From 7252934f9b133e3c120bc0f9480e09bd03f83ce5 Mon Sep 17 00:00:00 2001
From: Trustin Lee <t@motd.kr>
Date: Tue, 20 May 2014 17:16:15 +0900
Subject: [PATCH] Limit the number of bytes to copy per Unsafe.copyMemory()

Motivation:

During a large memory copy, safepoint polling is diabled, hindering
accurate profiling.

Modifications:

Only copy up to 1 MiB per Unsafe.copyMemory()

Result:

Potentially more reliable performance
---
 .../util/internal/PlatformDependent0.java     | 31 +++++++++++++++----
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/common/src/main/java/io/netty/util/internal/PlatformDependent0.java b/common/src/main/java/io/netty/util/internal/PlatformDependent0.java
index 9c4ca1cf72..ad22ace2a7 100644
--- a/common/src/main/java/io/netty/util/internal/PlatformDependent0.java
+++ b/common/src/main/java/io/netty/util/internal/PlatformDependent0.java
@@ -42,6 +42,13 @@ final class PlatformDependent0 {
     private static final boolean BIG_ENDIAN = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN;
     private static final long ADDRESS_FIELD_OFFSET;
 
+    /**
+     * Limits the number of bytes to copy per {@link Unsafe#copyMemory(long, long, long)} to allow safepoint polling
+     * during a large copy.
+     */
+    private static final long UNSAFE_COPY_THRESHOLD = 1024L * 1024L;
+
+
     /**
      * {@code true} if and only if the platform supports unaligned access.
      *
@@ -155,11 +162,9 @@ final class PlatformDependent0 {
         }
         try {
             Cleaner cleaner = ((DirectBuffer) buffer).cleaner();
-            if (cleaner == null) {
-                throw new IllegalArgumentException(
-                        "attempted to deallocate the buffer which was allocated via JNIEnv->NewDirectByteBuffer()");
+            if (cleaner != null) {
+                cleaner.clean();
             }
-            cleaner.clean();
         } catch (Throwable t) {
             // Nothing we can do here.
         }
@@ -308,11 +313,25 @@ final class PlatformDependent0 {
     }
 
     static void copyMemory(long srcAddr, long dstAddr, long length) {
-        UNSAFE.copyMemory(srcAddr, dstAddr, length);
+        //UNSAFE.copyMemory(srcAddr, dstAddr, length);
+        while (length > 0) {
+            long size = Math.min(length, UNSAFE_COPY_THRESHOLD);
+            UNSAFE.copyMemory(srcAddr, dstAddr, size);
+            length -= size;
+            srcAddr += size;
+            dstAddr += size;
+        }
     }
 
     static void copyMemory(Object src, long srcOffset, Object dst, long dstOffset, long length) {
-        UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, length);
+        //UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, length);
+        while (length > 0) {
+            long size = Math.min(length, UNSAFE_COPY_THRESHOLD);
+            UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, size);
+            length -= size;
+            srcOffset += size;
+            dstOffset += size;
+        }
     }
 
     static <U, W> AtomicReferenceFieldUpdater<U, W> newAtomicReferenceFieldUpdater(