From d4f7b4114bdaf5e9889686e77e9bc2d9c0aa588c 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: Sat, 30 Mar 2024 23:30:06 +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`buffer::clear=5Fand=5Freserve()`.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 mdbx.h++ | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/mdbx.h++ b/mdbx.h++
index e8a58bfe..8ef9b44b 100644
--- a/mdbx.h++
+++ b/mdbx.h++
@@ -1907,7 +1907,6 @@ private:
       const size_t old_capacity = bin_.capacity();
       const size_t new_capacity =
           bin::advise_capacity(old_capacity, wanna_capacity);
-      assert(new_capacity >= wanna_capacity);
       if (MDBX_LIKELY(new_capacity == old_capacity))
         MDBX_CXX20_LIKELY {
           assert(bin_.is_inplace() ==
@@ -2073,7 +2072,13 @@ private:
       return *this;
     }
 
-    MDBX_CXX20_CONSTEXPR void clear() { reshape<true>(0, 0, nullptr, 0); }
+    MDBX_CXX20_CONSTEXPR void *clear() {
+      return reshape<true>(0, 0, nullptr, 0);
+    }
+    MDBX_CXX20_CONSTEXPR void *clear_and_reserve(size_t whole_capacity,
+                                                 size_t headroom) {
+      return reshape<false>(whole_capacity, headroom, nullptr, 0);
+    }
     MDBX_CXX20_CONSTEXPR void resize(size_t capacity, size_t headroom,
                                      slice &content) {
       content.iov_base =
@@ -2803,9 +2808,11 @@ public:
   }
 
   /// \brief Clears the contents and storage.
-  void clear() noexcept {
-    slice_.clear();
-    silo_.clear();
+  void clear() noexcept { slice_.assign(silo_.clear(), size_t(0)); }
+
+  /// \brief Clears the contents and reserve storage.
+  void clear_and_reserve(size_t whole_capacity, size_t headroom = 0) noexcept {
+    slice_.assign(silo_.clear_and_reserve(whole_capacity, headroom), size_t(0));
   }
 
   /// \brief Reduces memory usage by freeing unused storage space.