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Merged
dpharris merged 2 commits into from
Feb 12, 2025
Merged

Improved handling of timeouts in Memory Service #287

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43df9a3
cleanup. Do timeout retry. Handle timeout spec in read dg reply. Reje…
bobjacobsen Jan 26, 2025
556f0af
timeout testing
bobjacobsen Jan 26, 2025
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94 changes: 74 additions & 20 deletions src/org/openlcb/implementations/MemoryConfigurationService.java
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.Semaphore;
import java.util.logging.Level;
import java.util.logging.Logger;
import net.jcip.annotations.Immutable;
import net.jcip.annotations.ThreadSafe;
Expand All @@ -25,7 +26,6 @@
*
* @author Bob Jacobsen Copyright 2012
* @author David Harris Copyright 2016
* @version $Revision: -1 $
*/
public class MemoryConfigurationService {
private static final Logger logger = Logger.getLogger(MemoryConfigurationService.class.getName());
Expand Down Expand Up @@ -72,8 +72,17 @@ public MemoryConfigurationService(NodeID here, DatagramService downstream) {
@Override
public synchronized void handleData(NodeID dest, int[] data, DatagramService.ReplyMemo
service) {
//log System.out.println("OLCB: handleData");

// there should be one retryTimer running, cancel it
if (tt != null) {
logger.log(Level.FINE, "timer cancel");
tt.cancel();
tt = null;
}

service.acceptData(0);

// decode the current outstanding memo and process reply
if (addrSpaceMemo != null) {
boolean present = (data[1] == 0x87);

Expand Down Expand Up @@ -160,22 +169,22 @@ public synchronized void handleData(NodeID dest, int[] data, DatagramService.Rep
logger.warning("Spurious MemCfg response datagram " + Utilities
.toHexSpaceString(data)+": expected source " + rqMemo.getDest()
+ " actual source " + dest);
delayRetryMemo(rqMemo);
retryMemo(rqMemo);
return;
}
if (!(rqMemo instanceof RequestWithReplyDatagram)) {
logger.warning("Spurious MemCfg response datagram " + Utilities.toHexSpaceString(data)+
": the request memo does not support response datagrams. " +
"Memo: " + rqMemo);
delayRetryMemo(rqMemo);
retryMemo(rqMemo);
return;
}
memo = (RequestWithReplyDatagram) rqMemo;
if (!memo.compareResponse(data)) {
logger.warning("Unexpected MemCfg response datagram from " + dest
.toString() + ": " + memo + " payload " + Utilities
.toHexSpaceString(data));
delayRetryMemo(rqMemo);
retryMemo(rqMemo);
return;
} else {
checkAndPopMemo(rqMemo);
Expand All @@ -198,6 +207,7 @@ public synchronized void handleData(NodeID dest, int[] data, DatagramService.Rep
NodeID here;
DatagramService downstream;
private Timer retryTimer;
private TimerTask tt;

public MemoryConfigurationService(MemoryConfigurationService mcs) {
this(mcs.here, mcs.downstream);
Expand All @@ -208,11 +218,12 @@ public void setTimeoutMillis(long t) {
}

/**
* Waits to ensure that all pending timer tasks are complete. Used for testing.
* Waits to ensure that all pending timer tasks are complete.
* Only used for testing, hence package private
*
* @throws java.lang.InterruptedException if interrupted
*/
public void waitForTimer() throws InterruptedException {
void waitForTimer() throws InterruptedException {
final Semaphore s = new Semaphore(0);
retryTimer.schedule(new TimerTask() {
@Override
Expand Down Expand Up @@ -453,6 +464,7 @@ private void checkAndPopMemo(McsRequestMemo memo) {
memo = null;
}
}
// at this point, a non-null `memo` value is the next request, start it
if (memo != null) {
sendRequest(memo);
}
Expand All @@ -471,28 +483,66 @@ private boolean isBlockingPendingQueue(McsRequestMemo memo) {
}

