From a351c9acd95495387aaa4bf0a60895f9d119c6d8 Mon Sep 17 00:00:00 2001
From: Luke Wahlmeier <lwahlmeier@gmail.com>
Date: Tue, 30 May 2017 15:01:10 -0600
Subject: [PATCH] Fixed issue with toArray on value/keySet in ConcurrentHashMap

---
 classpath/avian/Data.java       | 10 ++++++----
 test/ConcurrentHashMapTest.java | 29 +++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/classpath/avian/Data.java b/classpath/avian/Data.java
index 0914362e8..727fe3047 100644
--- a/classpath/avian/Data.java
+++ b/classpath/avian/Data.java
@@ -15,7 +15,6 @@
 import java.util.AbstractSet;
 import java.util.Collection;
 import java.util.Iterator;
-import java.util.Collections;
 
 public class Data {
   public static int nextPowerOfTwo(int n) {
@@ -28,10 +27,10 @@ public static <V> boolean equal(V a, V b) {
     return a == null ? b == null : a.equals(b);
   }
 
-  public static <T> T[] toArray(Collection collection, T[] array) {
+  public static <T> T[] toArray(Collection<?> collection, T[] array) {
     Class c = array.getClass().getComponentType();
-
-    if (array.length < collection.size()) {
+    int Csize = collection.size();
+    if (array.length < Csize) {
       array = (T[]) java.lang.reflect.Array.newInstance(c, collection.size());
     }
 
@@ -39,6 +38,9 @@ public static <T> T[] toArray(Collection collection, T[] array) {
     for (Object o: collection) {
       if (c.isInstance(o)) {
         array[i++] = (T) o;
+        if(Csize <= i) {
+          break;
+        }
       } else {
         throw new ArrayStoreException();
       }
diff --git a/test/ConcurrentHashMapTest.java b/test/ConcurrentHashMapTest.java
index f0d271f41..70f77a9c7 100644
--- a/test/ConcurrentHashMapTest.java
+++ b/test/ConcurrentHashMapTest.java
@@ -1,5 +1,7 @@
 import java.util.Iterator;
 import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -13,6 +15,31 @@ private static void expect(boolean v) {
     if (! v) throw new RuntimeException();
   }
 
+  private static void toArrayConcurrentMod() {
+    final AtomicBoolean run = new AtomicBoolean(true);
+    final Random RND = new Random();
+    final ConcurrentHashMap<Integer, Integer> map = new ConcurrentHashMap<Integer, Integer>();
+    Thread t = new Thread(new Runnable() {
+      @Override
+      public void run() {
+        while(run.get()) {
+          map.put(RND.nextInt(), RND.nextInt());
+          while(map.size() > 500) {
+            for(Integer i: map.keySet()) {
+              map.remove(i);
+              break;
+            }
+          }
+        }
+      }});
+    t.setDaemon(true);
+    t.start();
+    for(int i=0; i<1000; i++) {
+      map.values().toArray();
+    }
+    run.set(false);
+  }
+
   public static void main(String[] args) throws Throwable {
     final ConcurrentMap<Integer, Object> map = new ConcurrentHashMap();
     final int[] counter = new int[1];
@@ -103,6 +130,8 @@ public void run() {
         map.notifyAll();
       }
     }
+
+    toArrayConcurrentMod();
   }
 
   private static void populateCommon(ConcurrentMap<Integer, Object> map) {