Optimization on single vertex property.

Map objects take up a LOT of memory when storing just a single property, as is
often the case in the LDBC social network benchmark. So in the case that we
really want to fetch only a single property, we can now specify that property to
fillProperties(), and then we will store this property in key/value pair member
variables natively in a TorcVertex object, instead of creating a Map<Object,
Object> properties object. Then when getting properties on the vertex, these
variables are checked.

Author: jdellithorpe

src/main/java/net/ellitron/torc/TorcGraph.java

@@ -603,7 +603,7 @@ public void fillProperties(TraversalResult ... rs) {
     }
   }
 
-  public void fillProperties(Iterable<TorcVertex> vertices) {
+  public void fillProperties(Iterable<TorcVertex> vertices, String ... keys) {
     initialize();
 
     torcGraphTx.readWrite();
@@ -679,7 +679,6 @@ public void fillProperties(Iterable<TorcVertex> vertices) {
             if (requests[i].getStatus() != Status.STATUS_OK) {
               if (requests[i].getStatus() == Status.STATUS_OBJECT_DOESNT_EXIST) {
                 // This vertex has no properties set.
-                v.setProperties(new HashMap<>());
                 continue;
               } else {
                 throw new RuntimeException(
@@ -690,7 +689,11 @@ public void fillProperties(Iterable<TorcVertex> vertices) {
 
             Map<Object, Object> properties = (Map<Object, Object>)
               TorcHelper.deserializeObject(requests[i].getValueBytes());
-            v.setProperties(properties);
+            if (keys.length == 1) {
+              v.setProperty(keys[0], properties.get(keys[0]));
+            } else {
+              v.setProperties(properties);
+            }
           } 
         } 
       }
@@ -709,7 +712,6 @@ public void fillProperties(Iterable<TorcVertex> vertices) {
           if (requests[i].getStatus() != Status.STATUS_OK) {
             if (requests[i].getStatus() == Status.STATUS_OBJECT_DOESNT_EXIST) {
               // This vertex has no properties set.
-              v.setProperties(new HashMap<>());
               continue;
             } else {
               throw new RuntimeException(
@@ -720,7 +722,11 @@ public void fillProperties(Iterable<TorcVertex> vertices) {
 
           Map<Object, Object> properties = (Map<Object, Object>)
             TorcHelper.deserializeObject(requests[i].getValueBytes());
-          v.setProperties(properties);
+          if (keys.length == 1) {
+            v.setProperty(keys[0], properties.get(keys[0]));
+          } else {
+            v.setProperties(properties);
+          }
         }
       }
     }

src/main/java/net/ellitron/torc/TorcVertex.java

@@ -27,6 +27,7 @@
 import java.util.Iterator;
 import java.util.Arrays;
 import java.util.Map;
+import java.util.HashMap;
 import java.util.List;
 
 /**
@@ -38,6 +39,8 @@ public class TorcVertex implements Vertex, Element {
   private final TorcGraph graph;
   private UInt128 id;
   private String label;
+  private String propKey1 = null;
+  private Object propVal1 = null;
   private Map<Object, Object> properties = null;
 
   public TorcVertex(final TorcGraph graph, final UInt128 id,
@@ -123,26 +126,43 @@ public Iterator<Vertex> vertices(Direction direction, String... edgeLabels) {
     throw new UnsupportedOperationException("Must specify the neighbor vertex labels when fetching vertex neighbors.");
   }
 
-  public <V> V getProperty(String key) {
+  public Map<Object, Object> getProperties() {
     if (properties == null) {
       graph.fillProperties(this);
     }
 
-    return (V)properties.get(key);
+    return properties;
   }
 
-  public Map<Object, Object> getProperties() {
-    if (properties == null) {
-      graph.fillProperties(this);
+  public Object getProperty(String key) {
+    if (propKey1 != null) {
+      if (propKey1.equals(key))
+        return propVal1;
     }
 
-    return properties;
+    if (properties != null)
+      return properties.get(key);
+    else
+      return null;
   }
 
   public void setProperties(Map<Object, Object> properties) {
     this.properties = properties;
   }
 
+  public void setProperty(String key, Object value) {
+    if (properties == null && propKey1 != null) {
+      properties = new HashMap<>();
+      properties.put(propKey1, propVal1);
+      properties.put(key, value);
+    } else if (properties != null) {
+      properties.put(key, value);
+    }
+
+    propKey1 = key;
+    propVal1 = value;
+  }
+
   /**
    * {@inheritDoc}
    */