Java tutorial
/* * 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 org.bitcoinj.protocols.channels; import com.google.common.collect.ImmutableMultimap; import com.google.common.collect.Multimap; import org.bitcoinj.core.*; import org.bitcoinj.utils.Threading; import org.bitcoinj.wallet.Wallet; import org.bitcoinj.wallet.WalletExtension; import com.google.common.annotations.VisibleForTesting; import com.google.common.collect.HashMultimap; import com.google.common.util.concurrent.SettableFuture; import com.google.protobuf.ByteString; import net.jcip.annotations.GuardedBy; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.annotation.Nullable; import java.util.*; import java.util.concurrent.ExecutionException; import java.util.concurrent.TimeUnit; import java.util.concurrent.TimeoutException; 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 { private static final Logger log = LoggerFactory.getLogger(StoredPaymentChannelClientStates.class); static final String EXTENSION_ID = StoredPaymentChannelClientStates.class.getName(); static final int MAX_SECONDS_TO_WAIT_FOR_BROADCASTER_TO_BE_SET = 10; @GuardedBy("lock") @VisibleForTesting final HashMultimap<Sha256Hash, StoredClientChannel> mapChannels = HashMultimap.create(); @VisibleForTesting final Timer channelTimeoutHandler = new Timer(true); private Wallet containingWallet; private final SettableFuture<TransactionBroadcaster> announcePeerGroupFuture = SettableFuture.create(); 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(@Nullable Wallet containingWallet, TransactionBroadcaster announcePeerGroup) { setTransactionBroadcaster(announcePeerGroup); this.containingWallet = containingWallet; } /** * Creates a new StoredPaymentChannelClientStates and associates it with the given {@link Wallet} * * Use this constructor if you use WalletAppKit, it will provide the broadcaster for you (no need to call the setter) */ public StoredPaymentChannelClientStates(@Nullable Wallet containingWallet) { this.containingWallet = containingWallet; } /** * Use this setter if the broadcaster is not available during instantiation and you're not using WalletAppKit. * This setter will let you delay the setting of the broadcaster until the Bitcoin network is ready. * * @param transactionBroadcaster which is used to complete and announce contract and refund transactions. */ public final void setTransactionBroadcaster(TransactionBroadcaster transactionBroadcaster) { this.announcePeerGroupFuture.set(checkNotNull(transactionBroadcaster)); } /** Returns this extension from the given wallet, or null if no such extension was added. */ @Nullable public static StoredPaymentChannelClientStates getFromWallet(Wallet wallet) { return (StoredPaymentChannelClientStates) wallet.getExtensions().get(EXTENSION_ID); } /** Returns the outstanding amount of money sent back to us for all channels to this server added together. */ public Coin getBalanceForServer(Sha256Hash id) { Coin balance = Coin.ZERO; lock.lock(); try { Set<StoredClientChannel> setChannels = mapChannels.get(id); for (StoredClientChannel channel : setChannels) { synchronized (channel) { if (channel.close != null) continue; balance = balance.add(channel.valueToMe); } } return balance; } finally { lock.unlock(); } } /** * Returns the number of seconds from now until this servers next channel will expire, or zero if no unexpired * channels found. */ public long getSecondsUntilExpiry(Sha256Hash id) { lock.lock(); try { final Set<StoredClientChannel> setChannels = mapChannels.get(id); final long nowSeconds = Utils.currentTimeSeconds(); int earliestTime = Integer.MAX_VALUE; for (StoredClientChannel channel : setChannels) { synchronized (channel) { if (channel.expiryTimeSeconds() > nowSeconds) earliestTime = Math.min(earliestTime, (int) channel.expiryTimeSeconds()); } } return earliestTime == Integer.MAX_VALUE ? 