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290 lines
12 KiB
Diff
290 lines
12 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Zach Brown <1254957+zachbr@users.noreply.github.com>
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Date: Fri, 12 May 2017 23:34:11 -0500
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Subject: [PATCH] Properly handle async calls to restart the server
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The watchdog thread calls the server restart function asynchronously. Prior to
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this change, it attempted to do several non-safe operations from the watchdog
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thread, rather than the main. Specifically, because of a separate upstream change,
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it causes player entities to be ticked asynchronously, among other things.
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This is dangerous.
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This patch moves the old handling into a synchronous variant, for calls from the
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restart command, and adds separate handling for async calls, such as those from
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the watchdog thread.
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When calling from the watchdog thread, we cannot assume the main thread is in a
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tickable state; it may be completely deadlocked. In order to handle this, we mark
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the server as stopping, in order to account for situations where the server should
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complete a tick reasonbly soon, i.e. 99% of cases.
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Should the server not enter a state where it is stopping within 10 seconds, We
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will assume that the server has in fact deadlocked and will proceed to force
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kill the server.
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This modification does not force restart the server should we actually enter a
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deadlocked state where the server is stopping, whereas this will in most cases
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exit within a reasonable amount of time, to put a fixed limit on a process that
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will have plugins and worlds saving to the disk has a high potential to result
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in corruption/dataloss.
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diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
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index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
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--- a/src/main/java/net/minecraft/server/MinecraftServer.java
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+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
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@@ -0,0 +0,0 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
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private Map<ResourceKey<Level>, ServerLevel> levels;
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private PlayerList playerList;
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private volatile boolean running;
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+ private volatile boolean isRestarting = false; // Paper - flag to signify we're attempting to restart
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private boolean stopped;
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private int tickCount;
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private int ticksUntilAutosave;
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@@ -0,0 +0,0 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
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if (this.playerList != null) {
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MinecraftServer.LOGGER.info("Saving players");
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this.playerList.saveAll();
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- this.playerList.removeAll();
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+ this.playerList.removeAll(this.isRestarting); // Paper
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try { Thread.sleep(100); } catch (InterruptedException ex) {} // CraftBukkit - SPIGOT-625 - give server at least a chance to send packets
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}
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@@ -0,0 +0,0 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
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}
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public void halt(boolean waitForShutdown) {
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+ // Paper start - allow passing of the intent to restart
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+ this.safeShutdown(waitForShutdown, false);
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+ }
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+ public void safeShutdown(boolean waitForShutdown, boolean isRestarting) {
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+ this.isRestarting = isRestarting;
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+ // Paper end
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this.running = false;
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if (waitForShutdown) {
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try {
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diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
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index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
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--- a/src/main/java/net/minecraft/server/players/PlayerList.java
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+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
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@@ -0,0 +0,0 @@ public abstract class PlayerList {
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}
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public void removeAll() {
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+ // Paper start - Extract method to allow for restarting flag
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+ this.removeAll(false);
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+ }
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+
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+ public void removeAll(boolean isRestarting) {
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+ // Paper end
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// CraftBukkit start - disconnect safely
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for (ServerPlayer player : this.players) {
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+ if (isRestarting) player.connection.disconnect(org.spigotmc.SpigotConfig.restartMessage); else // Paper
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player.connection.disconnect(this.server.server.shutdownMessage()); // CraftBukkit - add custom shutdown message // Paper - Adventure
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}
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// CraftBukkit end
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diff --git a/src/main/java/org/spigotmc/RestartCommand.java b/src/main/java/org/spigotmc/RestartCommand.java
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index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
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--- a/src/main/java/org/spigotmc/RestartCommand.java
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+++ b/src/main/java/org/spigotmc/RestartCommand.java
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@@ -0,0 +0,0 @@ public class RestartCommand extends Command
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AsyncCatcher.enabled = false; // Disable async catcher incase it interferes with us
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try
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{
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- String[] split = restartScript.split( " " );
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- if ( split.length > 0 && new File( split[0] ).isFile() )
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+ // Paper - extract method and cleanup
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+ boolean isRestarting = addShutdownHook( restartScript );
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+ if ( isRestarting )
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{
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- System.out.println( "Attempting to restart with " + restartScript );
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+ System.out.println( "Attempting to restart with " + SpigotConfig.restartScript );
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+ } else
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+ {
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+ System.out.println( "Startup script '" + SpigotConfig.restartScript + "' does not exist! Stopping server." );
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+ }
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+ // Stop the watchdog
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+ WatchdogThread.doStop();
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- // Disable Watchdog
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- WatchdogThread.doStop();
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+ shutdownServer( isRestarting );
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+ // Paper end
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+ } catch ( Exception ex )
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+ {
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+ ex.printStackTrace();
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+ }
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+ }
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- // Kick all players
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- for ( ServerPlayer p : (List<ServerPlayer>) MinecraftServer.getServer().getPlayerList().players )
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- {
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- p.connection.disconnect(SpigotConfig.restartMessage);
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- }
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- // Give the socket a chance to send the packets
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- try
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- {
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- Thread.sleep( 100 );
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- } catch ( InterruptedException ex )
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- {
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- }
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- // Close the socket so we can rebind with the new process
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- MinecraftServer.getServer().getConnection().stop();
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+ // Paper start - sync copied from above with minor changes, async added
