fix bug

src/include/homestore/replication/repl_dev.h

@@ -56,7 +56,9 @@ struct repl_key {
     };
 
     bool operator==(repl_key const& other) const = default;
-    std::string to_string() const { return fmt::format("server={}, term={}, dsn={}", server_id, term, dsn); }
+    std::string to_string() const {
+        return fmt::format("server={}, term={}, dsn={}, hash={}", server_id, term, dsn, Hasher()(*this));
+    }
 };
 
 using repl_snapshot = nuraft::snapshot;

src/lib/replication/repl_dev/common.cpp

@@ -106,7 +106,8 @@ uint8_t* repl_req_ctx::raw_journal_buf() { return std::get< std::unique_ptr< uin
 
 void repl_req_ctx::set_lsn(int64_t lsn) {
     DEBUG_ASSERT((m_lsn == -1) || (m_lsn == lsn),
-                 "Changing lsn for request={} on the fly can cause race condition, not expected", to_string());
+                 "Changing lsn for request={} on the fly can cause race condition, not expected. lsn {}, m_lsn {}",
+                 to_string(), lsn, m_lsn);
     m_lsn = lsn;
     LOGTRACEMOD(replication, "Setting lsn={} for request={}", lsn, to_string());
 }

src/lib/replication/repl_dev/raft_repl_dev.cpp

@@ -1040,7 +1040,13 @@ std::pair< bool, nuraft::cb_func::ReturnCode > RaftReplDev::handle_raft_event(nu
                 if (entry->get_val_type() != nuraft::log_val_type::app_log) { continue; }
                 if (entry->get_buf_ptr()->size() == 0) { continue; }
                 auto req = m_state_machine->localize_journal_entry_prepare(*entry);
-                if (req == nullptr) {
+                // TODO :: we need to indentify whether this log entry should be appended to log store.
+                // 1 for lsn, if the req#lsn is not -1, it means this log has been localized and apeneded before, we
+                // should skip it.
+                // 2 for dsn, if the req#dsn is less than the next_dsn, it means this log has been
+                // committed, we should skip it.
+                // here, we only check the first condition for now. revisit here if we need to check the second
+                if (req == nullptr || req->lsn() != -1) {
                     sisl::VectorPool< repl_req_ptr_t >::free(reqs);
                     return {true, nuraft::cb_func::ReturnCode::ReturnNull};
                 }

src/tests/test_raft_repl_dev.cpp

@@ -184,6 +184,7 @@ class TestReplicatedDB : public homestore::ReplDevListener {
             snp_data->blob = sisl::io_blob_safe(sizeof(ulong));
             return 0;
         }
+        if (snp_data->offset == -1) snp_data->offset = 0;
         int64_t follower_last_lsn = snp_data->offset;
         std::vector< KeyValuePair > kv_snapshot_data;
         LOGINFOMOD(replication, "[Replica={}] Read logical snapshot callback follower lsn={}", g_helper->replica_num(),
@@ -223,8 +224,10 @@ class TestReplicatedDB : public homestore::ReplDevListener {
                    snp_data->is_last_obj);
 
         if (snp_data->offset == 0) {
-            // For obj_id 0 we sent back the last committed lsn.
-            snp_data->offset = last_committed_lsn;
+            // TODO: this is a workaround to avoid the first snapshot data write error. revisit here and refine
+            // it. if last_committed_lsn is 0 and we send it back, then the leader will resend this to us, in which the
+            // snp_data->offset is 0. This will cause the snapshot data write error. So we set it to -1 to avoid this.
+            snp_data->offset = last_committed_lsn == 0 ? -1 : last_committed_lsn;
             LOGINFOMOD(replication, "[Replica={}] Save logical snapshot callback return obj_id={}",
                        g_helper->replica_num(), snp_data->offset);
             return;