From 0ee01998645ce1aa130db19d4d413259684c3690 Mon Sep 17 00:00:00 2001
From: Jie Yao <jyao3@ebay.com>
Date: Fri, 27 Oct 2023 22:55:09 -0700
Subject: [PATCH] fix comments

---
 src/include/homestore/meta_service.hpp |  4 +++-
 src/lib/meta/meta_blk_service.cpp      | 11 +++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/include/homestore/meta_service.hpp b/src/include/homestore/meta_service.hpp
index 94067c9d4..0c1cd9872 100644
--- a/src/include/homestore/meta_service.hpp
+++ b/src/include/homestore/meta_service.hpp
@@ -24,6 +24,7 @@
 #include <string>
 #include <system_error>
 #include <vector>
+#include <optional>
 
 #include <sisl/fds/buffer.hpp>
 #include <sisl/metrics/metrics.hpp>
@@ -47,6 +48,7 @@ struct vdev_info;
 // new blk found subsystem callback
 typedef std::function< void(meta_blk* mblk, sisl::byte_view buf, size_t size) > meta_blk_found_cb_t;
 typedef std::string meta_sub_type;
+typedef std::vector< meta_sub_type > meta_subtype_vec_t;
 typedef std::function< void(bool success) > meta_blk_recover_comp_cb_t; // recover complete subsystem callbacks;
 typedef std::map< uint64_t, meta_blk* > meta_blk_map_t;                 // blkid to meta_blk map;
 typedef std::map< uint64_t, meta_blk_ovf_hdr* > ovf_hdr_map_t;          // ovf_blkid to ovf_blk_hdr map;
@@ -123,7 +125,7 @@ class MetaBlkService {
      * @param cb : subsystem cb
      */
     void register_handler(meta_sub_type type, const meta_blk_found_cb_t& cb, const meta_blk_recover_comp_cb_t& comp_cb,
-                          bool do_crc = true, std::vector< meta_sub_type > dependencies = {});
+                          bool do_crc = true, std::optional< meta_subtype_vec_t > deps = std::nullopt);
 
     /**
      * @brief
diff --git a/src/lib/meta/meta_blk_service.cpp b/src/lib/meta/meta_blk_service.cpp
index 8ddaa46d4..eb7733d0e 100644
--- a/src/lib/meta/meta_blk_service.cpp
+++ b/src/lib/meta/meta_blk_service.cpp
@@ -360,7 +360,7 @@ void MetaBlkService::deregister_handler(meta_sub_type type) {
 
 void MetaBlkService::register_handler(meta_sub_type type, const meta_blk_found_cb_t& cb,
                                       const meta_blk_recover_comp_cb_t& comp_cb, bool do_crc,
-                                      std::vector< meta_sub_type > dependencies) {
+                                      std::optional< meta_subtype_vec_t > deps) {
     std::lock_guard< decltype(m_meta_mtx) > lk(m_meta_mtx);
     HS_REL_ASSERT_LT(type.length(), MAX_SUBSYS_TYPE_LEN, "type len: {} should not exceed len: {}", type.length(),
                      MAX_SUBSYS_TYPE_LEN);
@@ -377,8 +377,7 @@ void MetaBlkService::register_handler(meta_sub_type type, const meta_blk_found_c
     m_sub_info[type].cb = cb;
     m_sub_info[type].comp_cb = comp_cb;
     m_sub_info[type].do_crc = do_crc ? 1 : 0;
-    m_dependency_topological_graph[type] = dependencies;
-    HS_LOG(INFO, metablk, "[type={}] registered with do_crc: {}", type, do_crc);
+    m_dependency_topological_graph[type] = deps.value_or(meta_subtype_vec_t());
 }
 
 void MetaBlkService::add_sub_sb(meta_sub_type type, const uint8_t* context_data, uint64_t sz, void*& cookie) {
@@ -1165,9 +1164,9 @@ MetaBlkService::topological_sort(std::unordered_map< meta_sub_type, std::vector<
 
     // Calculate in-degree of each vertex
     for (const auto& [vertex, edges] : topological_graph) {
-        in_degree[vertex] = 0;
-    }
-    for (const auto& [vertex, edges] : topological_graph) {
+        // we should make sure all the vertex in in_degree map;
+        // if vertex is not in the map, 0 will be assigned.
+        in_degree[vertex];
         for (const auto& edge : edges) {
             in_degree[edge]++;
         }