/**
* Returns the hashes of the currently stored orphan blocks and then deletes them from this
* objects storage. Used by Peer when a filter exhaustion event has occurred and thus any orphan
* blocks that have been downloaded might be inaccurate/incomplete.
*/
public Set<Sha256Hash> drainOrphanBlocks() {
lock.lock();
try {
Set<Sha256Hash> hashes = new HashSet<Sha256Hash>(orphanBlocks.keySet());
orphanBlocks.clear();
return hashes;
} finally {
lock.unlock();
}
}
/**
* 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
*/
@Nullable
public Block getOrphanRoot(Sha256Hash from) {
lock.lock();
try {
OrphanBlock cursor = orphanBlocks.get(from);
if (cursor == null) return null;
OrphanBlock tmp;
while ((tmp = orphanBlocks.get(cursor.block.getPrevBlockHash())) != null) {
cursor = tmp;
}
return cursor.block;
} finally {
lock.unlock();
}
}
/** Returns true if the given block is currently in the orphan blocks list. */
public boolean isOrphan(Sha256Hash block) {
lock.lock();
try {
return orphanBlocks.containsKey(block);
} finally {
lock.unlock();
}
}
@Override
@Nullable
public StoredBlock get(Sha256Hash hash) throws BlockStoreException {
final MappedByteBuffer buffer = this.buffer;
if (buffer == null) throw new BlockStoreException("Store closed");
lock.lock();
try {
StoredBlock cacheHit = blockCache.get(hash);
if (cacheHit != null) return cacheHit;
if (notFoundCache.get(hash) != null) return null;
// Starting from the current tip of the ring work backwards until we have either found the
// block or
// wrapped around.
int cursor = getRingCursor(buffer);
final int startingPoint = cursor;
final int fileSize = getFileSize();
final byte[] targetHashBytes = hash.getBytes();
byte[] scratch = new byte[32];
do {
cursor -= RECORD_SIZE;
if (cursor < FILE_PROLOGUE_BYTES) {
// We hit the start, so wrap around.
cursor = fileSize - RECORD_SIZE;
}
// Cursor is now at the start of the next record to check, so read the hash and compare it.
buffer.position(cursor);
buffer.get(scratch);
if (Arrays.equals(scratch, targetHashBytes)) {
// Found the target.
StoredBlock storedBlock = StoredBlock.deserializeCompact(params, buffer);
blockCache.put(hash, storedBlock);
return storedBlock;
}
} while (cursor != startingPoint);
// Not found.
notFoundCache.put(hash, notFoundMarker);
return null;
} catch (ProtocolException e) {
throw new RuntimeException(e); // Cannot happen.
} finally {
lock.unlock();
}
}
@Override
public void put(StoredBlock block) throws BlockStoreException {
final MappedByteBuffer buffer = this.buffer;
if (buffer == null) throw new BlockStoreException("Store closed");
lock.lock();
try {
int cursor = getRingCursor(buffer);
if (cursor == getFileSize()) {
// Wrapped around.
cursor = FILE_PROLOGUE_BYTES;
}
buffer.position(cursor);
Sha256Hash hash = block.getHeader().getHash();
notFoundCache.remove(hash);
buffer.put(hash.getBytes());
block.serializeCompact(buffer);
setRingCursor(buffer, buffer.position());
blockCache.put(hash, block);
} finally {
lock.unlock();
}
}
/**
* 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, BlockStoreException, PrunedException {
checkState(lock.isHeldByCurrentThread());
// 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<OrphanBlock> iter = orphanBlocks.values().iterator();
while (iter.hasNext()) {
OrphanBlock orphanBlock = iter.next();
// Look up the blocks previous.
StoredBlock prev = getStoredBlockInCurrentScope(orphanBlock.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.
log.info("Connected orphan {}", orphanBlock.block.getHash());
add(orphanBlock.block, false, orphanBlock.filteredTxHashes, orphanBlock.filteredTxn);
iter.remove();
blocksConnectedThisRound++;
}
if (blocksConnectedThisRound > 0) {
log.info("Connected {} orphan blocks.", blocksConnectedThisRound);
}
} while (blocksConnectedThisRound > 0);
}
// filteredTxHashList contains all transactions, filteredTxn just a subset
private boolean add(
Block block,
boolean tryConnecting,
@Nullable List<Sha256Hash> filteredTxHashList,
@Nullable Map<Sha256Hash, Transaction> filteredTxn)
throws BlockStoreException, VerificationException, PrunedException {
// TODO: Use read/write locks to ensure that during chain download properties are still low
// latency.
lock.lock();
try {
// 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())) {
return true;
}
if (tryConnecting && orphanBlocks.containsKey(block.getHash())) {
return false;
}
// 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");
// Check for already-seen block, but only for full pruned mode, where the DB is
// more likely able to handle these queries quickly.
if (shouldVerifyTransactions() && blockStore.get(block.getHash()) != null) {
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 = 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 = getStoredBlockInCurrentScope(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(), new OrphanBlock(block, filteredTxHashList, filteredTxn));
return false;
} else {
checkState(lock.isHeldByCurrentThread());
// It connects to somewhere on the chain. Not necessarily the top of the best known chain.
params.checkDifficultyTransitions(storedPrev, block, blockStore);
connectBlock(
block, storedPrev, shouldVerifyTransactions(), filteredTxHashList, filteredTxn);
}
if (tryConnecting) tryConnectingOrphans();
return true;
} finally {
lock.unlock();
}
}