[GitHub] [geode] bschuchardt commented on a change in pull request #5525: GEODE-8506: BufferPool returns byte buffers that may be much larger t…

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bschuchardt commented on a change in pull request #5525:
URL: https://github.com/apache/geode/pull/5525#discussion_r491013014



##########
File path: geode-core/src/main/java/org/apache/geode/internal/net/BufferPool.java
##########
@@ -295,19 +302,48 @@ void releaseBuffer(BufferPool.BufferType type, ByteBuffer buffer) {
   /**
    * Releases a previously acquired buffer.
    */
-  private void releaseBuffer(ByteBuffer bb, boolean send) {
-    if (bb.isDirect()) {
-      BBSoftReference bbRef = new BBSoftReference(bb, send);
-      if (bb.capacity() <= SMALL_BUFFER_SIZE) {
+  private void releaseBuffer(ByteBuffer buffer, boolean send) {
+    if (buffer.isDirect()) {
+      buffer = getPoolableBuffer(buffer);
+      BBSoftReference bbRef = new BBSoftReference(buffer, send);
+      if (buffer.capacity() <= SMALL_BUFFER_SIZE) {
         bufferSmallQueue.offer(bbRef);
-      } else if (bb.capacity() <= MEDIUM_BUFFER_SIZE) {
+      } else if (buffer.capacity() <= MEDIUM_BUFFER_SIZE) {
         bufferMiddleQueue.offer(bbRef);
       } else {
         bufferLargeQueue.offer(bbRef);
       }
     } else {
-      updateBufferStats(-bb.capacity(), send, false);
+      updateBufferStats(-buffer.capacity(), send, false);
+    }
+  }
+
+  /**
+   * If we hand out a buffer that is larger than the requested size we create a
+   * "slice" of the buffer having the requested capacity and hand that out instead.
+   * When we put the buffer back in the pool we need to find the original, non-sliced,
+   * buffer. This is held in DirectBuffer in its "attachment" field, which is a public
+   * method, though DirectBuffer is package-private.
+   */
+  @VisibleForTesting
+  public ByteBuffer getPoolableBuffer(ByteBuffer buffer) {

Review comment:
       That seems like an expensive change that would disturb a lot of code.




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