/**
* Copyright 2013 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.devcoin.core;
import com.google.devcoin.store.BlockStore;
import com.google.devcoin.store.BlockStoreException;
import com.google.devcoin.utils.ListenerRegistration;
import com.google.devcoin.utils.Threading;
import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import net.jcip.annotations.GuardedBy;
import org.jboss.netty.channel.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.annotation.Nullable;
import java.io.IOException;
import java.net.ConnectException;
import java.net.InetSocketAddress;
import java.util.*;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
/**
* A Peer handles the high level communication with a Bitcoin node.
*
* <p>{@link Peer#getHandler()} is part of a Netty Pipeline with a Bitcoin serializer downstream of it.
*/
public class Peer {
interface PeerLifecycleListener {
/** Called when the peer is connected */
public void onPeerConnected(Peer peer);
/** Called when the peer is disconnected */
public void onPeerDisconnected(Peer peer);
}
private static final Logger log = LoggerFactory.getLogger(Peer.class);
protected final ReentrantLock lock = Threading.lock("peer");
private final NetworkParameters params;
private final AbstractBlockChain blockChain;
private volatile PeerAddress vAddress;
private final CopyOnWriteArrayList<ListenerRegistration<PeerEventListener>> eventListeners;
private final CopyOnWriteArrayList<PeerLifecycleListener> lifecycleListeners;
// Whether to try and download blocks and transactions from this peer. Set to false by PeerGroup if not the
// primary peer. This is to avoid redundant work and concurrency problems with downloading the same chain
// in parallel.
private volatile boolean vDownloadData;
// The version data to announce to the other side of the connections we make: useful for setting our "user agent"
// equivalent and other things.
private final VersionMessage versionMessage;
// How many block messages the peer has announced to us. Peers only announce blocks that attach to their best chain
// so we can use this to calculate the height of the peers chain, by adding it to the initial height in the version
// message. This method can go wrong if the peer re-orgs onto a shorter (but harder) chain, however, this is rare.
private final AtomicInteger blocksAnnounced = new AtomicInteger();
// A class that tracks recent transactions that have been broadcast across the network, counts how many
// peers announced them and updates the transaction confidence data. It is passed to each Peer.
private final MemoryPool memoryPool;
// Each wallet added to the peer will be notified of downloaded transaction data.
private final CopyOnWriteArrayList<Wallet> wallets;
// A time before which we only download block headers, after that point we download block bodies.
@GuardedBy("lock") private long fastCatchupTimeSecs;
// Whether we are currently downloading headers only or block bodies. Starts at true. If the fast catchup time is
// set AND our best block is before that date, switch to false until block headers beyond that point have been
// received at which point it gets set to true again. This isn't relevant unless vDownloadData is true.
@GuardedBy("lock") private boolean downloadBlockBodies = true;
// Whether to request filtered blocks instead of full blocks if the protocol version allows for them.
@GuardedBy("lock") private boolean useFilteredBlocks = false;
// The current Bloom filter set on the connection, used to tell the remote peer what transactions to send us.
private volatile BloomFilter vBloomFilter;
// The last filtered block we received, we're waiting to fill it out with transactions.
private FilteredBlock currentFilteredBlock = null;
// How many filtered blocks have been received during the lifetime of this connection. Used to decide when to
// refresh the server-side side filter by sending a new one (it degrades over time as false positives are added
// on the remote side, see BIP 37 for a discussion of this).
private int filteredBlocksReceived;
// How frequently to refresh the filter. This should become dynamic in future and calculated depending on the
// actual false positive rate. For now a good value was determined empirically around January 2013.
private static final int RESEND_BLOOM_FILTER_BLOCK_COUNT = 25000;
// Keeps track of things we requested internally with getdata but didn't receive yet, so we can avoid re-requests.
// It's not quite the same as getDataFutures, as this is used only for getdatas done as part of downloading
// the chain and so is lighter weight (we just keep a bunch of hashes not futures).
//
// It is important to avoid a nasty edge case where we can end up with parallel chain downloads proceeding
// simultaneously if we were to receive a newly solved block whilst parts of the chain are streaming to us.
private final HashSet<Sha256Hash> pendingBlockDownloads = new HashSet<Sha256Hash>();
// The lowest version number we're willing to accept. Lower than this will result in an immediate disconnect.
private volatile int vMinProtocolVersion = Pong.MIN_PROTOCOL_VERSION;
// When an API user explicitly requests a block or transaction from a peer, the InventoryItem is put here
// whilst waiting for the response. Is not used for downloads Peer generates itself.
private static class GetDataRequest {
Sha256Hash hash;
SettableFuture future;
// If the peer does not support the notfound message, we'll use ping/pong messages to simulate it. This is
// a nasty hack that relies on the fact that bitcoin-qt is single threaded and processes messages in order.
// The nonce field records which pong should clear this request as "not found".
long nonce;
}
private final CopyOnWriteArrayList<GetDataRequest> getDataFutures;
// Outstanding pings against this peer and how long the last one took to complete.
private final ReentrantLock lastPingTimesLock = new ReentrantLock();
@GuardedBy("lastPingTimesLock") private long[] lastPingTimes = null;
private final CopyOnWriteArrayList<PendingPing> pendingPings;
private static final int PING_MOVING_AVERAGE_WINDOW = 20;
private volatile Channel vChannel;
private volatile VersionMessage vPeerVersionMessage;
private boolean isAcked;
private final PeerHandler handler;
/**
* Construct a peer that reads/writes from the given block chain.
*/
public Peer(NetworkParameters params, AbstractBlockChain chain, VersionMessage ver) {
this(params, chain, ver, null);
}
/**
* Construct a peer that reads/writes from the given block chain and memory pool. Transactions stored
* in a memory pool will have their confidence levels updated when a peer announces it, to reflect the greater
* likelyhood that the transaction is valid.
*/
public Peer(NetworkParameters params, @Nullable AbstractBlockChain chain, VersionMessage ver, @Nullable MemoryPool mempool) {
this.params = Preconditions.checkNotNull(params);
this.versionMessage = Preconditions.checkNotNull(ver);
this.blockChain = chain; // Allowed to be null.
this.vDownloadData = chain != null;
this.getDataFutures = new CopyOnWriteArrayList<GetDataRequest>();
this.eventListeners = new CopyOnWriteArrayList<ListenerRegistration<PeerEventListener>>();
this.lifecycleListeners = new CopyOnWriteArrayList<PeerLifecycleListener>();
this.fastCatchupTimeSecs = params.getGenesisBlock().getTimeSeconds();
this.isAcked = false;
this.handler = new PeerHandler();
this.pendingPings = new CopyOnWriteArrayList<PendingPing>();
this.wallets = new CopyOnWriteArrayList<Wallet>();
this.memoryPool = mempool;
}
/**
* Construct a peer that reads/writes from the given chain. Automatically creates a VersionMessage for you from the
* given software name/version strings, which should be something like "MySimpleTool", "1.0" and which will tell the
* remote node to relay transaction inv messages before it has received a filter.
