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409953 More efficient implementation of BufferUtil.writeTo(...)

This commit is contained in:
Thomas Becker 2013-06-06 11:39:07 +02:00 committed by Joakim Erdfelt
parent 5b60d42d3a
commit 7792c1dad7
2 changed files with 99 additions and 20 deletions
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51
jetty-util/src/main/java/org/eclipse/jetty/util/BufferUtil.java
View File

@ -84,6 +84,7 @@ import java.nio.charset.Charset;
*/
public class BufferUtil
{
static final int TEMP_BUFFER_SIZE = 4096;
static final byte SPACE = 0x20;
static final byte MINUS = '-';
static final byte[] DIGIT =
@ -96,7 +97,7 @@ public class BufferUtil
/** Allocate ByteBuffer in flush mode.
* The position and limit will both be zero, indicating that the buffer is
* empty and must be flipped before any data is put to it.
* @param capacity
* @param capacity capacity of the allocated ByteBuffer
* @return Buffer
*/
public static ByteBuffer allocate(int capacity)
@ -110,7 +111,7 @@ public class BufferUtil
/** Allocate ByteBuffer in flush mode.
* The position and limit will both be zero, indicating that the buffer is
* empty and in flush mode.
* @param capacity
* @param capacity capacity of the allocated ByteBuffer
* @return Buffer
*/
public static ByteBuffer allocateDirect(int capacity)
@ -264,7 +265,7 @@ public class BufferUtil
/* ------------------------------------------------------------ */
/** Get the space from the limit to the capacity
* @param buffer
* @param buffer the buffer to get the space from
* @return space
*/
public static int space(ByteBuffer buffer)
@ -276,7 +277,7 @@ public class BufferUtil
/* ------------------------------------------------------------ */
/** Compact the buffer
* @param buffer
* @param buffer the buffer to compact
* @return true if the compact made a full buffer have space
*/
public static boolean compact(ByteBuffer buffer)
@ -404,7 +405,7 @@ public class BufferUtil
/* ------------------------------------------------------------ */
public static void readFrom(File file, ByteBuffer buffer) throws IOException
{
try(RandomAccessFile raf = new RandomAccessFile(file,"r");)
try(RandomAccessFile raf = new RandomAccessFile(file,"r"))
{
FileChannel channel = raf.getChannel();
long needed=raf.length();
@ -437,9 +438,19 @@ public class BufferUtil
out.write(buffer.array(), buffer.arrayOffset() + buffer.position(), buffer.remaining());
else
{
// TODO this is horribly inefficient
byte[] bytes = new byte[TEMP_BUFFER_SIZE];
int j = 0;
for (int i = buffer.position(); i < buffer.limit(); i++)
out.write(buffer.get(i));
{
bytes[j] = buffer.get(i);
j++;
if (j == TEMP_BUFFER_SIZE)
{
out.write(bytes);
j = 0;
}
}
out.write(bytes, 0, j);
}
}
@ -615,9 +626,9 @@ public class BufferUtil
{
boolean started = false;
// This assumes constant time int arithmatic
for (int i = 0; i < hexDivisors.length; i++)
for (int hexDivisor : hexDivisors)
{
if (n < hexDivisors[i])
if (n < hexDivisor)
{
if (started)
buffer.put((byte)'0');
@ -625,9 +636,9 @@ public class BufferUtil
}
started = true;
int d = n / hexDivisors[i];
int d = n / hexDivisor;
buffer.put(DIGIT[d]);
n = n - d * hexDivisors[i];
n = n - d * hexDivisor;
}
}
}
@ -656,9 +667,9 @@ public class BufferUtil
{
boolean started = false;
// This assumes constant time int arithmatic
for (int i = 0; i < decDivisors.length; i++)
for (int decDivisor : decDivisors)
{
if (n < decDivisors[i])
if (n < decDivisor)
{
if (started)
buffer.put((byte)'0');
@ -666,9 +677,9 @@ public class BufferUtil
}
started = true;
int d = n / decDivisors[i];
int d = n / decDivisor;
buffer.put(DIGIT[d]);
n = n - d * decDivisors[i];
n = n - d * decDivisor;
}
}
}
@ -696,9 +707,9 @@ public class BufferUtil
{
boolean started = false;
// This assumes constant time int arithmatic
for (int i = 0; i < decDivisorsL.length; i++)
for (long aDecDivisorsL : decDivisorsL)
{
if (n < decDivisorsL[i])
if (n < aDecDivisorsL)
{
if (started)
buffer.put((byte)'0');
@ -706,9 +717,9 @@ public class BufferUtil
}
started = true;
long d = n / decDivisorsL[i];
long d = n / aDecDivisorsL;
buffer.put(DIGIT[(int)d]);
n = n - d * decDivisorsL[i];
n = n - d * aDecDivisorsL;
}
}
}
@ -785,7 +796,7 @@ public class BufferUtil
public static ByteBuffer toBuffer(File file) throws IOException
{
try (RandomAccessFile raf = new RandomAccessFile(file, "r");)
try (RandomAccessFile raf = new RandomAccessFile(file, "r"))
{
return raf.getChannel().map(MapMode.READ_ONLY, 0, raf.length());
}

