.
* @return The full set of all changes made to the set of open transaction outputs.
*/
protected abstract TransactionOutputChanges connectTransactions(StoredBlock newBlock) throws VerificationException, BlockStoreException, PrunedException;
// Stat counters.
private long statsLastTime = System.currentTimeMillis();
private long statsBlocksAdded;
private synchronized boolean add(Block block, boolean tryConnecting)
throws BlockStoreException, VerificationException, ScriptException, PrunedException {
// Note on locking: this method runs with the block chain locked. All mutations to the chain are serialized.
// This has the undesirable consequence that during block chain download, it's slow to read the current chain
// head and other chain info because the accessors are constantly waiting for the chain to become free. To
// solve this things viewable via accessors must use fine-grained locking as well as being mutated under the
// chain lock.
if (System.currentTimeMillis() - statsLastTime > 1000) {
// More than a second passed since last stats logging.
if (statsBlocksAdded > 1)
log.info("{} blocks per second", statsBlocksAdded);
statsLastTime = System.currentTimeMillis();
statsBlocksAdded = 0;
}
// Quick check for duplicates to avoid an expensive check further down (in findSplit). This can happen a lot
// when connecting orphan transactions due to the dumb brute force algorithm we use.
if (block.equals(getChainHead().getHeader()) || (tryConnecting && orphanBlocks.containsKey(block.getHash()))) {
return true;
}
// If we want to verify transactions (ie we are running with full blocks), verify that block has transactions
if (shouldVerifyTransactions() && block.transactions == null)
throw new VerificationException("Got a block header while running in full-block mode");
// Does this block contain any transactions we might care about? Check this up front before verifying the
// blocks validity so we can skip the merkle root verification if the contents aren't interesting. This saves
// a lot of time for big blocks.
boolean contentsImportant = shouldVerifyTransactions();
if (block.transactions != null) {
contentsImportant = contentsImportant || containsRelevantTransactions(block);
}
// Prove the block is internally valid: hash is lower than target, etc. This only checks the block contents
// if there is a tx sending or receiving coins using an address in one of our wallets. And those transactions
// are only lightly verified: presence in a valid connecting block is taken as proof of validity. See the
// article here for more details: http://code.google.com/p/bitcoinj/wiki/SecurityModel
try {
block.verifyHeader();
if (contentsImportant)
block.verifyTransactions();
} catch (VerificationException e) {
log.error("Failed to verify block: ", e);
log.error(block.getHashAsString());
throw e;
}
// Try linking it to a place in the currently known blocks.
StoredBlock storedPrev = blockStore.get(block.getPrevBlockHash());
if (storedPrev == null) {
// We can't find the previous block. Probably we are still in the process of downloading the chain and a
// block was solved whilst we were doing it. We put it to one side and try to connect it later when we
// have more blocks.
checkState(tryConnecting, "bug in tryConnectingOrphans");
log.warn("Block does not connect: {} prev {}", block.getHashAsString(), block.getPrevBlockHash());
orphanBlocks.put(block.getHash(), block);
return false;
} else {
// It connects to somewhere on the chain. Not necessarily the top of the best known chain.
//
// Create a new StoredBlock from this block. It will throw away the transaction data so when block goes
// out of scope we will reclaim the used memory.
checkDifficultyTransitions(storedPrev, block);
connectBlock(block, storedPrev);
}
if (tryConnecting)
tryConnectingOrphans();
statsBlocksAdded++;
return true;
}
private void connectBlock(Block block, StoredBlock storedPrev)
throws BlockStoreException, VerificationException, PrunedException {
StoredBlock head = getChainHead();
if (storedPrev.equals(head)) {
// This block connects to the best known block, it is a normal continuation of the system.
TransactionOutputChanges txOutChanges = null;
if (shouldVerifyTransactions())
txOutChanges = connectTransactions(storedPrev.getHeight() + 1, block);
StoredBlock newStoredBlock = addToBlockStore(storedPrev, block.cloneAsHeader(), txOutChanges);
setChainHead(newStoredBlock);
log.debug("Chain is now {} blocks high", newStoredBlock.getHeight());
// Notify the wallets of the new block, so the depth and workDone of stored transactions can be updated.
// The wallets need to know how deep each transaction is so coinbases aren't used before maturity.
for (Wallet wallet : wallets) {
if (block.transactions != null) {
sendTransactionsToWallet(newStoredBlock, NewBlockType.BEST_CHAIN, wallet, block.transactions);
}
wallet.notifyNewBestBlock(newStoredBlock.getHeader());
}
} else {
// This block connects to somewhere other than the top of the best known chain. We treat these differently.
//
// Note that we send the transactions to the wallet FIRST, even if we're about to re-organize this block
// to become the new best chain head. This simplifies handling of the re-org in the Wallet class.
StoredBlock newBlock = storedPrev.build(block);
boolean haveNewBestChain = newBlock.moreWorkThan(head);
if (haveNewBestChain) {
log.info("Block is causing a re-organize");
} else {
StoredBlock splitPoint = findSplit(newBlock, head);
if (splitPoint != null && splitPoint.equals(newBlock)) {
// newStoredBlock is a part of the same chain, there's no fork. This happens when we receive a block
// that we already saw and linked into the chain previously, which isn't the chain head.
// Re-processing it is confusing for the wallet so just skip.
log.warn("Saw duplicated block in main chain at height {}: {}",
newBlock.getHeight(), newBlock.getHeader().getHash());
return;
}
if (splitPoint == null) {
// This should absolutely never happen
// (lets not write the full block to disk to keep any bugs which allow this to happen
// from writing unreasonable amounts of data to disk)
throw new VerificationException("Block forks the chain but splitPoint is null");
} else {
// We aren't actually spending any transactions (yet) because we are on a fork
addToBlockStore(storedPrev, block);
int splitPointHeight = splitPoint.getHeight();
String splitPointHash = splitPoint.getHeader().getHashAsString();
log.info("Block forks the chain at height {}/block {}, but it did not cause a reorganize:\n{}",
new Object[]{splitPointHeight, splitPointHash, newBlock});
}
}
// We may not have any transactions if we received only a header, which can happen during fast catchup.
