Merge pull request #823 from MarcMil/improve-code

Fix lingering reference by MemoryWatcher

Author: StevenArzt

soot-infoflow/src/soot/jimple/infoflow/memory/MemoryWarningSystem.java

@@ -66,9 +66,9 @@ public interface OnMemoryThresholdReached {
 	private final static NotificationListener memoryListener;
 	private boolean isClosed = false;
 
-	private long threshold;
+	long threshold;
 
-	private static Thread thrLowMemoryWarningThread;
+	static Thread thrLowMemoryWarningThread;
 
 	private static TreeSet<MemoryWarningSystem> warningSystems = new TreeSet<>(new Comparator<MemoryWarningSystem>() {
 
@@ -103,7 +103,7 @@ public boolean isNotificationEnabled(Notification notification) {
 
 	}
 
-	private static long triggerNotification() {
+	static long triggerNotification() {
 		long maxMemory = tenuredGenPool.getUsage().getMax();
 		long usedMemory = tenuredGenPool.getUsage().getUsed();
 
@@ -206,54 +206,9 @@ public void setWarningThreshold(double percentage) {
 			if (useOwnImplementation) {
 				// No JVM support is available, use our own implementation
 				if (thrLowMemoryWarningThread == null) {
-					thrLowMemoryWarningThread = ThreadUtils.createGenericThread(new Runnable() {
-
-						@Override
-						public void run() {
-							while (true) {
-								MemoryWarningSystem l;
-								synchronized (warningSystems) {
-									if (warningSystems.isEmpty()) {
-										thrLowMemoryWarningThread = null;
-										return;
-									}
-									l = warningSystems.iterator().next();
-								}
-								long nextThreshold = l.threshold;
-								MemoryUsage usage = tenuredGenPool.getUsage();
-								if (usage == null) {
-									logger.warn(MessageFormat.format("Memory usage of {0} could not be estimated",
-											tenuredGenPool.getName()));
-									return;
-								} else {
-									long used = usage.getUsed();
-									if (used >= l.threshold) {
-										nextThreshold = triggerNotification();
-										if (nextThreshold == -1) {
-											synchronized (warningSystems) {
-												if (warningSystems.isEmpty()) {
-													thrLowMemoryWarningThread = null;
-													return;
-												}
-											}
-										}
-									}
-								}
-								long used = usage.getUsed();
-								// Depending on how far we are from the next threshold, we can rest longer
-								// or shorter
-								long missing = nextThreshold - used;
-								if (missing <= 0)
-									continue;
-								try {
-									long wait = (long) ((missing / (double) tenuredGenPool.getUsage().getMax()) * 500);
-									Thread.sleep(wait);
-								} catch (InterruptedException e) {
-								}
-							}
-						}
-
-					}, "Low memory monitor", true);
+					thrLowMemoryWarningThread = ThreadUtils.createGenericThread(
+							new MemoryWarningThreadRunnable(tenuredGenPool, warningSystems, logger),
+							"Low memory monitor", true);
 					thrLowMemoryWarningThread.setPriority(Thread.MIN_PRIORITY);
 					thrLowMemoryWarningThread.start();
 				}
@@ -281,6 +236,7 @@ public void close() {
 			// Doesn't matter, we wanted to get rid of it anyway
 		}
 		isClosed = true;
+		listeners.clear();
 	}
 
 }

soot-infoflow/src/soot/jimple/infoflow/memory/MemoryWarningThreadRunnable.java

@@ -0,0 +1,74 @@
+package soot.jimple.infoflow.memory;
+
+import java.lang.management.MemoryPoolMXBean;
+import java.lang.management.MemoryUsage;
+import java.text.MessageFormat;
+import java.util.TreeSet;
+
+import org.slf4j.Logger;
+
+/**
+ * We made this class separate to ensure that there is no direct connection to a concrete instance 
+ * of a MemoryWarningSystem, since this runner runs independently from all instances.
+ */
+final class MemoryWarningThreadRunnable implements Runnable {
+
+	private MemoryPoolMXBean tenuredGenPool;
+	private TreeSet<MemoryWarningSystem> warningSystems;
+	private Logger logger;
+
+	public MemoryWarningThreadRunnable(MemoryPoolMXBean tenuredgenpool, TreeSet<MemoryWarningSystem> warningSystems,
+			Logger logger) {
+		this.tenuredGenPool = tenuredgenpool;
+		this.warningSystems = warningSystems;
+		this.logger = logger;
+	}
+
+	@Override
+	public void run() {
+		try {
+			while (true) {
+				MemoryWarningSystem l;
+				synchronized (warningSystems) {
+					if (warningSystems.isEmpty()) {
+						return;
+					}
+					l = warningSystems.iterator().next();
+				}
+				long nextThreshold = l.threshold;
+				MemoryUsage usage = tenuredGenPool.getUsage();
+				if (usage == null) {
+					logger.warn(MessageFormat.format("Memory usage of {0} could not be estimated",
+							tenuredGenPool.getName()));
+					return;
+				} else {
+					long used = usage.getUsed();
+					if (used >= l.threshold) {
+						nextThreshold = MemoryWarningSystem.triggerNotification();
+						if (nextThreshold == -1) {
+							synchronized (warningSystems) {
+								if (warningSystems.isEmpty()) {
+									return;
+								}
+							}
+						}
+					}
+				}
+				long used = usage.getUsed();
+				// Depending on how far we are from the next threshold, we can rest longer
+				// or shorter
+				long missing = nextThreshold - used;
+				if (missing <= 0)
+					continue;
+				try {
+					long wait = (long) ((missing / (double) tenuredGenPool.getUsage().getMax()) * 500);
+					Thread.sleep(wait);
+				} catch (InterruptedException e) {
+				}
+			}
+		} finally {
+			MemoryWarningSystem.thrLowMemoryWarningThread = null;
+		}
+	}
+
+}