From 182ffdaf6d4c067514fc70b00c4a5abc67753531 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Sat, 18 Aug 2018 21:09:17 +0200
Subject: [PATCH] Only use manual safepoint polling in
 PlatformDependent0.copyMemory(...) when using java <= 8 (#8124)

Motivation:

Java9 and later does the safepoint polling by itself so there is not need for us to do it.

Modifications:

Check for java version before doing manual safepoint polling.

Result:

Less custom code and less overhead when using java9 and later. Fixes https://github.com/netty/netty/issues/8122.
---
 .../util/internal/PlatformDependent0.java     | 23 +++++++++++++++++--
 1 file changed, 21 insertions(+), 2 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 c6ebb55131..53e9ed7bdc 100644
--- a/common/src/main/java/io/netty/util/internal/PlatformDependent0.java
+++ b/common/src/main/java/io/netty/util/internal/PlatformDependent0.java
@@ -550,7 +550,16 @@ final class PlatformDependent0 {
     }
 
     static void copyMemory(long srcAddr, long dstAddr, long length) {
-        //UNSAFE.copyMemory(srcAddr, dstAddr, length);
+        // Manual safe-point polling is only needed prior Java9:
+        // See https://bugs.openjdk.java.net/browse/JDK-8149596
+        if (javaVersion() <= 8) {
+            copyMemoryWithSafePointPolling(srcAddr, dstAddr, length);
+        } else {
+            UNSAFE.copyMemory(srcAddr, dstAddr, length);
+        }
+    }
+
+    private static void copyMemoryWithSafePointPolling(long srcAddr, long dstAddr, long length) {
         while (length > 0) {
             long size = Math.min(length, UNSAFE_COPY_THRESHOLD);
             UNSAFE.copyMemory(srcAddr, dstAddr, size);
@@ -561,7 +570,17 @@ final class PlatformDependent0 {
     }
 
     static void copyMemory(Object src, long srcOffset, Object dst, long dstOffset, long length) {
-        //UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, length);
+        // Manual safe-point polling is only needed prior Java9:
+        // See https://bugs.openjdk.java.net/browse/JDK-8149596
+        if (javaVersion() <= 8) {
+            copyMemoryWithSafePointPolling(src, srcOffset, dst, dstOffset, length);
+        } else {
+            UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, length);
+        }
+    }
+
+    private static void copyMemoryWithSafePointPolling(
+            Object src, long srcOffset, Object dst, long dstOffset, long length) {
         while (length > 0) {
             long size = Math.min(length, UNSAFE_COPY_THRESHOLD);
             UNSAFE.copyMemory(src, srcOffset, dst, dstOffset, size);