// If we do, send them to the wallet but state that they are on a side chain so it knows not to try and
// spend them until they become activated.
if (block.transactions != null) {
for (Wallet wallet : wallets) {
sendTransactionsToWallet(newBlock, NewBlockType.SIDE_CHAIN, wallet, block.transactions);
}
}
if (haveNewBestChain)
handleNewBestChain(storedPrev, newBlock, block);
}
}
/**
* Disconnect each transaction in the block (after reading it from the block store)
* Only called if(shouldVerifyTransactions())
* @throws PrunedException if block does not exist as a {@link StoredUndoableBlock} in the block store.
* @throws BlockStoreException if the block store had an underlying error or block does not exist in the block store at all.
*/
protected abstract void disconnectTransactions(StoredBlock block) throws PrunedException, BlockStoreException;
/**
* Called as part of connecting a block when the new block results in a different chain having higher total work.
*
* if (shouldVerifyTransactions)
* Either newChainHead needs to be in the block store as a FullStoredBlock, or (block != null && block.transactions != null)
*/
private void handleNewBestChain(StoredBlock storedPrev, StoredBlock newChainHead, Block block)
throws BlockStoreException, VerificationException, PrunedException {
// This chain has overtaken the one we currently believe is best. Reorganize is required.
//
// Firstly, calculate the block at which the chain diverged. We only need to examine the
// chain from beyond this block to find differences.
StoredBlock head = getChainHead();
StoredBlock splitPoint = findSplit(newChainHead, head);
log.info("Re-organize after split at height {}", splitPoint.getHeight());
log.info("Old chain head: {}", head.getHeader().getHashAsString());
log.info("New chain head: {}", newChainHead.getHeader().getHashAsString());
log.info("Split at block: {}", splitPoint.getHeader().getHashAsString());
// Then build a list of all blocks in the old part of the chain and the new part.
LinkedList<StoredBlock> oldBlocks = getPartialChain(head, splitPoint);
LinkedList<StoredBlock> newBlocks = getPartialChain(newChainHead, splitPoint);
// Disconnect each transaction in the previous main chain that is no longer in the new main chain
StoredBlock storedNewHead = splitPoint;
if (shouldVerifyTransactions()) {
for (StoredBlock oldBlock : oldBlocks) {
try {
disconnectTransactions(oldBlock);
} catch (PrunedException e) {
// We threw away the data we need to re-org this deep! We need to go back to a peer with full
// block contents and ask them for the relevant data then rebuild the indexs. Or we could just
// give up and ask the human operator to help get us unstuck (eg, rescan from the genesis block).
// TODO: Retry adding this block when we get a block with hash e.getHash()
throw e;
}
}
StoredBlock cursor;
// Walk in ascending chronological order.
for (Iterator<StoredBlock> it = newBlocks.descendingIterator(); it.hasNext();) {
cursor = it.next();
TransactionOutputChanges txOutChanges;
if (cursor != newChainHead || block == null)
txOutChanges = connectTransactions(cursor);
else
txOutChanges = connectTransactions(newChainHead.getHeight(), block);
storedNewHead = addToBlockStore(storedNewHead, cursor.getHeader(), txOutChanges);
}
} else {
// (Finally) write block to block store
storedNewHead = addToBlockStore(storedPrev, newChainHead.getHeader());
}
// Now inform the wallets. This is necessary so the set of currently active transactions (that we can spend)
// can be updated to take into account the re-organize. We might also have received new coins we didn't have
// before and our previous spends might have been undone.
for (Wallet wallet : wallets) {
wallet.reorganize(splitPoint, oldBlocks, newBlocks);
}
// Update the pointer to the best known block.
setChainHead(storedNewHead);
}
/**
* Returns the set of contiguous blocks between 'higher' and 'lower'. Higher is included, lower is not.
*/
private LinkedList<StoredBlock> getPartialChain(StoredBlock higher, StoredBlock lower) throws BlockStoreException {
checkArgument(higher.getHeight() > lower.getHeight(), "higher and lower are reversed");
LinkedList<StoredBlock> results = new LinkedList<StoredBlock>();
StoredBlock cursor = higher;
while (true) {
results.add(cursor);
cursor = checkNotNull(cursor.getPrev(blockStore), "Ran off the end of the chain");
if (cursor.equals(lower)) break;
}
return results;
}
/**
* Locates the point in the chain at which newStoredBlock and chainHead diverge. Returns null if no split point was
* found (ie they are not part of the same chain). Returns newChainHead or chainHead if they don't actually diverge
* but are part of the same chain.
*/
private StoredBlock findSplit(StoredBlock newChainHead, StoredBlock oldChainHead) throws BlockStoreException {
StoredBlock currentChainCursor = oldChainHead;
StoredBlock newChainCursor = newChainHead;
// Loop until we find the block both chains have in common. Example:
//
// A -> B -> C -> D
// \--> E -> F -> G
//
// findSplit will return block B. oldChainHead = D and newChainHead = G.
while (!currentChainCursor.equals(newChainCursor)) {
if (currentChainCursor.getHeight() > newChainCursor.getHeight()) {
currentChainCursor = currentChainCursor.getPrev(blockStore);
checkNotNull(currentChainCursor, "Attempt to follow an orphan chain");
} else {
newChainCursor = newChainCursor.getPrev(blockStore);
checkNotNull(newChainCursor, "Attempt to follow an orphan chain");
}
}
return currentChainCursor;
}
/**
* @return the height of the best known chain, convenience for <tt>getChainHead().getHeight()</tt>.
