Asynchronous block remove!

Hi I have had almost complete plugin for 1.6.4, then came 1.7.2, and now there is an interesting error, my plugin uses "block.setType(Material.AIR);" and exactly here is the problem. This line is in the java timer. And the error from console is following:

Code:

[22:11:13] [Timer-51/WARN]: Exception in thread "Timer-51" 
[22:11:13] [Timer-51/WARN]: java.lang.IllegalStateException: Asynchronous block remove!
[22:11:13] [Timer-51/WARN]: at net.minecraft.server.v1_7_R1.Block.remove(Block.java:441)
[22:11:13] [Timer-51/WARN]: at net.minecraft.server.v1_7_R1.Chunk.a(Chunk.java:436)
[22:11:13] [Timer-51/WARN]: at net.minecraft.server.v1_7_R1.World.setTypeAndData(World.java:344)
[22:11:13] [Timer-51/WARN]: at org.bukkit.craftbukkit.v1_7_R1.block.CraftBlock.setTypeIdAndData(CraftBlock.java:127)
[22:11:13] [Timer-51/WARN]: at org.bukkit.craftbukkit.v1_7_R1.block.CraftBlock.setTypeId(CraftBlock.java:122)
[22:11:13] [Timer-51/WARN]: at org.bukkit.craftbukkit.v1_7_R1.block.CraftBlock.setTypeId(CraftBlock.java:118)
[22:11:13] [Timer-51/WARN]: at org.bukkit.craftbukkit.v1_7_R1.block.CraftBlock.setType(CraftBlock.java:114)
[22:11:13] [Timer-51/WARN]: at vip.prodction.dakado.wooljumper.Main.degenerate(Main.java:1356)
[22:11:13] [Timer-51/WARN]: at vip.prodction.dakado.wooljumper.Main$7$1.run(Main.java:1604)
[22:11:13] [Timer-51/WARN]: at java.util.TimerThread.mainLoop(Unknown Source)
[22:11:13] [Timer-51/WARN]: at java.util.TimerThread.run(Unknown Source)
  

 

Are you calling this within an asynchronous task?
If so, don't do it. Only call bukkit methods by using the main thread.

 

It seems as though you are trying to remove a block from a thread separate from the main thread. I'd call a new synchronous task from the Bukkit API in your situation...either that, or see if you can do what you were doing synchronously instead.

 

Here is my code, so I should change it to bukkit schedulers ? Please nooo.... I hate bukkit schedulers Java timers are much more better.

http://pastebin.com/RUWe5Kmv

In 1.6.4 it worked perfectly.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

I'm afraid the only way to schedule a task on the main thread from a separate thread is to use bukkit schedulers

 

And what if I move this to a method to another class ? Would it help ?

 

Welite you shouldn't use timers, use BukkitRunnable

 

No, in 1.6.4 you got lucky and didn't get an unexpected exception or corrupt yours or someone else's world.

World modification from another thread is a big no-no and always has been.

 

OK, and can someone help me with the Bukkit schedulers ? I never used them, I read the tutorial on bukkit but it is not explained well.

So for example I have this java timer and I want exactly the same but with bukkit timer what should I do ?
(Task which is repeating every 10 seconds):

Code:java

 
final Timer progresstimer= new Timer();  
TimerTask progresstask = new TimerTask(){
public void run(){  
  } };
  progresstimer.schedule(progresstask, 1000, 10*1000); 
 

And delayed task which runs once with delay 5 ten seconds:

Code:java

 
final Timer delaytimer= new Timer();  
TimerTask delaytask = new TimerTask(){
public void run(){  
  }};
  delaytimer.schedule(delaytask, 5*1000); 
 

How can I rewrite those task to bukkit shceduler please ?

 

A simple example from one of my own plugins (subclassing BukkitRunnable):

https://github.com/desht/checkers/blob/master/src/main/java/me/desht/checkers/TickTask.java

and I create a TickTask and start it off here:

https://github.com/desht/checkers/b...va/me/desht/checkers/CheckersPlugin.java#L170

(delay of 20 ticks, and runs every 20 ticks, i.e. once per second).

Another way to do it is to use BukkitScheduler to get yourself a BukkitTask object:

PHP:

BukkitTask task = Bukkit.getScheduler().runTaskTimer(plugin, new Runnable() {
  @Override
  public void run() { /* .... */ }
}, 20L, 20L);


BukkitTask gives you a few methods to help manage the task (in particular, .cancel()).

 

Nice thanks, but one more question, how to check for some condition and cancel task inside itself ?


Example:

Code:java

 
final BukkitTask progresstask = Bukkit.getScheduler().runTaskTimer(plugin, new Runnable() {
@Override
public void run() {
//some code
 
 
if (status.equals("lobby")) {
progresstask.cancel(); //here I want to cancel, I need to check this condition every cycle, but it gives me that variable may not be initialized, how to cancel it here ?
 
}
}
}, 20L, (20*runtime) + 7*20L);
 

 

Welite
Declare progresstask as null, then initialize it. That will allow you to cancel the task.

 

I tried this, but it wrote that I should change BukkitTask to final but when I do it then I cannot initialize it.

 

Welite
I'm not sure if it is the best solution, but you could declare a private variable at the top of your class.

Code:

private volatile BukkitTask progresstask = null;

Edit: Ehh.. That wouldn't work so hot if you had multiple tasks running at the same time.

 

Welite (@The_Doctor_123) Use a BukkitRunnable. This

Code:java

final BukkitTask progresstask = Bukkit.getScheduler().runTaskTimer(plugin, new Runnable() {
    @Override
    public void run()
    {
        //some code
        if (status.equals("lobby"))
        {
            progresstask.cancel(); //here I want to cancel, I need to check this condition every cycle, but it gives me that variable may not be initialized, how to cancel it here ?
        }
    }
}, 20L, (20*runtime) + 7*20L);

would be

Code:java

new BukkitRunnable()
{
    @Override
    public void run()
    {
        //some code
        if (status.equals("lobby"))
        {
            // Yay, cancelling from within a BukkitRunnable
            this.cancel();
        }
    }
}.runTaskTimer(plugin, 20L, (20*runtime) + 7*20L);

They still return BukkitTasks, in case you need to cancel them from another point.

I am amazed that so little people know about BukkitRunnables