*/
public Peer(NetworkParameters params, AbstractBlockChain blockChain, String thisSoftwareName, String thisSoftwareVersion) {
this(params, blockChain, new VersionMessage(params, blockChain.getBestChainHeight(), true));
this.versionMessage.appendToSubVer(thisSoftwareName, thisSoftwareVersion, null);
}
/**
* Registers the given object as an event listener that will be invoked on the user thread. Note that listeners
* added this way will <b>not</b> receive {@link PeerEventListener#getData(Peer, GetDataMessage)} or
* {@link PeerEventListener#onPreMessageReceived(Peer, Message)} calls because those require that the listener
* be added using {@link Threading#SAME_THREAD}, which requires the other addListener form.
*/
public void addEventListener(PeerEventListener listener) {
addEventListener(listener, Threading.USER_THREAD);
}
/**
* Registers the given object as an event listener that will be invoked by the given executor. Note that listeners
* added using any other executor than {@link Threading#SAME_THREAD} will <b>not</b> receive
* {@link PeerEventListener#getData(Peer, GetDataMessage)} or
* {@link PeerEventListener#onPreMessageReceived(Peer, Message)} calls because this class is not willing to cross
* threads in order to get the results of those hook methods.
*/
public void addEventListener(PeerEventListener listener, Executor executor) {
eventListeners.add(new ListenerRegistration<PeerEventListener>(listener, executor));
}
public boolean removeEventListener(PeerEventListener listener) {
return ListenerRegistration.removeFromList(listener, eventListeners);
}
void addLifecycleListener(PeerLifecycleListener listener) {
lifecycleListeners.add(listener);
}
boolean removeLifecycleListener(PeerLifecycleListener listener) {
return lifecycleListeners.remove(listener);
}
@Override
public String toString() {
PeerAddress addr = vAddress;
if (addr == null) {
// User-provided NetworkConnection object.
return "Peer()";
} else {
return addr.toString();
}
}
private void notifyDisconnect() {
for (PeerLifecycleListener listener : lifecycleListeners) {
listener.onPeerDisconnected(Peer.this);
}
}
class PeerHandler extends SimpleChannelHandler {
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
super.channelClosed(ctx, e);
notifyDisconnect();
}
@Override
public void connectRequested(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
vAddress = new PeerAddress((InetSocketAddress)e.getValue());
vChannel = e.getChannel();
super.connectRequested(ctx, e);
}
/** Catch any exceptions, logging them and then closing the channel. */
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
String s;
PeerAddress addr = vAddress;
s = addr == null ? "?" : addr.toString();
final Throwable cause = e.getCause();
if (cause instanceof ConnectException || cause instanceof IOException) {
// Short message for network errors
log.info(s + " - " + cause.getMessage());
} else {
log.warn(s + " - ", cause);
Thread.UncaughtExceptionHandler handler = Threading.uncaughtExceptionHandler;
if (handler != null)
handler.uncaughtException(Thread.currentThread(), cause);
}
e.getChannel().close();
}
/** Handle incoming Bitcoin messages */
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
Message m = (Message)e.getMessage();
processMessage(e, m);
}
public Peer getPeer() {
return Peer.this;
}
}
private void processMessage(MessageEvent e, Message m) throws Exception {
// Allow event listeners to filter the message stream. Listeners are allowed to drop messages by
// returning null.
for (ListenerRegistration<PeerEventListener> registration : eventListeners) {
// Skip any listeners that are supposed to run in another thread as we don't want to block waiting
// for it, which might cause circular deadlock.
if (registration.executor == Threading.SAME_THREAD) {
m = registration.listener.onPreMessageReceived(this, m);
if (m == null) break;
}
}
if (m == null) return;
// If we are in the middle of receiving transactions as part of a filtered block push from the remote node,
// and we receive something that's not a transaction, then we're done.
if (currentFilteredBlock != null && !(m instanceof Transaction)) {
endFilteredBlock(currentFilteredBlock);
currentFilteredBlock = null;
}
if (m instanceof NotFoundMessage) {
// This is sent to us when we did a getdata on some transactions that aren't in the peers memory pool.
// Because NotFoundMessage is a subclass of InventoryMessage, the test for it must come before the next.
processNotFoundMessage((NotFoundMessage) m);
} else if (m instanceof InventoryMessage) {
processInv((InventoryMessage) m);
} else if (m instanceof Block) {
processBlock((Block) m);
} else if (m instanceof FilteredBlock) {
startFilteredBlock((FilteredBlock) m);
} else if (m instanceof Transaction) {
processTransaction((Transaction) m);
} else if (m instanceof GetDataMessage) {
processGetData((GetDataMessage) m);
} else if (m instanceof AddressMessage) {
// We don't care about addresses of the network right now. But in future,
// we should save them in the wallet so we don't put too much load on the seed nodes and can
// properly explore the network.
} else if (m instanceof HeadersMessage) {
processHeaders((HeadersMessage) m);
} else if (m instanceof AlertMessage) {
processAlert((AlertMessage) m);
} else if (m instanceof VersionMessage) {
vPeerVersionMessage = (VersionMessage) m;
} else if (m instanceof VersionAck) {
if (vPeerVersionMessage == null) {
throw new ProtocolException("got a version ack before version");
}
if (isAcked) {
throw new ProtocolException("got more than one version ack");
}
isAcked = true;
for (PeerLifecycleListener listener : lifecycleListeners)
listener.onPeerConnected(this);
// We check min version after onPeerConnected as channel.close() will
// call onPeerDisconnected, and we should probably call onPeerConnected first.
final int version = vMinProtocolVersion;
if (vPeerVersionMessage.clientVersion < version) {
log.warn("Connected to a peer speaking protocol version {} but need {}, closing",
vPeerVersionMessage.clientVersion, version);
e.getChannel().close();
}
} else if (m instanceof Ping) {
if (((Ping) m).hasNonce())
sendMessage(new Pong(((Ping) m).getNonce()));
} else if (m instanceof Pong) {
processPong((Pong)m);
} else {
log.warn("Received unhandled message: {}", m);
}
}
private void startFilteredBlock(FilteredBlock m) throws IOException {
// Filtered blocks come before the data that they refer to, so stash it here and then fill it out as
// messages stream in. We'll call endFilteredBlock when a non-tx message arrives (eg, another
// FilteredBlock) or when a tx that isn't needed by that block is found. A ping message is sent after
// a getblocks, to force the non-tx message path.
currentFilteredBlock = m;
// Potentially refresh the server side filter. Because the remote node adds hits back into the filter
// to save round-tripping back through us, the filter degrades over time as false positives get added,
// triggering yet more false positives. We refresh it every so often to get the FP rate back down.
filteredBlocksReceived++;
if (filteredBlocksReceived % RESEND_BLOOM_FILTER_BLOCK_COUNT == RESEND_BLOOM_FILTER_BLOCK_COUNT - 1) {
sendMessage(vBloomFilter);
}
}
private void processNotFoundMessage(NotFoundMessage m) {
// This is received when we previously did a getdata but the peer couldn't find what we requested in it's
// memory pool. Typically, because we are downloading dependencies of a relevant transaction and reached
// the bottom of the dependency tree (where the unconfirmed transactions connect to transactions that are
// in the chain).
