Merge pull request #434 from kmgowda/kmg-cq-1

Atomic queue and CQueue performance optimisations Signed-off-by: Keshava Munegowda <keshava.gowda@gmail.com>
kmgowda · May 31, 2024 · 5f9e836 · 5f9e836
2 parents 1d9aa61 + 46587eb
commit 5f9e836
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Showing 2 changed files with 40 additions and 4 deletions.
diff --git a/perl/src/main/java/io/perl/api/impl/AtomicQueue.java b/perl/src/main/java/io/perl/api/impl/AtomicQueue.java
@@ -41,8 +41,7 @@ public AtomicQueue() {
         this.tail = new AtomicReference<>(firstNode);
     }
 
-    @Override
-    public T poll() {
+    public T pollOnce() {
         final Node<T> curHead = head.getAndSet(null);
         if (curHead == null) {
             return null;
@@ -56,6 +55,25 @@ public T poll() {
         return nxt.item;
     }
 
+    @Override
+    public T poll() {
+        Node<T> curHead = head.get();
+        Node<T> nxt = curHead.next.get();
+
+        while ( nxt != null && !head.compareAndSet(curHead, nxt) ) {
+            curHead = head.get();
+            nxt = curHead.next.get();
+        }
+
+        if (nxt == null) {
+            return null;
+        }
+        curHead.next.set(null);
+
+        return nxt.item;
+    }
+
+
     @Override
     public boolean add(T data) {
         final Node<T> node = new Node<>(data);
@@ -66,6 +84,7 @@ public boolean add(T data) {
 
     @Override
     public void clear() {
+        firstNode.next.set(null);
         Node<T> first = head.getAndSet(firstNode);
         tail.set(first);
         /*

diff --git a/perl/src/main/java/io/perl/api/impl/CQueue.java b/perl/src/main/java/io/perl/api/impl/CQueue.java
@@ -58,8 +58,7 @@ public CQueue() {
         this.tail = firstNode;
     }
 
-    @Override
-    public T poll() {
+    public T pollOnce() {
         final Object cur = NEXT.getAndSet(head, null);
         if (cur == null) {
             return null;
@@ -68,6 +67,23 @@ public T poll() {
         return (T) ITEM.getAndSet(cur, null);
     }
 
+    @Override
+    public T poll() {
+        Object curHead = HEAD.get(this);
+        Object nxt = NEXT.get(curHead);
+
+        while (nxt != null && !HEAD.compareAndSet(this, curHead, nxt)) {
+            curHead = HEAD.get(this);
+            nxt = NEXT.get(curHead);
+        }
+
+        if (nxt == null) {
+            return null;
+        }
+        NEXT.set(curHead, null);
+        return (T) ITEM.getAndSet(nxt, null);
+    }
+
     @Override
     public boolean add(T data) {
         final Node<T> node = new Node<>(data);
@@ -78,6 +94,7 @@ public boolean add(T data) {
 
     @Override
     public void clear() {
+        NEXT.set(firstNode, null);
         Object first = HEAD.getAndSet(this, firstNode);
         TAIL.set(this, firstNode);
         /*