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+ private static void shutdownServer(boolean isRestarting)
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+ {
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+ if ( MinecraftServer.getServer().isSameThread() )
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+ {
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+ // Kick all players
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+ for ( ServerPlayer p : com.google.common.collect.ImmutableList.copyOf( MinecraftServer.getServer().getPlayerList().players ) )
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+ {
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+ p.connection.disconnect(SpigotConfig.restartMessage);
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+ }
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+ // Give the socket a chance to send the packets
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+ try
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+ {
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+ Thread.sleep( 100 );
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+ } catch ( InterruptedException ex )
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+ {
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+ }
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- // Give time for it to kick in
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- try
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- {
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- Thread.sleep( 100 );
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- } catch ( InterruptedException ex )
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- {
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- }
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+ closeSocket();
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- // Actually shutdown
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- try
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- {
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- MinecraftServer.getServer().close();
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- } catch ( Throwable t )
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- {
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- }
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+ // Actually shutdown
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+ try
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+ {
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+ MinecraftServer.getServer().close(); // calls stop()
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+ } catch ( Throwable t )
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+ {
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+ }
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+
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+ // Actually stop the JVM
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+ System.exit( 0 );
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- // This will be done AFTER the server has completely halted
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- Thread shutdownHook = new Thread()
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+ } else
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+ {
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+ // Mark the server to shutdown at the end of the tick
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+ MinecraftServer.getServer().safeShutdown( false, isRestarting );
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+
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+ // wait 10 seconds to see if we're actually going to try shutdown
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+ try
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+ {
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+ Thread.sleep( 10000 );
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+ }
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+ catch (InterruptedException ignored)
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+ {
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+ }
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+
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+ // Check if we've actually hit a state where the server is going to safely shutdown
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+ // if we have, let the server stop as usual
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+ if (MinecraftServer.getServer().isStopped()) return;
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+
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+ // If the server hasn't stopped by now, assume worse case and kill
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+ closeSocket();
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+ System.exit( 0 );
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+ }
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+ }
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+ // Paper end
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+
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+ // Paper - Split from moved code
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+ private static void closeSocket()
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+ {
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+ // Close the socket so we can rebind with the new process
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+ MinecraftServer.getServer().getConnection().stop();
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+
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+ // Give time for it to kick in
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+ try
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+ {
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+ Thread.sleep( 100 );
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+ } catch ( InterruptedException ex )
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+ {
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+ }
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+ }
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+ // Paper end
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+
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+ // Paper start - copied from above and modified to return if the hook registered
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+ private static boolean addShutdownHook(String restartScript)
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+ {
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+ String[] split = restartScript.split( " " );
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+ if ( split.length > 0 && new File( split[0] ).isFile() )
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+ {
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+ Thread shutdownHook = new Thread()
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+ {
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+ @Override
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+ public void run()
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{
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- @Override
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- public void run()
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+ try
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{
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- try
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+ String os = System.getProperty( "os.name" ).toLowerCase(java.util.Locale.ENGLISH);
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+ if ( os.contains( "win" ) )
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{
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- String os = System.getProperty( "os.name" ).toLowerCase(java.util.Locale.ENGLISH);
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- if ( os.contains( "win" ) )
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- {
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- Runtime.getRuntime().exec( "cmd /c start " + restartScript );
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- } else
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- {
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- Runtime.getRuntime().exec( "sh " + restartScript );
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- }
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- } catch ( Exception e )
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+ Runtime.getRuntime().exec( "cmd /c start " + restartScript );
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+ } else
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{
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- e.printStackTrace();
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+ Runtime.getRuntime().exec( "sh " + restartScript );
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}
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+ } catch ( Exception e )
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+ {
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+ e.printStackTrace();
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}
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- };
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-
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- shutdownHook.setDaemon( true );
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- Runtime.getRuntime().addShutdownHook( shutdownHook );
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- } else
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- {
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- System.out.println( "Startup script '" + SpigotConfig.restartScript + "' does not exist! Stopping server." );
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-
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- // Actually shutdown
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- try
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- {
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- MinecraftServer.getServer().close();
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- } catch ( Throwable t )
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- {
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}
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- }
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- System.exit( 0 );
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- } catch ( Exception ex )
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+ };
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+
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+ shutdownHook.setDaemon( true );
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+ Runtime.getRuntime().addShutdownHook( shutdownHook );
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+ return true;
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+ } else
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{
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- ex.printStackTrace();
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+ return false;
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}
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}
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+ // Paper end
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+
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}
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