standardize semantics of all mergers,enhance mergeFactory and testcase

luchy0120 · luchy0120 · commit 9761fbc09d1a · 2018-12-12T12:52:31.000+08:00
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/ArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/ArrayMerger.java
@@ -16,6 +16,7 @@
  */
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 import java.lang.reflect.Array;
@@ -25,34 +26,48 @@ public class ArrayMerger implements Merger<Object[]> {
     public static final ArrayMerger INSTANCE = new ArrayMerger();
 
     @Override
-    public Object[] merge(Object[]... others) {
-        if (others.length == 0) {
-            return null;
+    public Object[] merge(Object[]... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return new Object[0];
         }
+
+        int i = 0;
+        while (i < items.length && items[i] == null) {
+            i++;
+        }
+
+        if (i == items.length) {
+            return new Object[0];
+        }
+
+        Class<?> type = items[i].getClass().getComponentType();
+
         int totalLen = 0;
-        for (int i = 0; i < others.length; i++) {
-            Object item = others[i];
-            if (item != null && item.getClass().isArray()) {
-                totalLen += Array.getLength(item);
-            } else {
-                throw new IllegalArgumentException((i + 1) + "th argument is not an array");
+        for (; i < items.length; i++) {
+            if (items[i] == null) {
+                continue;
+            }
+            Class<?> itemType = items[i].getClass().getComponentType();
+            if (itemType != type) {
+                throw new IllegalArgumentException("Arguments' types are different");
             }
+            totalLen += items[i].length;
         }
 
         if (totalLen == 0) {
-            return null;
+            return new Object[0];
         }
 
-        Class<?> type = others[0].getClass().getComponentType();
-
         Object result = Array.newInstance(type, totalLen);
+
         int index = 0;
-        for (Object array : others) {
-            for (int i = 0; i < Array.getLength(array); i++) {
-                Array.set(result, index++, Array.get(array, i));
+        for (Object[] array : items) {
+            if (array != null) {
+                for (int j = 0; j < array.length; j++) {
+                    Array.set(result, index++, array[j]);
+                }
             }
         }
         return (Object[]) result;
     }
-
 }
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/BooleanArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/BooleanArrayMerger.java
@@ -17,21 +17,29 @@
 
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 public class BooleanArrayMerger implements Merger<boolean[]> {
 
     @Override
     public boolean[] merge(boolean[]... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return new boolean[0];
+        }
         int totalLen = 0;
         for (boolean[] array : items) {
-            totalLen += array.length;
+            if (array != null) {
+                totalLen += array.length;
+            }
         }
         boolean[] result = new boolean[totalLen];
         int index = 0;
         for (boolean[] array : items) {
-            for (boolean item : array) {
-                result[index++] = item;
+            if (array != null) {
+                for (boolean item : array) {
+                    result[index++] = item;
+                }
             }
         }
         return result;
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/ByteArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/ByteArrayMerger.java
@@ -17,21 +17,29 @@
 
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 public class ByteArrayMerger implements Merger<byte[]> {
 
     @Override
     public byte[] merge(byte[]... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return new byte[0];
+        }
         int total = 0;
         for (byte[] array : items) {
-            total += array.length;
+            if (array != null) {
+                total += array.length;
+            }
         }
         byte[] result = new byte[total];
         int index = 0;
         for (byte[] array : items) {
-            for (byte item : array) {
-                result[index++] = item;
+            if (array != null) {
+                for (byte item : array) {
+                    result[index++] = item;
+                }
             }
         }
         return result;
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/CharArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/CharArrayMerger.java
@@ -17,21 +17,29 @@
 
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 public class CharArrayMerger implements Merger<char[]> {
 
     @Override
     public char[] merge(char[]... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return new char[0];
+        }
         int total = 0;
         for (char[] array : items) {
-            total += array.length;
+            if (array != null) {
+                total += array.length;
+            }
         }
         char[] result = new char[total];
         int index = 0;
         for (char[] array : items) {
-            for (char item : array) {
-                result[index++] = item;
+            if (array != null) {
+                for (char item : array) {
+                    result[index++] = item;
+                }
             }
         }
         return result;
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/DoubleArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/DoubleArrayMerger.java
@@ -17,21 +17,29 @@
 
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 public class DoubleArrayMerger implements Merger<double[]> {
 
     @Override
     public double[] merge(double[]... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return new double[0];
+        }
         int total = 0;
         for (double[] array : items) {
-            total += array.length;
+            if (array != null) {
+                total += array.length;
+            }
         }
         double[] result = new double[total];
         int index = 0;
         for (double[] array : items) {
-            for (double item : array) {
-                result[index++] = item;
+            if (array != null) {
+                for (double item : array) {
+                    result[index++] = item;
+                }
             }
         }
         return result;
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/FloatArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/FloatArrayMerger.java
@@ -17,21 +17,29 @@
 
