implementation of isCurrentlyRunning(int taskId);

Burrows down to the worker thread assigned to this task, and returns
its alive status. If no such thread exists, then the task is not
running!

src/main/java/org/bukkit/craftbukkit/scheduler/CraftScheduler.java

@@ -210,7 +210,7 @@ public class CraftScheduler implements BukkitScheduler, Runnable {
                 }
             }
         }
-        craftThreadManager.interruptTask(plugin);
+        craftThreadManager.interruptTasks(plugin);
     }
 
     public void cancelAllTasks() {
@@ -220,4 +220,7 @@ public class CraftScheduler implements BukkitScheduler, Runnable {
         craftThreadManager.interruptAllTasks();
     }
 
+    public boolean isCurrentlyRunning(int taskId){
+        return craftThreadManager.isAlive(taskId);
+    }
 }

src/main/java/org/bukkit/craftbukkit/scheduler/CraftTask.java

@@ -4,7 +4,7 @@ import java.lang.Comparable;
 
 import org.bukkit.plugin.Plugin;
 
-public class CraftTask implements Comparable {
+public class CraftTask implements Comparable<Object> {
 
     private final Runnable task;
     private final boolean syncTask;

src/main/java/org/bukkit/craftbukkit/scheduler/CraftThreadManager.java

@@ -1,7 +1,6 @@
 package org.bukkit.craftbukkit.scheduler;
 
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.Iterator;
 
 import org.bukkit.plugin.Plugin;
@@ -31,7 +30,7 @@ public class CraftThreadManager {
         }
     }
 
-    void interruptTask(Plugin owner) {
+    void interruptTasks(Plugin owner) {
         synchronized (workers) {
             Iterator<CraftWorker> itr = workers.iterator();
             while (itr.hasNext()) {
@@ -52,4 +51,18 @@ public class CraftThreadManager {
             }
         }
     }
+
+    boolean isAlive(int taskId) {
+        synchronized (workers) {
+            Iterator<CraftWorker> itr = workers.iterator();
+            while (itr.hasNext()) {
+                CraftWorker craftWorker = itr.next();
+                if (craftWorker.getTaskId() == taskId) {
+                    return craftWorker.isAlive();
+                }
+            }
+        }
+        // didn't find it, so it must have been removed
+        return false;
+    }
 }

src/main/java/org/bukkit/craftbukkit/scheduler/CraftWorker.java

@@ -53,6 +53,10 @@ public class CraftWorker implements Runnable {
         t.interrupt();
     }
 
+    public boolean isAlive() {
+        return t.isAlive();
+    }
+
     private static int getNextHashId() {
         synchronized (hashIdCounterSync) {
             return hashIdCounter++;