*/
public int getBestChainHeight() {
return getChainHead().getHeight();
}
public enum NewBlockType {
BEST_CHAIN,
SIDE_CHAIN
}
private void sendTransactionsToWallet(StoredBlock block, BlockChain.NewBlockType blockType, Wallet wallet,
List<Transaction> transactions) throws VerificationException {
for (Transaction tx : transactions) {
try {
if (wallet.isTransactionRelevant(tx, true))
wallet.receiveFromBlock(tx, block, blockType);
} catch (ScriptException e) {
// We don't want scripts we don't understand to break the block chain so just note that this tx was
// not scanned here and continue.
log.warn("Failed to parse a script: " + e.toString());
}
}
}
private void setChainHead(StoredBlock chainHead) throws BlockStoreException {
blockStore.setChainHead(chainHead);
preSetChainHead();
synchronized (chainHeadLock) {
this.chainHead = chainHead;
}
}
/**
* For each block in orphanBlocks, see if we can now fit it on top of the chain and if so, do so.
*/
private void tryConnectingOrphans() throws VerificationException, ScriptException, BlockStoreException, PrunedException {
// For each block in our orphan list, try and fit it onto the head of the chain. If we succeed remove it
// from the list and keep going. If we changed the head of the list at the end of the round try again until
// we can't fit anything else on the top.
//
// This algorithm is kind of crappy, we should do a topo-sort then just connect them in order, but for small
// numbers of orphan blocks it does OK.
int blocksConnectedThisRound;
do {
blocksConnectedThisRound = 0;
Iterator<Block> iter = orphanBlocks.values().iterator();
while (iter.hasNext()) {
Block block = iter.next();
log.debug("Trying to connect {}", block.getHash());
// Look up the blocks previous.
StoredBlock prev = blockStore.get(block.getPrevBlockHash());
if (prev == null) {
// This is still an unconnected/orphan block.
log.debug(" but it is not connectable right now");
continue;
}
// Otherwise we can connect it now.
// False here ensures we don't recurse infinitely downwards when connecting huge chains.
add(block, false);
iter.remove();
blocksConnectedThisRound++;
}
if (blocksConnectedThisRound > 0) {
log.info("Connected {} orphan blocks.", blocksConnectedThisRound);
}
} while (blocksConnectedThisRound > 0);
}
// February 16th 2012
private static Date testnetDiffDate = new Date(1329264000000L);
/**
* Throws an exception if the blocks difficulty is not correct.
*/
private void checkDifficultyTransitions(StoredBlock storedPrev, Block nextBlock)
throws BlockStoreException, VerificationException {
Block prev = storedPrev.getHeader();
// Is this supposed to be a difficulty transition point?
if ((storedPrev.getHeight() + 1) % params.interval != 0) {
// TODO: Refactor this hack after 0.5 is released and we stop supporting deserialization compatibility.
// This should be a method of the NetworkParameters, which should in turn be using singletons and a subclass
// for each network type. Then each network can define its own difficulty transition rules.
if (params.getId().equals(NetworkParameters.ID_TESTNET) && nextBlock.getTime().after(testnetDiffDate)) {
checkTestnetDifficulty(storedPrev, prev, nextBlock);
return;
}
// No ... so check the difficulty didn't actually change.
if (nextBlock.getDifficultyTarget() != prev.getDifficultyTarget())
throw new VerificationException("Unexpected change in difficulty at height " + storedPrev.getHeight() +
": " + Long.toHexString(nextBlock.getDifficultyTarget()) + " vs " +
Long.toHexString(prev.getDifficultyTarget()));
return;
}
// We need to find a block far back in the chain. It's OK that this is expensive because it only occurs every
// two weeks after the initial block chain download.
long now = System.currentTimeMillis();
StoredBlock cursor = blockStore.get(prev.getHash());
for (int i = 0; i < params.interval - 1; i++) {
if (cursor == null) {
// This should never happen. If it does, it means we are following an incorrect or busted chain.
throw new VerificationException(
"Difficulty transition point but we did not find a way back to the genesis block.");
}
cursor = blockStore.get(cursor.getHeader().getPrevBlockHash());
}
log.info("Difficulty transition traversal took {}msec", System.currentTimeMillis() - now);
Block blockIntervalAgo = cursor.getHeader();
int timespan = (int) (prev.getTimeSeconds() - blockIntervalAgo.getTimeSeconds());
// Limit the adjustment step.
if (timespan < params.targetTimespan / 4)
timespan = params.targetTimespan / 4;
if (timespan > params.targetTimespan * 4)
timespan = params.targetTimespan * 4;
BigInteger newDifficulty = Utils.decodeCompactBits(blockIntervalAgo.getDifficultyTarget());
newDifficulty = newDifficulty.multiply(BigInteger.valueOf(timespan));
newDifficulty = newDifficulty.divide(BigInteger.valueOf(params.targetTimespan));
if (newDifficulty.compareTo(params.proofOfWorkLimit) > 0) {
log.info("Difficulty hit proof of work limit: {}", newDifficulty.toString(16));
newDifficulty = params.proofOfWorkLimit;
}
int accuracyBytes = (int) (nextBlock.getDifficultyTarget() >>> 24) - 3;
BigInteger receivedDifficulty = nextBlock.getDifficultyTargetAsInteger();
// The calculated difficulty is to a higher precision than received, so reduce here.
