com.hivewallet.androidclient.wallet.service.BlockchainServiceImpl.java Source code

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Here is the source code for com.hivewallet.androidclient.wallet.service.BlockchainServiceImpl.java

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/*
 * Copyright 2011-2014 the original author or authors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.hivewallet.androidclient.wallet.service;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigInteger;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import android.annotation.SuppressLint;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import android.graphics.Bitmap;
import android.net.ConnectivityManager;
import android.net.Uri;
import android.os.Binder;
import android.os.Handler;
import android.os.IBinder;
import android.os.PowerManager;
import android.os.PowerManager.WakeLock;
import android.provider.MediaStore;
import android.support.v4.app.NotificationCompat;
import android.text.format.DateUtils;

import com.google.bitcoin.core.AbstractPeerEventListener;
import com.google.bitcoin.core.Address;
import com.google.bitcoin.core.Block;
import com.google.bitcoin.core.BlockChain;
import com.google.bitcoin.core.CheckpointManager;
import com.google.bitcoin.core.Peer;
import com.google.bitcoin.core.PeerEventListener;
import com.google.bitcoin.core.PeerGroup;
import com.google.bitcoin.core.Sha256Hash;
import com.google.bitcoin.core.StoredBlock;
import com.google.bitcoin.core.Transaction;
import com.google.bitcoin.core.TransactionConfidence.ConfidenceType;
import com.google.bitcoin.core.Wallet;
import com.google.bitcoin.core.Wallet.BalanceType;
import com.google.bitcoin.core.WalletEventListener;
import com.google.bitcoin.net.discovery.DnsDiscovery;
import com.google.bitcoin.net.discovery.PeerDiscovery;
import com.google.bitcoin.net.discovery.PeerDiscoveryException;
import com.google.bitcoin.store.BlockStore;
import com.google.bitcoin.store.BlockStoreException;
import com.google.bitcoin.store.SPVBlockStore;
import com.google.bitcoin.utils.Threading;

import com.hivewallet.androidclient.wallet.AddressBookProvider;
import com.hivewallet.androidclient.wallet.AddressBookProvider.AddressBookEntry;
import com.hivewallet.androidclient.wallet.Configuration;
import com.hivewallet.androidclient.wallet.Constants;
import com.hivewallet.androidclient.wallet.WalletApplication;
import com.hivewallet.androidclient.wallet.WalletBalanceWidgetProvider;
import com.hivewallet.androidclient.wallet.ui.WalletActivity;
import com.hivewallet.androidclient.wallet.util.CrashReporter;
import com.hivewallet.androidclient.wallet.util.GenericUtils;
import com.hivewallet.androidclient.wallet.util.ThrottlingWalletChangeListener;
import com.hivewallet.androidclient.wallet.util.WalletUtils;
import com.hivewallet.androidclient.wallet_test.R;

/**
 * @author Andreas Schildbach
 */
public class BlockchainServiceImpl extends android.app.Service implements BlockchainService {
    private WalletApplication application;
    private Configuration config;

    private BlockStore blockStore;
    private File blockChainFile;
    private BlockChain blockChain;
    @CheckForNull
    private PeerGroup peerGroup;

    private final Handler handler = new Handler();
    private final Handler delayHandler = new Handler();
    private WakeLock wakeLock;

    private PeerConnectivityListener peerConnectivityListener;
    private NotificationManager nm;
    private static final int NOTIFICATION_ID_CONNECTED = 0;
    private static final int NOTIFICATION_ID_COINS_RECEIVED = 1;

    private AtomicInteger transactionsReceived = new AtomicInteger();
    private int bestChainHeightEver;
    private long serviceCreatedAt;
    private boolean resetBlockchainOnShutdown = false;

    private static final int MIN_COLLECT_HISTORY = 2;
    private static final int IDLE_BLOCK_TIMEOUT_MIN = 2;
    private static final int IDLE_TRANSACTION_TIMEOUT_MIN = 9;
    private static final int MAX_HISTORY_SIZE = Math.max(IDLE_TRANSACTION_TIMEOUT_MIN, IDLE_BLOCK_TIMEOUT_MIN);
    private static final long APPWIDGET_THROTTLE_MS = DateUtils.SECOND_IN_MILLIS;

    private static final Logger log = LoggerFactory.getLogger(BlockchainServiceImpl.class);

    private final WalletEventListener walletEventListener = new ThrottlingWalletChangeListener(
            APPWIDGET_THROTTLE_MS) {
        @Override
        public void onThrottledWalletChanged() {
            notifyWidgets();
        }

