mirror of
https://github.com/moonlight-stream/moonlight-android.git
synced 2025-07-19 19:13:03 +00:00
Rewrite MdnsDiscoveryAgent to treat the singleton JmmDNS object safely
This commit is contained in:
Cameron Gutman
parent
da4fab2f3e
commit
a71a3e22e6
@ -8,8 +8,6 @@ import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Timer;
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import java.util.TimerTask;
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import javax.jmdns.JmmDNS;
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import javax.jmdns.ServiceEvent;
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@ -18,50 +16,95 @@ import javax.jmdns.ServiceListener;
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import com.limelight.LimeLog;
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public class MdnsDiscoveryAgent {
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public class MdnsDiscoveryAgent implements ServiceListener {
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public static final String SERVICE_TYPE = "_nvstream._tcp.local.";
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private JmmDNS resolver;
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private HashMap<InetAddress, MdnsComputer> computers;
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private MdnsDiscoveryListener listener;
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private HashSet<String> pendingResolution;
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private boolean stop;
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private ServiceListener nvstreamListener = new ServiceListener() {
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private Thread discoveryThread;
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private HashMap<InetAddress, MdnsComputer> computers = new HashMap<InetAddress, MdnsComputer>();
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private HashSet<String> pendingResolution = new HashSet<String>();
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// The resolver factory's instance member has a static lifetime which
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// means our ref count and listener must be static also.
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private static int resolverRefCount = 0;
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private static HashSet<ServiceListener> listeners = new HashSet<ServiceListener>();
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private static ServiceListener nvstreamListener = new ServiceListener() {
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@Override
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public void serviceAdded(ServiceEvent event) {
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LimeLog.info("mDNS: Machine appeared: "+event.getInfo().getName());
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HashSet<ServiceListener> localListeners;
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ServiceInfo info = event.getDNS().getServiceInfo(SERVICE_TYPE, event.getInfo().getName(), 500);
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if (info == null) {
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// This machine is pending resolution
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pendingResolution.add(event.getInfo().getName());
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return;
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// Copy the listener set into a new set so we can invoke
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// the callbacks without holding the listeners monitor the
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// whole time.
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synchronized (listeners) {
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localListeners = new HashSet<ServiceListener>(listeners);
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}
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LimeLog.info("mDNS: Resolved (blocking)");
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handleResolvedServiceInfo(info);
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for (ServiceListener listener : localListeners) {
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listener.serviceAdded(event);
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}
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}
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@Override
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public void serviceRemoved(ServiceEvent event) {
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LimeLog.info("mDNS: Machine disappeared: "+event.getInfo().getName());
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HashSet<ServiceListener> localListeners;
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Inet4Address addrs[] = event.getInfo().getInet4Addresses();
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for (Inet4Address addr : addrs) {
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synchronized (computers) {
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MdnsComputer computer = computers.remove(addr);
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if (computer != null) {
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listener.notifyComputerRemoved(computer);
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break;
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}
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}
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// Copy the listener set into a new set so we can invoke
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// the callbacks without holding the listeners monitor the
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// whole time.
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synchronized (listeners) {
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localListeners = new HashSet<ServiceListener>(listeners);
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}
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for (ServiceListener listener : localListeners) {
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listener.serviceRemoved(event);
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}
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}
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@Override
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public void serviceResolved(ServiceEvent event) {
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LimeLog.info("mDNS: Machine resolved (callback): "+event.getInfo().getName());
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handleResolvedServiceInfo(event.getInfo());
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HashSet<ServiceListener> localListeners;
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// Copy the listener set into a new set so we can invoke
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// the callbacks without holding the listeners monitor the
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// whole time.
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synchronized (listeners) {
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localListeners = new HashSet<ServiceListener>(listeners);
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}
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for (ServiceListener listener : localListeners) {
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listener.serviceResolved(event);
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}
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}
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};
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private static JmmDNS referenceResolver() {
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synchronized (MdnsDiscoveryAgent.class) {
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JmmDNS instance = JmmDNS.Factory.getInstance();
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if (++resolverRefCount == 1) {
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// This will cause the listener to be invoked for known hosts immediately.
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// JmDNS only supports one listener per service, so we have to do this here
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// with a static listener.
