From 24e0f734efdafca6b8cc1ffce7767d0d6bce9fae Mon Sep 17 00:00:00 2001
From: Michal Rehak <mirehak@cisco.com>
Date: Mon, 26 May 2014 17:22:22 +0200
Subject: [PATCH] BUG-1074: add javadoc for QueueKeeper

- added javadoc for QueueKeeper and QueueKeeperImpl

Change-Id: I5cf4d5c2798766435985bb9a93c45b07e18d4d8b
Signed-off-by: Michal Rehak <mirehak@cisco.com>
---
 .../openflow/md/queue/QueueKeeper.java        | 29 ++++++++++++++-----
 .../md/queue/QueueKeeperLightImpl.java        | 26 ++++++++++++++++-
 2 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/queue/QueueKeeper.java b/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/queue/QueueKeeper.java
index 94f8bb5c86..c22a81a220 100644
--- a/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/queue/QueueKeeper.java
+++ b/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/queue/QueueKeeper.java
@@ -16,34 +16,49 @@ import org.opendaylight.openflowplugin.openflow.md.core.IMDMessageTranslator;
 import org.opendaylight.openflowplugin.openflow.md.core.TranslatorKey;
 
 /**
- * @author mirehak
+ * This processing mechanism based on queue. Processing consists of 2 steps: translate and publish. 
+ * Proposed workflow (might slightly deviate in implementations):
+ * <ol>
+ * <li>messages of input type are pushed in (via {@link QueueKeeper#push(Object, ConnectionConductor)} and similar)</li>
+ * <li>ticket (executable task) is build upon each pushed message and enqueued</li>
+ * <li>ticket is translated using appropriate translator</li>
+ * <li>ticket is dequeued and result is published by appropriate popListener</li>
+ * </ol>
+ * Message order might be not important, e.g. when speed is of the essence
  * @param <IN> source type
  * @param <OUT> result type
  */
 public interface QueueKeeper<IN, OUT> {
     
-    public enum QueueType {DEFAULT, UNORDERED}
+    /** type of message enqueue */
+    public enum QueueType {
+        /** ordered processing */
+        DEFAULT,
+        /** unordered processing - bypass fair processing */
+        UNORDERED}
 
     /**
-     * @param translatorMapping
+     * @param translatorMapping translators for message processing
      */
     void setTranslatorMapping(Map<TranslatorKey, Collection<IMDMessageTranslator<IN, List<OUT>>>> translatorMapping);
 
     /**
+     * enqueue message for processing using {@link QueueType#DEFAULT}
      * @param message
-     * @param conductor
+     * @param conductor source of message
      */
     void push(IN message, ConnectionConductor conductor);
     
     /**
+     * enqueue message for processing
      * @param message
-     * @param conductor
-     * @param ordered - true if message order matters, false otherwise
+     * @param conductor source of message
+     * @param queueType - {@link QueueType#DEFAULT} if message order matters, {@link QueueType#UNORDERED} otherwise
      */
     void push(IN message, ConnectionConductor conductor, QueueType queueType);
 
     /**
-     * @param popListenersMapping the popListenersMapping to set
+     * @param popListenersMapping listeners invoked when processing done
      */
     void setPopListenersMapping(Map<Class<? extends OUT>, Collection<PopListener<OUT>>> popListenersMapping);
 }
diff --git a/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/queue/QueueKeeperLightImpl.java b/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/queue/QueueKeeperLightImpl.java
index 99c7c016cf..04a7ad78e9 100644
--- a/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/queue/QueueKeeperLightImpl.java
+++ b/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/queue/QueueKeeperLightImpl.java
@@ -12,6 +12,7 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.Future;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
 
@@ -26,8 +27,31 @@ import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+
 /**
- * @author mirehak
+ * {@link QueueKeeper} implementation focused to keep order and use up mutiple threads for translation phase.
+ * <br/>
+ * There is internal thread pool of limited size ({@link QueueKeeperLightImpl#setPoolSize(int)}) 
+ * dedicated to translation. Then there is singleThreadPool dedicated to publishing (via popListeners)
+ * <br/>
+ * Workflow:
+ * <ol>
+ * <li>upon message push ticket is created and enqueued</li>
+ * <li>available threads from internal pool translate the massage wrapped in ticket</li>
+ * <li>when translation of particular message is finished, result is set in future result of wrapping ticket</br>
+ *     (order of tickets in queue is not touched during translate)
+ * </li>
+ * <li>at the end of queue there is {@link TicketFinisher} running in singleThreadPool and for each ticket it does:
+ *    <ol>
+ *      <li>invoke blocking {@link BlockingQueue#take()} method in order to get the oldest ticket</li>
+ *      <li>invoke blocking {@link Future#get()} on the dequeued ticket</li>
+ *      <li>as soon as the result of translation is available, appropriate popListener is invoked</li>
+ *    </ol>
+ *    and this way the order of messages is preserved and also multiple threads are used by translating 
+ * </li>
+ * </ol>
+ * 
+ * 
  */
 public class QueueKeeperLightImpl implements QueueKeeper<OfHeader, DataObject> {
 
-- 
2.36.6