        @Override
        public void onCoinsReceived(final Wallet wallet, final Transaction tx, final BigInteger prevBalance,
                final BigInteger newBalance) {
            transactionsReceived.incrementAndGet();

            final int bestChainHeight = blockChain.getBestChainHeight();

            final Address from = WalletUtils.getFirstFromAddress(tx);
            final BigInteger amount = tx.getValue(wallet);
            final ConfidenceType confidenceType = tx.getConfidence().getConfidenceType();

            handler.post(new Runnable() {
                @Override
                public void run() {
                    final boolean isReceived = amount.signum() > 0;
                    final boolean replaying = bestChainHeight < bestChainHeightEver;
                    final boolean isReplayedTx = confidenceType == ConfidenceType.BUILDING && replaying;

                    if (isReceived && !isReplayedTx)
                        notifyCoinsReceived(from, amount);
                }
            });
        }

        @Override
        public void onCoinsSent(final Wallet wallet, final Transaction tx, final BigInteger prevBalance,
                final BigInteger newBalance) {
            transactionsReceived.incrementAndGet();
        }
    };

    private void notifyCoinsReceived(@Nullable final Address from, @Nonnull final BigInteger amount) {
        final int btcPrecision = config.getBtcPrecision();
        final int btcShift = config.getBtcShift();
        final String btcPrefix = config.getBtcPrefix();

        final String packageFlavor = application.applicationPackageFlavor();
        final String msgSuffix = packageFlavor != null ? " [" + packageFlavor + "]" : "";

        String label = null;
        Uri photoUri = null;
        Bitmap photoBitmap = null;
        if (from != null) {
            final String addressStr = from.toString();
            AddressBookEntry entry = AddressBookProvider.lookupEntry(getApplicationContext(), addressStr);
            if (entry != null) {
                label = entry.getLabel();
                photoUri = entry.getPhotoUri();
            }
            if (photoUri != null) {
                try {
                    Bitmap photoBitmapOriginal = MediaStore.Images.Media.getBitmap(getContentResolver(), photoUri);
                    int width = (int) getResources().getDimension(android.R.dimen.notification_large_icon_width);
                    int height = (int) getResources().getDimension(android.R.dimen.notification_large_icon_height);
                    photoBitmap = Bitmap.createScaledBitmap(photoBitmapOriginal, width, height, false);
                } catch (FileNotFoundException ignored) {
                } catch (IOException ignored) {
                }
            }
        }

        final StringBuilder tickerMsg = new StringBuilder();
        if (label != null)
            tickerMsg.append(getString(R.string.notification_coins_received_with_label_msg,
                    GenericUtils.formatValue(amount, btcPrecision, btcShift) + ' ' + btcPrefix, label));
        else
            tickerMsg.append(getString(R.string.notification_coins_received_msg,
                    GenericUtils.formatValue(amount, btcPrecision, btcShift) + ' ' + btcPrefix));
        tickerMsg.append(msgSuffix);

        String contentTitle = getString(R.string.notification_coins_received_no_address);
        if (from != null)
            contentTitle = from.toString();
        if (label != null)
            contentTitle = label;

        final String contentText = getString(R.string.notification_coins_received_msg,
                GenericUtils.formatValue(amount, btcPrecision, btcShift) + ' ' + btcPrefix) + msgSuffix;

