/*
* 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.protocols.channels;
import com.google.devcoin.core.*;
import com.google.devcoin.utils.Threading;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.HashMultimap;
import com.google.protobuf.ByteString;
import net.jcip.annotations.GuardedBy;
import javax.annotation.Nullable;
import java.math.BigInteger;
import java.util.Date;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.locks.ReentrantLock;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
/**
* This class maintains a set of {@link StoredClientChannel}s, automatically (re)broadcasting the contract transaction
* and broadcasting the refund transaction over the given {@link TransactionBroadcaster}.
*/
public class StoredPaymentChannelClientStates implements WalletExtension {
static final String EXTENSION_ID = StoredPaymentChannelClientStates.class.getName();
@GuardedBy("lock") @VisibleForTesting final HashMultimap<Sha256Hash, StoredClientChannel> mapChannels = HashMultimap.create();
@VisibleForTesting final Timer channelTimeoutHandler = new Timer(true);
private Wallet containingWallet;
private final TransactionBroadcaster announcePeerGroup;
protected final ReentrantLock lock = Threading.lock("StoredPaymentChannelClientStates");
/**
* Creates a new StoredPaymentChannelClientStates and associates it with the given {@link Wallet} and
* {@link TransactionBroadcaster} which are used to complete and announce contract and refund
* transactions.
*/
public StoredPaymentChannelClientStates(Wallet containingWallet, TransactionBroadcaster announcePeerGroup) {
this.announcePeerGroup = checkNotNull(announcePeerGroup);
this.containingWallet = checkNotNull(containingWallet);
}
/**
* Finds an inactive channel with the given id and returns it, or returns null.
*/
@Nullable
public StoredClientChannel getUsableChannelForServerID(Sha256Hash id) {
lock.lock();
try {
Set<StoredClientChannel> setChannels = mapChannels.get(id);
for (StoredClientChannel channel : setChannels) {
synchronized (channel) {
// Check if the channel is usable (has money, inactive) and if so, activate it.
if (channel.valueToMe.equals(BigInteger.ZERO))
continue;
if (!channel.active) {
channel.active = true;
return channel;
}
}
}
} finally {
lock.unlock();
}
return null;
}
/**
* Finds a channel with the given id and contract hash and returns it, or returns null.
*/
public StoredClientChannel getChannel(Sha256Hash id, Sha256Hash contractHash) {
lock.lock();
try {
Set<StoredClientChannel> setChannels = mapChannels.get(id);
for (StoredClientChannel channel : setChannels) {
if (channel.contract.getHash().equals(contractHash))
return channel;
}
return null;
} finally {
lock.unlock();
}
}
/**
* Adds the given channel to this set of stored states, broadcasting the contract and refund transactions when the
* channel expires and notifies the wallet of an update to this wallet extension
*/
public void putChannel(final StoredClientChannel channel) {
putChannel(channel, true);
}
// Adds this channel and optionally notifies the wallet of an update to this extension (used during deserialize)
private void putChannel(final StoredClientChannel channel, boolean updateWallet) {
lock.lock();
try {
mapChannels.put(channel.id, channel);
channelTimeoutHandler.schedule(new TimerTask() {
@Override
public void run() {
removeChannel(channel);
announcePeerGroup.broadcastTransaction(channel.contract);
announcePeerGroup.broadcastTransaction(channel.refund);
}
// Add the difference between real time and Utils.now() so that test-cases can use a mock clock.
