commit de003d9763b64a9887cd0427c8080bab61e96ded
author Madan Jampani <madan@onlab.us> Mon May 11 17:14:20 2015 -0700
committer Gerrit Code Review <gerrit@onlab.us> Thu May 14 23:31:27 2015 +0000
tree eeda2677f66d42975ad21f61d453b1b889882abf
parent 3cc2330018584191153d1998f57404b69b27689d

LeadershipService and MastershipService/Store APIs return CompletableFutures so that callers can (optionally) chain together dependent operations

Change-Id: Ia00fcb7d98fbfce897527f67ea9690abf6fe846a

core/net/src/main/java/org/onosproject/cluster/impl/MastershipManager.java

diff --git a/core/net/src/main/java/org/onosproject/cluster/impl/MastershipManager.java b/core/net/src/main/java/org/onosproject/cluster/impl/MastershipManager.java
index 1f3b360..ee60cc7 100644
--- a/core/net/src/main/java/org/onosproject/cluster/impl/MastershipManager.java
+++ b/core/net/src/main/java/org/onosproject/cluster/impl/MastershipManager.java
@@ -17,6 +17,8 @@
 
 import com.codahale.metrics.Timer;
 import com.codahale.metrics.Timer.Context;
+import com.google.common.collect.Lists;
+import com.google.common.util.concurrent.Futures;
 
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
@@ -109,7 +111,7 @@
     }
 
     @Override
-    public void setRole(NodeId nodeId, DeviceId deviceId, MastershipRole role) {
+    public CompletableFuture<Void> setRole(NodeId nodeId, DeviceId deviceId, MastershipRole role) {
         checkNotNull(nodeId, NODE_ID_NULL);
         checkNotNull(deviceId, DEVICE_ID_NULL);
         checkNotNull(role, ROLE_NULL);
@@ -128,14 +130,14 @@
                 break;
             default:
                 log.info("Unknown role; ignoring");
-                return;
+                return CompletableFuture.completedFuture(null);
         }
 
-        eventFuture.whenComplete((event, error) -> {
+        return eventFuture.whenComplete((event, error) -> {
             if (event != null) {
                 post(event);
             }
-        });
+        }).thenApply(v -> null);
     }
 
     @Override
@@ -155,14 +157,11 @@
     }
 
     @Override
-    public MastershipRole requestRoleFor(DeviceId deviceId) {
+    public CompletableFuture<MastershipRole> requestRoleFor(DeviceId deviceId) {
         checkNotNull(deviceId, DEVICE_ID_NULL);
         final Context timer = startTimer(requestRoleTimer);
-        try {
-            return store.requestRole(deviceId);
-        } finally {
-            stopTimer(timer);
-        }
+        return store.requestRole(deviceId).whenComplete((result, error) -> stopTimer(timer));
+
     }
 
     @Override
@@ -222,13 +221,18 @@
         }
 
         // Now re-balance the buckets until they are roughly even.
+        List<CompletableFuture<Void>> balanceBucketsFutures = Lists.newLinkedList();
         int rounds = controllerDevices.keySet().size();
         for (int i = 0; i < rounds; i++) {
             // Iterate over the buckets and find the smallest and the largest.
             ControllerNode smallest = findBucket(true, controllerDevices);
             ControllerNode largest = findBucket(false, controllerDevices);
-            balanceBuckets(smallest, largest, controllerDevices, deviceCount);
+            balanceBucketsFutures.add(balanceBuckets(smallest, largest, controllerDevices, deviceCount));
         }
+        CompletableFuture<Void> balanceRolesFuture = CompletableFuture.allOf(
+                balanceBucketsFutures.toArray(new CompletableFuture[balanceBucketsFutures.size()]));
+
+        Futures.getUnchecked(balanceRolesFuture);
     }
 
     private ControllerNode findBucket(boolean min,
@@ -245,7 +249,7 @@
         return xNode;
     }
 
-    private void balanceBuckets(ControllerNode smallest, ControllerNode largest,
+    private CompletableFuture<Void> balanceBuckets(ControllerNode smallest, ControllerNode largest,
                                 Map<ControllerNode, Set<DeviceId>>  controllerDevices,
                                 int deviceCount) {
         Collection<DeviceId> minBucket = controllerDevices.get(smallest);
@@ -255,6 +259,8 @@
         int delta = (maxBucket.size() - minBucket.size()) / 2;
         delta = Math.min(deviceCount / bucketCount, delta);
 
+        List<CompletableFuture<Void>> setRoleFutures = Lists.newLinkedList();
+
         if (delta > 0) {
             log.info("Attempting to move {} nodes from {} to {}...", delta,
                      largest.id(), smallest.id());
@@ -264,12 +270,14 @@
             while (it.hasNext() && i < delta) {
                 DeviceId deviceId = it.next();
                 log.info("Setting {} as the master for {}", smallest.id(), deviceId);
-                setRole(smallest.id(), deviceId, MASTER);
+                setRoleFutures.add(setRole(smallest.id(), deviceId, MASTER));
                 controllerDevices.get(smallest).add(deviceId);
                 it.remove();
                 i++;
             }
         }
+
+        return CompletableFuture.allOf(setRoleFutures.toArray(new CompletableFuture[setRoleFutures.size()]));
     }