0 : earliestTime - nowSeconds; } finally { lock.unlock(); } } /** * Finds an inactive channel with the given id and returns it, or returns null. */ @Nullable 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. log.info("Considering channel {} contract {}", channel.hashCode(), channel.contract.getHash()); if (channel.close != null || channel.valueToMe.equals(Coin.ZERO)) { log.info(" ... but is closed or empty"); continue; } if (!channel.active) { log.info(" ... activating"); channel.active = true; return channel; } log.info(" ... but is already active"); } } } finally { lock.unlock(); } return null; } /** * Finds a channel with the given id and contract hash and returns it, or returns null. */ @Nullable 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(); } } /** * Get a copy of all {@link StoredClientChannel}s */ public Multimap<Sha256Hash, StoredClientChannel> getChannelMap() { lock.lock(); try { return ImmutableMultimap.copyOf(mapChannels); } finally { lock.unlock(); } } /** * Notifies the set of stored states that a channel has been updated. Use to notify the wallet of an update to this * wallet extension. */ void updatedChannel(final StoredClientChannel channel) { log.info("Stored client channel {} was updated", channel.hashCode()); containingWallet.addOrUpdateExtension(this); } /** * 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 */ 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() { try { TransactionBroadcaster announcePeerGroup = getAnnouncePeerGroup(); removeChannel(channel); announcePeerGroup.broadcastTransaction(channel.contract); announcePeerGroup.broadcastTransaction(channel.refund); } catch (Exception e) { // Something went wrong closing the channel - we catch // here or else we take down the whole Timer. log.error("Auto-closing channel failed", e); } } // Add the difference between real time and Utils.now() so that test-cases can use a mock clock. }, new Date( channel.expiryTimeSeconds() * 1000 + (System.currentTimeMillis() - Utils.currentTimeMillis()))); } finally { lock.unlock(); } if (updateWallet) updatedChannel(channel); } /** * If the peer group has not been set for MAX_SECONDS_TO_WAIT_FOR_BROADCASTER_TO_BE_SET seconds, then * the programmer probably forgot to set it and we should throw exception. */ private TransactionBroadcaster getAnnouncePeerGroup() { try { return announcePeerGroupFuture.get(MAX_SECONDS_TO_WAIT_FOR_BROADCASTER_TO_BE_SET, TimeUnit.SECONDS); } catch (InterruptedException e) { throw new RuntimeException(e); } catch (ExecutionException e) { throw new RuntimeException(e); } catch (TimeoutException e) { String err = "Transaction broadcaster not set"; log.error(err); throw new RuntimeException(err, e); } } /** * <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> */ void removeChannel(StoredClientChannel channel) { lock.lock(); try { mapChannels.remove(channel.id, channel); } finally { lock.unlock(); } updatedChannel(channel); } @Override public String getWalletExtensionID() { return EXTENSION_ID; } @Override public boolean isWalletExtensionMandatory() { return false; } @Override public byte[] serializeWalletExtension() { lock.lock(); try { final NetworkParameters params = getNetworkParameters(); // If we haven't attached to a wallet yet we can't check against network parameters final boolean hasMaxMoney = params != null ? params.hasMaxMoney() : true; final Coin networkMaxMoney = params != null ? params.getMaxMoney() : NetworkParameters.MAX_MONEY; 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.signum() >= 0 && (!hasMaxMoney || channel.valueToMe.compareTo(networkMaxMoney) <= 0)); checkState(channel.refundFees.signum() >= 0 && (!hasMaxMoney || channel.refundFees.compareTo(networkMaxMoney) <= 0)); checkNotNull(channel.myKey.getPubKey()); checkState(channel.refund.getConfidence().getSource() == TransactionConfidence.Source.SELF); checkNotNull(channel.myKey.getPubKey()); final ClientState.StoredClientPaymentChannel.Builder value = ClientState.StoredClientPaymentChannel .newBuilder().setMajorVersion(channel.majorVersion) .setId(ByteString.copyFrom(channel.id.getBytes())) .setContractTransaction(ByteString.copyFrom(channel.contract.unsafeBitcoinSerialize())) .setRefundFees(channel.refundFees.value) .setRefundTransaction(ByteString.copyFrom(channel.refund.unsafeBitcoinSerialize())) .setMyKey(ByteString.copyFrom(new byte[0])) // Not used, but protobuf message requires .setMyPublicKey(ByteString.copyFrom(channel.myKey.getPubKey())) .setServerKey(ByteString.copyFrom(channel.serverKey.getPubKey())) .setValueToMe(channel.valueToMe.value).setExpiryTime(channel.expiryTime); if (channel.close != null) value.setCloseTransactionHash(ByteString.copyFrom(channel.close.getHash().getBytes())); builder.addChannels(value); } 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 = params.getDefaultSerializer() .makeTransaction(storedState.getRefundTransaction().toByteArray()); refundTransaction.getConfidence().setSource(TransactionConfidence.Source.SELF); ECKey myKey = (storedState.getMyKey().isEmpty()) ? containingWallet.findKeyFromPubKey(storedState.getMyPublicKey().toByteArray()) : ECKey.fromPrivate(storedState.getMyKey().toByteArray()); ECKey serverKey = storedState.hasServerKey() ? ECKey.fromPublicOnly(storedState.getServerKey().toByteArray()) : null; StoredClientChannel channel = new StoredClientChannel(storedState.getMajorVersion(), Sha256Hash.wrap(storedState.getId().toByteArray()), params.getDefaultSerializer() .makeTransaction(storedState.getContractTransaction().toByteArray()), refundTransaction, myKey, serverKey, Coin.valueOf(storedState.getValueToMe()), Coin.valueOf(storedState.getRefundFees()), storedState.getExpiryTime(), false); if (storedState.hasCloseTransactionHash()) { Sha256Hash closeTxHash = Sha256Hash.wrap(storedState.getCloseTransactionHash().toByteArray()); channel.close = containingWallet.getTransaction(closeTxHash); } 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(); } } private @Nullable NetworkParameters getNetworkParameters() { return this.containingWallet != null ? this.containingWallet.getNetworkParameters() : null; } } /** * 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 { int majorVersion; Sha256Hash id; Transaction contract, refund; // The expiry time of the contract in protocol v2. long expiryTime; // The transaction that closed the channel (generated by the server) Transaction close; ECKey myKey; ECKey serverKey; Coin valueToMe, refundFees; // In-memory flag to indicate intent to resume this channel (or that the channel is already in use) boolean active = false; StoredClientChannel(int majorVersion, Sha256Hash id, Transaction contract, Transaction refund, ECKey myKey, ECKey serverKey, Coin valueToMe, Coin refundFees, long expiryTime, boolean active) { this.majorVersion = majorVersion; this.id = id; this.contract = contract; this.refund = refund; this.myKey = myKey; this.serverKey = serverKey; this.valueToMe = valueToMe; this.refundFees = refundFees; this.expiryTime = expiryTime; this.active = active; } long expiryTimeSeconds() { switch (majorVersion) { case 1: return refund.getLockTime() + 60 * 5; case 2: return expiryTime + 60 * 5; default: throw new IllegalStateException("Invalid version"); } } @Override public String toString() { final String newline = String.format(Locale.US, "%n"); final String closeStr = close == null ? "still open" : close.toString().replaceAll(newline, newline + " "); return String.format(Locale.US, "Stored client channel for server ID %s (%s)%n" + " Version: %d%n" + " Key: %s%n" + " Server key: %s%n" + " Value left: %s%n" + " Refund fees: %s%n" + " Expiry : %s%n" + " Contract: %s" + "Refund: %s" + "Close: %s", id, active ? "active" : "inactive", majorVersion, myKey, serverKey, valueToMe, refundFees, expiryTime, contract.toString().replaceAll(newline, newline + " "), refund.toString().replaceAll(newline, newline + " "), closeStr); } }