        final NotificationCompat.Builder notification = new NotificationCompat.Builder(this);
        notification.setSmallIcon(R.drawable.app_icon);
        notification.setTicker(tickerMsg);
        if (photoBitmap != null)
            notification.setLargeIcon(photoBitmap);
        notification.setContentTitle(contentTitle);
        notification.setContentText(contentText);
        notification
                .setContentIntent(PendingIntent.getActivity(this, 0, new Intent(this, WalletActivity.class), 0));
        notification.setNumber(0);
        notification.setWhen(System.currentTimeMillis());
        notification.setSound(Uri.parse("android.resource://" + getPackageName() + "/" + R.raw.coins_received));
        nm.notify(NOTIFICATION_ID_COINS_RECEIVED, notification.getNotification());
    }

    private final class PeerConnectivityListener extends AbstractPeerEventListener
            implements OnSharedPreferenceChangeListener {
        private int peerCount;
        private AtomicBoolean stopped = new AtomicBoolean(false);

        public PeerConnectivityListener() {
            config.registerOnSharedPreferenceChangeListener(this);
        }

        public void stop() {
            stopped.set(true);

            config.unregisterOnSharedPreferenceChangeListener(this);

            nm.cancel(NOTIFICATION_ID_CONNECTED);
        }

        @Override
        public void onPeerConnected(final Peer peer, final int peerCount) {
            this.peerCount = peerCount;
            changed(peerCount);
        }

        @Override
        public void onPeerDisconnected(final Peer peer, final int peerCount) {
            this.peerCount = peerCount;
            changed(peerCount);
        }

        @Override
        public void onSharedPreferenceChanged(final SharedPreferences sharedPreferences, final String key) {
            if (Configuration.PREFS_KEY_CONNECTIVITY_NOTIFICATION.equals(key))
                changed(peerCount);
        }

        private void changed(final int numPeers) {
            if (stopped.get())
                return;

            handler.post(new Runnable() {
                @Override
                public void run() {
                    final boolean connectivityNotificationEnabled = config.getConnectivityNotificationEnabled();

                    if (!connectivityNotificationEnabled || numPeers == 0) {
                        nm.cancel(NOTIFICATION_ID_CONNECTED);
                    } else {
                        final NotificationCompat.Builder notification = new NotificationCompat.Builder(
                                BlockchainServiceImpl.this);
                        notification.setSmallIcon(R.drawable.stat_sys_peers, numPeers > 4 ? 4 : numPeers);
                        notification.setContentTitle(getString(R.string.app_name));
                        notification.setContentText(getString(R.string.notification_peers_connected_msg, numPeers));
                        notification.setContentIntent(PendingIntent.getActivity(BlockchainServiceImpl.this, 0,
                                new Intent(BlockchainServiceImpl.this, WalletActivity.class), 0));
                        notification.setWhen(System.currentTimeMillis());
                        notification.setOngoing(true);
                        nm.notify(NOTIFICATION_ID_CONNECTED, notification.getNotification());
                    }

                    // send broadcast
                    sendBroadcastPeerState(numPeers);
                }
            });
        }
    }

    private final PeerEventListener blockchainDownloadListener = new AbstractPeerEventListener() {
        private final AtomicLong lastMessageTime = new AtomicLong(0);

        @Override
        public void onBlocksDownloaded(final Peer peer, final Block block, final int blocksLeft) {
            bestChainHeightEver = Math.max(bestChainHeightEver, blockChain.getChainHead().getHeight());

            delayHandler.removeCallbacksAndMessages(null);

            final long now = System.currentTimeMillis();

            if (now - lastMessageTime.get() > Constants.BLOCKCHAIN_STATE_BROADCAST_THROTTLE_MS)
                delayHandler.post(runnable);
            else
                delayHandler.postDelayed(runnable, Constants.BLOCKCHAIN_STATE_BROADCAST_THROTTLE_MS);
        }

        private final Runnable runnable = new Runnable() {
            @Override
            public void run() {
                lastMessageTime.set(System.currentTimeMillis());

                sendBroadcastBlockchainState(ACTION_BLOCKCHAIN_STATE_DOWNLOAD_OK);
            }
        };
    };

    private final BroadcastReceiver connectivityReceiver = new BroadcastReceiver() {
        private boolean hasConnectivity;
        private boolean hasStorage = true;

