Implemented get() and get() for lists, plus tests

src/org/jgroups/util/RingBuffer.java

@@ -146,6 +146,36 @@ public List<T> removeMany(boolean nullify, int max_results) {
         return list;
     }
 
+    public T get(long seqno) {
+        validate(seqno);
+        if(seqno <= low || seqno > hr.get())
+            return null;
+        int index=index(seqno);
+        return buf.get(index);
+    }
+
+    /**
+     * Returns a list of messages in the range [from .. to], including from and to
+     * @param from
+     * @param to
+     * @return A list of messages, or null if none in range [from .. to] was found
+     */
+    public List<T> get(long from, long to) {
+        if(from > to)
+            throw new IllegalArgumentException("from (" + from + ") has to be <= to (" + to + ")");
+        validate(from);
+        List<T> retval=null;
+        for(long i=from; i <= to; i++) {
+            T element=get(i);
+            if(element != null) {
+                if(retval == null)
+                    retval=new ArrayList<T>();
+                retval.add(element);
+            }
+        }
+        return retval;
+    }
+
 
     /** Nulls elements between low and seqno and forwards low */
     public void stable(long seqno) {
@@ -179,14 +209,8 @@ public void destroy() {
     }
 
     public final int capacity() {return buf.length();}
-
-    public int size() {
-        return count(false);
-    }
-
-    public int missing() {
-        return count(true);
-    }
+    public int       size()     {return count(false);}
+    public int       missing()  {return count(true);}
 
     public SeqnoList getMissing() {
         SeqnoList missing=null;
@@ -218,6 +242,7 @@ public String toString() {
     }
 
 
+
     protected static final void validate(long seqno) {
         if(seqno < 0)
             throw new IllegalArgumentException("seqno " + seqno + " cannot be negative");
@@ -235,7 +260,6 @@ protected boolean block(long seqno) {
                     buffer_full.await();
                 }
                 catch(InterruptedException e) {
-                    ;
                 }
             }
             return running;

tests/junit-functional/org/jgroups/tests/RingBufferTest.java

@@ -7,6 +7,7 @@
 import org.testng.annotations.Test;
 
 import java.util.Arrays;
+import java.util.List;
 import java.util.concurrent.CountDownLatch;
 
 /**
@@ -167,6 +168,35 @@ public void run() {
         assert buf.missing() == 0;
     }
 
+    public void testGet() {
+        final RingBuffer<Integer> buf=new RingBuffer<Integer>(10, 0);
+        for(int i: Arrays.asList(1,2,3,4,5))
+            buf.add(i, i);
+        assert buf.get(0) == null;
+        assert buf.get(1) == 1;
+        assert buf.get(10) == null;
+        assert buf.get(5) == 5;
+        assert buf.get(6) == null;
+    }
+
+    public void testGetList() {
+        final RingBuffer<Integer> buf=new RingBuffer<Integer>(10, 0);
+        for(int i: Arrays.asList(1,2,3,4,5))
+            buf.add(i, i);
+        List<Integer> elements=buf.get(3,5);
+        System.out.println("elements = " + elements);
+        assert elements != null && elements.size() == 3;
+        assert elements.contains(3) && elements.contains(4) && elements.contains(5);
+
+        elements=buf.get(4, 10);
+        System.out.println("elements = " + elements);
+        assert elements != null && elements.size() == 2;
+        assert elements.contains(4) && elements.contains(5);
+
+        elements=buf.get(10, 20);
+        assert elements == null;
+    }
+
     public void testRemovedPastHighestReceived() {
         RingBuffer<Integer> buf=new RingBuffer<Integer>(10, 0);
         for(int i=1; i <= 15; i++) {
@@ -187,7 +217,24 @@ public void testRemovedPastHighestReceived() {
     }
 
     public void testRemoveMany() {
-
+        RingBuffer<Integer> buf=new RingBuffer<Integer>(10, 0);
+        for(int i: Arrays.asList(1,2,3,4,5,6,7,9,10))
+            buf.add(i, i);
+        List<Integer> list=buf.removeMany(false,3);
+        System.out.println("list = " + list);
+        assert list != null && list.size() == 3;
+
+        list=buf.removeMany(false, 20);
+        System.out.println("list = " + list);
+        assert list != null && list.size() == 4;
+
+        list=buf.removeMany(false, 10);
+        assert list == null;
+
+        buf.add(8, 8);
+        list=buf.removeMany(false, 10);
+        System.out.println("list = " + list);
+        assert list != null && list.size() == 3;
     }