//
// We go through and cancel the pending getdata futures for the items we were told weren't found.
for (GetDataRequest req : getDataFutures) {
for (InventoryItem item : m.getItems()) {
if (item.hash.equals(req.hash)) {
log.info("{}: Bottomed out dep tree at {}", this, req.hash);
req.future.cancel(true);
getDataFutures.remove(req);
break;
}
}
}
}
private void processAlert(AlertMessage m) {
try {
if (m.isSignatureValid()) {
log.info("Received alert from peer {}: {}", toString(), m.getStatusBar());
} else {
log.warn("Received alert with invalid signature from peer {}: {}", toString(), m.getStatusBar());
}
} catch (Throwable t) {
// Signature checking can FAIL on Android platforms before Gingerbread apparently due to bugs in their
// BigInteger implementations! See issue 160 for discussion. As alerts are just optional and not that
// useful, we just swallow the error here.
log.error("Failed to check signature: bug in platform libraries?", t);
}
}
/** Returns the Netty Pipeline stage handling the high level Bitcoin protocol. */
public PeerHandler getHandler() {
return handler;
}
private void processHeaders(HeadersMessage m) throws IOException, ProtocolException {
// Runs in network loop thread for this peer.
//
// This method can run if a peer just randomly sends us a "headers" message (should never happen), or more
// likely when we've requested them as part of chain download using fast catchup. We need to add each block to
// the chain if it pre-dates the fast catchup time. If we go past it, we can stop processing the headers and
// request the full blocks from that point on instead.
boolean downloadBlockBodies;
long fastCatchupTimeSecs;
lock.lock();
try {
if (blockChain == null) {
// Can happen if we are receiving unrequested data, or due to programmer error.
log.warn("Received headers when Peer is not configured with a chain.");
return;
}
fastCatchupTimeSecs = this.fastCatchupTimeSecs;
downloadBlockBodies = this.downloadBlockBodies;
} finally {
lock.unlock();
}
try {
// log.info("fast Catch up: {}", fastCatchupTimeSecs);
checkState(!downloadBlockBodies, toString());
for (int i = 0; i < m.getBlockHeaders().size(); i++) {
Block header = m.getBlockHeaders().get(i);
// log.info("i: {}, size: {}", i, m.getBlockHeaders().size());
// log.info("header.getTimeSeconds(): {}", header.getTimeSeconds());
// Process headers until we pass the fast catchup time, or are about to catch up with the head
// of the chain - always process the last block as a full/filtered block to kick us out of the
// fast catchup mode (in which we ignore new blocks).
boolean passedTime = header.getTimeSeconds() >= fastCatchupTimeSecs;
boolean reachedTop = blockChain.getBestChainHeight() >= vPeerVersionMessage.bestHeight;
if (!passedTime && !reachedTop) {
if (!vDownloadData) {
// Not download peer anymore, some other peer probably became better.
log.info("Lost download peer status, throwing away downloaded headers.");
return;
}
if (blockChain.add(header)) {
// The block was successfully linked into the chain. Notify the user of our progress.
invokeOnBlocksDownloaded(header);
} else {
// This block is unconnected - we don't know how to get from it back to the genesis block yet.
// That must mean that the peer is buggy or malicious because we specifically requested for
// headers that are part of the best chain.
throw new ProtocolException("Got unconnected header from peer: " + header.getHashAsString());
}
} else {
lock.lock();
try {
log.info("Passed the fast catchup time, discarding {} headers and requesting full blocks",
m.getBlockHeaders().size() - i);
this.downloadBlockBodies = true;
// Prevent this request being seen as a duplicate.
this.lastGetBlocksBegin = Sha256Hash.ZERO_HASH;
blockChainDownloadLocked(Sha256Hash.ZERO_HASH);
} finally {
lock.unlock();
}
return;
}
}
// We added all headers in the message to the chain. Request some more if we got up to the limit, otherwise
// we are at the end of the chain.
if (m.getBlockHeaders().size() >= HeadersMessage.MAX_HEADERS) {
lock.lock();
try {
blockChainDownloadLocked(Sha256Hash.ZERO_HASH);
} finally {
lock.unlock();
}
}
} catch (VerificationException e) {
log.warn("Block header verification failed", e);
} catch (PrunedException e) {
// Unreachable when in SPV mode.
throw new RuntimeException(e);
}
}
private void processGetData(GetDataMessage getdata) throws IOException {
log.info("{}: Received getdata message: {}", vAddress, getdata.toString());
ArrayList<Message> items = new ArrayList<Message>();
for (ListenerRegistration<PeerEventListener> registration : eventListeners) {
if (registration.executor != Threading.SAME_THREAD) continue;
List<Message> listenerItems = registration.listener.getData(this, getdata);
if (listenerItems == null) continue;
items.addAll(listenerItems);
}
if (items.size() == 0) {
return;
}
log.info("{}: Sending {} items gathered from listeners to peer", vAddress, items.size());
for (Message item : items) {
sendMessage(item);
}
}
private void processTransaction(Transaction tx) throws VerificationException, IOException {
// Check a few basic syntax issues to ensure the received TX isn't nonsense.
tx.verify();
final Transaction fTx;
lock.lock();
try {
log.debug("{}: Received tx {}", vAddress, tx.getHashAsString());
if (memoryPool != null) {
// We may get back a different transaction object.
tx = memoryPool.seen(tx, getAddress());
}
fTx = tx;
// Label the transaction as coming in from the P2P network (as opposed to being created by us, direct import,
// etc). This helps the wallet decide how to risk analyze it later.
fTx.getConfidence().setSource(TransactionConfidence.Source.NETWORK);
if (maybeHandleRequestedData(fTx)) {
return;
}
if (currentFilteredBlock != null) {
if (!currentFilteredBlock.provideTransaction(tx)) {
// Got a tx that didn't fit into the filtered block, so we must have received everything.
endFilteredBlock(currentFilteredBlock);
currentFilteredBlock = null;
}
// Don't tell wallets or listeners about this tx as they'll learn about it when the filtered block is
// fully downloaded instead.
return;
}
// It's a broadcast transaction. Tell all wallets about this tx so they can check if it's relevant or not.
for (final Wallet wallet : wallets) {
try {
if (wallet.isPendingTransactionRelevant(fTx)) {
// This transaction seems interesting to us, so let's download its dependencies. This has several
// purposes: we can check that the sender isn't attacking us by engaging in protocol abuse games,
// like depending on a time-locked transaction that will never confirm, or building huge chains
// of unconfirmed transactions (again - so they don't confirm and the money can be taken
// back with a Finney attack). Knowing the dependencies also lets us store them in a serialized
// wallet so we always have enough data to re-announce to the network and get the payment into
// the chain, in case the sender goes away and the network starts to forget.
// TODO: Not all the above things are implemented.
Futures.addCallback(downloadDependencies(fTx), new FutureCallback<List<Transaction>>() {
public void onSuccess(List<Transaction> dependencies) {
try {
log.info("{}: Dependency download complete!", vAddress);
wallet.receivePending(fTx, dependencies);
} catch (VerificationException e) {
log.error("{}: Wallet failed to process pending transaction {}",
vAddress, fTx.getHashAsString());
log.error("Error was: ", e);
// Not much more we can do at this point.
