How to handle java.nio.channels.ClosedByInterruptException correctly?

Here is what I think is happening in this case:

1) The main Thread is busy writing data. This is a blocking operation:

	private int writeByteBufferToFile(
		MoSyncFileHandle fileHandle,
		ByteBuffer byteBuffer)
	{
		try
		{
			int ret = fileHandle.mFileChannel.write(byteBuffer);
			log("writeByteBufferToFile bytes written: "  + ret);
			fileHandle.mCurrentPosition =
				(int)fileHandle.mFileChannel.position();
			return ret;
		}
		catch (Throwable t)
		{
			logerr("writeByteBufferToFile Exception - " + t);
			t.printStackTrace();
			return MA_FERR_GENERIC;
		}
	}

2) The Socket reader thread has received data or any does a state change and wants to notify the main thread about it by posting a message to it via postResultEvent:

	/**
	 * Post a event to the MoSync event queue.
	 */
	public void postEvent(int[] event)
	{
		mMoSyncThread.postEvent(event);
	}

		/**
		 * Post CONNOP result event. Here the state flag bits for 
		 * the event is cleared.
		 */
		public synchronized void postResultEvent(int opType, int result)
		{
			//Log.i("ConnectionObject.postResultEvent",
			//	"mHandle: " + mHandle +
			//	" mState: " + mState +
			//	" opType: " + opType +
			//	" result: " + result +
			//	" connobj (this): " + this);
	
			// Check that state is ongoing.
			MYASSERT((mState & opType) != 0);
			
			// Clear state bit.
			mState &= ~opType;
	
			int[] event = new int[4];
			event[0] = EVENT_TYPE_CONN;
			event[1] = mHandle;
			event[2] = opType;
			event[3] = result;
			
			//Log.i("ConnectionObject.postResultEvent",
			//	"Calling nativePostEvent");
			mMoSyncNetwork.postEvent(event);
		}

postEvent in the main thread does interrupt the thread:

	/**
	 * Post a event to the MoSync event queue.
	 */
	public synchronized void postEvent(int[] event)
	{
		// Add event to queue.
		nativePostEvent(event);
		// Wake up thread if sleeping.
		interrupt();
	}

With the call to interrupt(), the blocking write operation is cancelled throwing the exception and invalidating our handle.
Maybe you can guard all blocking operations with a Mutex that postEvent tries to wait for before calling interrupt() so that the operation remains synchronous. 
Just an idea, I'm not a Java programmer, it's just the way I would do it in C, I guess...

Regards,
Ludwig 

Hi again,

Here is a sample program to reproduce the problem (if it's not working for you, increase the loop count in the for-loop so that you have enough time to receive downloaded data):

#include <ma.h>
#include <conprint.h>
#define NUM_HANDLES		3
void ThreadingBug()
{
	MAHandle http[NUM_HANDLES];
	char szFile[256]={0}, Buffer[16384];
	MAHandle file;
	MAEvent event={0};
	int i;
	// Create HTTP connections
	for (i=0; i<sizeof(http)/sizeof(http[0]); i++)
		http[i] = maHttpCreate ("http://www.csp.at/joomla/index.php", HTTP_GET);
	// No main loop, doing heavy IO instead so that messages get queued
	// and interrupt the main thread
	maGetSystemProperty("mosync.path.local", szFile, sizeof(szFile));
	strcat (szFile, "testfil.txt");
	if ((file = maFileOpen(szFile, MA_ACCESS_READ_WRITE))<0)
	{
		lprintfln ("Error opening file %s\n", szFile);
		return;
	}
	if (maFileCreate(file)<0)
	{
		lprintfln ("Error on maFileCreate %s\n", szFile);
		maFileClose(file);
		return;
	}
	for (i=0; i<sizeof(http)/sizeof(http[0]); i++)
		maHttpFinish (http[i]);
	for (i=0; i<30000; i++)
	{
		if (maFileWrite(file, Buffer, sizeof(Buffer))<0)
		{
			lprintfln ("maFileWrite failed! Possibly the thread got interrupted!\n");
			break;
		}
		maFileSeek (file, 0, 0);
	}
	maFileDelete(file);
	maFileClose(file);
	for (i=0; i<sizeof(http)/sizeof(http[0]); i++)
		maConnClose (http[i]);

	maExit(0);
}

int MAMain() {
	ThreadingBug();
}

Outputs the following for me on the device, as expected:

11-17 10:06:39.905 18877 18884 I MoSyncFile: maFileSeek (1)
11-17 10:06:39.905 18877 18884 I MoSyncFile: maFileWrite (1)
11-17 10:06:39.921 18877 18884 E MoSyncFile ERROR: writeByteBufferToFile Exception - java.nio.channels.ClosedByInterruptException
11-17 10:06:39.921 18877 18884 W System.err: java.nio.channels.ClosedByInterruptException
11-17 10:06:39.928 18877 18884 W System.err:    at java.nio.channels.spi.AbstractInterruptibleChannel.end(AbstractInterruptibleChannel.java:166)
11-17 10:06:39.928 18877 18884 W System.err:    at org.apache.harmony.nio.internal.FileChannelImpl.writeImpl(FileChannelImpl.java:555)
11-17 10:06:39.928 18877 18884 W System.err:    at org.apache.harmony.nio.internal.FileChannelImpl.write(FileChannelImpl.java:539)
11-17 10:06:39.928 18877 18884 W System.err:    at com.mosync.internal.android.MoSyncFile.writeByteBufferToFile(MoSyncFile.java:596)
11-17 10:06:39.928 18877 18884 W System.err:    at com.mosync.internal.android.MoSyncFile.maFileWrite(MoSyncFile.java:661)
11-17 10:06:39.928 18877 18884 W System.err:    at com.mosync.internal.android.MoSyncThread.maFileWrite(MoSyncThread.java:3854)
11-17 10:06:39.928 18877 18884 W System.err:    at com.mosync.internal.android.MoSyncThread.nativeRun(Native Method)
11-17 10:06:39.928 18877 18884 W System.err:    at com.mosync.internal.android.MoSyncThread.run(MoSyncThread.java:902)
11-17 10:06:39.928 18877 18884 I maWriteLog: maFileWrite failed! Possibly the thread got interrupted!

Regards,
Ludwig