Added opaque methods to Position (#324)

agrona/src/main/java/org/agrona/concurrent/status/AtomicLongPosition.java

@@ -88,12 +88,22 @@ public long getVolatile()
         return value.get();
     }
 
-    @Override
+    /**
+     * {@inheritDoc}
+     */
     public long getAcquire()
     {
         return value.getAcquire();
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public long getOpaque()
+    {
+        return value.getOpaque();
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -102,6 +112,14 @@ public void set(final long value)
         this.value.setPlain(value);
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public void setOpaque(final long value)
+    {
+        this.value.setOpaque(value);
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -158,6 +176,22 @@ public boolean proposeMaxRelease(final long proposedValue)
         return updated;
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public boolean proposeMaxOpaque(final long proposedValue)
+    {
+        boolean updated = false;
+
+        if (value.get() < proposedValue)
+        {
+            value.setOpaque(proposedValue);
+            updated = true;
+        }
+
+        return updated;
+    }
+
     /**
      * {@inheritDoc}
      */

agrona/src/main/java/org/agrona/concurrent/status/Position.java

@@ -18,7 +18,7 @@
 /**
  * Reports on how far through a buffer some component has progressed.
  * <p>
- * Threadsafe to write to from a single writer.
+ * Threadsafe to write to from a single writer unless methods with plain memory semantics are used.
  */
 public abstract class Position extends ReadablePosition
 {
@@ -36,19 +36,19 @@ public Position()
      */
     public abstract boolean isClosed();
 
-    /**
-     * Get the current position of a component with plain memory ordering semantics.
+     /**
+     * Get the current position of a component with plain memory semantics.
      *
      * @return the current position of a component
      */
     public abstract long get();
 
     /**
-     * Sets the current position of the component without memory ordering semantics.
+     * Sets the current position of the component with volatile memory semantics.
      *
      * @param value the current position of the component.
      */
-    public abstract void set(long value);
+    public abstract void setVolatile(long value);
 
     /**
      * Sets the current position of the component with ordered memory semantics.
@@ -68,22 +68,30 @@ public Position()
     public abstract void setRelease(long value);
 
     /**
-     * Sets the current position of the component with volatile memory semantics.
+     * Sets the current position of the component with opaque memory semantics.
      *
      * @param value the current position of the component.
+     * @since 2.1.0
      */
-    public abstract void setVolatile(long value);
+    public abstract void setOpaque(long value);
+
+    /**
+     * Sets the current position of the component plain memory semantics.
+     *
+     * @param value the current position of the component.
+     */
+    public abstract void set(long value);
 
     /**
-     * Set the position to a new proposedValue if greater than the current value without memory ordering semantics.
+     * Set the position to a new proposedValue if greater than the current value with plain memory semantics.
      *
      * @param proposedValue for the new max.
      * @return true if a new max as been set otherwise false.
      */
     public abstract boolean proposeMax(long proposedValue);
 
     /**
-     * Set the position to the new proposedValue if greater than the current value with memory ordering semantics.
+     * Set the position to the new proposedValue if greater than the current value with release memory semantics.
      * <p>
      * This method is identical to {@link #proposeMaxRelease(long)} and that method should be preferred instead.
      *
@@ -93,11 +101,20 @@ public Position()
     public abstract boolean proposeMaxOrdered(long proposedValue);
 
     /**
-     * Set the position to the new proposedValue if greater than the current value with release memory ordering
+     * Set the position to the new proposedValue if greater than the current value with release memory
      * semantics.
      *
      * @param proposedValue for the new max.
      * @return true if a new max as been set otherwise false.
      */
     public abstract boolean proposeMaxRelease(long proposedValue);
+
+    /**
+     * Set the position to the new proposedValue if greater than the current value with opaque memory
+     * semantics.
+     *
+     * @param proposedValue for the new max.
+     * @return true if a new max as been set otherwise false.
+     */
+    public abstract boolean proposeMaxOpaque(long proposedValue);
 }

agrona/src/main/java/org/agrona/concurrent/status/ReadablePosition.java

@@ -35,20 +35,28 @@ public ReadablePosition()
     public abstract int id();
 
     /**
-     * Get the current position of a component with volatile semantics.
+     * Get the current position of a component with volatile memory semantics.
      *
-     * @return the current position of a component with volatile semantics.
+     * @return the current position of a component.
      */
     public abstract long getVolatile();
 
     /**
-     * Get the current position of a component with acquire semantics.
+     * Get the current position of a component with acquire memory semantics.
      *
      * @return the current position of a component.
      * @since 2.1.0
      */
     public abstract long getAcquire();
 
+    /**
+     * Get the current position of a component with opaque memory semantics.
+     *
+     * @return the current position of a component
+     * @since 2.1.0
+     */
+    public abstract long getOpaque();
+
     /**
      * {@inheritDoc}
      */

agrona/src/main/java/org/agrona/concurrent/status/UnsafeBufferPosition.java

@@ -86,33 +86,41 @@ public int id()
     /**
      * {@inheritDoc}
      */
-    public long get()
+    public long getVolatile()
     {
-        return UnsafeApi.getLong(byteArray, addressOffset);
+        return UnsafeApi.getLongVolatile(byteArray, addressOffset);
     }
 
     /**
      * {@inheritDoc}
      */
-    public long getVolatile()
+    public long getAcquire()
     {
-        return UnsafeApi.getLongVolatile(byteArray, addressOffset);
+        return UnsafeApi.getLongAcquire(byteArray, addressOffset);
     }
 
     /**
      * {@inheritDoc}
      */
-    public long getAcquire()
+    public long getOpaque()
     {
-        return UnsafeApi.getLongAcquire(byteArray, addressOffset);
+        return UnsafeApi.getLongOpaque(byteArray, addressOffset);
     }
 
     /**
      * {@inheritDoc}
      */
-    public void set(final long value)
+    public long get()
     {
-        UnsafeApi.putLong(byteArray, addressOffset, value);
+        return UnsafeApi.getLong(byteArray, addressOffset);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public void setVolatile(final long value)
+    {
+        UnsafeApi.putLongVolatile(byteArray, addressOffset, value);
     }
 
     /**
@@ -134,11 +142,20 @@ public void setRelease(final long value)
     /**
      * {@inheritDoc}
      */
-    public void setVolatile(final long value)
+    public void setOpaque(final long value)
     {
-        UnsafeApi.putLongVolatile(byteArray, addressOffset, value);
+        UnsafeApi.putLongOpaque(byteArray, addressOffset, value);
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public void set(final long value)
+    {
+        UnsafeApi.putLong(byteArray, addressOffset, value);
+    }
+
+
     /**
      * {@inheritDoc}
      */
@@ -183,6 +200,24 @@ public boolean proposeMaxRelease(final long proposedValue)
         return updated;
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public boolean proposeMaxOpaque(final long proposedValue)
+    {
+        boolean updated = false;
+
+        final byte[] array = byteArray;
+        final long offset = addressOffset;
+        if (UnsafeApi.getLong(array, offset) < proposedValue)
+        {
+            UnsafeApi.putLongOpaque(array, offset, proposedValue);
+            updated = true;
+        }
+
+        return updated;
+    }
+
     /**
      * {@inheritDoc}
      */