Initial commit.

src/main/java/com/ryanmichela/sshd/Waitable.java

@@ -0,0 +1,48 @@
+package com.ryanmichela.sshd;
+
+import java.util.concurrent.ExecutionException;
+
+/**
+ * Copyright 2013 Ryan Michela
+ */
+public abstract class Waitable<T> implements Runnable {
+    private enum Status {
+        WAITING,
+        RUNNING,
+        FINISHED,
+    }
+    Throwable t = null;
+    T value = null;
+    Status status = Status.WAITING;
+
+    public final void run() {
+        synchronized (this) {
+            if (status != Status.WAITING) {
+                throw new IllegalStateException("Invalid state " + status);
+            }
+            status = Status.RUNNING;
+        }
+        try {
+            value = evaluate();
+        } catch (Throwable t) {
+            this.t = t;
+        } finally {
+            synchronized (this) {
+                status = Status.FINISHED;
+                this.notifyAll();
+            }
+        }
+    }
+
+    protected abstract T evaluate();
+
+    public synchronized T get() throws InterruptedException, ExecutionException {
+        while (status != Status.FINISHED) {
+            this.wait();
+        }
+        if (t != null) {
+            throw new ExecutionException(t);
+        }
+        return value;
+    }
+}