Rewrite a large portion of the computer manager service to fix some thread leaks and improve performance

app/src/main/java/com/limelight/computers/ComputerManagerService.java

@@ -1,8 +1,7 @@
 package com.limelight.computers;
 
 import java.net.InetAddress;
-import java.util.HashMap;
-import java.util.List;
+import java.util.LinkedList;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import com.limelight.LimeLog;
@@ -30,7 +29,7 @@ public class ComputerManagerService extends Service {
 	private AtomicInteger dbRefCount = new AtomicInteger(0);
 	
 	private IdentityManager idManager;
-	private final HashMap<ComputerDetails, Thread> pollingThreads = new HashMap<ComputerDetails, Thread>();
+	private final LinkedList<PollingTuple> pollingTuples = new LinkedList<PollingTuple>();
 	private ComputerManagerListener listener = null;
 	private AtomicInteger activePolls = new AtomicInteger(0);
 
@@ -102,20 +101,8 @@ public class ComputerManagerService extends Service {
             @Override
             public void run() {
                 while (!isInterrupted()) {
-                    ComputerDetails originalDetails = new ComputerDetails();
-                    originalDetails.update(details);
-
                     // Check if this poll has modified the details
-                    if (runPoll(details) && !originalDetails.equals(details)) {
-                        // Replace our thread entry with the new one
-                        synchronized (pollingThreads) {
-                            if (pollingThreads.remove(originalDetails) != null) {
-                                // This could have gone away in the meantime, so don't
-                                // add it back if it has
-                                pollingThreads.put(details, this);
-                            }
-                        }
-                    }
+                    runPoll(details);
 
                     // Wait until the next polling interval
                     try {
@@ -138,23 +125,15 @@ public class ComputerManagerService extends Service {
 			// Start mDNS autodiscovery too
 			discoveryBinder.startDiscovery(MDNS_QUERY_PERIOD_MS);
 
-			// Start polling known machines
-            if (!getLocalDatabaseReference()) {
-                return;
-            }
-            List<ComputerDetails> computerList = dbManager.getAllComputers();
-            releaseLocalDatabaseReference();
-
-            synchronized (pollingThreads) {
-                for (ComputerDetails computer : computerList) {
+            synchronized (pollingTuples) {
+                for (PollingTuple tuple : pollingTuples) {
                     // This polling thread might already be there
-                    if (!pollingThreads.containsKey(computer)) {
+                    if (tuple.thread == null) {
                         // Report this computer initially
-                        listener.notifyComputerUpdated(computer);
+                        listener.notifyComputerUpdated(tuple.computer);
 
-                        Thread t = createPollingThread(computer);
-                        pollingThreads.put(computer, t);
-                        t.start();
+                        tuple.thread = createPollingThread(tuple.computer);
+                        tuple.thread.start();
                     }
                 }
             }
@@ -208,11 +187,14 @@ public class ComputerManagerService extends Service {
 		discoveryBinder.stopDiscovery();
 		
 		// Stop polling
-        synchronized (pollingThreads) {
-            for (Thread t : pollingThreads.values()) {
-                t.interrupt();
+        synchronized (pollingTuples) {
+            for (PollingTuple tuple : pollingTuples) {
+                if (tuple.thread != null) {
+                    // Interrupt and remove the thread
+                    tuple.thread.interrupt();
+                    tuple.thread = null;
+                }
             }
-            pollingThreads.clear();
         }
 		
 		// Remove the listener
@@ -249,13 +231,26 @@ public class ComputerManagerService extends Service {
 		fakeDetails.remoteIp = addr;
 
 		// Spawn a thread for this computer
-        synchronized (pollingThreads) {
+        synchronized (pollingTuples) {
             // This polling thread might already be there
-            if (!pollingThreads.containsKey(fakeDetails)) {
-                Thread t = createPollingThread(fakeDetails);
-                pollingThreads.put(fakeDetails, t);
-                t.start();
+            for (PollingTuple tuple : pollingTuples) {
+                if (tuple.computer.localIp.equals(addr) ||
+                    tuple.computer.remoteIp.equals(addr)) {
+                    // This is the same computer
+                    if (tuple.thread == null) {
+                        tuple.thread = createPollingThread(fakeDetails);
+                        tuple.thread.start();
+                    }
+
+                    // Found an entry so we're done
+                    return;
+                }
             }
+
+            // If we got here, we didn't find an entry
+            PollingTuple tuple = new PollingTuple(fakeDetails, createPollingThread(fakeDetails));
+            pollingTuples.add(tuple);
+            tuple.thread.start();
         }
 	}
 
@@ -280,6 +275,20 @@ public class ComputerManagerService extends Service {
 		// Remove it from the database
 		dbManager.deleteComputer(name);
 
+        synchronized (pollingTuples) {
+            // Remove the computer from the computer list
+            for (PollingTuple tuple : pollingTuples) {
+                if (tuple.computer.name.equals(name)) {
+                    if (tuple.thread != null) {
+                        // Interrupt the thread on this entry
+                        tuple.thread.interrupt();
+                    }
+                    pollingTuples.remove(tuple);
+                    break;
+                }
+            }
+        }
+		
 		releaseLocalDatabaseReference();
 	}
 	
@@ -376,6 +385,18 @@ public class ComputerManagerService extends Service {
 		// Initialize the DB
 		dbManager = new ComputerDatabaseManager(this);
 		dbRefCount.set(1);
+
+        // Grab known machines into our computer list
+        if (!getLocalDatabaseReference()) {
+            return;
+        }
+
+        for (ComputerDetails computer : dbManager.getAllComputers()) {
+            // Add this computer without a thread
+            pollingTuples.add(new PollingTuple(computer, null));
+        }
+
+        releaseLocalDatabaseReference();
 	}
 	
 	@Override
@@ -396,3 +417,13 @@ public class ComputerManagerService extends Service {
 		return binder;
 	}
 }
+
+class PollingTuple {
+    public Thread thread;
+    public ComputerDetails computer;
+
+    public PollingTuple(ComputerDetails computer, Thread thread) {
+        this.computer = computer;
+        this.thread = thread;
+    }
+}