程序清单 14-2 有界缓存实现的基类

Author: zhangquanli

src/main/java/chapter_14/code_02/BaseBoundedBuffer.java

@@ -0,0 +1,49 @@
+package chapter_14.code_02;
+
+import net.jcip.annotations.GuardedBy;
+import net.jcip.annotations.ThreadSafe;
+
+/**
+ * 程序清单 14-2 有界缓存实现的基类
+ */
+@ThreadSafe
+public class BaseBoundedBuffer<V> {
+    @GuardedBy("this")
+    private final V[] buf;
+    @GuardedBy("this")
+    private int tail;
+    @GuardedBy("this")
+    private int head;
+    @GuardedBy("this")
+    private int count;
+
+    protected BaseBoundedBuffer(int capacity) {
+        this.buf = (V[]) new Object[capacity];
+    }
+
+    protected synchronized final void doPut(V v) {
+        buf[tail] = v;
+        if (++tail == buf.length) {
+            tail = 0;
+        }
+        ++count;
+    }
+
+    protected synchronized final V doTake() {
+        V v = buf[head];
+        buf[head] = null;
+        if (++head == buf.length) {
+            head = 0;
+        }
+        --count;
+        return v;
+    }
+
+    public synchronized final boolean isFull() {
+        return count == buf.length;
+    }
+
+    public synchronized final boolean isEmpty() {
+        return count == 0;
+    }
+}