68
jetty-util/src/test/java/org/eclipse/jetty/util/BufferUtilTest.java
View File

@ -19,15 +19,22 @@
package org.eclipse.jetty.util;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.BufferOverflowException;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Random;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
import org.junit.Assert;
import org.junit.Ignore;
import org.junit.Test;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.assertTrue;
public class BufferUtilTest
@ -226,4 +233,65 @@ public class BufferUtilTest
Assert.assertEquals("Count of bytes",length,count);
}
private static final Logger LOG = Log.getLogger(BufferUtilTest.class);
@Test
@Ignore("Very simple microbenchmark to compare different writeTo implementations. Only for development thus " +
"ignored.")
public void testWriteToMicrobenchmark() throws IOException
{
int capacity = 1024 * 1024;
int iterations = 30;
byte[] bytes = new byte[capacity];
new Random().nextBytes(bytes);
ByteBuffer buffer = BufferUtil.allocate(capacity);
BufferUtil.append(buffer, bytes, 0, capacity);
long start = System.nanoTime();
for (int i = 0; i < iterations; i++)
{
ByteArrayOutputStream out = new ByteArrayOutputStream();
long startRun = System.nanoTime();
BufferUtil.writeTo(buffer.asReadOnlyBuffer(), out);
long elapsedRun = System.nanoTime() - startRun;
LOG.warn("run elapsed={}ms", elapsedRun / 1000);
assertThat("Bytes in out equal bytes in buffer", Arrays.equals(bytes, out.toByteArray()), is(true));
}
long elapsed = System.nanoTime() - start;
LOG.warn("elapsed={}ms average={}ms", elapsed / 1000, elapsed/iterations/1000);
}
@Test
public void testWriteToWithBufferThatDoesNotExposeArrayAndSmallContent() throws IOException
{
int capacity = BufferUtil.TEMP_BUFFER_SIZE/4;
testWriteToWithBufferThatDoesNotExposeArray(capacity);
}
@Test
public void testWriteToWithBufferThatDoesNotExposeArrayAndContentLengthMatchingTempBufferSize() throws IOException
{
int capacity = BufferUtil.TEMP_BUFFER_SIZE;
testWriteToWithBufferThatDoesNotExposeArray(capacity);
}
@Test
public void testWriteToWithBufferThatDoesNotExposeArrayAndContentSlightlyBiggerThanTwoTimesTempBufferSize()
throws
IOException
{
int capacity = BufferUtil.TEMP_BUFFER_SIZE*2+1024;
testWriteToWithBufferThatDoesNotExposeArray(capacity);
}
private void testWriteToWithBufferThatDoesNotExposeArray(int capacity) throws IOException
{
ByteArrayOutputStream out = new ByteArrayOutputStream();
byte[] bytes = new byte[capacity];
new Random().nextBytes(bytes);
ByteBuffer buffer = BufferUtil.allocate(capacity);
BufferUtil.append(buffer, bytes, 0, capacity);
BufferUtil.writeTo(buffer.asReadOnlyBuffer(), out);
assertThat("Bytes in out equal bytes in buffer", Arrays.equals(bytes, out.toByteArray()), is(true));
}
}