}
}
public void onFailure(Throwable throwable) {
log.error("Could not download dependencies of tx {}", fTx.getHashAsString());
log.error("Error was: ", throwable);
// Not much more we can do at this point.
}
});
}
} catch (VerificationException e) {
log.error("Wallet failed to verify tx", e);
// Carry on, listeners may still want to know.
}
}
} finally {
lock.unlock();
}
// Tell all listeners about this tx so they can decide whether to keep it or not. If no listener keeps a
// reference around then the memory pool will forget about it after a while too because it uses weak references.
for (final ListenerRegistration<PeerEventListener> registration : eventListeners) {
registration.executor.execute(new Runnable() {
@Override
public void run() {
registration.listener.onTransaction(Peer.this, fTx);
}
});
}
}
/**
* <p>Returns a future that wraps a list of all transactions that the given transaction depends on, recursively.
* Only transactions in peers memory pools are included; the recursion stops at transactions that are in the
* current best chain. So it doesn't make much sense to provide a tx that was already in the best chain and
* a precondition checks this.</p>
*
* <p>For example, if tx has 2 inputs that connect to transactions A and B, and transaction B is unconfirmed and
* has one input connecting to transaction C that is unconfirmed, and transaction C connects to transaction D
* that is in the chain, then this method will return either {B, C} or {C, B}. No ordering is guaranteed.</p>
*
* <p>This method is useful for apps that want to learn about how long an unconfirmed transaction might take
* to confirm, by checking for unexpectedly time locked transactions, unusually deep dependency trees or fee-paying
* transactions that depend on unconfirmed free transactions.</p>
*
* <p>Note that dependencies downloaded this way will not trigger the onTransaction method of event listeners.</p>
*/
public ListenableFuture<List<Transaction>> downloadDependencies(Transaction tx) {
checkNotNull(memoryPool, "Must have a configured MemoryPool object to download dependencies.");
TransactionConfidence.ConfidenceType txConfidence = tx.getConfidence().getConfidenceType();
Preconditions.checkArgument(txConfidence != TransactionConfidence.ConfidenceType.BUILDING);
log.info("{}: Downloading dependencies of {}", vAddress, tx.getHashAsString());
final LinkedList<Transaction> results = new LinkedList<Transaction>();
// future will be invoked when the entire dependency tree has been walked and the results compiled.
final ListenableFuture future = downloadDependenciesInternal(tx, new Object(), results);
final SettableFuture<List<Transaction>> resultFuture = SettableFuture.create();
Futures.addCallback(future, new FutureCallback() {
public void onSuccess(Object _) {
resultFuture.set(results);
}
public void onFailure(Throwable throwable) {
resultFuture.setException(throwable);
}
});
return resultFuture;
}
// The marker object in the future returned is the same as the parameter. It is arbitrary and can be anything.
private ListenableFuture<Object> downloadDependenciesInternal(final Transaction tx,
final Object marker,
final List<Transaction> results) {
checkNotNull(memoryPool, "Must have a configured MemoryPool object to download dependencies.");
final SettableFuture<Object> resultFuture = SettableFuture.create();
final Sha256Hash rootTxHash = tx.getHash();
// We want to recursively grab its dependencies. This is so listeners can learn important information like
// whether a transaction is dependent on a timelocked transaction or has an unexpectedly deep dependency tree
// or depends on a no-fee transaction.
//
// Firstly find any that are already in the memory pool so if they weren't garbage collected yet, they won't
// be deleted. Use COW sets to make unit tests deterministic and because they are small. It's slower for
// the case of transactions with tons of inputs.
Set<Transaction> dependencies = new CopyOnWriteArraySet<Transaction>();
Set<Sha256Hash> needToRequest = new CopyOnWriteArraySet<Sha256Hash>();
for (TransactionInput input : tx.getInputs()) {
// There may be multiple inputs that connect to the same transaction.
Sha256Hash hash = input.getOutpoint().getHash();
Transaction dep = memoryPool.get(hash);
if (dep == null) {
needToRequest.add(hash);
} else {
dependencies.add(dep);
}
}
results.addAll(dependencies);
lock.lock();
try {
// Build the request for the missing dependencies.
List<ListenableFuture<Transaction>> futures = Lists.newArrayList();
GetDataMessage getdata = new GetDataMessage(params);
final long nonce = (long)(Math.random()*Long.MAX_VALUE);
if (needToRequest.size() > 1)
log.info("{}: Requesting {} transactions for dep resolution", vAddress, needToRequest.size());
for (Sha256Hash hash : needToRequest) {
getdata.addTransaction(hash);
GetDataRequest req = new GetDataRequest();
req.hash = hash;
req.future = SettableFuture.create();
if (!isNotFoundMessageSupported()) {
req.nonce = nonce;
}
futures.add(req.future);
getDataFutures.add(req);
}
// The transactions we already grabbed out of the mempool must still be considered by the code below.
for (Transaction dep : dependencies) {
futures.add(Futures.immediateFuture(dep));
}
ListenableFuture<List<Transaction>> successful = Futures.successfulAsList(futures);
Futures.addCallback(successful, new FutureCallback<List<Transaction>>() {
public void onSuccess(List<Transaction> transactions) {
// Once all transactions either were received, or we know there are no more to come ...
// Note that transactions will contain "null" for any positions that weren't successful.
List<ListenableFuture<Object>> childFutures = Lists.newLinkedList();
for (Transaction tx : transactions) {
if (tx == null) continue;
log.info("{}: Downloaded dependency of {}: {}", new Object[]{vAddress,
rootTxHash, tx.getHashAsString()});
results.add(tx);
// Now recurse into the dependencies of this transaction too.
childFutures.add(downloadDependenciesInternal(tx, marker, results));
}
if (childFutures.size() == 0) {
// Short-circuit: we're at the bottom of this part of the tree.
resultFuture.set(marker);
} else {
// There are some children to download. Wait until it's done (and their children and their
// children...) to inform the caller that we're finished.
Futures.addCallback(Futures.successfulAsList(childFutures), new FutureCallback<List<Object>>() {
public void onSuccess(List<Object> objects) {
resultFuture.set(marker);
}
public void onFailure(Throwable throwable) {
resultFuture.setException(throwable);
}
});
}
}
public void onFailure(Throwable throwable) {
resultFuture.setException(throwable);
}
});
// Start the operation.
sendMessage(getdata);
if (!isNotFoundMessageSupported()) {
// If the peer isn't new enough to support the notfound message, we use a nasty hack instead and
// assume if we send a ping message after the getdata message, it'll be processed after all answers
// from getdata are done, so we can watch for the pong message as a substitute.
log.info("{}: Dep resolution waiting for a pong with nonce {}", this, nonce);
ping(nonce).addListener(new Runnable() {
public void run() {
// The pong came back so clear out any transactions we requested but didn't get.
for (GetDataRequest req : getDataFutures) {
if (req.nonce == nonce) {
log.info("{}: Bottomed out dep tree at {}", this, req.hash);
req.future.cancel(true);
getDataFutures.remove(req);
}
}
}
}, Threading.SAME_THREAD);
}
} catch (Exception e) {
log.error("{}: Couldn't send getdata in downloadDependencies({})", this, tx.getHash());
resultFuture.setException(e);
return resultFuture;
} finally {
lock.unlock();
}
return resultFuture;
}
private void processBlock(Block m) throws IOException {
// if (log.isDebugEnabled()) {
log.debug("{}: Received broadcast block {}", vAddress, m.getHashAsString());
// }
// Was this block requested by getBlock()?