BigInteger mask = BigInteger.valueOf(0xFFFFFFL).shiftLeft(accuracyBytes * 8);
newDifficulty = newDifficulty.and(mask);
if (newDifficulty.compareTo(receivedDifficulty) != 0)
throw new VerificationException("Network provided difficulty bits do not match what was calculated: " +
receivedDifficulty.toString(16) + " vs " + newDifficulty.toString(16));
}
private void checkTestnetDifficulty(StoredBlock storedPrev, Block prev, Block next) throws VerificationException, BlockStoreException {
// After 15th February 2012 the rules on the testnet change to avoid people running up the difficulty
// and then leaving, making it too hard to mine a block. On non-difficulty transition points, easy
// blocks are allowed if there has been a span of 20 minutes without one.
final long timeDelta = next.getTimeSeconds() - prev.getTimeSeconds();
// There is an integer underflow bug in bitcoin-qt that means mindiff blocks are accepted when time
// goes backwards.
if (timeDelta >= 0 && timeDelta <= NetworkParameters.TARGET_SPACING * 2) {
// Walk backwards until we find a block that doesn't have the easiest proof of work, then check
// that difficulty is equal to that one.
StoredBlock cursor = storedPrev;
while (!cursor.getHeader().equals(params.genesisBlock) &&
cursor.getHeight() % params.interval != 0 &&
cursor.getHeader().getDifficultyTargetAsInteger().equals(params.proofOfWorkLimit))
cursor = cursor.getPrev(blockStore);
BigInteger cursorDifficulty = cursor.getHeader().getDifficultyTargetAsInteger();
BigInteger newDifficulty = next.getDifficultyTargetAsInteger();
if (!cursorDifficulty.equals(newDifficulty))
throw new VerificationException("Testnet block transition that is not allowed: " +
Long.toHexString(cursor.getHeader().getDifficultyTarget()) + " vs " +
Long.toHexString(next.getDifficultyTarget()));
}
}
/**
* Returns true if any connected wallet considers any transaction in the block to be relevant.
*/
private boolean containsRelevantTransactions(Block block) {
for (Transaction tx : block.transactions) {
try {
for (Wallet wallet : wallets) {
if (wallet.isTransactionRelevant(tx, true)) return true;
}
} catch (ScriptException e) {
// We don't want scripts we don't understand to break the block chain so just note that this tx was
// not scanned here and continue.
log.warn("Failed to parse a script: " + e.toString());
}
}
return false;
}
/**
* Returns the block at the head of the current best chain. This is the block which represents the greatest
* amount of cumulative work done.
*/
public StoredBlock getChainHead() {
synchronized (chainHeadLock) {
return chainHead;
}
}
/**
* An orphan block is one that does not connect to the chain anywhere (ie we can't find its parent, therefore
* it's an orphan). Typically this occurs when we are downloading the chain and didn't reach the head yet, and/or
* if a block is solved whilst we are downloading. It's possible that we see a small amount of orphan blocks which
* chain together, this method tries walking backwards through the known orphan blocks to find the bottom-most.
*
* @return from or one of froms parents, or null if "from" does not identify an orphan block
*/
public synchronized Block getOrphanRoot(Sha256Hash from) {
Block cursor = orphanBlocks.get(from);
if (cursor == null)
return null;
Block tmp;
while ((tmp = orphanBlocks.get(cursor.getPrevBlockHash())) != null) {
cursor = tmp;
}
return cursor;
}
/** Returns true if the given block is currently in the orphan blocks list. */
public synchronized boolean isOrphan(Sha256Hash block) {
return orphanBlocks.containsKey(block);
}
}

530
core/src/main/java/com/google/bitcoin/core/BlockChain.java
View File

@ -18,67 +18,17 @@ package com.google.bitcoin.core;
import com.google.bitcoin.store.BlockStore;
import com.google.bitcoin.store.BlockStoreException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.math.BigInteger;
import java.util.*;
import static com.google.common.base.Preconditions.*;
import java.util.ArrayList;
import java.util.List;
/**
* A BlockChain holds a series of {@link Block} objects, links them together, and knows how to verify that the
* chain follows the rules of the {@link NetworkParameters} for this chain.<p>
*
* A BlockChain requires a {@link Wallet} to receive transactions that it finds during the initial download. However,
* if you don't care about this, you can just pass in an empty wallet and nothing bad will happen.<p>
*
* A newly constructed BlockChain is empty. To fill it up, use a {@link Peer} object to download the chain from the
* network.<p>
*
* <b>Notes</b><p>
*
* The 'chain' can actually be a tree although in normal operation it can be thought of as a simple list. In such a
* situation there are multiple stories of the economy competing to become the one true consensus. This can happen
* naturally when two miners solve a block within a few seconds of each other, or it can happen when the chain is
* under attack.<p>
*
* A reference to the head block of every chain is stored. If you can reach the genesis block by repeatedly walking
* through the prevBlock pointers, then we say this is a full chain. If you cannot reach the genesis block we say it is
* an orphan chain.<p>
*
* Orphan chains can occur when blocks are solved and received during the initial block chain download,
* or if we connect to a peer that doesn't send us blocks in order.
* A BlockChain forms a usable BlockChain class which implements basic SPV and storage using a {@link BlockStore}
*/
public class BlockChain {
private static final Logger log = LoggerFactory.getLogger(BlockChain.class);
public class BlockChain extends AbstractBlockChain {
/** Keeps a map of block hashes to StoredBlocks. */
protected final BlockStore blockStore;
/**
* Tracks the top of the best known chain.<p>
*
* Following this one down to the genesis block produces the story of the economy from the creation of BitCoin
* until the present day. The chain head can change if a new set of blocks is received that results in a chain of
* greater work than the one obtained by following this one down. In that case a reorganize is triggered,
* potentially invalidating transactions in our wallet.
