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Merge pull request #1555 from matthiasblaesing/terminating_cleaner
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Shutdown CleanerThread once the last cleanable is removed
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@matthiasblaesing
matthiasblaesing committed Oct 17, 2023
2 parents 2372067 + 45ef6b2 commit e8182b2
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Showing 2 changed files with 83 additions and 48 deletions.
1 change: 1 addition & 0 deletions CHANGES.md
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Expand Up @@ -12,6 +12,7 @@ Features
* [#1548](https://github.com/java-native-access/jna/pull/1548): Make interface `c.s.j.p.mac.XAttr public` - [@matthiasblaesing](https://github.com/matthiasblaesing).
* [#1551](https://github.com/java-native-access/jna/pull/1551): Add `c.s.j.p.bsd.ExtAttr` and `c.s.j.p.bsd.ExtAttrUtil` to wrap BSD [<sys/extattr.h>](https://man.freebsd.org/cgi/man.cgi?query=extattr&sektion=2) system calls. [@rednoah](https://github.com/rednoah).
* [#1517](https://github.com/java-native-access/jna/pull/1517): Add missing `O_*` (e.g. `O_APPEND`, `O_SYNC`, `O_DIRECT`, ...) to `c.s.j.p.linux.Fcntl` - [@matthiasblaesing](https://github.com/matthiasblaesing).
* [#1521](https://github.com/java-native-access/jna/issues/1521): Shutdown CleanerThread once the last cleanable is removed - [@matthiasblaesing](https://github.com/matthiasblaesing).

Bug Fixes
---------
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130 changes: 82 additions & 48 deletions src/com/sun/jna/internal/Cleaner.java
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Expand Up @@ -45,35 +45,11 @@ public static Cleaner getCleaner() {
}

private final ReferenceQueue<Object> referenceQueue;
private final Thread cleanerThread;
private Thread cleanerThread;
private CleanerRef firstCleanable;

private Cleaner() {
referenceQueue = new ReferenceQueue<Object>();
cleanerThread = new Thread() {
@Override
public void run() {
while(true) {
try {
Reference<? extends Object> ref = referenceQueue.remove();
if(ref instanceof CleanerRef) {
((CleanerRef) ref).clean();
}
} catch (InterruptedException ex) {
// Can be raised on shutdown. If anyone else messes with
// our reference queue, well, there is no way to separate
// the two cases.
// https://groups.google.com/g/jna-users/c/j0fw96PlOpM/m/vbwNIb2pBQAJ
break;
} catch (Exception ex) {
Logger.getLogger(Cleaner.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
};
cleanerThread.setName("JNA Cleaner");
cleanerThread.setDaemon(true);
cleanerThread.start();
}

public synchronized Cleanable register(Object obj, Runnable cleanupTask) {
Expand All @@ -83,34 +59,43 @@ public synchronized Cleanable register(Object obj, Runnable cleanupTask) {
}

private synchronized CleanerRef add(CleanerRef ref) {
if(firstCleanable == null) {
firstCleanable = ref;
} else {
ref.setNext(firstCleanable);
firstCleanable.setPrevious(ref);
firstCleanable = ref;
synchronized (referenceQueue) {
if (firstCleanable == null) {
firstCleanable = ref;
} else {
ref.setNext(firstCleanable);
firstCleanable.setPrevious(ref);
firstCleanable = ref;
}
if (cleanerThread == null) {
Logger.getLogger(Cleaner.class.getName()).log(Level.FINE, "Starting CleanerThread");
cleanerThread = new CleanerThread();
cleanerThread.start();
}
return ref;
}
return ref;
}

private synchronized boolean remove(CleanerRef ref) {
boolean inChain = false;
if(ref == firstCleanable) {
firstCleanable = ref.getNext();
inChain = true;
}
if(ref.getPrevious() != null) {
ref.getPrevious().setNext(ref.getNext());
}
if(ref.getNext() != null) {
ref.getNext().setPrevious(ref.getPrevious());
}
if(ref.getPrevious() != null || ref.getNext() != null) {
inChain = true;
synchronized (referenceQueue) {
boolean inChain = false;
if (ref == firstCleanable) {
firstCleanable = ref.getNext();
inChain = true;
}
if (ref.getPrevious() != null) {
ref.getPrevious().setNext(ref.getNext());
}
if (ref.getNext() != null) {
ref.getNext().setPrevious(ref.getPrevious());
}
if (ref.getPrevious() != null || ref.getNext() != null) {
inChain = true;
}
ref.setNext(null);
ref.setPrevious(null);
return inChain;
}
ref.setNext(null);
ref.setPrevious(null);
return inChain;
}

private static class CleanerRef extends PhantomReference<Object> implements Cleanable {
Expand All @@ -125,6 +110,7 @@ public CleanerRef(Cleaner cleaner, Object referent, ReferenceQueue<? super Objec
this.cleanupTask = cleanupTask;
}

@Override
public void clean() {
if(cleaner.remove(this)) {
cleanupTask.run();
Expand All @@ -151,4 +137,52 @@ void setNext(CleanerRef next) {
public static interface Cleanable {
public void clean();
}

private class CleanerThread extends Thread {

private static final long CLEANER_LINGER_TIME = 30000;

public CleanerThread() {
super("JNA Cleaner");
setDaemon(true);
}

@Override
public void run() {
while (true) {
try {
Reference<? extends Object> ref = referenceQueue.remove(CLEANER_LINGER_TIME);
if (ref instanceof CleanerRef) {
((CleanerRef) ref).clean();
} else if (ref == null) {
synchronized (referenceQueue) {
Logger logger = Logger.getLogger(Cleaner.class.getName());
if (firstCleanable == null) {
cleanerThread = null;
logger.log(Level.FINE, "Shutting down CleanerThread");
break;
} else if (logger.isLoggable(Level.FINER)) {
StringBuilder registeredCleaners = new StringBuilder();
for(CleanerRef cleanerRef = firstCleanable; cleanerRef != null; cleanerRef = cleanerRef.next) {
if(registeredCleaners.length() != 0) {
registeredCleaners.append(", ");
}
registeredCleaners.append(cleanerRef.cleanupTask.toString());
}
logger.log(Level.FINER, "Registered Cleaners: {0}", registeredCleaners.toString());
}
}
}
} catch (InterruptedException ex) {
// Can be raised on shutdown. If anyone else messes with
// our reference queue, well, there is no way to separate
// the two cases.
// https://groups.google.com/g/jna-users/c/j0fw96PlOpM/m/vbwNIb2pBQAJ
break;
} catch (Exception ex) {
Logger.getLogger(Cleaner.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}
}

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