From ec26266fe6b05bdb6863498f77299f38d571d996 Mon Sep 17 00:00:00 2001
From: 6unyoung <mukmulpasta@naver.com>
Date: Fri, 28 Nov 2025 18:30:14 +0900
Subject: [PATCH] INTERNAL: Bundle nested fields of prefix_t with NESTED_PREFIX

---
 engines/default/prefix.c | 45 +++++++++++++++++++++++++++-------------
 engines/default/prefix.h |  8 +++----
 2 files changed, 35 insertions(+), 18 deletions(-)

diff --git a/engines/default/prefix.c b/engines/default/prefix.c
index cff69199b..8d629d65a 100644
--- a/engines/default/prefix.c
+++ b/engines/default/prefix.c
@@ -266,8 +266,6 @@ static int _prefix_insert(prefix_t *pt, uint32_t hash)
         prefxp->total_prefix_items++;
     }
 #else
-    assert(pt->parent_prefix != NULL);
-    pt->parent_prefix->child_prefix_items++;
     prefxp->total_prefix_items++;
 #endif
     return 1;
@@ -294,8 +292,6 @@ static void _prefix_delete(const char *prefix, const int nprefix, uint32_t hash)
             prefxp->total_prefix_items--;
         }
 #else
-        assert(pt->parent_prefix != NULL);
-        pt->parent_prefix->child_prefix_items--;
         prefxp->total_prefix_items--;
 #endif
         /* unlink and free the prefix structure */
@@ -351,6 +347,9 @@ ENGINE_ERROR_CODE prefix_link(hash_item *it, const uint32_t item_size, bool *int
         if (prefix_depth >= DEFAULT_PREFIX_MAX_DEPTH) {
             break;
         }
+#ifndef NESTED_PREFIX
+        break;
+#endif
     }
 
     if (prefix_depth == 0) {
@@ -413,7 +412,6 @@ ENGINE_ERROR_CODE prefix_link(hash_item *it, const uint32_t item_size, bool *int
                 if (PREFIX_IS_RSVD(key, pt->nprefix)) {
                     pt->internal = 1; /* internal prefix */
                 }
-                pt->parent_prefix = (j == 0 ? null_pt : prefix_list[j-1].pt);
 #endif
                 time(&pt->create_time);
 
@@ -445,13 +443,22 @@ void prefix_unlink(hash_item *it, const uint32_t item_size, bool drop_if_empty)
 
     if (drop_if_empty) {
         while (pt != NULL && pt != null_pt) {
-            prefix_t *parent_pt = pt->parent_prefix;
-            if (pt->child_prefix_items > 0 || pt->total_count_exclusive > 0)
+            bool has_items = pt->total_count_exclusive > 0;
+            bool has_children = false;
+            prefix_t *next_pt = NULL;
+
+#ifdef NESTED_PREFIX
+            has_children = pt->child_prefix_items > 0;
+            next_pt = pt->parent_prefix;
+#endif
+            if (has_items || has_children) {
                 break; /* NOT empty */
+            }
+
             assert(pt->total_bytes_exclusive == 0);
             _prefix_delete(_get_prefix(pt), pt->nprefix,
                            svcore->hash(_get_prefix(pt), pt->nprefix, 0));
-            pt = parent_pt;
+            pt = next_pt;
         }
     }
 }
@@ -512,8 +519,12 @@ bool prefix_isvalid(hash_item *it, rel_time_t current_time)
             it->time <= pt->oldest_live)
             return false;
         /* traverse parent prefixes to validate them */
+#ifdef NESTED_PREFIX
         pt = pt->parent_prefix;
-    } while(pt != NULL && pt != null_pt);
+#else
+        pt = NULL;
+#endif
+    } while (pt != NULL && pt != null_pt);
 
     return true;
 }
@@ -528,8 +539,12 @@ static uint32_t do_count_invalid_prefix(void)
     for (i = 0; i < size; i++) {
         pt = prefxp->hashtable[i];
         while (pt) {
-            if (pt->child_prefix_items == 0 && pt->total_count_exclusive == 0)
-                invalid_prefix++;
+            if (pt->total_count_exclusive == 0) {
+#ifdef NESTED_PREFIX
+                if (pt->child_prefix_items == 0)
+#endif
+                    invalid_prefix++;
+            }
             pt = pt->h_next;
         }
     }
@@ -593,7 +608,6 @@ static int _prefix_stats_write_buffer(char *buffer, const size_t buflen,
             pt->items_bytes_exclusive[ITEM_TYPE_MAP],
             pt->items_bytes_exclusive[ITEM_TYPE_BTREE],
             /* FUTURE: NESTED_PREFIX
-            (uint64_t)pt->child_prefix_items,
             (uint64_t)0,
             (uint64_t)0,
             */
@@ -665,7 +679,6 @@ char *prefix_dump_stats(token_t *tokens, const size_t ntokens, int *length)
         /* write prefix stats in the buffer */
         if (num_prefixes > prefxp->total_prefix_items) { /* include null prefix */
             pt = null_pt;
-            assert(pt->child_prefix_items == 0);
             pos += _prefix_stats_write_buffer(buffer+pos, buflen-pos, format, pt, false);
             assert(pos < buflen);
         }
@@ -714,7 +727,11 @@ char *prefix_dump_stats(token_t *tokens, const size_t ntokens, int *length)
 #ifdef SCAN_COMMAND
 static bool _prefix_isempty(prefix_t *pt)
 {
-    return pt->child_prefix_items == 0 && pt->total_count_exclusive == 0;
+#ifdef NESTED_PREFIX
+        return pt->child_prefix_items == 0 && pt->total_count_exclusive == 0;
+#else
+        return pt->total_count_exclusive == 0;
+#endif
 }
 
 static int _prefix_scan_direct(const char *cursor, int req_count, void **item_array, int item_arrsz)
diff --git a/engines/default/prefix.h b/engines/default/prefix.h
index b346e9f75..ae79b8ec7 100644
--- a/engines/default/prefix.h
+++ b/engines/default/prefix.h
@@ -36,10 +36,6 @@ typedef struct _prefix_t {
     time_t     create_time;
 
     struct _prefix_t *h_next;  /* prefix hash chain */
-    struct _prefix_t *parent_prefix;
-
-    /* Number of child prefix items */
-    uint32_t child_prefix_items;
 
     /* count and bytes of cache items per item type */
     uint64_t total_count_exclusive;
@@ -48,6 +44,10 @@ typedef struct _prefix_t {
     uint64_t items_bytes_exclusive[ITEM_TYPE_MAX];
 
 #ifdef NESTED_PREFIX
+    struct _prefix_t *parent_prefix;
+    /* Number of child prefix items */
+    uint32_t child_prefix_items;
+
     /* includes cache items that belong to child prefixes */
     uint64_t total_count_inclusive; /* NOT yet used */
     uint64_t total_bytes_inclusive; /* NOT yet used */