Changed RaftCore API; giving up Leader status if the leader cannot write its log

libuavcan/include/uavcan/protocol/dynamic_node_id_server/distributed/raft_core.hpp

@@ -812,10 +812,10 @@ public:
 
     /**
      * Inserts one entry into log.
-     * Failures are tolerble because all operations are idempotent.
      * This method will trigger an assertion failure and return error if the current node is not the leader.
+     * If operation fails, the node may give up its Leader status.
      */
-    int appendLog(const Entry::FieldTypes::unique_id& unique_id, NodeID node_id)
+    void appendLog(const Entry::FieldTypes::unique_id& unique_id, NodeID node_id)
     {
         if (isLeader())
         {
@@ -825,12 +825,15 @@ public:
             entry.term = persistent_state_.getCurrentTerm();
 
             trace(TraceRaftNewLogEntry, entry.node_id);
-            return persistent_state_.getLog().append(entry);
+            const int res = persistent_state_.getLog().append(entry);
+            if (res < 0)
+            {
+                handlePersistentStateUpdateError(res);
+            }
         }
         else
         {
             UAVCAN_ASSERT(0);
-            return -ErrLogic;
         }
     }
 
@@ -853,8 +856,8 @@ public:
      * Predicate is a callable of the following prototype:
      *  bool (const LogEntryInfo& entry)
      * Once the predicate returns true, the loop will be terminated and the method will return an initialized lazy
-     * contructor to the last visited entry; otherwise the constructor will not be initialized. In this case, lazy
+     * contructor with the last visited entry; otherwise the constructor will not be initialized.
-     * constructor is used as boost::optional.
+     * In this case, lazy constructor is used as boost::optional.
      * The log is always traversed from HIGH to LOW index values, i.e. entry 0 will be traversed last.
      */
     template <typename Predicate>

libuavcan/include/uavcan/protocol/dynamic_node_id_server/distributed/server.hpp

@@ -169,11 +169,7 @@ class Server : IAllocationRequestHandler
 
         if (raft_core_.isLeader())
         {
-            const int res = raft_core_.appendLog(uid, node_id);
+            raft_core_.appendLog(uid, node_id);
-            if (res < 0)
-            {
-                node_.registerInternalFailure("Raft log append discovered node");
-            }
         }
     }
 
@@ -200,11 +196,7 @@ class Server : IAllocationRequestHandler
 
         if (!result.isConstructed())
         {
-            const int res = raft_core_.appendLog(own_unique_id_, node_.getNodeID());
+            raft_core_.appendLog(own_unique_id_, node_.getNodeID());
-            if (res < 0)
-            {
-                node_.registerInternalFailure("Raft log append with self ID");
-            }
         }
     }
 
@@ -230,11 +222,7 @@ class Server : IAllocationRequestHandler
 
         UAVCAN_TRACE("dynamic_node_id_server::distributed::Server", "New node ID allocated: %d",
                      int(allocated_node_id.get()));
-        const int res = raft_core_.appendLog(unique_id, allocated_node_id);
+        raft_core_.appendLog(unique_id, allocated_node_id);
-        if (res < 0)
-        {
-            node_.registerInternalFailure("Raft log append new allocation");
-        }
     }
 
     void tryPublishAllocationResult(const protocol::dynamic_node_id::server::Entry& entry)

libuavcan/test/protocol/dynamic_node_id_server/distributed/server.cpp

@@ -83,7 +83,7 @@ TEST(DynamicNodeIDServer, RaftCoreBasic)
     Entry::FieldTypes::unique_id unique_id;
     uavcan::fill_n(unique_id.begin(), 16, uint8_t(0xAA));
 
-    ASSERT_LE(0, raft_a->appendLog(unique_id, uavcan::NodeID(1)));
+    raft_a->appendLog(unique_id, uavcan::NodeID(1));
 
     nodes.spinBoth(uavcan::MonotonicDuration::fromMSec(2000));