if (maybeHandleRequestedData(m)) return;
if (blockChain == null) {
log.warn("Received block but was not configured with an AbstractBlockChain");
return;
}
// Did we lose download peer status after requesting block data?
if (!vDownloadData) {
log.debug("{}: Received block we did not ask for: {}", vAddress, m.getHashAsString());
return;
}
pendingBlockDownloads.remove(m.getHash());
try {
// Otherwise it's a block sent to us because the peer thought we needed it, so add it to the block chain.
if (blockChain.add(m)) {
// The block was successfully linked into the chain. Notify the user of our progress.
invokeOnBlocksDownloaded(m);
} else {
// This block is an orphan - we don't know how to get from it back to the genesis block yet. That
// must mean that there are blocks we are missing, so do another getblocks with a new block locator
// to ask the peer to send them to us. This can happen during the initial block chain download where
// the peer will only send us 500 at a time and then sends us the head block expecting us to request
// the others.
//
// We must do two things here:
// (1) Request from current top of chain to the oldest ancestor of the received block in the orphan set
// (2) Filter out duplicate getblock requests (done in blockChainDownloadLocked).
//
// The reason for (1) is that otherwise if new blocks were solved during the middle of chain download
// we'd do a blockChainDownloadLocked() on the new best chain head, which would cause us to try and grab the
// chain twice (or more!) on the same connection! The block chain would filter out the duplicates but
// only at a huge speed penalty. By finding the orphan root we ensure every getblocks looks the same
// no matter how many blocks are solved, and therefore that the (2) duplicate filtering can work.
//
// We only do this if we are not currently downloading headers. If we are then we don't want to kick
// off a request for lots more headers in parallel.
lock.lock();
try {
if (downloadBlockBodies) {
final Block orphanRoot = checkNotNull(blockChain.getOrphanRoot(m.getHash()));
blockChainDownloadLocked(orphanRoot.getHash());
} else {
log.info("Did not start chain download on solved block due to in-flight header download.");
}
} finally {
lock.unlock();
}
}
} catch (VerificationException e) {
// We don't want verification failures to kill the thread.
log.warn("{}: Block verification failed", vAddress, e);
} catch (PrunedException e) {
// Unreachable when in SPV mode.
throw new RuntimeException(e);
}
}
// TODO: Fix this duplication.
private void endFilteredBlock(FilteredBlock m) throws IOException {
if (log.isDebugEnabled()) {
log.debug("{}: Received broadcast filtered block {}", vAddress, m.getHash().toString());
}
if (!vDownloadData) {
log.debug("{}: Received block we did not ask for: {}", vAddress, m.getHash().toString());
return;
}
if (blockChain == null) {
log.warn("Received filtered block but was not configured with an AbstractBlockChain");
return;
}
// Note that we currently do nothing about peers which maliciously do not include transactions which
// actually match our filter or which simply do not send us all the transactions we need: it can be fixed
// by cross-checking peers against each other.
pendingBlockDownloads.remove(m.getBlockHeader().getHash());
try {
// Otherwise it's a block sent to us because the peer thought we needed it, so add it to the block chain.
// The FilteredBlock m here contains a list of hashes, and may contain Transaction objects for a subset
// of the hashes (those that were sent to us by the remote peer). Any hashes that haven't had a tx
// provided in processTransaction are ones that were announced to us previously via an 'inv' so the
// assumption is we have already downloaded them and either put them in the wallet, or threw them away
// for being false positives.
//
// TODO: Fix the following protocol race.
// It is possible for this code to go wrong such that we miss a confirmation. If the remote peer announces
// a relevant transaction via an 'inv' and then it immediately announces the block that confirms
// the tx before we had a chance to download it+its dependencies and provide them to the wallet, then we
// will add the block to the chain here without the tx being in the wallet and thus it will miss its
// confirmation and become stuck forever. The fix is to notice that there's a pending getdata for a tx
// that appeared in this block and delay processing until it arrived ... it's complicated by the fact that
// the data may be requested by a different peer to this one.
if (blockChain.add(m)) {
// The block was successfully linked into the chain. Notify the user of our progress.
invokeOnBlocksDownloaded(m.getBlockHeader());
} else {
// This block is an orphan - we don't know how to get from it back to the genesis block yet. That
// must mean that there are blocks we are missing, so do another getblocks with a new block locator
// to ask the peer to send them to us. This can happen during the initial block chain download where
// the peer will only send us 500 at a time and then sends us the head block expecting us to request
// the others.
//
// We must do two things here:
// (1) Request from current top of chain to the oldest ancestor of the received block in the orphan set
// (2) Filter out duplicate getblock requests (done in blockChainDownloadLocked).
//
// The reason for (1) is that otherwise if new blocks were solved during the middle of chain download
// we'd do a blockChainDownloadLocked() on the new best chain head, which would cause us to try and grab the
// chain twice (or more!) on the same connection! The block chain would filter out the duplicates but
// only at a huge speed penalty. By finding the orphan root we ensure every getblocks looks the same
// no matter how many blocks are solved, and therefore that the (2) duplicate filtering can work.
lock.lock();
try {
final Block orphanRoot = checkNotNull(blockChain.getOrphanRoot(m.getHash()));
blockChainDownloadLocked(orphanRoot.getHash());
} finally {
lock.unlock();
}
}
} catch (VerificationException e) {
// We don't want verification failures to kill the thread.
log.warn("{}: FilteredBlock verification failed", vAddress, 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);
}
}
private boolean maybeHandleRequestedData(Message m) {
boolean found = false;
Sha256Hash hash = m.getHash();
for (GetDataRequest req : getDataFutures) {
if (hash.equals(req.hash)) {
req.future.set(m);
getDataFutures.remove(req);
found = true;
// Keep going in case there are more.
}
}
return found;
}
private void invokeOnBlocksDownloaded(final Block m) {
// It is possible for the peer block height difference to be negative when blocks have been solved and broadcast
// since the time we first connected to the peer. However, it's weird and unexpected to receive a callback
// with negative "blocks left" in this case, so we clamp to zero so the API user doesn't have to think about it.
final int blocksLeft = Math.max(0, (int) vPeerVersionMessage.bestHeight - checkNotNull(blockChain).getBestChainHeight());
for (final ListenerRegistration<PeerEventListener> registration : eventListeners) {
registration.executor.execute(new Runnable() {
@Override
public void run() {
registration.listener.onBlocksDownloaded(Peer.this, m, blocksLeft);
}
});
}
}
private void processInv(InventoryMessage inv) throws IOException {
List<InventoryItem> items = inv.getItems();
// Separate out the blocks and transactions, we'll handle them differently
List<InventoryItem> transactions = new LinkedList<InventoryItem>();
List<InventoryItem> blocks = new LinkedList<InventoryItem>();
for (InventoryItem item : items) {
switch (item.type) {
case Transaction:
transactions.add(item);
break;
case Block:
blocks.add(item);
break;
default:
throw new IllegalStateException("Not implemented: " + item.type);
}
}
final boolean downloadData = this.vDownloadData;
if (transactions.size() == 0 && blocks.size() == 1) {
// Single block announcement. If we're downloading the chain this is just a tickle to make us continue
// (the block chain download protocol is very implicit and not well thought out). If we're not downloading
// the chain then this probably means a new block was solved and the peer believes it connects to the best
// chain, so count it. This way getBestChainHeight() can be accurate.
