Migrated source code from Simantics SVN

[simantics/platform.git] / bundles / org.simantics.graphviz / src / org / simantics / graphviz / continuation / Computation.java

diff --git a/bundles/org.simantics.graphviz/src/org/simantics/graphviz/continuation/Computation.java b/bundles/org.simantics.graphviz/src/org/simantics/graphviz/continuation/Computation.java
new file mode 100644 (file)
index 0000000..c99ece3
--- /dev/null
+++ b/bundles/org.simantics.graphviz/src/org/simantics/graphviz/continuation/Computation.java
@@ -0,0 +1,66 @@
+package org.simantics.graphviz.continuation;\r
+\r
+import java.util.ArrayList;\r
+import java.util.concurrent.CancellationException;\r
+import java.util.concurrent.CountDownLatch;\r
+\r
+public abstract class Computation<T> {\r
+    T result;\r
+    Exception exception;\r
+    ArrayList<Continuation<T>> continuations = new ArrayList<Continuation<T>>(); \r
+    CountDownLatch doneGate = new CountDownLatch(1); \r
+\r
+    public void addContinuation(Continuation<T> continuation) {\r
+        synchronized(doneGate) {\r
+            if(doneGate.getCount() == 0) {\r
+                if(exception == null)\r
+                    continuation.succeeded(result);\r
+                else\r
+                    continuation.failed(exception);\r
+            }\r
+            else\r
+                continuations.add(continuation);\r
+        }\r
+    }\r
+\r
+    public boolean isDone() {\r
+        return doneGate.getCount() == 0;\r
+    }\r
+    \r
+    protected void failWith(Exception exception) {\r
+        this.exception = exception;\r
+        ArrayList<Continuation<T>> cs;\r
+        synchronized (doneGate) {\r
+            cs = this.continuations;\r
+            this.continuations = null;\r
+            doneGate.countDown();\r
+        }\r
+        if(cs != null)\r
+            for(Continuation<T> continuation : cs)\r
+                continuation.failed(exception);\r
+    }\r
+    \r
+    protected void doneWith(T result) {\r
+        this.result = result;\r
+        ArrayList<Continuation<T>> cs;\r
+        synchronized (doneGate) {\r
+            cs = this.continuations;\r
+            this.continuations = null;\r
+            doneGate.countDown();\r
+        }\r
+        if(cs != null)\r
+            for(Continuation<T> continuation : cs)\r
+                continuation.succeeded(result);\r
+    }\r
+    \r
+    public void cancel() {\r
+        failWith(new CancellationException());\r
+    }\r
+    \r
+    public T get() throws Exception {\r
+        doneGate.await();\r
+        if(exception != null)\r
+            throw exception;\r
+        return result;\r
+    }\r
+}\r