[RPC] Register with the backend when the executors are ready.

rpc/protos/erdos_scheduler.proto

@@ -32,6 +32,10 @@ service SchedulerService {
  // itself with the backend scheduler, and is intended as an EHLO.
  rpc RegisterTaskGraph(RegisterTaskGraphRequest) returns (RegisterTaskGraphResponse) {}
 
+ /// Informs the backend that the environment for the TaskGraph is ready.
+ /// This RPC call enables the backend to begin considering the TaskGraph for scheduling.
+ rpc RegisterEnvironmentReady(RegisterEnvironmentReadyRequest) returns (RegisterEnvironmentReadyResponse) {}
+
  /// Registers a new Worker with the backend scheduler.
  /// This is invoked whenever a new Worker joins the framework.
  rpc RegisterWorker(RegisterWorkerRequest) returns (RegisterWorkerResponse) {}
@@ -115,7 +119,21 @@ message RegisterTaskGraphResponse {
  string message = 2;
  // Respond to the driver with how many executors it should request initially
  // from the Master.
- int32 num_executors = 3;
+ uint32 num_executors = 3;
+}
+
+message RegisterEnvironmentReadyRequest {
+ /// The ID of the Application / TaskGraph that is ready for scheduling.
+ string id = 1;
+ /// The number of executors that were registered to be ready.
+ uint32 num_executors = 2;
+ /// The timestamp at which the environment was considered ready.
+ uint64 timestamp = 3;
+}
+
+message RegisterEnvironmentReadyResponse {
+ bool success = 1;
+ string message = 2;
 }
 
 /// Worker related RPC structures.