From 49a954590346babfa42a78115f2fea638039323a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=9B=D0=B5=D0=BE=D0=BD=D0=B8=D0=B4=20=D0=AE=D1=80=D1=8C?=
 =?UTF-8?q?=D0=B5=D0=B2=20=28Leonid=20Yuriev=29?= <leo@yuriev.ru>
Date: Tue, 3 Jun 2025 17:11:40 +0300
Subject: [PATCH] =?UTF-8?q?mdbx:=20=D0=B4=D0=BE=D0=B1=D0=B0=D0=B2=D0=BB?=
 =?UTF-8?q?=D0=B5=D0=BD=D0=B8=D0=B5=20`rkl=5Fdestructive=5Fmerge()`=20?=
 =?UTF-8?q?=D0=B8=20=D1=83=D0=BD=D0=B8=D1=84=D0=B8=D0=BA=D0=B0=D1=86=D0=B8?=
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---
 src/gc-put.c | 2 +-
 src/rkl.c    | 8 +++++++-
 src/rkl.h    | 3 ++-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/gc-put.c b/src/gc-put.c
index fa141968..0a4066d5 100644
--- a/src/gc-put.c
+++ b/src/gc-put.c
@@ -1195,7 +1195,7 @@ static int gc_rerere(MDBX_txn *txn, gcu_t *ctx) {
         return err;
 
       if (!rkl_empty(&ctx->sequel)) {
-        err = rkl_merge(&ctx->ready4reuse, &ctx->sequel, false);
+        err = rkl_merge(&ctx->sequel, &ctx->ready4reuse, false);
         if (unlikely(err != MDBX_SUCCESS)) {
           if (err == MDBX_RESULT_TRUE) {
             ERROR("%s/%d: %s", "MDBX_PROBLEM", MDBX_PROBLEM, "unexpected duplicate(s) during rkl-merge");
diff --git a/src/rkl.c b/src/rkl.c
index 1a0fd84b..4de9fd75 100644
--- a/src/rkl.c
+++ b/src/rkl.c
@@ -393,7 +393,7 @@ txnid_t rkl_highest(const rkl_t *rkl) {
   return !solid_empty(rkl) ? rkl->solid_end - 1 : 0;
 }
 
-int rkl_merge(rkl_t *dst, const rkl_t *src, bool ignore_duplicates) {
+int rkl_merge(const rkl_t *src, rkl_t *dst, bool ignore_duplicates) {
   if (src->list_length) {
     size_t i = src->list_length;
     do {
@@ -413,6 +413,12 @@ int rkl_merge(rkl_t *dst, const rkl_t *src, bool ignore_duplicates) {
   return MDBX_SUCCESS;
 }
 
+int rkl_destructive_merge(rkl_t *src, rkl_t *dst, bool ignore_duplicates) {
+  int err = rkl_merge(src, dst, ignore_duplicates);
+  rkl_destroy(src);
+  return err;
+}
+
 rkl_iter_t rkl_iterator(const rkl_t *rkl, const bool reverse) {
   rkl_iter_t iter = {.rkl = rkl, .pos = reverse ? rkl_len(rkl) : 0, .solid_offset = 0};
   if (!solid_empty(rkl) && rkl->list_length) {
diff --git a/src/rkl.h b/src/rkl.h
index e982d8c8..a9c98ab0 100644
--- a/src/rkl.h
+++ b/src/rkl.h
@@ -50,7 +50,8 @@ MDBX_MAYBE_UNUSED MDBX_NOTHROW_PURE_FUNCTION static inline txnid_t rkl_edge(cons
 }
 MDBX_MAYBE_UNUSED MDBX_INTERNAL __must_check_result int rkl_push(rkl_t *rkl, const txnid_t id);
 MDBX_MAYBE_UNUSED MDBX_INTERNAL txnid_t rkl_pop(rkl_t *rkl, const bool highest_not_lowest);
-MDBX_MAYBE_UNUSED MDBX_INTERNAL __must_check_result int rkl_merge(rkl_t *dst, const rkl_t *src, bool ignore_duplicates);
+MDBX_MAYBE_UNUSED MDBX_INTERNAL __must_check_result int rkl_merge(const rkl_t *src, rkl_t *dst, bool ignore_duplicates);
+MDBX_MAYBE_UNUSED MDBX_INTERNAL int rkl_destructive_merge(rkl_t *src, rkl_t *dst, bool ignore_duplicates);
 
 /* Итератор для rkl.
  * Обеспечивает изоляцию внутреннего устройства rkl от остального кода, чем существенно его упрощает.