From 0f9ef0bc57aa0e7d8457b645374be74d510ea7ae Mon Sep 17 00:00:00 2001
Date: Thu, 18 Mar 2021 12:35:14 +0000
Subject: [PATCH 2/4] 8254078: DataOutputStream is very slow post disabling

---
 .../classes/java/io/DataInputStream.java      |   7 +-
 .../classes/java/io/DataOutputStream.java     |  24 ++--
 .../bench/java/io/DataOutputStreamTest.java   | 124 ++++++++++++++++++
 3 files changed, 144 insertions(+), 11 deletions(-)
 create mode 100644 test/micro/org/openjdk/bench/java/io/DataOutputStreamTest.java

diff --git a/src/java.base/share/classes/java/io/DataInputStream.java b/src/java.base/share/classes/java/io/DataInputStream.java
index f92c4f91b..114857691 100644
--- a/src/java.base/share/classes/java/io/DataInputStream.java
+++ b/src/java.base/share/classes/java/io/DataInputStream.java
@@ -31,9 +31,10 @@ package java.io;
  * way. An application uses a data output stream to write data that
  * can later be read by a data input stream.
  * <p>
- * DataInputStream is not necessarily safe for multithreaded access.
- * Thread safety is optional and is the responsibility of users of
- * methods in this class.
+ * A DataInputStream is not safe for use by multiple concurrent
+ * threads. If a DataInputStream is to be used by more than one
+ * thread then access to the data input stream should be controlled
+ * by appropriate synchronization.
  *
  * @author  Arthur van Hoff
  * @see     java.io.DataOutputStream
diff --git a/src/java.base/share/classes/java/io/DataOutputStream.java b/src/java.base/share/classes/java/io/DataOutputStream.java
index 392abba92..7c0962442 100644
--- a/src/java.base/share/classes/java/io/DataOutputStream.java
+++ b/src/java.base/share/classes/java/io/DataOutputStream.java
@@ -29,6 +29,11 @@ package java.io;
  * A data output stream lets an application write primitive Java data
  * types to an output stream in a portable way. An application can
  * then use a data input stream to read the data back in.
+ * <p>
+ * A DataOutputStream is not safe for use by multiple concurrent
+ * threads. If a DataOutputStream is to be used by more than one
+ * thread then access to the data output stream should be controlled
+ * by appropriate synchronization.
  *
  * @author  unascribed
  * @see     java.io.DataInputStream
@@ -164,8 +169,9 @@ class DataOutputStream extends FilterOutputStream implements DataOutput {
      * @see        java.io.FilterOutputStream#out
      */
     public final void writeShort(int v) throws IOException {
-        out.write((v >>> 8) & 0xFF);
-        out.write((v >>> 0) & 0xFF);
+        writeBuffer[0] = (byte)(v >>> 8);
+        writeBuffer[1] = (byte)(v >>> 0);
+        out.write(writeBuffer, 0, 2);
         incCount(2);
     }
 
@@ -179,8 +185,9 @@ class DataOutputStream extends FilterOutputStream implements DataOutput {
      * @see        java.io.FilterOutputStream#out
      */
     public final void writeChar(int v) throws IOException {
-        out.write((v >>> 8) & 0xFF);
-        out.write((v >>> 0) & 0xFF);
+        writeBuffer[0] = (byte)(v >>> 8);
+        writeBuffer[1] = (byte)(v >>> 0);
+        out.write(writeBuffer, 0, 2);
         incCount(2);
     }
 