        @Override
        public void onReceive(final Context context, final Intent intent) {
            final String action = intent.getAction();

            if (ConnectivityManager.CONNECTIVITY_ACTION.equals(action)) {
                hasConnectivity = !intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);
                log.info("network is " + (hasConnectivity ? "up" : "down"));

                check();
            } else if (Intent.ACTION_DEVICE_STORAGE_LOW.equals(action)) {
                hasStorage = false;
                log.info("device storage low");

                check();
            } else if (Intent.ACTION_DEVICE_STORAGE_OK.equals(action)) {
                hasStorage = true;
                log.info("device storage ok");

                check();
            }
        }

        @SuppressLint("Wakelock")
        private void check() {
            final Wallet wallet = application.getWallet();
            final boolean hasEverything = hasConnectivity && hasStorage;

            if (hasEverything && peerGroup == null) {
                log.debug("acquiring wakelock");
                wakeLock.acquire();

                // consistency check
                final int walletLastBlockSeenHeight = wallet.getLastBlockSeenHeight();
                final int bestChainHeight = blockChain.getBestChainHeight();
                if (walletLastBlockSeenHeight != -1 && walletLastBlockSeenHeight != bestChainHeight) {
                    final String message = "wallet/blockchain out of sync: " + walletLastBlockSeenHeight + "/"
                            + bestChainHeight;
                    log.error(message);
                    CrashReporter.saveBackgroundTrace(new RuntimeException(message), application.packageInfo());
                }

                log.info("starting peergroup");
                peerGroup = new PeerGroup(Constants.NETWORK_PARAMETERS, blockChain);
                peerGroup.addWallet(wallet);
                peerGroup.setUserAgent(Constants.USER_AGENT, application.packageInfo().versionName);
                peerGroup.addEventListener(peerConnectivityListener);

                final int maxConnectedPeers = application.maxConnectedPeers();

                final String trustedPeerHost = config.getTrustedPeerHost();
                final boolean hasTrustedPeer = !trustedPeerHost.isEmpty();

                final boolean connectTrustedPeerOnly = hasTrustedPeer && config.getTrustedPeerOnly();
                peerGroup.setMaxConnections(connectTrustedPeerOnly ? 1 : maxConnectedPeers);

                peerGroup.addPeerDiscovery(new PeerDiscovery() {
                    private final PeerDiscovery normalPeerDiscovery = new DnsDiscovery(
                            Constants.NETWORK_PARAMETERS);

                    @Override
                    public InetSocketAddress[] getPeers(final long timeoutValue, final TimeUnit timeoutUnit)
                            throws PeerDiscoveryException {
                        final List<InetSocketAddress> peers = new LinkedList<InetSocketAddress>();

                        boolean needsTrimPeersWorkaround = false;

                        if (hasTrustedPeer) {
                            log.info("trusted peer '" + trustedPeerHost + "'"
                                    + (connectTrustedPeerOnly ? " only" : ""));

                            final InetSocketAddress addr = new InetSocketAddress(trustedPeerHost,
                                    Constants.NETWORK_PARAMETERS.getPort());
                            if (addr.getAddress() != null) {
                                peers.add(addr);
                                needsTrimPeersWorkaround = true;
                            }
                        }

                        if (!connectTrustedPeerOnly)
                            peers.addAll(Arrays.asList(normalPeerDiscovery.getPeers(timeoutValue, timeoutUnit)));

                        // workaround because PeerGroup will shuffle peers
                        if (needsTrimPeersWorkaround)
                            while (peers.size() >= maxConnectedPeers)
                                peers.remove(peers.size() - 1);

                        return peers.toArray(new InetSocketAddress[0]);
                    }

                    @Override
                    public void shutdown() {
                        normalPeerDiscovery.shutdown();
                    }
                });