}, new Date((channel.refund.getLockTime() + 60 * 5) * 1000 + (System.currentTimeMillis() - Utils.now().getTime())));
} finally {
lock.unlock();
}
if (updateWallet)
containingWallet.addOrUpdateExtension(this);
}
/**
* <p>Removes the channel with the given id from this set of stored states and notifies the wallet of an update to
* this wallet extension.</p>
*
* <p>Note that the channel will still have its contract and refund transactions broadcast via the connected
* {@link TransactionBroadcaster} as long as this {@link StoredPaymentChannelClientStates} continues to
* exist in memory.</p>
*/
public void removeChannel(StoredClientChannel channel) {
lock.lock();
try {
mapChannels.remove(channel.id, channel);
} finally {
lock.unlock();
}
containingWallet.addOrUpdateExtension(this);
}
@Override
public String getWalletExtensionID() {
return EXTENSION_ID;
}
@Override
public boolean isWalletExtensionMandatory() {
return false;
}
@Override
public byte[] serializeWalletExtension() {
lock.lock();
try {
ClientState.StoredClientPaymentChannels.Builder builder = ClientState.StoredClientPaymentChannels.newBuilder();
for (StoredClientChannel channel : mapChannels.values()) {
// First a few asserts to make sure things won't break
checkState(channel.valueToMe.compareTo(BigInteger.ZERO) >= 0 && channel.valueToMe.compareTo(NetworkParameters.MAX_MONEY) < 0);
checkState(channel.refundFees.compareTo(BigInteger.ZERO) >= 0 && channel.refundFees.compareTo(NetworkParameters.MAX_MONEY) < 0);
checkNotNull(channel.myKey.getPrivKeyBytes());
checkState(channel.refund.getConfidence().getSource() == TransactionConfidence.Source.SELF);
builder.addChannels(ClientState.StoredClientPaymentChannel.newBuilder()
.setId(ByteString.copyFrom(channel.id.getBytes()))
.setContractTransaction(ByteString.copyFrom(channel.contract.bitcoinSerialize()))
.setRefundTransaction(ByteString.copyFrom(channel.refund.bitcoinSerialize()))
.setMyKey(ByteString.copyFrom(channel.myKey.getPrivKeyBytes()))
.setValueToMe(channel.valueToMe.longValue())
.setRefundFees(channel.refundFees.longValue()));
}
return builder.build().toByteArray();
} finally {
lock.unlock();
}
}
@Override
public void deserializeWalletExtension(Wallet containingWallet, byte[] data) throws Exception {
lock.lock();
try {
checkState(this.containingWallet == null || this.containingWallet == containingWallet);
this.containingWallet = containingWallet;
NetworkParameters params = containingWallet.getParams();
ClientState.StoredClientPaymentChannels states = ClientState.StoredClientPaymentChannels.parseFrom(data);
for (ClientState.StoredClientPaymentChannel storedState : states.getChannelsList()) {
Transaction refundTransaction = new Transaction(params, storedState.getRefundTransaction().toByteArray());
refundTransaction.getConfidence().setSource(TransactionConfidence.Source.SELF);
StoredClientChannel channel = new StoredClientChannel(new Sha256Hash(storedState.getId().toByteArray()),
new Transaction(params, storedState.getContractTransaction().toByteArray()),
refundTransaction,
new ECKey(new BigInteger(1, storedState.getMyKey().toByteArray()), null, true),
BigInteger.valueOf(storedState.getValueToMe()),
BigInteger.valueOf(storedState.getRefundFees()), false);
putChannel(channel, false);
}
} finally {
lock.unlock();
}
}
@Override
public String toString() {
lock.lock();
try {
StringBuilder buf = new StringBuilder("Client payment channel states:\n");
for (StoredClientChannel channel : mapChannels.values())
buf.append(" ").append(channel).append("\n");
return buf.toString();
} finally {
lock.unlock();
}
}
}
/**
* Represents the state of a channel once it has been opened in such a way that it can be stored and used to resume a
* channel which was interrupted (eg on connection failure) or keep track of refund transactions which need broadcast
* when they expire.
*/
class StoredClientChannel {
Sha256Hash id;
Transaction contract, refund;
ECKey myKey;
BigInteger valueToMe, refundFees;
// In-memory flag to indicate intent to resume this channel (or that the channel is already in use)
boolean active = false;
StoredClientChannel(Sha256Hash id, Transaction contract, Transaction refund, ECKey myKey, BigInteger valueToMe,
BigInteger refundFees, boolean active) {
this.id = id;
this.contract = contract;
this.refund = refund;
this.myKey = myKey;
this.valueToMe = valueToMe;
this.refundFees = refundFees;
this.active = active;
}
@Override
public String toString() {
final String newline = String.format("%n");
return String.format("Stored client channel for server ID %s (%s)%n" +
" Key: %s%n" +
" Value left: %d%n" +
" Refund fees: %d%n" +
" Contract: %s" +
"Refund: %s",
id, active ? "active" : "inactive", myKey, valueToMe, refundFees,
contract.toString().replaceAll(newline, newline + " "),
refund.toString().replaceAll(newline, newline + " "));
}
}