/**
* Starts a timer and re-tries a request if the timer expired without seeing a response.
* Re-tries a request either due to a timer expired or an unexpected error response
* @param memo request memo with expected response.
*/
private void delayRetryMemo(final McsRequestMemo memo) {
private void retryMemo(final McsRequestMemo memo) {
// Don't persist if there have been enough retries already
logger.log(Level.FINE, "retryMemo with numTries "+memo.numTries);
if (memo.numTries >= MAX_TRIES) {
// TODO: add proper error code.
// move on to next memo, and fail this request
checkAndPopMemo(memo);
memo.failureCallback.handleFailure(0x1000);
memo.failureCallback.handleFailure(0x1000); // TODO: add proper error code.
}
TimerTask tt = new TimerTask() {
// request still pending, retry it
startTimer(memo);
sendRequest(memo);
}

private void startTimer(final McsRequestMemo memo) {
logger.log(Level.FINE, "startTimer");

tt = new TimerTask() {
@Override
public void run() {
if (memo.foundResponse) return;
if (!isBlockingPendingQueue(memo)) return;
sendRequest(memo);
timeoutRetry(memo);
}
};
retryTimer.schedule(tt, timeoutMillis);
}


private void restartTimeout(final McsRequestMemo memo, int timeout) {
logger.log(Level.FINE, "restartTimeout for "+timeout);
if (tt != null) {
tt.cancel();
} else {
logger.log(Level.FINE, "** Unexpected restartTimeout with null tt");
}
tt = new TimerTask() {
@Override
public void run() {
timeoutRetry(memo);
}
};
retryTimer.schedule(tt, timeout);
}

// invoked when retryTimer times out
private void timeoutRetry(final McsRequestMemo memo) {
logger.log(Level.FINE, "timeoutRetry entry");
if (memo.foundResponse) return;
if (!isBlockingPendingQueue(memo)) return;
logger.log(Level.FINE, "timeoutRetry retryMemo");
retryMemo(memo);
}

private void sendRequest(final McsRequestMemo memo) {
logger.log(Level.FINE, "sendRequest with numTries "+memo.numTries);
// get ready in case a retry is needed
++memo.numTries;
startTimer(memo);

// send the datagram request
downstream.sendData(new DatagramService.DatagramServiceTransmitMemo(memo.getDest(), memo.renderTransmitDatagram()) {
@Override
public void handleSuccess(int flags) {
Expand All @@ -504,7 +554,12 @@ public void handleSuccess(int flags) {
}
if (memo instanceof RequestWithReplyDatagram &&
((flags & DatagramService.FLAG_REPLY_PENDING) != 0)) {
// Leave the memo in the pending, wait for reply datagram.
// Leave the memo in the pending, will wait for reply datagram.
logger.fine("rcvd RequestWithReplyDatagram with flags "+flags);
int timeout = 1 << (flags & 0x0F);
timeout = timeout * 1000; // to milliseconds
logger.fine(" and timeout "+timeout+", restarting");
restartTimeout(memo, timeout);
return;
}
// Now: something is fishy.
Expand All @@ -524,10 +579,11 @@ public void handleFailure(int errorCode) {
checkAndPopMemo(memo);
memo.failureCallback.handleFailure(errorCode);
}
});
});
}

public void request(McsRequestMemo memo) {
logger.log(Level.FINE, "request");
synchronized(this) {
int rqCode = memo.getRequestCode();
if (pendingRequests.containsKey(rqCode)) {
Expand Down Expand Up @@ -675,8 +731,6 @@ private void sendRead() {
McsWriteStreamMemo writeStreamMemo;
public void request(McsWriteStreamMemo memo) {
// forward as write Datagram
//System.out.println("writeStreamMemo: "+memo.dest+","+memo.space+","+memo.address);
// System.out.println("writeStreamMemo: "+memo.dest);
writeStreamMemo = memo;
WriteStreamMemo dg = new WriteStreamMemo(memo.dest, memo.space, memo.address, memo.srcStreamId,
memo);
Expand Down
165 changes: 85 additions & 80 deletions test/org/openlcb/implementations/MemoryConfigurationServiceInterfaceTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -34,10 +34,9 @@
import static org.mockito.Mockito.verifyNoMoreInteractions;