if (downloadData && blockChain != null) {
if (!blockChain.isOrphan(blocks.get(0).hash)) {
blocksAnnounced.incrementAndGet();
}
} else {
blocksAnnounced.incrementAndGet();
}
}
GetDataMessage getdata = new GetDataMessage(params);
Iterator<InventoryItem> it = transactions.iterator();
while (it.hasNext()) {
InventoryItem item = it.next();
if (memoryPool == null) {
if (downloadData) {
// If there's no memory pool only download transactions if we're configured to.
getdata.addItem(item);
}
} else {
// Only download the transaction if we are the first peer that saw it be advertised. Other peers will also
// see it be advertised in inv packets asynchronously, they co-ordinate via the memory pool. We could
// potentially download transactions faster by always asking every peer for a tx when advertised, as remote
// peers run at different speeds. However to conserve bandwidth on mobile devices we try to only download a
// transaction once. This means we can miss broadcasts if the peer disconnects between sending us an inv and
// sending us the transaction: currently we'll never try to re-fetch after a timeout.
if (memoryPool.maybeWasSeen(item.hash)) {
// Some other peer already announced this so don't download.
it.remove();
} else {
log.debug("{}: getdata on tx {}", vAddress, item.hash);
getdata.addItem(item);
}
// This can trigger transaction confidence listeners.
memoryPool.seen(item.hash, this.getAddress());
}
}
// If we are requesting filteredblocks we have to send a ping after the getdata so that we have a clear
// end to the final FilteredBlock's transactions (in the form of a pong) sent to us
boolean pingAfterGetData = false;
lock.lock();
try {
if (blocks.size() > 0 && downloadData && blockChain != null) {
// Ideally, we'd only ask for the data here if we actually needed it. However that can imply a lot of
// disk IO to figure out what we've got. Normally peers will not send us inv for things we already have
// so we just re-request it here, and if we get duplicates the block chain / wallet will filter them out.
for (InventoryItem item : blocks) {
if (blockChain.isOrphan(item.hash) && downloadBlockBodies) {
// If an orphan was re-advertised, ask for more blocks unless we are not currently downloading
// full block data because we have a getheaders outstanding.
final Block orphanRoot = checkNotNull(blockChain.getOrphanRoot(item.hash));
blockChainDownloadLocked(orphanRoot.getHash());
} else {
// Don't re-request blocks we already requested. Normally this should not happen. However there is
// an edge case: if a block is solved and we complete the inv<->getdata<->block<->getblocks cycle
// whilst other parts of the chain are streaming in, then the new getblocks request won't match the
// previous one: whilst the stopHash is the same (because we use the orphan root), the start hash
// will be different and so the getblocks req won't be dropped as a duplicate. We'll end up
// requesting a subset of what we already requested, which can lead to parallel chain downloads
// and other nastyness. So we just do a quick removal of redundant getdatas here too.
//
// Note that as of June 2012 the Satoshi client won't actually ever interleave blocks pushed as
// part of chain download with newly announced blocks, so it should always be taken care of by
// the duplicate check in blockChainDownloadLocked(). But the satoshi client may change in future so
// it's better to be safe here.
if (!pendingBlockDownloads.contains(item.hash)) {
if (vPeerVersionMessage.isBloomFilteringSupported() && useFilteredBlocks) {
getdata.addItem(new InventoryItem(InventoryItem.Type.FilteredBlock, item.hash));
pingAfterGetData = true;
} else {
getdata.addItem(item);
}
pendingBlockDownloads.add(item.hash);
}
}
}
// If we're downloading the chain, doing a getdata on the last block we were told about will cause the
// peer to advertize the head block to us in a single-item inv. When we download THAT, it will be an
// orphan block, meaning we'll re-enter blockChainDownloadLocked() to trigger another getblocks between the
// current best block we have and the orphan block. If more blocks arrive in the meantime they'll also
// become orphan.
}
} finally {
lock.unlock();
}
if (!getdata.getItems().isEmpty()) {
// This will cause us to receive a bunch of block or tx messages.
sendMessage(getdata);
}
if (pingAfterGetData)
sendMessage(new Ping((long) (Math.random() * Long.MAX_VALUE)));
}
/**
* Asks the connected peer for the block of the given hash, and returns a future representing the answer.
* If you want the block right away and don't mind waiting for it, just call .get() on the result. Your thread
* will block until the peer answers.
*/
public ListenableFuture<Block> getBlock(Sha256Hash blockHash) throws IOException {
// This does not need to be locked.
log.info("Request to fetch block {}", blockHash);
GetDataMessage getdata = new GetDataMessage(params);
getdata.addBlock(blockHash);
return sendSingleGetData(getdata);
}
/**
* Asks the connected peer for the given transaction from its memory pool. Transactions in the chain cannot be
* retrieved this way because peers don't have a transaction ID to transaction-pos-on-disk index, and besides,
* in future many peers will delete old transaction data they don't need.
*/
public ListenableFuture<Transaction> getPeerMempoolTransaction(Sha256Hash hash) throws IOException {
// This does not need to be locked.
// TODO: Unit test this method.
log.info("Request to fetch peer mempool tx {}", hash);
GetDataMessage getdata = new GetDataMessage(params);
getdata.addTransaction(hash);
return sendSingleGetData(getdata);
}
/** Sends a getdata with a single item in it. */
private ListenableFuture sendSingleGetData(GetDataMessage getdata) throws IOException {
// This does not need to be locked.
Preconditions.checkArgument(getdata.getItems().size() == 1);
GetDataRequest req = new GetDataRequest();
req.future = SettableFuture.create();
req.hash = getdata.getItems().get(0).hash;
getDataFutures.add(req);
sendMessage(getdata);
return req.future;
}
/**
* When downloading the block chain, the bodies will be skipped for blocks created before the given date. Any
* transactions relevant to the wallet will therefore not be found, but if you know your wallet has no such
* transactions it doesn't matter and can save a lot of bandwidth and processing time. Note that the times of blocks
* isn't known until their headers are available and they are requested in chunks, so some headers may be downloaded
* twice using this scheme, but this optimization can still be a large win for newly created wallets.
*
* @param secondsSinceEpoch Time in seconds since the epoch or 0 to reset to always downloading block bodies.