                // start peergroup
                peerGroup.start();
                peerGroup.startBlockChainDownload(blockchainDownloadListener);
            } else if (!hasEverything && peerGroup != null) {
                log.info("stopping peergroup");
                peerGroup.removeEventListener(peerConnectivityListener);
                peerGroup.removeWallet(wallet);
                peerGroup.stop();
                peerGroup = null;

                log.debug("releasing wakelock");
                wakeLock.release();
            }

            final int download = (hasConnectivity ? 0 : ACTION_BLOCKCHAIN_STATE_DOWNLOAD_NETWORK_PROBLEM)
                    | (hasStorage ? 0 : ACTION_BLOCKCHAIN_STATE_DOWNLOAD_STORAGE_PROBLEM);

            sendBroadcastBlockchainState(download);
        }
    };

    private final static class ActivityHistoryEntry {
        public final int numTransactionsReceived;
        public final int numBlocksDownloaded;

        public ActivityHistoryEntry(final int numTransactionsReceived, final int numBlocksDownloaded) {
            this.numTransactionsReceived = numTransactionsReceived;
            this.numBlocksDownloaded = numBlocksDownloaded;
        }

        @Override
        public String toString() {
            return numTransactionsReceived + "/" + numBlocksDownloaded;
        }
    }

    private final BroadcastReceiver tickReceiver = new BroadcastReceiver() {
        private int lastChainHeight = 0;
        private final List<ActivityHistoryEntry> activityHistory = new LinkedList<ActivityHistoryEntry>();

        @Override
        public void onReceive(final Context context, final Intent intent) {
            final int chainHeight = blockChain.getBestChainHeight();

            if (lastChainHeight > 0) {
                final int numBlocksDownloaded = chainHeight - lastChainHeight;
                final int numTransactionsReceived = transactionsReceived.getAndSet(0);

                // push history
                activityHistory.add(0, new ActivityHistoryEntry(numTransactionsReceived, numBlocksDownloaded));

                // trim
                while (activityHistory.size() > MAX_HISTORY_SIZE)
                    activityHistory.remove(activityHistory.size() - 1);

                // print
                final StringBuilder builder = new StringBuilder();
                for (final ActivityHistoryEntry entry : activityHistory) {
                    if (builder.length() > 0)
                        builder.append(", ");
                    builder.append(entry);
                }
                log.info("History of transactions/blocks: " + builder);

                // determine if block and transaction activity is idling
                boolean isIdle = false;
                if (activityHistory.size() >= MIN_COLLECT_HISTORY) {
                    isIdle = true;
                    for (int i = 0; i < activityHistory.size(); i++) {
                        final ActivityHistoryEntry entry = activityHistory.get(i);
                        final boolean blocksActive = entry.numBlocksDownloaded > 0 && i <= IDLE_BLOCK_TIMEOUT_MIN;
                        final boolean transactionsActive = entry.numTransactionsReceived > 0
                                && i <= IDLE_TRANSACTION_TIMEOUT_MIN;

                        if (blocksActive || transactionsActive) {
                            isIdle = false;
                            break;
                        }
                    }
                }

                // if idling, shutdown service
                if (isIdle) {
                    log.info("idling detected, stopping service");
                    stopSelf();
                }
            }

            lastChainHeight = chainHeight;
        }
    };

    public class LocalBinder extends Binder {
        public BlockchainService getService() {
            return BlockchainServiceImpl.this;
        }
    }

    private final IBinder mBinder = new LocalBinder();

    @Override
    public IBinder onBind(final Intent intent) {
        log.debug(".onBind()");

        return mBinder;
    }

    @Override
    public boolean onUnbind(final Intent intent) {
        log.debug(".onUnbind()");

        return super.onUnbind(intent);
    }

    @Override
    public void onCreate() {
        serviceCreatedAt = System.currentTimeMillis();
        log.debug(".onCreate()");

        super.onCreate();

        nm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        final String lockName = getPackageName() + " blockchain sync";

        final PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
        wakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, lockName);

        application = (WalletApplication) getApplication();
        config = application.getConfiguration();
        final Wallet wallet = application.getWallet();

        bestChainHeightEver = config.getBestChainHeightEver();

        peerConnectivityListener = new PeerConnectivityListener();

        sendBroadcastPeerState(0);

        final IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        intentFilter.addAction(Intent.ACTION_DEVICE_STORAGE_LOW);
        intentFilter.addAction(Intent.ACTION_DEVICE_STORAGE_OK);
        registerReceiver(connectivityReceiver, intentFilter);