*/
protected StoredBlock chainHead;
// The chainHead field is read/written synchronized with this object rather than BlockChain. However writing is
// also guaranteed to happen whilst BlockChain is synchronized (see setChainHead). The goal of this is to let
// clients quickly access the chain head even whilst the block chain is downloading and thus the BlockChain is
// locked most of the time.
protected final Object chainHeadLock = new Object();
protected final NetworkParameters params;
protected final List<Wallet> wallets;
// Holds blocks that we have received but can't plug into the chain yet, eg because they were created whilst we
// were downloading the block chain.
private final LinkedHashMap<Sha256Hash, Block> orphanBlocks = new LinkedHashMap<Sha256Hash, Block>();
/**
* 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)}
@ -106,459 +56,55 @@ public class BlockChain {
*/
public BlockChain(NetworkParameters params, List<Wallet> wallets,
BlockStore blockStore) throws BlockStoreException {
super(params, wallets, blockStore);
this.blockStore = blockStore;
chainHead = blockStore.getChainHead();
log.info("chain head is at height {}:\n{}", chainHead.getHeight(), chainHead.getHeader());
this.params = params;
this.wallets = new ArrayList<Wallet>(wallets);
}
/**
* Add a wallet to the BlockChain. Note that the wallet will be unaffected by any blocks received while it
* was not part of this BlockChain. This method is useful if the wallet has just been created, and its keys
* have never been in use, or if the wallet has been loaded along with the BlockChain
*/
public synchronized void addWallet(Wallet wallet) {
wallets.add(wallet);
}
/**
* Returns the {@link BlockStore} the chain was constructed with. You can use this to iterate over the chain.
*/
public BlockStore getBlockStore() {
return blockStore;
}
/**
* Processes a received block and tries to add it to the chain. If there's something wrong with the block an
* exception is thrown. If the block is OK but cannot be connected to the chain at this time, returns false.
* If the block can be connected to the chain, returns true.
*/
public synchronized boolean add(Block block) throws VerificationException, ScriptException {
try {
return add(block, true);
} catch (BlockStoreException e) {
// TODO: Figure out a better way to propagate this exception to the user.
throw new RuntimeException(e);
}
}
// Stat counters.
private long statsLastTime = System.currentTimeMillis();
private long statsBlocksAdded;
private synchronized boolean add(Block block, boolean tryConnecting)
throws BlockStoreException, VerificationException, ScriptException {
// Note on locking: this method runs with the block chain locked. All mutations to the chain are serialized.
// This has the undesirable consequence that during block chain download, it's slow to read the current chain
// head and other chain info because the accessors are constantly waiting for the chain to become free. To
// solve this things viewable via accessors must use fine-grained locking as well as being mutated under the
// chain lock.
if (System.currentTimeMillis() - statsLastTime > 1000) {
// More than a second passed since last stats logging.
if (statsBlocksAdded > 1)
log.info("{} blocks per second", statsBlocksAdded);
statsLastTime = System.currentTimeMillis();
statsBlocksAdded = 0;
}
// Quick check for duplicates to avoid an expensive check further down (in findSplit). This can happen a lot
// when connecting orphan transactions due to the dumb brute force algorithm we use.
if (block.equals(getChainHead().getHeader()) || (tryConnecting && orphanBlocks.containsKey(block.getHash()))) {
return true;
}
// Does this block contain any transactions we might care about? Check this up front before verifying the
// blocks validity so we can skip the merkle root verification if the contents aren't interesting. This saves
// a lot of time for big blocks.
boolean contentsImportant = false;
if (block.transactions != null) {
contentsImportant = containsRelevantTransactions(block);
}
// Prove the block is internally valid: hash is lower than target, etc. This only checks the block contents
// if there is a tx sending or receiving coins using an address in one of our wallets. And those transactions
// are only lightly verified: presence in a valid connecting block is taken as proof of validity. See the
// article here for more details: http://code.google.com/p/bitcoinj/wiki/SecurityModel
try {
block.verifyHeader();
if (contentsImportant)
block.verifyTransactions();
} catch (VerificationException e) {
log.error("Failed to verify block: ", e);
log.error(block.getHashAsString());
throw e;
}
// Try linking it to a place in the currently known blocks.
StoredBlock storedPrev = blockStore.get(block.getPrevBlockHash());
if (storedPrev == null) {
// We can't find the previous block. Probably we are still in the process of downloading the chain and a
// block was solved whilst we were doing it. We put it to one side and try to connect it later when we
// have more blocks.
checkState(tryConnecting, "bug in tryConnectingOrphans");
log.warn("Block does not connect: {} prev {}", block.getHashAsString(), block.getPrevBlockHash());
orphanBlocks.put(block.getHash(), block);
return false;
} else {
// It connects to somewhere on the chain. Not necessarily the top of the best known chain.
//
// Create a new StoredBlock from this block. It will throw away the transaction data so when block goes
// out of scope we will reclaim the used memory.
StoredBlock newStoredBlock = storedPrev.build(block);
checkDifficultyTransitions(storedPrev, newStoredBlock);
blockStore.put(newStoredBlock);
connectBlock(newStoredBlock, storedPrev, block.transactions);
}
if (tryConnecting)
tryConnectingOrphans();
statsBlocksAdded++;
return true;
}
private void connectBlock(StoredBlock newStoredBlock, StoredBlock storedPrev,
List<Transaction> transactions)
@Override
protected StoredBlock addToBlockStore(StoredBlock storedPrev, Block blockHeader, TransactionOutputChanges txOutChanges)
throws BlockStoreException, VerificationException {
StoredBlock head = getChainHead();
if (storedPrev.equals(head)) {
// This block connects to the best known block, it is a normal continuation of the system.
setChainHead(newStoredBlock);
log.debug("Chain is now {} blocks high", newStoredBlock.getHeight());
// Notify the wallets of the new block, so the depth and workDone of stored transactions can be updated.
