From 653d7c24da01cac9d5b90076f0897fbfe6f1c569 Mon Sep 17 00:00:00 2001
From: jiacheliu3 <jiacheliu3@gmail.com>
Date: Wed, 25 Oct 2023 11:09:37 +0800
Subject: [PATCH 1/3] release buffer

---
 .../java/alluxio/worker/netty/NettyReadHandlerStateMachine.java | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java b/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
index 1caf6fda465e..f638e04c288d 100644
--- a/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
+++ b/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
@@ -672,6 +672,8 @@ private void readData(RequestContext requestContext, Transition<State, TriggerEv
             requestContext.getRequest());
       }
       fireNext(mTriggerEventsWithParam.mOutputLengthFulfilled, requestContext);
+      // Release the packet as there is nothing more to read
+      packet.release();
       return;
     }
     requestContext.increaseReadProgress(packet.readableBytes());

From b1d81cfc07772bb5b2f6e2980fcc41b1e01d1343 Mon Sep 17 00:00:00 2001
From: jiacheliu3 <jiacheliu3@gmail.com>
Date: Thu, 26 Oct 2023 16:17:48 +0800
Subject: [PATCH 2/3] improve code comments and api

---
 .../java/alluxio/worker/netty/AbstractReadHandler.java    | 2 +-
 .../main/java/alluxio/worker/netty/FileReadHandler.java   | 7 ++++---
 .../worker/netty/NettyReadHandlerStateMachine.java        | 8 +++++---
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/dora/core/server/worker/src/main/java/alluxio/worker/netty/AbstractReadHandler.java b/dora/core/server/worker/src/main/java/alluxio/worker/netty/AbstractReadHandler.java
index 437365f4f89b..8bbd439044e6 100644
--- a/dora/core/server/worker/src/main/java/alluxio/worker/netty/AbstractReadHandler.java
+++ b/dora/core/server/worker/src/main/java/alluxio/worker/netty/AbstractReadHandler.java
@@ -157,6 +157,6 @@ interface Factory<T extends ReadRequest, P extends PacketReader<T>> {
      * @param len The length, in bytes, of the data to read from the block
      * @return a {@link DataBuffer} representing the data
      */
-    DataBuffer getDataBuffer(Channel channel, long offset, int len) throws Exception;
+    DataBuffer getOrCreateDataBuffer(Channel channel, long offset, int len) throws Exception;
   }
 }
diff --git a/dora/core/server/worker/src/main/java/alluxio/worker/netty/FileReadHandler.java b/dora/core/server/worker/src/main/java/alluxio/worker/netty/FileReadHandler.java
index f5d5c03925d0..a9dad4f67135 100644
--- a/dora/core/server/worker/src/main/java/alluxio/worker/netty/FileReadHandler.java
+++ b/dora/core/server/worker/src/main/java/alluxio/worker/netty/FileReadHandler.java
@@ -141,7 +141,8 @@ public static final class FilePacketReader implements PacketReader<BlockReadRequ
     }
 
     @Override
-    public DataBuffer getDataBuffer(Channel channel, long offset, int len) throws Exception {
+    public DataBuffer getOrCreateDataBuffer(Channel channel, long offset, int len)
+        throws Exception {
       if (mTransferType == FileTransferType.TRANSFER) {
         if (mReader instanceof PagedFileReader) {
           PagedFileReader pagedFileReader = (PagedFileReader) mReader;
@@ -153,10 +154,10 @@ public DataBuffer getDataBuffer(Channel channel, long offset, int len) throws Ex
               + "is no longer supported in Alluxio 3.x");
         }
       }
-      return getDataBufferByCopying(channel, len);
+      return createDataBufferByCopying(channel, len);
     }
 