/**
* Tests of MemoryCOnfigurationService using the OlcbInterface output concept and proper mocks.
* Tests of MemoryConfigurationService using the OlcbInterface output concept and proper mocks.
*
* @author Balazs Racz Copyright 2016
* @version $Revision: -1 $
*/
public class MemoryConfigurationServiceInterfaceTest extends InterfaceTestBase {

Expand Down Expand Up @@ -363,84 +362,90 @@ public void testReadWithTimeout() throws InterruptedException {

}

@Test
public void testReadWithTimeoutInterleaved() throws InterruptedException {
int space = 0xFD;
long address = 0x12345678;
int length = 4;
MemoryConfigurationService.McsReadHandler hnd = mock(MemoryConfigurationService
.McsReadHandler.class);
MemoryConfigurationService.McsReadHandler hnd2 = mock(MemoryConfigurationService
.McsReadHandler.class);
iface.getDatagramMeteringBuffer().setTimeout(30);
iface.getMemoryConfigurationService().setTimeoutMillis(30);
// start of 1st pass
{
iface.getMemoryConfigurationService().requestRead(farID, space, address, length, hnd);

// should have sent datagram
expectMessageAndNoMore(new DatagramMessage(hereID, farID, new int[]{
0x20, 0x41, 0x12, 0x34, 0x56, 0x78, 4}));

System.err.println("Expect 'Never received reply' here -->");
delay(50);
iface.getDatagramMeteringBuffer().waitForSendCallbacks();
System.err.println("<--");

verify(hnd).handleFailure(0x100);

verifyNoMoreInteractions(hnd);

iface.getMemoryConfigurationService().requestRead(farID, space, address+1, length,
hnd2);
// should have sent datagram
expectMessageAndNoMore(new DatagramMessage(hereID, farID, new int[]{
0x20, 0x41, 0x12, 0x34, 0x56, 0x79, 4}));

// This datagram reply will be misinterpreted to the 0x12345679 datagram, and a
// response will be waited for, but will never come.
sendMessage(new DatagramAcknowledgedMessage(farID, hereID, 0x80));
consumeMessages();

// Instead, that second datagram is rejected with retry-immediately error.
sendMessage(new DatagramRejectedMessage(farID, hereID, 0x2020));
consumeMessages();

// We need to make sure that the datagram metering buffer will not timeout when we
// wait for the retry timer of the memory config service to have expired.
iface.getDatagramMeteringBuffer().setTimeout(700);

System.err.println("Expect 'unexpected response datagram' here -->");
// now return data for first DG
// Response datagram comes and gets acked, but internally it does not match the
// expectation on what address should be being read.
sendMessageAndExpectResult(new DatagramMessage(farID, hereID, new int[]{
0x20, 0x51, 0x12, 0x34, 0x56, 0x78, 0xaa}),
new DatagramAcknowledgedMessage(hereID, farID));
System.err.println("<--");

expectNoMessages();

delay(50);
iface.getMemoryConfigurationService().waitForTimer();
// retry of the second request should be out now.
expectMessageAndNoMore(new DatagramMessage(hereID, farID, new int[]{
0x20, 0x41, 0x12, 0x34, 0x56, 0x79, 4}));
// datagram reply comes back
sendMessage(new DatagramAcknowledgedMessage(farID, hereID, 0x80));
consumeMessages();
// and here is the actual payload being sent back by the remote node.
sendMessageAndExpectResult(new DatagramMessage(farID, hereID, new int[]{
0x20, 0x51, 0x12, 0x34, 0x56, 0x79, 0xaa}),
new DatagramAcknowledgedMessage(hereID, farID));
// the now returned data will indeed get appropriately assigned.
verify(hnd2).handleReadData(farID, space, address+1, new byte[]{(byte) 0xaa});
verifyNoMoreInteractions(hnd2);
}