// The wallets need to know how deep each transaction is so coinbases aren't used before maturity.
for (Wallet wallet : wallets) {
if (transactions != null) {
sendTransactionsToWallet(newStoredBlock, NewBlockType.BEST_CHAIN, wallet, transactions);
}
wallet.notifyNewBestBlock(newStoredBlock.getHeader());
}
} else {
// This block connects to somewhere other than the top of the best known chain. We treat these differently.
//
// Note that we send the transactions to the wallet FIRST, even if we're about to re-organize this block
// to become the new best chain head. This simplifies handling of the re-org in the Wallet class.
boolean haveNewBestChain = newStoredBlock.moreWorkThan(head);
if (haveNewBestChain) {
log.info("Block is causing a re-organize");
} else {
StoredBlock splitPoint = findSplit(newStoredBlock, head);
if (splitPoint == newStoredBlock) {
// newStoredBlock is a part of the same chain, there's no fork. This happens when we receive a block
// that we already saw and linked into the chain previously, which isn't the chain head.
// Re-processing it is confusing for the wallet so just skip.
log.warn("Saw duplicated block in main chain at height {}: {}",
newStoredBlock.getHeight(), newStoredBlock.getHeader().getHash());
return;
}
if (splitPoint == null) {
log.error("Block forks the chain but splitPoint is null");
} else {
int splitPointHeight = splitPoint.getHeight();
String splitPointHash = splitPoint.getHeader().getHashAsString();
log.info("Block forks the chain at height {}/block {}, but it did not cause a reorganize:\n{}",
new Object[]{splitPointHeight, splitPointHash, newStoredBlock});
}
}
// We may not have any transactions if we received only a header, which can happen during fast catchup.
// If we do, send them to the wallet but state that they are on a side chain so it knows not to try and
// spend them until they become activated.
if (transactions != null) {
for (Wallet wallet : wallets) {
sendTransactionsToWallet(newStoredBlock, NewBlockType.SIDE_CHAIN, wallet, transactions);
}
}
if (haveNewBestChain)
handleNewBestChain(newStoredBlock);
}
StoredBlock newBlock = storedPrev.build(blockHeader);
blockStore.put(newBlock);
return newBlock;
}
/**
* Called as part of connecting a block when the new block results in a different chain having higher total work.
*/
private void handleNewBestChain(StoredBlock newChainHead) throws BlockStoreException, VerificationException {
// This chain has overtaken the one we currently believe is best. Reorganize is required.
//
// Firstly, calculate the block at which the chain diverged. We only need to examine the
// chain from beyond this block to find differences.
StoredBlock head = getChainHead();
StoredBlock splitPoint = findSplit(newChainHead, head);
log.info("Re-organize after split at height {}", splitPoint.getHeight());
log.info("Old chain head: {}", head.getHeader().getHashAsString());
log.info("New chain head: {}", newChainHead.getHeader().getHashAsString());
log.info("Split at block: {}", splitPoint.getHeader().getHashAsString());
// Then build a list of all blocks in the old part of the chain and the new part.
List<StoredBlock> oldBlocks = getPartialChain(head, splitPoint);
List<StoredBlock> newBlocks = getPartialChain(newChainHead, splitPoint);
// Now inform the wallets. This is necessary so the set of currently active transactions (that we can spend)
// can be updated to take into account the re-organize. We might also have received new coins we didn't have
// before and our previous spends might have been undone.
for (Wallet wallet : wallets) {
wallet.reorganize(splitPoint, oldBlocks, newBlocks);
}
// Update the pointer to the best known block.
setChainHead(newChainHead);
}
/**
* Returns the set of contiguous blocks between 'higher' and 'lower'. Higher is included, lower is not.
*/
private List<StoredBlock> getPartialChain(StoredBlock higher, StoredBlock lower) throws BlockStoreException {
checkArgument(higher.getHeight() > lower.getHeight(), "higher and lower are reversed");
LinkedList<StoredBlock> results = new LinkedList<StoredBlock>();
StoredBlock cursor = higher;
while (true) {
results.add(cursor);
cursor = checkNotNull(cursor.getPrev(blockStore), "Ran off the end of the chain");
if (cursor.equals(lower)) break;
}
return results;
}
/**
* Locates the point in the chain at which newStoredBlock and chainHead diverge. Returns null if no split point was
* found (ie they are not part of the same chain). Returns newChainHead or chainHead if they don't actually diverge
* but are part of the same chain.
*/
private StoredBlock findSplit(StoredBlock newChainHead, StoredBlock oldChainHead) throws BlockStoreException {
StoredBlock currentChainCursor = oldChainHead;
StoredBlock newChainCursor = newChainHead;
// Loop until we find the block both chains have in common. Example:
//
// A -> B -> C -> D
// \--> E -> F -> G
//
// findSplit will return block B. oldChainHead = D and newChainHead = G.
while (!currentChainCursor.equals(newChainCursor)) {
if (currentChainCursor.getHeight() > newChainCursor.getHeight()) {
currentChainCursor = currentChainCursor.getPrev(blockStore);
checkNotNull(currentChainCursor, "Attempt to follow an orphan chain");
} else {
newChainCursor = newChainCursor.getPrev(blockStore);
checkNotNull(newChainCursor, "Attempt to follow an orphan chain");
}
}
return currentChainCursor;
}
/**
* @return the height of the best known chain, convenience for <tt>getChainHead().getHeight()</tt>.
