ftp: Refactor FTP door to separate FTP interpreter from I/O logic

This patch splits the FTP protocol interpreter logic from the low
level I/O logic. This structure mimics a similar split in the DCAP
door. The refactoring improves coherence, makes the FTP interpreter
easier to unit test, and is a step towards alternative implementations
of the I/O logic (e.g. using Netty).

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Patch: http://rb.dcache.org/r/6280/

modules/dcache-ftp/src/main/java/diskCacheV111/doors/AbstractInterruptibleLineBasedInterpreter.java

@@ -0,0 +1,48 @@
+package diskCacheV111.doors;
+
+public abstract class AbstractInterruptibleLineBasedInterpreter implements LineBasedDoor.LineBasedInterpreter
+{
+    private boolean isStopped;
+
+    /**
+     * The thread to interrupt when the command poller is
+     * closed. May be null if interrupts are disabled.
+     */
+    private Thread executingThread;
+
+    /**
+     * Enables interrupt upon stop. Until the next call of
+     * disableInterrupt(), a call to <code>stop</code> will cause
+     * the calling thread to be interrupted.
+     *
+     * @throws InterruptedException if command poller is already
+     * closed
+     */
+    protected synchronized void enableInterrupt()
+            throws InterruptedException
+    {
+        if (isStopped) {
+            throw new InterruptedException();
+        }
+        executingThread = Thread.currentThread();
+    }
+
+    /**
+     * Disables interrupt upon stop.
+     */
+    protected synchronized void disableInterrupt()
+    {
+        executingThread = null;
+    }
+
+    public synchronized void shutdown()
+    {
+        if (!isStopped) {
+            isStopped = true;
+
+            if (executingThread != null) {
+                executingThread.interrupt();
+            }
+        }
+    }
+}

modules/dcache-ftp/src/main/java/diskCacheV111/doors/GsiFtpDoorV1.java

@@ -24,9 +24,6 @@
 import diskCacheV111.util.CacheException;
 import diskCacheV111.util.PermissionDeniedCacheException;
 
-import dmg.util.Args;
-import dmg.util.StreamEngine;
-
 import org.dcache.auth.LoginNamePrincipal;
 import org.dcache.auth.Subjects;
 import org.dcache.cells.Option;
@@ -71,22 +68,13 @@ public class GsiFtpDoorV1 extends GssFtpDoorV1
 
     private String _user;
 
-    /** Creates a new instance of GsiFtpDoorV1 */
-    public GsiFtpDoorV1(String name, StreamEngine engine, Args args)
-    {
-        super(name,engine,args);
-    }
-
     @Override
-    protected void init()
-        throws Exception
+    public void init()
     {
-        super.init();
-        cf = CertificateFactories.newX509CertificateFactory();
-
         _gssFlavor = "gsi";
-
         ftpDoorName="GSI FTP";
+        cf = CertificateFactories.newX509CertificateFactory();
+        super.init();
     }
 
     @Override

modules/dcache-ftp/src/main/java/diskCacheV111/doors/GssFtpDoorV1.java

@@ -16,9 +16,7 @@
 
 import diskCacheV111.util.Base64;
 
-import dmg.util.Args;
 import dmg.util.CommandExitException;
-import dmg.util.StreamEngine;
 
 import static com.google.common.collect.Iterables.filter;
 import static com.google.common.collect.Iterables.getFirst;
@@ -39,18 +37,11 @@ public abstract class GssFtpDoorV1 extends AbstractFtpDoorV1
     // GSS GSI context and others
     protected GSSContext _serviceContext;
 
-    /** Creates a new instance of GsiFtpDoorV1 */
-    public GssFtpDoorV1(String name, StreamEngine engine, Args args)
-    {
-        super(name,engine,args);
-    }
-
     @Override
-    protected void init()
-        throws Exception
+    public void init()
     {
-        super.init();
         _gssFlavor = "unknown";
+        super.init();
     }
 
     @Override

modules/dcache-ftp/src/main/java/diskCacheV111/doors/KerberosFtpDoorV1.java

@@ -20,16 +20,9 @@
 import diskCacheV111.util.CacheException;
 import diskCacheV111.util.PermissionDeniedCacheException;
 
-import dmg.util.Args;
-import dmg.util.StreamEngine;
-import dmg.util.command.Option;
-
 import org.dcache.auth.LoginNamePrincipal;
 import org.dcache.auth.Subjects;
-
-//java net
-//cells
-//jgss
+import org.dcache.cells.Option;
 
 /**
  *
@@ -49,22 +42,16 @@ public class KerberosFtpDoorV1 extends GssFtpDoorV1 {
 
     private String[] _kdcList;
 
-    /** Creates a new instance of KerberosFtpDoorV1 */
-    public KerberosFtpDoorV1(String name, StreamEngine engine, Args args)
-    {
-        super(name,engine,args);
-    }
 
     @Override
-    protected void init()
-        throws Exception
+    public void init()
     {
-        super.init();
         _gssFlavor = "k5";
         ftpDoorName = "Kerberos FTP";
         if (_kdcListOption != null) {
             _kdcList = _kdcListOption.split(",");
         }
+        super.init();
     }
 
     @Override