Added improved keyPrefix genereation in get{Vertices, Edges}.

Re-use the buffer and don't re-serialize the edge label and neighbor label over
and over again.

Author: jdellithorpe

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

@@ -479,8 +479,10 @@ public Map<TorcVertex, List<TorcVertex>> getVertices(
       String edgeLabel, 
       Direction dir, 
       String ... neighborLabels) {
-    return getVertices(TorcHelper.neighborList(vMap), edgeLabel, dir, 
+    List<TorcVertex> vList = TorcHelper.neighborList(vMap);
+    Map<TorcVertex, List<TorcVertex>> ret = getVertices(vList, edgeLabel, dir,
         neighborLabels);
+    return ret;
   }
 
   /** 
@@ -508,10 +510,20 @@ public Map<TorcVertex, List<TorcVertex>> getVertices(
     /* Build arguments to TorcEdgeList.batchRead(). */
     List<byte[]> keyPrefixes = new ArrayList<>(vList.size());
 
-    for (TorcVertex vertex : vList) {
-      for (String neighborLabel : neighborLabels) {
-        keyPrefixes.add(TorcHelper.getEdgeListKeyPrefix(vertex.id(), 
-              edgeLabel, dir, neighborLabel));
+    byte[] edgeLabelByteArray = TorcHelper.serializeString(edgeLabel);
+    for (String neighborLabel : neighborLabels) {
+      byte[] neighborLabelByteArray = TorcHelper.serializeString(neighborLabel);
+      ByteBuffer buffer =
+          ByteBuffer.allocate(UInt128.BYTES 
+              + Short.BYTES + edgeLabelByteArray.length
+              + Byte.BYTES 
+              + Short.BYTES + neighborLabelByteArray.length)
+          .order(ByteOrder.LITTLE_ENDIAN);
+      for (TorcVertex vertex : vList) {
+        buffer.rewind();
+        TorcHelper.appendEdgeListKeyPrefixToBuffer(vertex.id(), 
+            edgeLabelByteArray, dir, neighborLabelByteArray, buffer);
+        keyPrefixes.add(buffer.array().clone());
       }
     }
 
@@ -526,8 +538,8 @@ public Map<TorcVertex, List<TorcVertex>> getVertices(
     Map<UInt128, TorcVertex> neighborDedupMap = new HashMap<>();
 
     int i = 0;
-    for (TorcVertex vertex : vList) {
-      for (String neighborLabel : neighborLabels) {
+    for (String neighborLabel : neighborLabels) {
+      for (TorcVertex vertex : vList) {
         byte[] keyPrefix = keyPrefixes.get(i);
 
         if (serEdgeLists.containsKey(keyPrefix)) {
@@ -601,10 +613,20 @@ public Map<TorcVertex, List<TorcEdge>> getEdges(
     /* Build arguments to TorcEdgeList.batchRead(). */
     List<byte[]> keyPrefixes = new ArrayList<>(vList.size());
 
-    for (TorcVertex vertex : vList) {
-      for (String neighborLabel : neighborLabels) {
-        keyPrefixes.add(TorcHelper.getEdgeListKeyPrefix(vertex.id(), 
-              edgeLabel, dir, neighborLabel));
+    byte[] edgeLabelByteArray = TorcHelper.serializeString(edgeLabel);
+    for (String neighborLabel : neighborLabels) {
+      byte[] neighborLabelByteArray = TorcHelper.serializeString(neighborLabel);
+      ByteBuffer buffer =
+          ByteBuffer.allocate(UInt128.BYTES 
+              + Short.BYTES + edgeLabelByteArray.length
+              + Byte.BYTES 
+              + Short.BYTES + neighborLabelByteArray.length)
+          .order(ByteOrder.LITTLE_ENDIAN);
+      for (TorcVertex vertex : vList) {
+        buffer.rewind();
+        TorcHelper.appendEdgeListKeyPrefixToBuffer(vertex.id(), 
+            edgeLabelByteArray, dir, neighborLabelByteArray, buffer);
+        keyPrefixes.add(buffer.array().clone());
       }
     }
 
@@ -618,8 +640,8 @@ public Map<TorcVertex, List<TorcEdge>> getEdges(
     Map<TorcVertex, List<TorcEdge>> edgeListMap = new HashMap<>();
 
     int i = 0;
-    for (TorcVertex vertex : vList) {
-      for (String neighborLabel : neighborLabels) {
+    for (String neighborLabel : neighborLabels) {
+      for (TorcVertex vertex : vList) {
         byte[] keyPrefix = keyPrefixes.get(i);
 
         if (serEdgeLists.containsKey(keyPrefix)) {

src/main/java/net/ellitron/torc/util/TorcHelper.java

@@ -309,14 +309,39 @@ public static byte[] getEdgeListKeyPrefix(UInt128 vertexId, String edgeLabel,
             + Byte.BYTES 
             + Short.BYTES + vertexLabelByteArray.length)
         .order(ByteOrder.LITTLE_ENDIAN);
+    appendEdgeListKeyPrefixToBuffer(vertexId, edgeLabelByteArray, dir, 
+        vertexLabelByteArray, buffer);
+    return buffer.array();
+  }
+
+  /**
+   * Generates a key prefix that defines an exclusive key-space for this
+   * combination of vertex ID, edge label, edge direction, and vertex label. No
+   * other (vertex ID, elabel, direction, vlabel) combination will have a key
+   * prefix that is a prefix of this key, or for which this key is a prefix of.
+   * This key-prefix is used to generate unique keys for RAMCloud objects that
+   * store the potentially multiple segments that make up an edge list.
+   *
+   * @param vertexId
+   * @param edgeLabel
+   * @param dir
+   * @param vertexLabel
+   * @param byteBuffer
+   *
+   * @return RAMCloud Key.
+   */
+  public static void appendEdgeListKeyPrefixToBuffer(UInt128 vertexId, 
+      byte[] edgeLabelByteArray,
+      Direction dir, 
+      byte[] vertexLabelByteArray, 
+      ByteBuffer buffer) {
     buffer.putLong(vertexId.getUpperLong());
     buffer.putLong(vertexId.getLowerLong());
     buffer.putShort((short) edgeLabelByteArray.length);
     buffer.put(edgeLabelByteArray);
     buffer.put((byte) dir.ordinal());
     buffer.putShort((short) vertexLabelByteArray.length);
     buffer.put(vertexLabelByteArray);
-    return buffer.array();
   }
 
   /**