Use System.nanoTime in place of System.currentTimeMillis when comparing timestamps. (#1174)

proxy/src/main/java/com/velocitypowered/proxy/Velocity.java

@@ -20,6 +20,7 @@ package com.velocitypowered.proxy;
 import io.netty.util.ResourceLeakDetector;
 import io.netty.util.ResourceLeakDetector.Level;
 import java.text.DecimalFormat;
+import java.util.concurrent.TimeUnit;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -63,14 +64,14 @@ public class Velocity {
       return;
     }
 
-    long startTime = System.currentTimeMillis();
+    long startTime = System.nanoTime();
 
     VelocityServer server = new VelocityServer(options);
     server.start();
     Runtime.getRuntime().addShutdownHook(new Thread(() -> server.shutdown(false),
         "Shutdown thread"));
 
-    double bootTime = (System.currentTimeMillis() - startTime) / 1000d;
+    double bootTime = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime) / 1000d;
     logger.info("Done ({}s)!", new DecimalFormat("#.##").format(bootTime));
     server.getConsoleCommandSource().start();
 

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java

@@ -137,7 +137,7 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(KeepAlive packet) {
-    serverConn.getPendingPings().put(packet.getRandomId(), System.currentTimeMillis());
+    serverConn.getPendingPings().put(packet.getRandomId(), System.nanoTime());
     return false; // forwards on
   }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientConfigSessionHandler.java

@@ -36,6 +36,7 @@ import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
 import org.apache.logging.log4j.LogManager;
@@ -81,7 +82,7 @@ public class ClientConfigSessionHandler implements MinecraftSessionHandler {
       if (sentTime != null) {
         MinecraftConnection smc = serverConnection.getConnection();
         if (smc != null) {
-          player.setPing(System.currentTimeMillis() - sentTime);
+          player.setPing(TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - sentTime));
           smc.write(packet);
         }
       }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -81,6 +81,7 @@ import java.util.Queue;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.TimeUnit;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
 import org.apache.logging.log4j.LogManager;
@@ -177,7 +178,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
       if (sentTime != null) {
         MinecraftConnection smc = serverConnection.getConnection();
         if (smc != null) {
-          player.setPing(System.currentTimeMillis() - sentTime);
+          player.setPing(TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - sentTime));
           smc.write(packet);
         }
       }