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 public class FloatArrayMerger implements Merger<float[]> {
 
     @Override
     public float[] merge(float[]... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return new float[0];
+        }
         int total = 0;
         for (float[] array : items) {
-            total += array.length;
+            if (array != null) {
+                total += array.length;
+            }
         }
         float[] result = new float[total];
         int index = 0;
         for (float[] array : items) {
-            for (float item : array) {
-                result[index++] = item;
+            if (array != null) {
+                for (float item : array) {
+                    result[index++] = item;
+                }
             }
         }
         return result;
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/IntArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/IntArrayMerger.java
@@ -17,21 +17,29 @@
 
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 public class IntArrayMerger implements Merger<int[]> {
 
     @Override
     public int[] merge(int[]... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return new int[0];
+        }
         int totalLen = 0;
-        for (int[] item : items) {
-            totalLen += item.length;
+        for (int[] array : items) {
+            if (array != null) {
+                totalLen += array.length;
+            }
         }
         int[] result = new int[totalLen];
         int index = 0;
-        for (int[] item : items) {
-            for (int i : item) {
-                result[index++] = i;
+        for (int[] array : items) {
+            if (array != null) {
+                for (int item : array) {
+                    result[index++] = item;
+                }
             }
         }
         return result;
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/ListMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/ListMerger.java
@@ -17,15 +17,20 @@
 
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class ListMerger implements Merger<List<?>> {
 
     @Override
     public List<Object> merge(List<?>... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return Collections.emptyList();
+        }
         List<Object> result = new ArrayList<Object>();
         for (List<?> item : items) {
             if (item != null) {
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/LongArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/LongArrayMerger.java
@@ -17,21 +17,29 @@
 
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
 public class LongArrayMerger implements Merger<long[]> {
 
     @Override
     public long[] merge(long[]... items) {
+        if (ArrayUtils.isEmpty(items)) {
+            return new long[0];
+        }
         int total = 0;
         for (long[] array : items) {
-            total += array.length;
+            if (array != null) {
+                total += array.length;
+            }
         }
         long[] result = new long[total];
         int index = 0;
         for (long[] array : items) {
-            for (long item : array) {
-                result[index++] = item;
+            if (array != null) {
+                for (long item : array) {
+                    result[index++] = item;
+                }
             }
         }
         return result;
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/MapMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/MapMerger.java
@@ -16,17 +16,19 @@
  */
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
 public class MapMerger implements Merger<Map<?, ?>> {
 
     @Override
     public Map<?, ?> merge(Map<?, ?>... items) {
-        if (items.length == 0) {
-            return null;
+        if (ArrayUtils.isEmpty(items)) {
+            return Collections.emptyMap();
         }
         Map<Object, Object> result = new HashMap<Object, Object>();
         for (Map<?, ?> item : items) {
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/MergerFactory.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/MergerFactory.java
@@ -30,7 +30,19 @@ public class MergerFactory {
     private static final ConcurrentMap<Class<?>, Merger<?>> mergerCache =
             new ConcurrentHashMap<Class<?>, Merger<?>>();
 
+    /**
+     * Find the merger according to the returnType class, the merger will
+     * merge an array of returnType into one
+     *
+     * @param returnType the merger will return this type
+     * @return the merger which merges an array of returnType into one, return null if not exist
+     * @throws IllegalArgumentException if returnType is null
+     */
     public static <T> Merger<T> getMerger(Class<T> returnType) {
+        if (returnType == null) {
+            throw new IllegalArgumentException("returnType is null");
+        }
+
         Merger result;
         if (returnType.isArray()) {
             Class type = returnType.getComponentType();
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/SetMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/SetMerger.java
@@ -16,16 +16,20 @@
  */
 package org.apache.dubbo.rpc.cluster.merger;
 
+import org.apache.dubbo.common.utils.ArrayUtils;
 import org.apache.dubbo.rpc.cluster.Merger;
 
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
 
 public class SetMerger implements Merger<Set<?>> {
 
     @Override
     public Set<Object> merge(Set<?>... items) {
-
+        if (ArrayUtils.isEmpty(items)) {
+            return Collections.emptySet();
+        }
         Set<Object> result = new HashSet<Object>();
 
         for (Set<?> item : items) {
diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/ShortArrayMerger.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/merger/ShortArrayMerger.java
diff --git a/dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/merger/ResultMergerTest.java b/dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/merger/ResultMergerTest.java
