refact: fix some bugs & clean code

hugegraph-api/src/main/java/com/baidu/hugegraph/api/API.java

@@ -45,7 +45,7 @@
 
 public class API {
 
-    public static final Logger LOG = Log.logger(RestServer.class);
+    protected static final Logger LOG = Log.logger(RestServer.class);
 
     public static final String CHARSET = "UTF-8";
 

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/AdamicAdarAPI.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2022 HugeGraph Authors
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with this
+ * work for additional information regarding copyright ownership. The ASF
+ * licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package com.baidu.hugegraph.api.traversers;
+
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_ELEMENTS_LIMIT;
+import static com.baidu.hugegraph.traversal.algorithm.HugeTraverser.DEFAULT_MAX_DEGREE;
+
+import javax.inject.Singleton;
+import javax.ws.rs.DefaultValue;
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.PathParam;
+import javax.ws.rs.Produces;
+import javax.ws.rs.QueryParam;
+import javax.ws.rs.core.Context;
+
+import com.baidu.hugegraph.HugeGraph;
+import com.baidu.hugegraph.api.API;
+import com.baidu.hugegraph.api.graph.EdgeAPI;
+import com.baidu.hugegraph.api.graph.VertexAPI;
+import com.baidu.hugegraph.backend.id.Id;
+import com.baidu.hugegraph.core.GraphManager;
+import com.baidu.hugegraph.traversal.algorithm.PredictionTraverser;
+import com.baidu.hugegraph.type.define.Directions;
+import com.baidu.hugegraph.util.E;
+import com.baidu.hugegraph.util.JsonUtil;
+import com.codahale.metrics.annotation.Timed;
+import com.google.common.collect.ImmutableMap;
+
+/**
+ * This API include similar prediction algorithms, now include:
+ *  - Adamic Adar
+ *  - Resource Allocation
+ *
+ * Could add more prediction algorithms in future
+ */
+@Path("graphs/{graph}/traversers/adamicadar")
+@Singleton
+public class AdamicAdarAPI extends API {
+
+    @GET
+    @Timed
+    @Produces(APPLICATION_JSON_WITH_CHARSET)
+    public String get(@Context GraphManager manager,
+                      @PathParam("graph") String graph,
+                      @QueryParam("vertex") String current,
+                      @QueryParam("other") String other,
+                      @QueryParam("direction") String direction,
+                      @QueryParam("label") String edgeLabel,
+                      @QueryParam("max_degree")
+                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
+                      @QueryParam("limit")
+                      @DefaultValue(DEFAULT_ELEMENTS_LIMIT) long limit) {
+        LOG.debug("Graph [{}] get adamic adar between '{}' and '{}' with " +
+                  "direction {}, edge label {}, max degree '{}' and limit '{}'",
+                  graph, current, other, direction, edgeLabel, maxDegree,
+                  limit);
+
+        Id sourceId = VertexAPI.checkAndParseVertexId(current);
+        Id targetId = VertexAPI.checkAndParseVertexId(other);
+        E.checkArgument(!current.equals(other),
+                        "The source and target vertex id can't be same");
+        Directions dir = Directions.convert(EdgeAPI.parseDirection(direction));
+
+        HugeGraph g = graph(manager, graph);
+        PredictionTraverser traverser = new PredictionTraverser(g);
+        double score = traverser.adamicAdar(sourceId, targetId, dir,
+                                            edgeLabel, maxDegree, limit);
+        return JsonUtil.toJson(ImmutableMap.of("adamic_adar", score));
+    }
+}

hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/PredictionAPI.java → hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/ResourceAllocationAPI.java

@@ -51,45 +51,12 @@
  *
  * Could add more prediction algorithms in future
  */
-@Path("graphs/{graph}/traversers/")
+@Path("graphs/{graph}/traversers/resourceallocation")
 @Singleton
-public class PredictionAPI extends API {
+public class ResourceAllocationAPI extends API {
 
     @GET
     @Timed
-    @Path("adamicadar")
-    @Produces(APPLICATION_JSON_WITH_CHARSET)
-    public String get(@Context GraphManager manager,
-                      @PathParam("graph") String graph,
-                      @QueryParam("vertex") String current,
-                      @QueryParam("other") String other,
-                      @QueryParam("direction") String direction,
-                      @QueryParam("label") String edgeLabel,
-                      @QueryParam("max_degree")
-                      @DefaultValue(DEFAULT_MAX_DEGREE) long maxDegree,
-                      @QueryParam("limit")
-                      @DefaultValue(DEFAULT_ELEMENTS_LIMIT) long limit) {
-        LOG.debug("Graph [{}] get adamic adar between '{}' and '{}' with " +
-                  "direction {}, edge label {}, max degree '{}' and limit '{}'",
-                  graph, current, other, direction, edgeLabel, maxDegree,
-                  limit);
-
-        Id sourceId = VertexAPI.checkAndParseVertexId(current);
-        Id targetId = VertexAPI.checkAndParseVertexId(other);
-        E.checkArgument(!current.equals(other),
-                        "The source and target vertex id can't be same");
-        Directions dir = Directions.convert(EdgeAPI.parseDirection(direction));
-
-        HugeGraph g = graph(manager, graph);
-        PredictionTraverser traverser = new PredictionTraverser(g);
-        double score = traverser.adamicAdar(sourceId, targetId, dir,
-                                            edgeLabel, maxDegree, limit);
-        return JsonUtil.toJson(ImmutableMap.of("adamic_adar", score));
-    }
-
-    @GET
-    @Timed
-    @Path("resourceallocation")
     @Produces(APPLICATION_JSON_WITH_CHARSET)
     public String create(@Context GraphManager manager,
                          @PathParam("graph") String graph,

hugegraph-core/src/main/java/com/baidu/hugegraph/traversal/algorithm/PredictionTraverser.java

@@ -19,8 +19,6 @@
 
 package com.baidu.hugegraph.traversal.algorithm;
 
-import static java.lang.Math.log;
-
 import java.util.Set;
 
 import com.baidu.hugegraph.HugeGraph;
@@ -43,9 +41,11 @@ public double adamicAdar(Id source, Id target, Directions dir,
         EdgeStep step = label == null ? new EdgeStep(graph(), dir) :
                         new EdgeStep(graph(), dir, ImmutableList.of(label));
 
-        return neighbors.stream()
-                        .mapToDouble(vid -> 1.0 / log(edgesCount(vid, step)))
-                        .sum();
+        double sum = 0.0;
+        for (Id vid : neighbors) {
+            sum += 1.0 / Math.log(this.edgesCount(vid, step));
+        }
+        return sum;
     }
 
     public double resourceAllocation(Id source, Id target, Directions dir,
@@ -55,9 +55,11 @@ public double resourceAllocation(Id source, Id target, Directions dir,
         EdgeStep step = label == null ? new EdgeStep(graph(), dir) :
                         new EdgeStep(graph(), dir, ImmutableList.of(label));
 
-        return neighbors.stream()
-                        .mapToDouble(vid -> 1.0 / edgesCount(vid, step))
-                        .sum();
+        double sum = 0.0;
+        for (Id vid : neighbors) {
+            sum += 1.0 / this.edgesCount(vid, step);
+        }
+        return sum;
     }
 
     private Set<Id> checkAndGetCommonNeighbors(Id source, Id target,