[#23960] DocDB: Fix WriteBuffer crash in move ctor

Summary:
WriteBuffer move ctor does not initialize consumption_.
So segmentation fault could happen when WriteBuffer is constucted over non zeroed memory.
Jira: DB-12860

Test Plan: WriteBufferTest.MoveCtor

Reviewers: rthallam, esheng

Reviewed By: esheng

Subscribers: ybase

Differential Revision: https://phorge.dev.yugabyte.com/D38158

src/yb/util/write_buffer-test.cc

@@ -49,4 +49,15 @@ TEST(WriteBufferTest, AppendPerformance) {
   });
 }
 
+TEST(WriteBufferTest, MoveCtor) {
+  std::string text("Hello");
+  WriteBuffer original(0x10);
+  original.Append(text.c_str(), text.size());
+  alignas(alignof(WriteBuffer)) char buffer[sizeof(WriteBuffer)];
+  std::fill_n(buffer, sizeof (buffer), 0x40);
+  auto* moved = new (buffer) WriteBuffer(std::move(original));
+  ASSERT_EQ(moved->ToBuffer(), text);
+  moved->~WriteBuffer();
+}
+
 }  // namespace yb

src/yb/util/write_buffer.h

@@ -36,8 +36,11 @@ class WriteBuffer {
   explicit WriteBuffer(size_t block_size, ScopedTrackedConsumption* consumption = nullptr)
       : block_size_(block_size), consumption_(consumption) {}
 
-  WriteBuffer(WriteBuffer&& rhs) : block_size_(rhs.block_size_) {
+  WriteBuffer(WriteBuffer&& rhs) : block_size_(rhs.block_size_), consumption_(nullptr) {
+    auto consumption = rhs.consumption_;
+    rhs.consumption_ = nullptr;
     Take(&rhs);
+    consumption_ = consumption;
   }
 
   void operator=(WriteBuffer&& rhs) {