@@ -194,10 +201,11 @@ class DataOutputStream extends FilterOutputStream implements DataOutput {
      * @see        java.io.FilterOutputStream#out
      */
     public final void writeInt(int v) throws IOException {
-        out.write((v >>> 24) & 0xFF);
-        out.write((v >>> 16) & 0xFF);
-        out.write((v >>>  8) & 0xFF);
-        out.write((v >>>  0) & 0xFF);
+        writeBuffer[0] = (byte)(v >>> 24);
+        writeBuffer[1] = (byte)(v >>> 16);
+        writeBuffer[2] = (byte)(v >>>  8);
+        writeBuffer[3] = (byte)(v >>>  0);
+        out.write(writeBuffer, 0, 4);
         incCount(4);
     }
 
diff --git a/test/micro/org/openjdk/bench/java/io/DataOutputStreamTest.java b/test/micro/org/openjdk/bench/java/io/DataOutputStreamTest.java
new file mode 100644
index 000000000..2f573e6dd
--- /dev/null
+++ b/test/micro/org/openjdk/bench/java/io/DataOutputStreamTest.java
@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2020, Red Hat Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package org.openjdk.bench.java.io;
+
+import org.openjdk.jmh.annotations.*;
+
+import java.io.*;
+import java.util.concurrent.TimeUnit;
+
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MICROSECONDS)
+@Fork(value = 1, warmups = 0)
+@Measurement(iterations = 6, time = 1)
+@Warmup(iterations=2, time = 2)
+@State(Scope.Benchmark)
+public class DataOutputStreamTest {
+
+    public enum BasicType {CHAR, SHORT, INT, STRING}
+    @Param({"CHAR", "SHORT", "INT", /* "STRING"*/}) BasicType basicType;
+
+    @Param({"4096"}) int size;
+
+    final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(size);
+    File f;
+    String outputString;
+    FileOutputStream fileOutputStream;
+    DataOutput bufferedFileStream, rawFileStream, byteArrayStream;
+
+    @Setup(Level.Trial)
+    public void setup() throws Exception {
+        f = File.createTempFile("DataOutputStreamTest","out");
+        fileOutputStream = new FileOutputStream(f);
+        byteArrayStream = new DataOutputStream(byteArrayOutputStream);
+        rawFileStream = new DataOutputStream(fileOutputStream);
+        bufferedFileStream = new DataOutputStream(new BufferedOutputStream(fileOutputStream));
+        outputString = new String(new byte[size]);
+    }
+
+    public void writeChars(DataOutput dataOutput)
+            throws Exception {
+        for (int i = 0; i < size; i += 2) {
+            dataOutput.writeChar(i);
+        }
+    }
+
+    public void writeShorts(DataOutput dataOutput)
+            throws Exception {
+        for (int i = 0; i < size; i += 2) {
+            dataOutput.writeShort(i);
+        }
+    }
+
+    public void writeInts(DataOutput dataOutput)
+            throws Exception {
+        for (int i = 0; i < size; i += 4) {
+            dataOutput.writeInt(i);
+        }
+    }
+
+    public void writeString(DataOutput dataOutput)
+            throws Exception {
+        dataOutput.writeChars(outputString);
+    }
+
+    public void write(DataOutput dataOutput)
+            throws Exception {
+        switch (basicType) {
+            case CHAR:
+                writeChars(dataOutput);
+                break;
+            case SHORT:
+                writeShorts(dataOutput);
+                break;
+            case INT:
+                writeInts(dataOutput);
+                break;
+            case STRING:
+                writeString(dataOutput);
+                break;
+        }
+    }
+
+    @Benchmark
+    public void dataOutputStreamOverByteArray() throws Exception {
+        byteArrayOutputStream.reset();
+        write(byteArrayStream);
+        byteArrayOutputStream.flush();
+    }
+
+    @Benchmark
+    public void dataOutputStreamOverRawFileStream() throws Exception {
+        fileOutputStream.getChannel().position(0);
+        write(rawFileStream);
+        fileOutputStream.flush();
+    }
+
+    @Benchmark
+    public void dataOutputStreamOverBufferedFileStream() throws Exception{
+        fileOutputStream.getChannel().position(0);
+        write(bufferedFileStream);
+        fileOutputStream.flush();
+    }
+}
-- 
2.19.0