Refactor: Remove try-catch by using CompletableFuture#exceptionally()

Change-Id: I728fbcfe8fc4a81da2b08e6dddc1fa63add694a3

@@ -317,13 +317,7 @@ public class IntentManager
 
             // batchExecutor is single-threaded, so only one batch is in flight at a time
             CompletableFuture.runAsync(() -> {
-                try {
-                /*
-                 1. wrap each intentdata in a runnable and submit
-                 2. wait for completion of all the work
-                 3. accumulate results and submit batch write of IntentData to store
-                    (we can also try to update these individually)
-                 */
+                // process intent until the phase reaches one of the final phases
                 List<CompletableFuture<IntentData>> futures = operations.stream()
                         .map(x -> CompletableFuture.completedFuture(x)
                                 .thenApply(IntentManager.this::createInitialPhase)
@@ -333,12 +327,13 @@ public class IntentManager
                                     //FIXME
                                     log.warn("Future failed: {}", e);
                                     return null;
-                                    }))
-                            .collect(Collectors.toList());
+                                })).collect(Collectors.toList());
+
+                // write multiple data to store in order
                 store.batchWrite(Tools.allOf(futures).join().stream()
                         .filter(Objects::nonNull)
                         .collect(Collectors.toList()));
-                } catch (Exception e) {
+            }, batchExecutor).exceptionally(e -> {
                 log.error("Error submitting batches:", e);
                 // FIXME incomplete Intents should be cleaned up
                 //       (transition to FAILED, etc.)
@@ -348,9 +343,9 @@ public class IntentManager
                 log.error("Walk the plank, matey...");
                 //FIXME
 //            batchService.removeIntentOperations(data);
-                }
-                accumulator.ready();
-            }, batchExecutor);
+                return null;
+            }).thenRun(accumulator::ready);
+
         }
     }