Update to remove FIXMEs

examples/C/src/leader-election/HeartbeatBully.lf

@@ -14,19 +14,7 @@
  * is set so that each primary fails after sending three heartbeat messages. When all nodes have
  * failed, then the program exits.
  *
- * This example is designed to be run as a federated program with decentralized coordination.
- * However, as of this writing, bugs in the federated code generator cause the program to fail
- * because all federates get the same bank_index == 0. This may be related to these bugs:
- *
- * - https://github.com/lf-lang/lingua-franca/issues/1961
- * - https://github.com/lf-lang/lingua-franca/issues/1962
- *
- * When these bugs are fixed, then the federated version should operate exactly the same as the
- * unfederated version except that it will become possible to kill the federates instead of having
- * them fail on their own. The program should also be extended to include STP violation handlers to
- * deal with the fundamental CAL theorem limitations, where unexpected network delays make it
- * impossible to execute the program as designed. For example, if the network becomes partitioned,
- * then it becomes possible to have two primary nodes simultaneously active.
+ * This example is designed to be run as a federated program.
  *
  * @author Edward A. Lee
  * @author Marjan Sirjani
@@ -101,10 +89,6 @@ reactor Node(
           }
         }
       }
-      // FIXME
-      // =} STP (0) {=
-      // FIXME: What should we do here.
-      //  lf_print_error("Node %d had an STP violation. Ignoring heartbeat as if it didn't arrive at all.", self->bank_index);
     =}
 
     reaction(t) -> reset(Prospect) {=

examples/C/src/leader-election/README.md

@@ -1,11 +1,14 @@
 # Leader Election
 
-These federated programs implements a redundant fault-tolerant system where a primary node, if and when it fails, is replaced by a backup node. The protocol is described in this paper:
+These federated programs implement redundant fault-tolerant systems where a primary node, if and when it fails, is replaced by a backup node. The HeartbeatBully example is described in this paper:
 
-> Bjarne Johansson; Mats Rågberger; Alessandro V. Papadopoulos; Thomas Nolte, "Consistency Before Availability: Network Reference Point based Failure Detection for Controller Redundancy," Emerging Technologies and Factory Automation (ETFA), 12-15 September 2023, [DOI:10.1109/ETFA54631.2023.10275664](https://doi.org/10.1109/ETFA54631.2023.10275664)
+> B. Johansson, M. Rågberger, A. V. Papadopoulos and T. Nolte, "Heartbeat Bully: Failure Detection and Redundancy Role Selection for Network-Centric Controller," IECON 2020 The 46th Annual Conference of the IEEE Industrial Electronics Society, Singapore, 2020, pp. 2126-2133, [DOI: 10.1109/IECON43393.2020.9254494](https://doi.org/10.1109/IECON43393.2020.9254494).
 
+The NRP examples extend the algorithm to reduce the likelihood of getting multiple primaries when the network becomes partitioned. The NRP protocol is described in this paper:
 
-The key idea in this protocol is that when a backup fails to detect the heartbeats of a primary node, it becomes primary only if it has access to Network Reference Point (NRP), which is a point in the network. This way, if the network becomes partitioned, only a backup that is on the side of the partition that still has access to the NRP can become a primary. If a primary loses access to the NRP, then it relinquishes its primary role because it is now on the wrong side of a network partition. A backup on the right side of the partition will take over.  The "FD" in the names of the programs stands for "fault detection."
+> B. Johansson, M. Rågberger, A. V. Papadopoulos, and  T. Nolte, "Consistency Before Availability: Network Reference Point based Failure Detection for Controller Redundancy," Emerging Technologies and Factory Automation (ETFA), 12-15 September 2023, [DOI:10.1109/ETFA54631.2023.10275664](https://doi.org/10.1109/ETFA54631.2023.10275664)
+
+The key idea in the NRP protocol is that when a backup fails to detect the heartbeats of a primary node, it becomes primary only if it has access to Network Reference Point (NRP), which is a point in the network. This way, if the network becomes partitioned, only a backup that is on the side of the partition that still has access to the NRP can become a primary. If a primary loses access to the NRP, then it relinquishes its primary role because it is now on the wrong side of a network partition. A backup on the right side of the partition will take over.  The "FD" in the names of the programs stands for "fault detection."
 
 ## Prerequisite
 
@@ -15,8 +18,12 @@ To run these programs, you are required to first [install the RTI](https://www.l
 
 <table>
 <tr>
+<td> <img src="img/HeartbeatBully.png" alt="Heartbeat Bully" width="100%"> </td>
+<td> <a href="HeartbeatBully.lf"> HeartbeatBully.lf </a>: Basic leader electrion protocol called "heartbeat bully".</td>
+</tr>
+<tr>
 <td> <img src="img/NRP_FD.png" alt="NRP_FD" width="100%"> </td>
-<td> <a href="NRP_FD.lf"> NRP_FD.lf </a>: This version has switch1 failing at 3s, node1 failing at 10s, and node2 failing at 15s.</td>
+<td> <a href="NRP_FD.lf"> NRP_FD.lf </a>: Extension using a network reference point (NRP) to help prevent multiple primaries. This version has switch1 failing at 3s, node1 failing at 10s, and node2 failing at 15s.</td>
 </tr>
 <tr>
 <td> <img src="img/NRP_FD_PrimaryFails.png" alt="NRP_FD_PrimaryFails" width="100%"> </td>