Issue #6556 Ensure context classloader set when operating on memcache. (#6557)

* Issue #6556 Ensure context classloader set when operating on memcache.

Signed-off-by: Jan Bartel <janb@webtide.com>

jetty-memcached/jetty-memcached-sessions/src/main/java/org/eclipse/jetty/memcached/session/MemcachedSessionDataMap.java

@@ -25,6 +25,7 @@ import org.eclipse.jetty.server.session.SessionContext;
 import org.eclipse.jetty.server.session.SessionData;
 import org.eclipse.jetty.server.session.SessionDataMap;
 import org.eclipse.jetty.util.ClassLoadingObjectInputStream;
+import org.eclipse.jetty.util.FuturePromise;
 import org.eclipse.jetty.util.annotation.ManagedAttribute;
 import org.eclipse.jetty.util.annotation.ManagedObject;
 import org.eclipse.jetty.util.component.AbstractLifeCycle;
@@ -43,6 +44,7 @@ public class MemcachedSessionDataMap extends AbstractLifeCycle implements Sessio
     protected int _expirySec = 0;
     protected boolean _heartbeats = true;
     protected XMemcachedClientBuilder _builder;
+    protected SessionContext _context;
 
     /**
      * SessionDataTranscoder
@@ -140,8 +142,12 @@ public class MemcachedSessionDataMap extends AbstractLifeCycle implements Sessio
     @Override
     public void initialize(SessionContext context)
     {
+        if (isStarted())
+            throw new IllegalStateException("Context set after MemcachedSessionDataMap started");
+        
         try
         {
+            _context = context;
             _builder.setTranscoder(new SessionDataTranscoder());
             _client = _builder.build();
             _client.setEnableHeartBeat(isHeartbeats());
@@ -155,14 +161,48 @@ public class MemcachedSessionDataMap extends AbstractLifeCycle implements Sessio
     @Override
     public SessionData load(String id) throws Exception
     {
-        SessionData data = _client.get(id);
+        if (!isStarted())
-        return data;
+            throw new IllegalStateException("Not started");
+        
+        final FuturePromise<SessionData> result = new FuturePromise<>();
+
+        Runnable r = () ->
+        {
+            try
+            {
+                result.succeeded(_client.get(id));
+            }
+            catch (Exception e)
+            {
+                result.failed(e);
+            }
+        };
+
+        _context.run(r);
+        return result.getOrThrow();
     }
 
     @Override
     public void store(String id, SessionData data) throws Exception
     {
-        _client.set(id, _expirySec, data);
+        if (!isStarted())
+            throw new IllegalStateException("Not started");
+        
+        final FuturePromise<Void> result = new FuturePromise<>();
+        Runnable r = () ->
+        {
+            try
+            {
+                _client.set(id, _expirySec, data);
+                result.succeeded(null);
+            }
+            catch (Exception e)
+            {
+                result.failed(e);
+            }
+        };
+        _context.run(r);
+        result.getOrThrow();
     }
 
     @Override

jetty-server/src/main/java/org/eclipse/jetty/server/session/AbstractSessionDataStore.java

@@ -15,8 +15,10 @@ package org.eclipse.jetty.server.session;
 
 import java.util.HashSet;
 import java.util.Set;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 
+import org.eclipse.jetty.util.FuturePromise;
 import org.eclipse.jetty.util.annotation.ManagedAttribute;
 import org.eclipse.jetty.util.annotation.ManagedObject;
 import org.eclipse.jetty.util.component.ContainerLifeCycle;
@@ -40,41 +42,6 @@ public abstract class AbstractSessionDataStore extends ContainerLifeCycle implem
     protected long _lastOrphanSweepTime = 0; //last time in ms that we deleted orphaned sessions
     protected int _savePeriodSec = DEFAULT_SAVE_PERIOD_SEC; //time in sec between saves
     
-    /**
-     * Small utility class to allow us to
-     * return a result and an Exception
-     * from invocation of Runnables.
-     *
-     * @param <V> the type of the result.
-     */
-    private class Result<V>
-    {
-        private V _result;
-        private Exception _exception;
-        
-        public void setResult(V result)
-        {
-            _result = result;
-        }
-        
-        public void setException(Exception exception)
-        {
-            _exception = exception;
-        }
-        
-        private void throwIfException() throws Exception
-        {
-            if (_exception != null)
-                throw _exception;
-        }
-        
-        public V getOrThrow() throws Exception
-        {
-            throwIfException();
-            return _result;
-        }
-    }
-    
     /**
      * Check if a session for the given id exists.
      * 
@@ -171,21 +138,22 @@ public abstract class AbstractSessionDataStore extends ContainerLifeCycle implem
         if (!isStarted())
             throw new IllegalStateException("Not started");
 
-        final Result<SessionData> result = new Result<>();
+        final FuturePromise<SessionData> result = new FuturePromise<>();
-
+        
         Runnable r = () ->
         {
             try
             {
-                result.setResult(doLoad(id));
+                result.succeeded(doLoad(id));
             }
             catch (Exception e)
             {
-                result.setException(e);
+                result.failed(e);
             }
         };
 
         _context.run(r);
+
         return result.getOrThrow();
     }
 
@@ -214,7 +182,7 @@ public abstract class AbstractSessionDataStore extends ContainerLifeCycle implem
             //set the last saved time to now
             data.setLastSaved(System.currentTimeMillis());
             
-            final Result<Object> result = new Result<>();
+            final FuturePromise<Void> result = new FuturePromise<>();
             Runnable r = () ->
             {
                 try
@@ -222,32 +190,33 @@ public abstract class AbstractSessionDataStore extends ContainerLifeCycle implem
                     //call the specific store method, passing in previous save time
                     doStore(id, data, lastSave);
                     data.clean(); //unset all dirty flags
+                    result.succeeded(null);
                 }
                 catch (Exception e)
                 {
                     //reset last save time if save failed
                     data.setLastSaved(lastSave);
-                    result.setException(e);
+                    result.failed(e);
                 }
             };
             _context.run(r);
-            result.throwIfException();
+            result.getOrThrow();
         }
     }
 
     @Override
     public boolean exists(String id) throws Exception
     {
-        Result<Boolean> result = new Result<>();
+        FuturePromise<Boolean> result = new FuturePromise<>();
         Runnable r = () ->
         {
             try
             {
-                result.setResult(doExists(id));
+                result.succeeded(doExists(id));
             }
             catch (Exception e)
             {
-                result.setException(e);
+                result.failed(e);
             }
         };
 

jetty-util/src/main/java/org/eclipse/jetty/util/FuturePromise.java

@@ -118,6 +118,30 @@ public class FuturePromise<C> implements Future<C>, Promise<C>
             throw (CancellationException)new CancellationException().initCause(_cause);
         throw new ExecutionException(_cause);
     }
+    
+    /**
+     * Return the result if completed successfully
+     * or in the case of failure, throw the
+     * Exception/Error, or an ExecutionException wrapping
+     * the cause if it is neither an Exception or Error.
+     * 
+     * @return the computed result
+     * @throws Exception if the cause is an Exception or Error,
+     * otherwise an ExecutionException wrapping the cause
+     */
+    public C getOrThrow() throws Exception
+    {
+        _latch.await();
+
+        if (_cause == COMPLETED)
+            return _result;
+        if (_cause instanceof Exception)
+            throw (Exception)_cause;
+        if (_cause instanceof Error)
+            throw (Error)_cause;
+        
+        throw new ExecutionException(_cause);
+    }
 
     @Override
     public C get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException