merge: Support snapshotting simulated workloads (#113)

This pull request adds support for snapshotting simulated workloads in OpenDC, which
serves as the basis for virtual machine migration/suspension support.

Part of #32 

## Implementation Notes :hammer_and_pick:

* Support synchronous update of FlowStage
* Report exceptions in onStop as suppressed 
* Add support for snapshotting workloads

1 files changed, 9 insertions, 0 deletions

diff --git a/opendc-simulator/opendc-simulator-flow/src/main/java/org/opendc/simulator/flow2/FlowStage.java b/opendc-simulator/opendc-simulator-flow/src/main/java/org/opendc/simulator/flow2/FlowStage.java
index 4d098043..ed5579ea 100644
--- a/opendc-simulator/opendc-simulator-flow/src/main/java/org/opendc/simulator/flow2/FlowStage.java
+++ b/opendc-simulator/opendc-simulator-flow/src/main/java/org/opendc/simulator/flow2/FlowStage.java
@@ -152,6 +152,15 @@ public final class FlowStage {
     }
 
     /**
+     * Synchronously update the {@link FlowStage} at the current timestamp.
+     */
+    public void sync() {
+        this.flags |= STAGE_INVALIDATE;
+        onUpdate(clock.millis());
+        engine.scheduleDelayed(this);
+    }
+
+    /**
      * Close the {@link FlowStage} and disconnect all inlets and outlets.
      */
     public void close() {