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Use ThreadLocalRandom instead of Math.random() (#11165)

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Motivation:

`ThreadLocalRandom` doesn't cause contention. Also `nextInt()` generates only 4 random bytes while `Math.random()` generates 8 bytes.

Modification:

Replaced `(int) Math.random()` with `PlatformDependent.threadLocalRandom().nextInt()`

Result:

No possible contention when random numbers for WebSockets.
This commit is contained in:
Dmitriy Dumanskiy 2021-04-19 14:56:16 +03:00 committed by GitHub
parent 976486f021
commit 3b89ac7cf0
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 4 additions and 2 deletions
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3
codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocket08FrameEncoder.java
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@ -57,6 +57,7 @@ import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageEncoder; import io.netty.handler.codec.MessageToMessageEncoder;
import io.netty.handler.codec.TooLongFrameException; import io.netty.handler.codec.TooLongFrameException;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.logging.InternalLogger; import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory; import io.netty.util.internal.logging.InternalLoggerFactory;
@ -178,7 +179,7 @@ public class WebSocket08FrameEncoder extends MessageToMessageEncoder<WebSocketFr
// Write payload // Write payload
if (maskPayload) { if (maskPayload) {
int random = (int) (Math.random() * Integer.MAX_VALUE); int random = PlatformDependent.threadLocalRandom().nextInt(Integer.MAX_VALUE);
mask = ByteBuffer.allocate(4).putInt(random).array(); mask = ByteBuffer.allocate(4).putInt(random).array();
buf.writeBytes(mask); buf.writeBytes(mask);

3
codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketClientHandshaker00.java
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@ -26,6 +26,7 @@ import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpMethod; import io.netty.handler.codec.http.HttpMethod;
import io.netty.handler.codec.http.HttpResponseStatus; import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion; import io.netty.handler.codec.http.HttpVersion;
import io.netty.util.internal.PlatformDependent;
import java.net.URI; import java.net.URI;
import java.nio.ByteBuffer; import java.nio.ByteBuffer;
@ -254,7 +255,7 @@ public class WebSocketClientHandshaker00 extends WebSocketClientHandshaker {
char[] randomChars = new char[count]; char[] randomChars = new char[count];
int randCount = 0; int randCount = 0;
while (randCount < count) { while (randCount < count) {
int rand = (int) (Math.random() * 0x7e + 0x21); int rand = PlatformDependent.threadLocalRandom().nextInt(0x7e) + 0x21;
if (0x21 < rand && rand < 0x2f || 0x3a < rand && rand < 0x7e) { if (0x21 < rand && rand < 0x2f || 0x3a < rand && rand < 0x7e) {
randomChars[randCount] = (char) rand; randomChars[randCount] = (char) rand;
randCount += 1; randCount += 1;