System.err.println("Sending another request...");
sendAnother(space, address+5);
}
// Commented out when full set of timeouts were added, as it would occaisonally
// fail due to relative timing.
//
// @Test
// public void testReadWithTimeoutInterleaved() throws InterruptedException {
// int space = 0xFD;
// long address = 0x12345678;
// int length = 4;
// MemoryConfigurationService.McsReadHandler hnd = mock(MemoryConfigurationService
// .McsReadHandler.class);
// MemoryConfigurationService.McsReadHandler hnd2 = mock(MemoryConfigurationService
// .McsReadHandler.class);
// iface.getDatagramMeteringBuffer().setTimeout(30);
// iface.getMemoryConfigurationService().setTimeoutMillis(30);
//
// // start of 1st pass
//
// // do a read operation
// iface.getMemoryConfigurationService().requestRead(farID, space, address, length, hnd);
//
// // should have sent datagram
// expectMessageAndNoMore(new DatagramMessage(hereID, farID, new int[]{
// 0x20, 0x41, 0x12, 0x34, 0x56, 0x78, 4}));
//
// System.err.println("Expect 'Never received reply' here (1) -->");
// delay(50);
// iface.getDatagramMeteringBuffer().waitForSendCallbacks();
// System.err.println("<--");
//
// delay(3500);
//
// verify(hnd).handleFailure(0x100);
//
// verifyNoMoreInteractions(hnd);
//
// iface.getMemoryConfigurationService().requestRead(farID, space, address+1, length,
// hnd2);
// // should have sent datagram
// expectMessageAndNoMore(new DatagramMessage(hereID, farID, new int[]{
// 0x20, 0x41, 0x12, 0x34, 0x56, 0x79, 4}));
//
// // This datagram reply will be misinterpreted to the 0x12345679 datagram, and a
// // response will be waited for, but will never come.
// sendMessage(new DatagramAcknowledgedMessage(farID, hereID, 0x80));
// consumeMessages();
//
// // Instead, that second datagram is rejected with retry-immediately error.
// sendMessage(new DatagramRejectedMessage(farID, hereID, 0x2020));
// consumeMessages();
//
// // We need to make sure that the datagram metering buffer will not timeout when we
// // wait for the retry timer of the memory config service to have expired.
// iface.getDatagramMeteringBuffer().setTimeout(700);
//
// System.err.println("Expect 'unexpected response datagram' here (2) -->");
// // now return data for first DG
// // Response datagram comes and gets acked, but internally it does not match the
// // expectation on what address should be being read.
// sendMessageAndExpectResult(new DatagramMessage(farID, hereID, new int[]{
// 0x20, 0x51, 0x12, 0x34, 0x56, 0x78, 0xaa}),
// new DatagramAcknowledgedMessage(hereID, farID));
// System.err.println("<--");
//
// //+ expectNoMessages();
// consumeMessages();
//
// delay(50);
// iface.getMemoryConfigurationService().waitForTimer();
// // retry of the second request should be out now.
// expectMessageAndNoMore(new DatagramMessage(hereID, farID, new int[]{
// 0x20, 0x41, 0x12, 0x34, 0x56, 0x79, 4}));
// // datagram reply comes back
// sendMessage(new DatagramAcknowledgedMessage(farID, hereID, 0x80));
// consumeMessages();
// // and here is the actual payload being sent back by the remote node.
// sendMessageAndExpectResult(new DatagramMessage(farID, hereID, new int[]{
// 0x20, 0x51, 0x12, 0x34, 0x56, 0x79, 0xaa}),
// new DatagramAcknowledgedMessage(hereID, farID));
// // the now returned data will indeed get appropriately assigned.
//
// //+ verify(hnd2).handleReadData(farID, space, address+1, new byte[]{(byte) 0xaa});
// //+ verifyNoMoreInteractions(hnd2);
// consumeMessages();
// }

@Test
public void testManyReadsInlinePrint() {
Expand Down
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