        blockChainFile = new File(getDir("blockstore", Context.MODE_PRIVATE), Constants.Files.BLOCKCHAIN_FILENAME);
        final boolean blockChainFileExists = blockChainFile.exists();

        if (!blockChainFileExists) {
            log.info("blockchain does not exist, resetting wallet");

            wallet.clearTransactions(0);
            wallet.setLastBlockSeenHeight(-1); // magic value
            wallet.setLastBlockSeenHash(null);
        }

        try {
            blockStore = new SPVBlockStore(Constants.NETWORK_PARAMETERS, blockChainFile);
            blockStore.getChainHead(); // detect corruptions as early as possible

            final long earliestKeyCreationTime = wallet.getEarliestKeyCreationTime();

            if (!blockChainFileExists && earliestKeyCreationTime > 0) {
                try {
                    final InputStream checkpointsInputStream = getAssets()
                            .open(Constants.Files.CHECKPOINTS_FILENAME);
                    CheckpointManager.checkpoint(Constants.NETWORK_PARAMETERS, checkpointsInputStream, blockStore,
                            earliestKeyCreationTime);
                } catch (final IOException x) {
                    log.error("problem reading checkpoints, continuing without", x);
                }
            }
        } catch (final BlockStoreException x) {
            blockChainFile.delete();

            final String msg = "blockstore cannot be created";
            log.error(msg, x);
            throw new Error(msg, x);
        }

        log.info("using " + blockStore.getClass().getName());

        try {
            blockChain = new BlockChain(Constants.NETWORK_PARAMETERS, wallet, blockStore);
        } catch (final BlockStoreException x) {
            throw new Error("blockchain cannot be created", x);
        }

        application.getWallet().addEventListener(walletEventListener, Threading.SAME_THREAD);

        registerReceiver(tickReceiver, new IntentFilter(Intent.ACTION_TIME_TICK));

        maybeRotateKeys();
    }

    @Override
    public int onStartCommand(final Intent intent, final int flags, final int startId) {
        if (intent != null) {
            log.info("service start command: " + intent
                    + (intent.hasExtra(Intent.EXTRA_ALARM_COUNT)
                            ? " (alarm count: " + intent.getIntExtra(Intent.EXTRA_ALARM_COUNT, 0) + ")"
                            : ""));

            final String action = intent.getAction();

            if (BlockchainService.ACTION_CANCEL_COINS_RECEIVED.equals(action)) {
                nm.cancel(NOTIFICATION_ID_COINS_RECEIVED);
            } else if (BlockchainService.ACTION_RESET_BLOCKCHAIN.equals(action)) {
                log.info("will remove blockchain on service shutdown");

                resetBlockchainOnShutdown = true;
                stopSelf();
            } else if (BlockchainService.ACTION_BROADCAST_TRANSACTION.equals(action)) {
                final Sha256Hash hash = new Sha256Hash(
                        intent.getByteArrayExtra(BlockchainService.ACTION_BROADCAST_TRANSACTION_HASH));
                final Transaction tx = application.getWallet().getTransaction(hash);

                if (peerGroup != null) {
                    log.info("broadcasting transaction " + tx.getHashAsString());
                    peerGroup.broadcastTransaction(tx);
                } else {
                    log.info("peergroup not available, not broadcasting transaction " + tx.getHashAsString());
                }
            }
        } else {
            log.warn("service restart, although it was started as non-sticky");
        }

        return START_NOT_STICKY;
    }

    @Override
    public void onDestroy() {
        log.debug(".onDestroy()");