*/
public int getBestChainHeight() {
return getChainHead().getHeight();
}
public enum NewBlockType {
BEST_CHAIN,
SIDE_CHAIN
}
private void sendTransactionsToWallet(StoredBlock block, NewBlockType blockType, Wallet wallet,
List<Transaction> transactions) throws VerificationException {
for (Transaction tx : transactions) {
try {
if (wallet.isTransactionRelevant(tx, true))
wallet.receiveFromBlock(tx, block, blockType);
} catch (ScriptException e) {
// We don't want scripts we don't understand to break the block chain so just note that this tx was
// not scanned here and continue.
log.warn("Failed to parse a script: " + e.toString());
}
}
}
private void setChainHead(StoredBlock chainHead) throws BlockStoreException {
blockStore.setChainHead(chainHead);
synchronized (chainHeadLock) {
this.chainHead = chainHead;
}
}
/**
* For each block in orphanBlocks, see if we can now fit it on top of the chain and if so, do so.
*/
private void tryConnectingOrphans() throws VerificationException, ScriptException, BlockStoreException {
// For each block in our orphan list, try and fit it onto the head of the chain. If we succeed remove it
// from the list and keep going. If we changed the head of the list at the end of the round try again until
// we can't fit anything else on the top.
//
// This algorithm is kind of crappy, we should do a topo-sort then just connect them in order, but for small
// numbers of orphan blocks it does OK.
int blocksConnectedThisRound;
do {
blocksConnectedThisRound = 0;
Iterator<Block> iter = orphanBlocks.values().iterator();
while (iter.hasNext()) {
Block block = iter.next();
log.debug("Trying to connect {}", block.getHash());
// Look up the blocks previous.
StoredBlock prev = blockStore.get(block.getPrevBlockHash());
if (prev == null) {
// This is still an unconnected/orphan block.
log.debug(" but it is not connectable right now");
continue;
}
// Otherwise we can connect it now.
// False here ensures we don't recurse infinitely downwards when connecting huge chains.
add(block, false);
iter.remove();
blocksConnectedThisRound++;
}
if (blocksConnectedThisRound > 0) {
log.info("Connected {} orphan blocks.", blocksConnectedThisRound);
}
} while (blocksConnectedThisRound > 0);
}
// February 16th 2012
private static Date testnetDiffDate = new Date(1329264000000L);
/**
* Throws an exception if the blocks difficulty is not correct.
*/
private void checkDifficultyTransitions(StoredBlock storedPrev, StoredBlock storedNext)
@Override
protected StoredBlock addToBlockStore(StoredBlock storedPrev, Block blockHeader)
throws BlockStoreException, VerificationException {
Block prev = storedPrev.getHeader();
Block next = storedNext.getHeader();
// Is this supposed to be a difficulty transition point?
if ((storedPrev.getHeight() + 1) % params.interval != 0) {
// TODO: Refactor this hack after 0.5 is released and we stop supporting deserialization compatibility.
// This should be a method of the NetworkParameters, which should in turn be using singletons and a subclass
// for each network type. Then each network can define its own difficulty transition rules.
if (params.getId().equals(NetworkParameters.ID_TESTNET) && next.getTime().after(testnetDiffDate)) {
checkTestnetDifficulty(storedPrev, prev, next);
return;
}
// No ... so check the difficulty didn't actually change.
if (next.getDifficultyTarget() != prev.getDifficultyTarget())
throw new VerificationException("Unexpected change in difficulty at height " + storedPrev.getHeight() +
": " + Long.toHexString(next.getDifficultyTarget()) + " vs " +
Long.toHexString(prev.getDifficultyTarget()));
return;
}
// We need to find a block far back in the chain. It's OK that this is expensive because it only occurs every
// two weeks after the initial block chain download.
long now = System.currentTimeMillis();
StoredBlock cursor = blockStore.get(prev.getHash());
for (int i = 0; i < params.interval - 1; i++) {
if (cursor == null) {
// This should never happen. If it does, it means we are following an incorrect or busted chain.
throw new VerificationException(
"Difficulty transition point but we did not find a way back to the genesis block.");
}
cursor = blockStore.get(cursor.getHeader().getPrevBlockHash());
}
log.info("Difficulty transition traversal took {}msec", System.currentTimeMillis() - now);
Block blockIntervalAgo = cursor.getHeader();
int timespan = (int) (prev.getTimeSeconds() - blockIntervalAgo.getTimeSeconds());
// Limit the adjustment step.
if (timespan < params.targetTimespan / 4)
timespan = params.targetTimespan / 4;
if (timespan > params.targetTimespan * 4)
timespan = params.targetTimespan * 4;
BigInteger newDifficulty = Utils.decodeCompactBits(blockIntervalAgo.getDifficultyTarget());
newDifficulty = newDifficulty.multiply(BigInteger.valueOf(timespan));
newDifficulty = newDifficulty.divide(BigInteger.valueOf(params.targetTimespan));
if (newDifficulty.compareTo(params.proofOfWorkLimit) > 0) {
log.info("Difficulty hit proof of work limit: {}", newDifficulty.toString(16));
newDifficulty = params.proofOfWorkLimit;
}
int accuracyBytes = (int) (next.getDifficultyTarget() >>> 24) - 3;
BigInteger receivedDifficulty = next.getDifficultyTargetAsInteger();
// The calculated difficulty is to a higher precision than received, so reduce here.
BigInteger mask = BigInteger.valueOf(0xFFFFFFL).shiftLeft(accuracyBytes * 8);
newDifficulty = newDifficulty.and(mask);
if (newDifficulty.compareTo(receivedDifficulty) != 0)
throw new VerificationException("Network provided difficulty bits do not match what was calculated: " +
receivedDifficulty.toString(16) + " vs " + newDifficulty.toString(16));
StoredBlock newBlock = storedPrev.build(blockHeader);
blockStore.put(newBlock);
return newBlock;
}
private void checkTestnetDifficulty(StoredBlock storedPrev, Block prev, Block next) throws VerificationException, BlockStoreException {
// After 15th February 2012 the rules on the testnet change to avoid people running up the difficulty
// and then leaving, making it too hard to mine a block. On non-difficulty transition points, easy
// blocks are allowed if there has been a span of 20 minutes without one.
final long timeDelta = next.getTimeSeconds() - prev.getTimeSeconds();
// There is an integer underflow bug in bitcoin-qt that means mindiff blocks are accepted when time
// goes backwards.
if (timeDelta >= 0 && timeDelta <= NetworkParameters.TARGET_SPACING * 2) {
// Walk backwards until we find a block that doesn't have the easiest proof of work, then check
// that difficulty is equal to that one.