*/
public void setDownloadParameters(long secondsSinceEpoch, boolean useFilteredBlocks) {
lock.lock();
try {
Preconditions.checkNotNull(blockChain);
if (secondsSinceEpoch == 0) {
fastCatchupTimeSecs = params.getGenesisBlock().getTimeSeconds();
downloadBlockBodies = true;
} else {
fastCatchupTimeSecs = secondsSinceEpoch;
// If the given time is before the current chains head block time, then this has no effect (we already
// downloaded everything we need).
if (fastCatchupTimeSecs > blockChain.getChainHead().getHeader().getTimeSeconds()) {
downloadBlockBodies = false;
}
}
this.useFilteredBlocks = useFilteredBlocks;
} finally {
lock.unlock();
}
}
/**
* Links the given wallet to this peer. If you have multiple peers, you should use a {@link PeerGroup} to manage
* them and use the {@link PeerGroup#addWallet(Wallet)} method instead of registering the wallet with each peer
* independently, otherwise the wallet will receive duplicate notifications.
*/
public void addWallet(Wallet wallet) {
wallets.add(wallet);
}
/** Unlinks the given wallet from peer. See {@link Peer#addWallet(Wallet)}. */
public void removeWallet(Wallet wallet) {
wallets.remove(wallet);
}
/**
* Sends the given message on the peers Channel.
*/
public ChannelFuture sendMessage(Message m) {
// This does not need to be locked.
return Channels.write(vChannel, m);
}
// Keep track of the last request we made to the peer in blockChainDownloadLocked so we can avoid redundant and harmful
// getblocks requests.
@GuardedBy("lock")
private Sha256Hash lastGetBlocksBegin, lastGetBlocksEnd;
@GuardedBy("lock")
private void blockChainDownloadLocked(Sha256Hash toHash) throws IOException {
checkState(lock.isHeldByCurrentThread());
// The block chain download process is a bit complicated. Basically, we start with one or more blocks in a
// chain that we have from a previous session. We want to catch up to the head of the chain BUT we don't know
// where that chain is up to or even if the top block we have is even still in the chain - we
// might have got ourselves onto a fork that was later resolved by the network.
//
// To solve this, we send the peer a block locator which is just a list of block hashes. It contains the
// blocks we know about, but not all of them, just enough of them so the peer can figure out if we did end up
// on a fork and if so, what the earliest still valid block we know about is likely to be.
//
// Once it has decided which blocks we need, it will send us an inv with up to 500 block messages. We may
// have some of them already if we already have a block chain and just need to catch up. Once we request the
// last block, if there are still more to come it sends us an "inv" containing only the hash of the head
// block.
//
// That causes us to download the head block but then we find (in processBlock) that we can't connect
// it to the chain yet because we don't have the intermediate blocks. So we rerun this function building a
// new block locator describing where we're up to.
//
// The getblocks with the new locator gets us another inv with another bunch of blocks. We download them once
// again. This time when the peer sends us an inv with the head block, we already have it so we won't download
// it again - but we recognize this case as special and call back into blockChainDownloadLocked to continue the
// process.
//
// So this is a complicated process but it has the advantage that we can download a chain of enormous length
// in a relatively stateless manner and with constant memory usage.
//
// All this is made more complicated by the desire to skip downloading the bodies of blocks that pre-date the
// 'fast catchup time', which is usually set to the creation date of the earliest key in the wallet. Because
// we know there are no transactions using our keys before that date, we need only the headers. To do that we
// use the "getheaders" command. Once we find we've gone past the target date, we throw away the downloaded
// headers and then request the blocks from that point onwards. "getheaders" does not send us an inv, it just
// sends us the data we requested in a "headers" message.
// TODO: Block locators should be abstracted out rather than special cased here.
List<Sha256Hash> blockLocator = new ArrayList<Sha256Hash>(51);
// For now we don't do the exponential thinning as suggested here:
//
// https://en.bitcoin.it/wiki/Protocol_specification#getblocks
//
// This is because it requires scanning all the block chain headers, which is very slow. Instead we add the top
// 50 block headers. If there is a re-org deeper than that, we'll end up downloading the entire chain. We
// must always put the genesis block as the first entry.
BlockStore store = checkNotNull(blockChain).getBlockStore();
StoredBlock chainHead = blockChain.getChainHead();
Sha256Hash chainHeadHash = chainHead.getHeader().getHash();
// Did we already make this request? If so, don't do it again.
if (Objects.equal(lastGetBlocksBegin, chainHeadHash) && Objects.equal(lastGetBlocksEnd, toHash)) {
log.info("blockChainDownloadLocked({}): ignoring duplicated request", toHash.toString());
return;
}
log.info("{}: blockChainDownloadLocked({}) current head = {}", new Object[]{toString(),
toHash.toString(), chainHead.getHeader().getHashAsString()});
StoredBlock cursor = chainHead;
for (int i = 100; cursor != null && i > 0; i--) {
blockLocator.add(cursor.getHeader().getHash());
try {
cursor = cursor.getPrev(store);
} catch (BlockStoreException e) {
log.error("Failed to walk the block chain whilst constructing a locator");
throw new RuntimeException(e);
}
}
// Only add the locator if we didn't already do so. If the chain is < 50 blocks we already reached it.
if (cursor != null) {
blockLocator.add(params.getGenesisBlock().getHash());
}
// Record that we requested this range of blocks so we can filter out duplicate requests in the event of a
// block being solved during chain download.
lastGetBlocksBegin = chainHeadHash;
lastGetBlocksEnd = toHash;
if (downloadBlockBodies) {
GetBlocksMessage message = new GetBlocksMessage(params, blockLocator, toHash);
sendMessage(message);
} else {
// Downloading headers for a while instead of full blocks.
GetHeadersMessage message = new GetHeadersMessage(params, blockLocator, toHash);
sendMessage(message);
}
}
/**
* Starts an asynchronous download of the block chain. The chain download is deemed to be complete once we've
* downloaded the same number of blocks that the peer advertised having in its version handshake message.
*/
public void startBlockChainDownload() throws IOException {
setDownloadData(true);
// TODO: peer might still have blocks that we don't have, and even have a heavier
// chain even if the chain block count is lower.
final int blocksLeft = getPeerBlockHeightDifference();
if (blocksLeft >= 0) {
for (final ListenerRegistration<PeerEventListener> registration : eventListeners) {
registration.executor.execute(new Runnable() {
@Override
public void run() {
registration.listener.onChainDownloadStarted(Peer.this, blocksLeft);
}
});
}
// When we just want as many blocks as possible, we can set the target hash to zero.
lock.lock();
try {
blockChainDownloadLocked(Sha256Hash.ZERO_HASH);
} finally {
lock.unlock();
}
}
}
private class PendingPing {
// The future that will be invoked when the pong is heard back.
public SettableFuture<Long> future;
// The random nonce that lets us tell apart overlapping pings/pongs.
public final long nonce;
// Measurement of the time elapsed.
public final long startTimeMsec;
public PendingPing(long nonce) {
future = SettableFuture.create();
this.nonce = nonce;
startTimeMsec = Utils.now().getTime();
}
public void complete() {
checkNotNull(future, "Already completed");
Long elapsed = Utils.now().getTime() - startTimeMsec;
Peer.this.addPingTimeData(elapsed);
log.debug("{}: ping time is {} msec", Peer.this.toString(), elapsed);
future.set(elapsed);
future = null;
}
}
/** Adds a ping time sample to the averaging window. */
private void addPingTimeData(long sample) {
lastPingTimesLock.lock();
try {
if (lastPingTimes == null) {
lastPingTimes = new long[PING_MOVING_AVERAGE_WINDOW];
// Initialize the averaging window to the first sample.