-    private DataBuffer getDataBufferByCopying(Channel channel, int len)
+    private DataBuffer createDataBufferByCopying(Channel channel, int len)
         throws IOException {
       ByteBuf buf = channel.alloc().buffer(len, len);
       try {
diff --git a/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java b/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
index f638e04c288d..2905d2aaa394 100644
--- a/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
+++ b/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
@@ -650,7 +650,8 @@ private void readData(RequestContext requestContext, Transition<State, TriggerEv
     PacketReader<ReqT> packetReader = requestContext.getPacketReader(mRequestType);
     final DataBuffer packet;
     try {
-      packet = packetReader.getDataBuffer(mChannel, requestContext.positionRead(), packetSize);
+      packet = packetReader.getOrCreateDataBuffer(
+          mChannel, requestContext.positionRead(), packetSize);
     } catch (Exception e) {
       LOG.error("Failed to read data.", e);
       if (!(e instanceof IOException)) {
@@ -662,6 +663,8 @@ private void readData(RequestContext requestContext, Transition<State, TriggerEv
       return;
     }
     if (packet.readableBytes() == 0) {
+      // The packet can be released when there is nothing more to read
+      packet.release();
       // an empty packet means the underlying storage thinks it's EOF
       if (requestContext.positionRead() != requestContext.positionEnd()) {
         // it's possible that client expects more than what's available
@@ -672,10 +675,9 @@ private void readData(RequestContext requestContext, Transition<State, TriggerEv
             requestContext.getRequest());
       }
       fireNext(mTriggerEventsWithParam.mOutputLengthFulfilled, requestContext);
-      // Release the packet as there is nothing more to read
-      packet.release();
       return;
     }
+    // The packet will be released in sendData() where the channel flushes the response
     requestContext.increaseReadProgress(packet.readableBytes());
     fireNext(mTriggerEventsWithParam.mDataAvailable, requestContext, packet);
   }

From 2cc8dd257c30dea8d7e396fdbd89a6cfef17646f Mon Sep 17 00:00:00 2001
From: jiacheliu3 <jiacheliu3@gmail.com>
Date: Fri, 27 Oct 2023 15:39:19 +0800
Subject: [PATCH 3/3] rename

---
 .../src/main/java/alluxio/worker/netty/AbstractReadHandler.java | 2 +-
 .../src/main/java/alluxio/worker/netty/FileReadHandler.java     | 2 +-
 .../java/alluxio/worker/netty/NettyReadHandlerStateMachine.java | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/dora/core/server/worker/src/main/java/alluxio/worker/netty/AbstractReadHandler.java b/dora/core/server/worker/src/main/java/alluxio/worker/netty/AbstractReadHandler.java
index 8bbd439044e6..2a6261f111ac 100644
--- a/dora/core/server/worker/src/main/java/alluxio/worker/netty/AbstractReadHandler.java
+++ b/dora/core/server/worker/src/main/java/alluxio/worker/netty/AbstractReadHandler.java
@@ -157,6 +157,6 @@ interface Factory<T extends ReadRequest, P extends PacketReader<T>> {
      * @param len The length, in bytes, of the data to read from the block
      * @return a {@link DataBuffer} representing the data
      */
-    DataBuffer getOrCreateDataBuffer(Channel channel, long offset, int len) throws Exception;
+    DataBuffer createDataBuffer(Channel channel, long offset, int len) throws Exception;
   }
 }
diff --git a/dora/core/server/worker/src/main/java/alluxio/worker/netty/FileReadHandler.java b/dora/core/server/worker/src/main/java/alluxio/worker/netty/FileReadHandler.java
index a9dad4f67135..f1dea41c301a 100644
--- a/dora/core/server/worker/src/main/java/alluxio/worker/netty/FileReadHandler.java
+++ b/dora/core/server/worker/src/main/java/alluxio/worker/netty/FileReadHandler.java
@@ -141,7 +141,7 @@ public static final class FilePacketReader implements PacketReader<BlockReadRequ
     }
 
     @Override
-    public DataBuffer getOrCreateDataBuffer(Channel channel, long offset, int len)
+    public DataBuffer createDataBuffer(Channel channel, long offset, int len)
         throws Exception {
       if (mTransferType == FileTransferType.TRANSFER) {
         if (mReader instanceof PagedFileReader) {
diff --git a/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java b/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
index 2905d2aaa394..ce0e63040901 100644
--- a/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
+++ b/dora/core/server/worker/src/main/java/alluxio/worker/netty/NettyReadHandlerStateMachine.java
@@ -650,7 +650,7 @@ private void readData(RequestContext requestContext, Transition<State, TriggerEv
     PacketReader<ReqT> packetReader = requestContext.getPacketReader(mRequestType);
     final DataBuffer packet;
     try {
-      packet = packetReader.getOrCreateDataBuffer(
+      packet = packetReader.createDataBuffer(
           mChannel, requestContext.positionRead(), packetSize);
     } catch (Exception e) {
       LOG.error("Failed to read data.", e);