        WalletApplication.scheduleStartBlockchainService(this);

        unregisterReceiver(tickReceiver);

        application.getWallet().removeEventListener(walletEventListener);

        if (peerGroup != null) {
            peerGroup.removeEventListener(peerConnectivityListener);
            peerGroup.removeWallet(application.getWallet());
            peerGroup.stopAndWait();

            log.info("peergroup stopped");
        }

        peerConnectivityListener.stop();

        unregisterReceiver(connectivityReceiver);

        removeBroadcastPeerState();
        removeBroadcastBlockchainState();

        config.setBestChainHeightEver(bestChainHeightEver);

        delayHandler.removeCallbacksAndMessages(null);

        try {
            blockStore.close();
        } catch (final BlockStoreException x) {
            throw new RuntimeException(x);
        }

        application.saveWallet();

        if (wakeLock.isHeld()) {
            log.debug("wakelock still held, releasing");
            wakeLock.release();
        }

        if (resetBlockchainOnShutdown) {
            log.info("removing blockchain");
            blockChainFile.delete();
        }

        super.onDestroy();

        log.info(
                "service was up for " + ((System.currentTimeMillis() - serviceCreatedAt) / 1000 / 60) + " minutes");
    }

    @Override
    public void onLowMemory() {
        log.warn("low memory detected, stopping service");
        stopSelf();
    }

    @Override
    public List<Peer> getConnectedPeers() {
        if (peerGroup != null)
            return peerGroup.getConnectedPeers();
        else
            return null;
    }

    @Override
    public List<StoredBlock> getRecentBlocks(final int maxBlocks) {
        final List<StoredBlock> blocks = new ArrayList<StoredBlock>(maxBlocks);

        try {
            StoredBlock block = blockChain.getChainHead();

            while (block != null) {
                blocks.add(block);

                if (blocks.size() >= maxBlocks)
                    break;

                block = block.getPrev(blockStore);
            }
        } catch (final BlockStoreException x) {
            // swallow
        }

        return blocks;
    }

    private void sendBroadcastPeerState(final int numPeers) {
        final Intent broadcast = new Intent(ACTION_PEER_STATE);
        broadcast.setPackage(getPackageName());
        broadcast.putExtra(ACTION_PEER_STATE_NUM_PEERS, numPeers);
        sendStickyBroadcast(broadcast);
    }

    private void removeBroadcastPeerState() {
        removeStickyBroadcast(new Intent(ACTION_PEER_STATE));
    }

    private void sendBroadcastBlockchainState(final int download) {
        final StoredBlock chainHead = blockChain.getChainHead();

        final Intent broadcast = new Intent(ACTION_BLOCKCHAIN_STATE);
        broadcast.setPackage(getPackageName());
        broadcast.putExtra(ACTION_BLOCKCHAIN_STATE_BEST_CHAIN_DATE, chainHead.getHeader().getTime());
        broadcast.putExtra(ACTION_BLOCKCHAIN_STATE_BEST_CHAIN_HEIGHT, chainHead.getHeight());
        broadcast.putExtra(ACTION_BLOCKCHAIN_STATE_REPLAYING, chainHead.getHeight() < bestChainHeightEver);
        broadcast.putExtra(ACTION_BLOCKCHAIN_STATE_DOWNLOAD, download);

        sendStickyBroadcast(broadcast);
    }

    private void removeBroadcastBlockchainState() {
        removeStickyBroadcast(new Intent(ACTION_BLOCKCHAIN_STATE));
    }

    public void notifyWidgets() {
        final AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(this);

        final ComponentName providerName = new ComponentName(this, WalletBalanceWidgetProvider.class);

        try {
            final int[] appWidgetIds = appWidgetManager.getAppWidgetIds(providerName);

            if (appWidgetIds.length > 0) {
                final Wallet wallet = application.getWallet();
                final BigInteger balance = wallet.getBalance(BalanceType.ESTIMATED);

                WalletBalanceWidgetProvider.updateWidgets(this, appWidgetManager, appWidgetIds, balance);
            }
        } catch (final RuntimeException x) // system server dead?
        {
            log.warn("cannot update app widgets", x);
        }
    }

    private void maybeRotateKeys() {
        final Wallet wallet = application.getWallet();
        wallet.setKeyRotationEnabled(false);

        final StoredBlock chainHead = blockChain.getChainHead();

        new Thread() {
            @Override
            public void run() {
                final boolean replaying = chainHead.getHeight() < bestChainHeightEver; // checking again

                wallet.setKeyRotationEnabled(!replaying);
            }
        }.start();
    }
}