Fix comments

conanfile.py

@@ -9,7 +9,7 @@
 
 class HomestoreConan(ConanFile):
     name = "homestore"
-    version = "6.5.17"
+    version = "6.5.18"
 
     homepage = "https://github.com/eBay/Homestore"
     description = "HomeStore Storage Engine"

src/include/homestore/replication/repl_dev.h

@@ -124,6 +124,8 @@ struct snapshot_obj {
     bool is_last_obj{false};
 };
 
+//HomeStore has some meta information to be transmitted during the baseline resync,
+//Although now only dsn needs to be synced, this structure is defined as a general message, and we can easily add data if needed in the future.
 struct snp_repl_dev_data {
     uint64_t magic_num{HOMESTORE_RESYNC_DATA_MAGIC};
     uint32_t protocol_version{HOMESTORE_RESYNC_DATA_PROTOCOL_VERSION_V1};

src/lib/replication/repl_dev/raft_repl_dev.cpp

@@ -1510,15 +1510,19 @@ bool RaftReplDev::apply_snp_resync_data(nuraft::buffer& data) {
         return false;
     }
     auto received_crc = msg->crc;
-    msg->crc = 0;
     RD_LOGD("received snapshot resync msg, dsn={}, crc={}, received crc={}", msg->dsn, msg->crc, received_crc);
+    msg->crc = 0;
     auto computed_crc = crc32_ieee(0, reinterpret_cast< const unsigned char* >(msg),
                                    sizeof(snp_repl_dev_data));
     if (received_crc != computed_crc) {
         RD_LOGE("Snapshot resync data crc mismatch, received_crc={}, computed_crc={}", received_crc, computed_crc);
         return false;
     }
-    m_next_dsn = msg->dsn;
+    if (msg->dsn > m_next_dsn) {
+        m_next_dsn = msg->dsn;
+        RD_LOGD("Update next_dsn from {} to {}", m_next_dsn.load(), msg->dsn);
+        return true;
+    }
     return true;
 }
 

src/lib/replication/repl_dev/raft_state_machine.cpp

@@ -297,6 +297,8 @@ void RaftStateMachine::create_snapshot(nuraft::snapshot& s, nuraft::async_result
 
 int RaftStateMachine::read_logical_snp_obj(nuraft::snapshot& s, void*& user_ctx, ulong obj_id, raft_buf_ptr_t& data_out,
                                            bool& is_last_obj) {
+    // For Nuraft baseline resync, we separate the process into two layers: HomeStore layer and Application layer.
+    // We use the highest bit of the obj_id to indicate the message type: 0 is for HS, 1 is for Application.
     if ((obj_id & snp_obj_id_type_mask) == 0) {
         // This is the preserved msg for homestore to resync data
         m_rd.create_snp_resync_data(data_out);
@@ -326,6 +328,10 @@ int RaftStateMachine::read_logical_snp_obj(nuraft::snapshot& s, void*& user_ctx,
 
 void RaftStateMachine::save_logical_snp_obj(nuraft::snapshot& s, ulong& obj_id, nuraft::buffer& data, bool is_first_obj,
                                             bool is_last_obj) {
+    if (is_last_obj) {
+        //make sure the changes are flushed.
+        hs()->cp_mgr().trigger_cp_flush(true /* force */);
+    }
     if ((obj_id & snp_obj_id_type_mask) == 0) {
         // Homestore preserved msg
         if (m_rd.apply_snp_resync_data(data)) {

src/lib/replication/repl_dev/raft_state_machine.h

@@ -86,7 +86,9 @@ class StateMachineStore;
 #define RD_LOGE(...) RD_LOG(ERROR, ##__VA_ARGS__)
 #define RD_LOGC(...) RD_LOG(CRITICAL, ##__VA_ARGS__)
 
-static constexpr uint64_t snp_obj_id_type_mask = 0x8000000000000000;
+// For the logic snapshot obj_id, we use the highest bit to indicate the type of the snapshot message.
+// 0 is for HS, 1 is for Application.
+static constexpr uint64_t snp_obj_id_type_mask = 1ULL << 63;
 
 using AsyncNotify = folly::SemiFuture< folly::Unit >;
 using AsyncNotifier = folly::Promise< folly::Unit >;

src/tests/test_common/raft_repl_test_base.hpp

@@ -183,10 +183,10 @@ class TestReplicatedDB : public homestore::ReplDevListener {
     }
 
     static int64_t get_next_lsn(uint64_t& obj_id) {
-        return obj_id & 0x7fffffffffffffff;
+        return obj_id & ((1ULL << 63) - 1);
     }
     static void set_resync_msg_type_bit(uint64_t& obj_id) {
-        obj_id |= 1ull << 63;
+        obj_id |= 1ULL << 63;
     }
 
     int read_snapshot_obj(shared< snapshot_context > context, shared< snapshot_obj > snp_data) override {