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instance.addServiceListener(SERVICE_TYPE, nvstreamListener);
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}
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return instance;
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}
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}
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private static void dereferenceResolver() {
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synchronized (MdnsDiscoveryAgent.class) {
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if (--resolverRefCount == 0) {
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try {
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JmmDNS.Factory.close();
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} catch (IOException e) {}
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}
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}
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}
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public MdnsDiscoveryAgent(MdnsDiscoveryListener listener) {
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this.listener = listener;
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}
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private void handleResolvedServiceInfo(ServiceInfo info) {
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MdnsComputer computer;
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@ -100,65 +143,67 @@ public class MdnsDiscoveryAgent {
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return new MdnsComputer(name, address);
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}
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public MdnsDiscoveryAgent(MdnsDiscoveryListener listener) {
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computers = new HashMap<InetAddress, MdnsComputer>();
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pendingResolution = new HashSet<String>();
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this.listener = listener;
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}
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public void startDiscovery(final int discoveryIntervalMs) {
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stop = false;
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// Kill any existing discovery before starting a new one
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stopDiscovery();
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final Timer t = new Timer();
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t.schedule(new TimerTask() {
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// Add our listener to the set
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synchronized (listeners) {
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listeners.add(MdnsDiscoveryAgent.this);
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}
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discoveryThread = new Thread() {
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@Override
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public void run() {
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synchronized (MdnsDiscoveryAgent.this) {
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// Stop if requested
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if (stop) {
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// There will be no further timer invocations now
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t.cancel();
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// This may result in listener callbacks so we must register
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// our listener first.
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JmmDNS resolver = referenceResolver();
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try {
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while (!Thread.interrupted()) {
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// Start an mDNS request
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resolver.requestServiceInfo(SERVICE_TYPE, null, discoveryIntervalMs);
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if (resolver != null) {
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resolver.removeServiceListener(SERVICE_TYPE, nvstreamListener);
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try {
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JmmDNS.Factory.close();
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} catch (IOException e) {}
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resolver = null;
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// Run service resolution again for pending machines
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ArrayList<String> pendingNames = new ArrayList<String>(pendingResolution);
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for (String name : pendingNames) {
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LimeLog.info("mDNS: Retrying service resolution for machine: "+name);
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ServiceInfo[] infos = resolver.getServiceInfos(SERVICE_TYPE, name, 500);
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if (infos != null && infos.length != 0) {
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LimeLog.info("mDNS: Resolved (retry) with "+infos.length+" service entries");
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handleResolvedServiceInfo(infos[0]);
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}
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}
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return;
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}
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// Perform initialization
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if (resolver == null) {
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resolver = JmmDNS.Factory.getInstance();
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// This will cause the listener to be invoked for known hosts immediately.
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// We do this in the timer callback to be off the main thread when this happens.
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resolver.addServiceListener(SERVICE_TYPE, nvstreamListener);
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}
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// Send another mDNS query
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resolver.requestServiceInfo(SERVICE_TYPE, null, discoveryIntervalMs);
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// Run service resolution again for pending machines
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ArrayList<String> pendingNames = new ArrayList<String>(pendingResolution);
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for (String name : pendingNames) {
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LimeLog.info("mDNS: Retrying service resolution for machine: "+name);
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ServiceInfo[] infos = resolver.getServiceInfos(SERVICE_TYPE, name, 500);
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if (infos != null && infos.length != 0) {
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LimeLog.info("mDNS: Resolved (retry) with "+infos.length+" service entries");
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handleResolvedServiceInfo(infos[0]);
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// Wait for the next polling interval
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try {
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Thread.sleep(discoveryIntervalMs);
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} catch (InterruptedException e) {
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break;
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}
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}
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}
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finally {
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// Dereference the resolver
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dereferenceResolver();
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}
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}
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}, 0, discoveryIntervalMs);
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};
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discoveryThread.setName("mDNS Discovery Thread");
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discoveryThread.start();
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}
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public void stopDiscovery() {
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// Trigger a stop on the next timer expiration
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stop = true;
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// Remove our listener from the set
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synchronized (listeners) {
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listeners.remove(MdnsDiscoveryAgent.this);
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}
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// If there's already a running thread, interrupt it
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if (discoveryThread != null) {
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discoveryThread.interrupt();
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discoveryThread = null;
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}
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}
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public List<MdnsComputer> getComputerSet() {
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@ -166,4 +211,41 @@ public class MdnsDiscoveryAgent {
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return new ArrayList<MdnsComputer>(computers.values());
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}
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}
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@Override
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public void serviceAdded(ServiceEvent event) {
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LimeLog.info("mDNS: Machine appeared: "+event.getInfo().getName());
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ServiceInfo info = event.getDNS().getServiceInfo(SERVICE_TYPE, event.getInfo().getName(), 500);
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if (info == null) {
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// This machine is pending resolution
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pendingResolution.add(event.getInfo().getName());
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return;
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}
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LimeLog.info("mDNS: Resolved (blocking)");
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handleResolvedServiceInfo(info);
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}
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@Override
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public void serviceRemoved(ServiceEvent event) {
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LimeLog.info("mDNS: Machine disappeared: "+event.getInfo().getName());
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Inet4Address addrs[] = event.getInfo().getInet4Addresses();
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for (Inet4Address addr : addrs) {
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synchronized (computers) {
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MdnsComputer computer = computers.remove(addr);
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if (computer != null) {
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listener.notifyComputerRemoved(computer);
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break;
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}
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}
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}
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}
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@Override
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public void serviceResolved(ServiceEvent event) {
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LimeLog.info("mDNS: Machine resolved (callback): "+event.getInfo().getName());
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handleResolvedServiceInfo(event.getInfo());
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}
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}
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