From 3e6cc7601c035423c536f410af8a8bbb649d118f Mon Sep 17 00:00:00 2001
From: Jono Morris <jono.morris@xtra.co.nz>
Date: Sat, 26 Jul 2025 01:39:00 +1200
Subject: [PATCH] JCS-242 fix lateral cache in error state

---
 .../lateral/LateralCacheMonitor.java          | 13 ++++
 .../socket/tcp/TestTCPLateralUnitTest.java    | 73 +++++++++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/commons-jcs3-core/src/main/java/org/apache/commons/jcs3/auxiliary/lateral/LateralCacheMonitor.java b/commons-jcs3-core/src/main/java/org/apache/commons/jcs3/auxiliary/lateral/LateralCacheMonitor.java
index fd207c946..60effc8a1 100644
--- a/commons-jcs3-core/src/main/java/org/apache/commons/jcs3/auxiliary/lateral/LateralCacheMonitor.java
+++ b/commons-jcs3-core/src/main/java/org/apache/commons/jcs3/auxiliary/lateral/LateralCacheMonitor.java
@@ -72,6 +72,19 @@ public void addCache(final LateralCacheNoWait<?, ?> cache)
     {
         this.caches.put(cache.getCacheName(), (LateralCacheNoWait<Object, Object>)cache);
 
+        // Fix a cache where an exception occurred before it was added to this monitor.
+        // For instance, where a cache failed to connect to lateral TCP server.
+        if (cache.getStatus() == CacheStatus.ERROR) {
+            if (getState() == Thread.State.NEW)
+            {
+                // no need to signal trigger if monitor hasn't started
+                allright.compareAndSet(true, false);
+            }
+            else {
+                notifyError();
+            }
+        }
+
         // if not yet started, go ahead
         if (getState() == Thread.State.NEW)
         {
diff --git a/commons-jcs3-core/src/test/java/org/apache/commons/jcs3/auxiliary/lateral/socket/tcp/TestTCPLateralUnitTest.java b/commons-jcs3-core/src/test/java/org/apache/commons/jcs3/auxiliary/lateral/socket/tcp/TestTCPLateralUnitTest.java
index 2790bd23c..ecd452840 100644
--- a/commons-jcs3-core/src/test/java/org/apache/commons/jcs3/auxiliary/lateral/socket/tcp/TestTCPLateralUnitTest.java
+++ b/commons-jcs3-core/src/test/java/org/apache/commons/jcs3/auxiliary/lateral/socket/tcp/TestTCPLateralUnitTest.java
@@ -27,10 +27,13 @@
 import java.util.Set;
 
 import org.apache.commons.jcs3.JCS;
+import org.apache.commons.jcs3.auxiliary.AbstractAuxiliaryCacheMonitor;
 import org.apache.commons.jcs3.auxiliary.lateral.LateralCacheAttributes;
+import org.apache.commons.jcs3.auxiliary.lateral.LateralCacheNoWait;
 import org.apache.commons.jcs3.auxiliary.lateral.LateralCommand;
 import org.apache.commons.jcs3.auxiliary.lateral.LateralElementDescriptor;
 import org.apache.commons.jcs3.engine.CacheElement;
+import org.apache.commons.jcs3.engine.CacheStatus;
 import org.apache.commons.jcs3.engine.behavior.ICacheElement;
 import org.apache.commons.jcs3.engine.behavior.ICompositeCacheManager;
 import org.apache.commons.jcs3.engine.behavior.IElementSerializer;
@@ -313,6 +316,55 @@ void testSameKeyObjectDifferentValueObject()
         assertEquals( element2.getVal(), cacheElement.getVal(), "Didn't get the correct object: " + cacheElement );
     }
 
+    /**
+     * Test that the cache has an error status after failing to connect to a TCP server.
+     */
+    @Test
+    void testCacheErrorStatusTcpConnectionFail()
+    {
+        final TCPLateralCacheAttributes lattr = new TCPLateralCacheAttributes();
+        lattr.setCacheName("test");
+        lattr.setTransmissionType(LateralCacheAttributes.Type.TCP);
+        lattr.setTcpServer("localhost:1109");
+        LateralTCPCacheFactory factory = new LateralTCPCacheFactory();
+        factory.initialize();
+
+        LateralCacheNoWait<String, String> lateralNoWait = factory.createCacheNoWait(lattr, null, new StandardSerializer());
+
+        assertEquals(CacheStatus.ERROR, lateralNoWait.getStatus());
+    }
+
+    /**
+     * Test that the cache monitor can fix a cache that is in error state after failing to connect to a TCP server.
+     *
+     * @throws Exception
+     */
+    @Test
+    void testCacheRecoveryUsingMonitor() throws Exception
+    {
+        final TCPLateralCacheAttributes lattr = new TCPLateralCacheAttributes();
+        lattr.setCacheName("test");
+        lattr.setTransmissionType(LateralCacheAttributes.Type.TCP);
+        lattr.setTcpServer("localhost:1110");
+        LateralTCPCacheFactory factory = new LateralTCPCacheFactory();
+        factory.initialize();
+
+        // reduce the monitor idle period between 'fix' attempts for testing purposes
+        MyCacheMonitor.setIdle(500L);
+        LateralCacheNoWait<String, String> lateralNoWait = factory.createCacheNoWait(lattr, null, new StandardSerializer());
+
+        // start a TCP server for the cache to connect to
+        createCache(1110);
+        // adding the cache to the monitor releases the monitor 'fix' thread
+        factory.monitorCache(lateralNoWait);
+
+        Thread.sleep(2000L);
+
+        // verify that the monitor has fixed the cache
+        assertEquals(CacheStatus.ALIVE, lateralNoWait.getStatus());
+    }
+
+
     /**
      * @throws Exception
      */
@@ -338,4 +390,25 @@ void testSimpleSend()
     {
     	simpleSend(new StandardSerializer(), 8111);
     }
+
+    // used to reduce the monitor idle period between 'fix' attempts for testing purposes
+    private static class MyCacheMonitor extends AbstractAuxiliaryCacheMonitor {
+        public static void setIdle(long idlePeriod) {
+            AbstractAuxiliaryCacheMonitor.idlePeriod = idlePeriod;
+        }
+
+        public MyCacheMonitor() {
+            super("test");
+        }
+
+        @Override
+        protected void dispose() {
+            // nothing to dispose
+        }
+
+        @Override
+        protected void doWork() {
+            // nothing to do
+        }
+    }
 }