Arrays.fill(lastPingTimes, sample);
} else {
// Shift all elements backwards by one.
System.arraycopy(lastPingTimes, 1, lastPingTimes, 0, lastPingTimes.length - 1);
// And append the new sample to the end.
lastPingTimes[lastPingTimes.length - 1] = sample;
}
} finally {
lastPingTimesLock.unlock();
}
}
/**
* Sends the peer a ping message and returns a future that will be invoked when the pong is received back.
* The future provides a number which is the number of milliseconds elapsed between the ping and the pong.
* Once the pong is received the value returned by {@link com.google.devcoin.core.Peer#getLastPingTime()} is
* updated.
* @throws ProtocolException if the peer version is too low to support measurable pings.
*/
public ListenableFuture<Long> ping() throws IOException, ProtocolException {
return ping((long) (Math.random() * Long.MAX_VALUE));
}
protected ListenableFuture<Long> ping(long nonce) throws IOException, ProtocolException {
final VersionMessage ver = vPeerVersionMessage;
if (!ver.isPingPongSupported())
throw new ProtocolException("Peer version is too low for measurable pings: " + ver);
PendingPing pendingPing = new PendingPing(nonce);
pendingPings.add(pendingPing);
sendMessage(new Ping(pendingPing.nonce));
return pendingPing.future;
}
/**
* Returns the elapsed time of the last ping/pong cycle. If {@link com.google.devcoin.core.Peer#ping()} has never
* been called or we did not hear back the "pong" message yet, returns {@link Long#MAX_VALUE}.
*/
public long getLastPingTime() {
lastPingTimesLock.lock();
try {
if (lastPingTimes == null)
return Long.MAX_VALUE;
return lastPingTimes[lastPingTimes.length - 1];
} finally {
lastPingTimesLock.unlock();
}
}
/**
* Returns a moving average of the last N ping/pong cycles. If {@link com.google.devcoin.core.Peer#ping()} has never
* been called or we did not hear back the "pong" message yet, returns {@link Long#MAX_VALUE}. The moving average
* window is 5 buckets.
*/
public long getPingTime() {
lastPingTimesLock.lock();
try {
if (lastPingTimes == null)
return Long.MAX_VALUE;
long sum = 0;
for (long i : lastPingTimes) sum += i;
return (long)((double) sum / lastPingTimes.length);
} finally {
lastPingTimesLock.unlock();
}
}
private void processPong(Pong m) {
// Iterates over a snapshot of the list, so we can run unlocked here.
for (PendingPing ping : pendingPings) {
if (m.getNonce() == ping.nonce) {
pendingPings.remove(ping);
// This line may trigger an event listener that re-runs ping().
ping.complete();
return;
}
}
}
/**
* Returns the difference between our best chain height and the peers, which can either be positive if we are
* behind the peer, or negative if the peer is ahead of us.
*/
public int getPeerBlockHeightDifference() {
checkNotNull(blockChain, "No block chain configured");
// Chain will overflow signed int blocks in ~41,000 years.
int chainHeight = (int) getBestHeight();
// chainHeight should not be zero/negative because we shouldn't have given the user a Peer that is to another
// client-mode node, nor should it be unconnected. If that happens it means the user overrode us somewhere or
// there is a bug in the peer management code.
checkState(params.allowEmptyPeerChain() || chainHeight > 0, "Connected to peer with zero/negative chain height", chainHeight);
return chainHeight - blockChain.getBestChainHeight();
}
private boolean isNotFoundMessageSupported() {
return vPeerVersionMessage.clientVersion >= 70001;
}
/**
* Returns true if this peer will try and download things it is sent in "inv" messages. Normally you only need
* one peer to be downloading data. Defaults to true.
*/
public boolean getDownloadData() {
return vDownloadData;
}
/**
* If set to false, the peer won't try and fetch blocks and transactions it hears about. Normally, only one
* peer should download missing blocks. Defaults to true. Changing this value from false to true may trigger
* a request to the remote peer for the contents of its memory pool, if Bloom filtering is active.
*/
public void setDownloadData(boolean downloadData) {
this.vDownloadData = downloadData;
}
/**
* @return the IP address and port of peer.
*/
public PeerAddress getAddress() {
return vAddress;
}
/** Returns version data announced by the remote peer. */
public VersionMessage getPeerVersionMessage() {
return vPeerVersionMessage;
}
/** Returns version data we announce to our remote peers. */
public VersionMessage getVersionMessage() {
return versionMessage;
}
/**
* @return the height of the best chain as claimed by peer: sum of its ver announcement and blocks announced since.
*/
public long getBestHeight() {
return vPeerVersionMessage.bestHeight + blocksAnnounced.get();
}
/**
* The minimum P2P protocol version that is accepted. If the peer speaks a protocol version lower than this, it
* will be disconnected.
* @return if not-null then this is the future for the Peer disconnection event.
*/
@Nullable public ChannelFuture setMinProtocolVersion(int minProtocolVersion) {
this.vMinProtocolVersion = minProtocolVersion;
if (getVersionMessage().clientVersion < minProtocolVersion) {
log.warn("{}: Disconnecting due to new min protocol version {}", this, minProtocolVersion);
return Channels.close(vChannel);
} else {
return null;
}
}
/**
* <p>Sets a Bloom filter on this connection. This will cause the given {@link BloomFilter} object to be sent to the
* remote peer and if either a memory pool has been set using the constructor or the
* vDownloadData property is true, a {@link MemoryPoolMessage} is sent as well to trigger downloading of any
* pending transactions that may be relevant.</p>
*
* <p>The Peer does not automatically request filters from any wallets added using {@link Peer#addWallet(Wallet)}.
* This is to allow callers to avoid redundantly recalculating the same filter repeatedly when using multiple peers
* and multiple wallets together.</p>
*
* <p>Therefore, you should not use this method if your app uses a {@link PeerGroup}. It is called for you.</p>
*
* <p>If the remote peer doesn't support Bloom filtering, then this call is ignored. Once set you presently cannot
* unset a filter, though the underlying p2p protocol does support it.</p>
*/
public void setBloomFilter(BloomFilter filter) throws IOException {
checkNotNull(filter, "Clearing filters is not currently supported");
final VersionMessage ver = vPeerVersionMessage;
if (ver == null || !ver.isBloomFilteringSupported())
return;
vBloomFilter = filter;
boolean shouldQueryMemPool = memoryPool != null || vDownloadData;
log.info("{}: Sending Bloom filter{}", this, shouldQueryMemPool ? " and querying mempool" : "");
ChannelFuture future = sendMessage(filter);
if (shouldQueryMemPool)
future.addListener(new ChannelFutureListener() {
public void operationComplete(ChannelFuture future) throws Exception {
sendMessage(new MemoryPoolMessage());
}
});
}
/**
* Returns the last {@link BloomFilter} set by {@link Peer#setBloomFilter(BloomFilter)}. Bloom filters tell
* the remote node what transactions to send us, in a compact manner.
*/
public BloomFilter getBloomFilter() {
return vBloomFilter;
}
}