StoredBlock cursor = storedPrev;
while (!cursor.getHeader().equals(params.genesisBlock) &&
cursor.getHeight() % params.interval != 0 &&
cursor.getHeader().getDifficultyTargetAsInteger().equals(params.proofOfWorkLimit))
cursor = cursor.getPrev(blockStore);
BigInteger cursorDifficulty = cursor.getHeader().getDifficultyTargetAsInteger();
BigInteger newDifficulty = next.getDifficultyTargetAsInteger();
if (!cursorDifficulty.equals(newDifficulty))
throw new VerificationException("Testnet block transition that is not allowed: " +
Long.toHexString(cursor.getHeader().getDifficultyTarget()) + " vs " +
Long.toHexString(next.getDifficultyTarget()));
}
}
/**
* Returns true if any connected wallet considers any transaction in the block to be relevant.
*/
private boolean containsRelevantTransactions(Block block) {
for (Transaction tx : block.transactions) {
try {
for (Wallet wallet : wallets) {
if (wallet.isTransactionRelevant(tx, true)) return true;
}
} catch (ScriptException e) {
// We don't want scripts we don't understand to break the block chain so just note that this tx was
// not scanned here and continue.
log.warn("Failed to parse a script: " + e.toString());
}
}
@Override
protected boolean shouldVerifyTransactions() {
return false;
}
/**
* Returns the block at the head of the current best chain. This is the block which represents the greatest
* amount of cumulative work done.
*/
public StoredBlock getChainHead() {
synchronized (chainHeadLock) {
return chainHead;
}
@Override
protected TransactionOutputChanges connectTransactions(int height, Block block) {
// Don't have to do anything as this is only called if(shouldVerifyTransactions())
return null;
}
/**
* An orphan block is one that does not connect to the chain anywhere (ie we can't find its parent, therefore
* it's an orphan). Typically this occurs when we are downloading the chain and didn't reach the head yet, and/or
* if a block is solved whilst we are downloading. It's possible that we see a small amount of orphan blocks which
* chain together, this method tries walking backwards through the known orphan blocks to find the bottom-most.
*
* @return from or one of froms parents, or null if "from" does not identify an orphan block
*/
public synchronized Block getOrphanRoot(Sha256Hash from) {
Block cursor = orphanBlocks.get(from);
if (cursor == null)
return null;
Block tmp;
while ((tmp = orphanBlocks.get(cursor.getPrevBlockHash())) != null) {
cursor = tmp;
}
return cursor;
@Override
protected TransactionOutputChanges connectTransactions(StoredBlock newBlock) {
// Don't have to do anything as this is only called if(shouldVerifyTransactions())
return null;
}
/** Returns true if the given block is currently in the orphan blocks list. */
public synchronized boolean isOrphan(Sha256Hash block) {
return orphanBlocks.containsKey(block);
@Override
protected void disconnectTransactions(StoredBlock block) {
// Don't have to do anything as this is only called if(shouldVerifyTransactions())
}
@Override
protected void preSetChainHead() {
// We don't use DB transactions here, so we don't need to do anything
}
@Override
protected void notSettingChainHead() throws BlockStoreException {
// We don't use DB transactions here, so we don't need to do anything
}
}

8
core/src/main/java/com/google/bitcoin/core/Peer.java
View File

@ -312,6 +312,9 @@ public class Peer {
} catch (ScriptException e) {
// There are no transactions and thus no scripts in these blocks, so this should never happen.
throw new RuntimeException(e);
} catch (PrunedException e) {
// Unreachable when in SPV mode.
throw new RuntimeException(e);
}
}
@ -399,6 +402,11 @@ public class Peer {
} catch (ScriptException e) {
// We don't want script failures to kill the thread.
log.warn("Script exception", e);
} catch (PrunedException e) {
// We pruned away some of the data we need to properly handle this block. We need to request the needed
// data from the remote peer and fix things. Or just give up.
// TODO: Request e.getHash() and submit it to the block store before any other blocks
throw new RuntimeException(e);
}
}

37
core/src/main/java/com/google/bitcoin/core/PrunedException.java Normal file
View File

@ -0,0 +1,37 @@
/*
* Copyright 2012 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.bitcoin.core;
// TODO: Rename PrunedException to something like RequiredDataWasPrunedException
/**
* PrunedException is thrown in cases where a fully verifying node has deleted (pruned) old block data that turned
* out to be necessary for handling a re-org. Normally this should never happen unless you're playing with the testnet
* as the pruning parameters should be set very conservatively, such that an absolutely enormous re-org would be
* required to trigger it.
*/
@SuppressWarnings("serial")
public class PrunedException extends Exception {
private Sha256Hash hash;
public PrunedException(Sha256Hash hash) {
super(hash.toString());
this.hash = hash;
}
public Sha256Hash getHash() {
return hash;
}
}

2
core/src/test/java/com/google/bitcoin/core/CoinbaseBlockTest.java
View File

@ -27,7 +27,7 @@ import java.util.List;
import org.junit.Test;
import com.google.bitcoin.core.BlockChain.NewBlockType;
import com.google.bitcoin.core.AbstractBlockChain.NewBlockType;
import com.google.bitcoin.core.Wallet.BalanceType;
/**