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DHT: Fix thread-safety issue in AbstractWriteBuffer 

There is a data corruption issue with the 'running' list if a
background thread schedules something onto the buffer while the
application thread is also using it.

Change-Id: I5ba78b98b6632965d677a9c8f209f0cf8320cc3d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This commit is contained in:
Shawn O. Pearce 2011-05-26 17:19:30 -07:00
parent 0a39fb2ab6
commit 042a66fe8c
1 changed files with 18 additions and 7 deletions
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25
org.eclipse.jgit.storage.dht/src/org/eclipse/jgit/storage/dht/spi/util/AbstractWriteBuffer.java
View File

@ -82,6 +82,8 @@ public abstract class AbstractWriteBuffer implements WriteBuffer {
private final List<Future<?>> running;
private final Object runningLock;
private final Semaphore spaceAvailable;
private int queuedCount;
@ -102,6 +104,7 @@ protected AbstractWriteBuffer(ExecutorService executor, int bufferSize) {
this.executor = executor;
this.bufferSize = bufferSize;
this.running = new LinkedList<Future<?>>();
this.runningLock = new Object();
this.spaceAvailable = new Semaphore(bufferSize);
}
@ -189,14 +192,18 @@ public void flush() throws DhtException {
}
}
checkRunningTasks(true);
synchronized (runningLock) {
checkRunningTasks(true);
}
} finally {
flushing = false;
}
}
public void abort() throws DhtException {
checkRunningTasks(true);
synchronized (runningLock) {
checkRunningTasks(true);
}
}
private void acquireSpace(int sz) throws DhtException {
@ -259,9 +266,11 @@ public T call() throws Exception {
return;
}
if (!flushing)
checkRunningTasks(false);
running.add(executor.submit(op));
synchronized (runningLock) {
if (!flushing)
checkRunningTasks(false);
running.add(executor.submit(op));
}
}
/**
@ -284,8 +293,10 @@ protected <T> AsyncCallback<T> wrap(final AsyncCallback<T> callback,
int size) throws DhtException {
int permits = permitsForSize(size);
WrappedCallback<T> op = new WrappedCallback<T>(callback, permits);
checkRunningTasks(false);
running.add(op);
synchronized (runningLock) {
checkRunningTasks(false);
running.add(op);
}
return op;
}