[GitHub] [incubator-kvrocks] caipengbo commented on a diff in pull request #973: Add `UniqueFD` and `ScopeExit`

[GitBox <gi...@apache.org>]

caipengbo commented on code in PR #973:
URL: https://github.com/apache/incubator-kvrocks/pull/973#discussion_r992900734


##########
src/fd_util.h:
##########
@@ -0,0 +1,111 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+
+#pragma once
+
+#include <unistd.h>
+#include <utility>
+
+constexpr const int NullFD = -1;
+
+// just like an unique_ptr, but for (int) fd
+struct UniqueFD {
+  UniqueFD() : fd_(NullFD) {}
+  explicit UniqueFD(int fd) : fd_(fd) {}
+
+  ~UniqueFD() { if (fd_ != NullFD) close(fd_); }
+
+  UniqueFD(const UniqueFD&) = delete;
+  UniqueFD(UniqueFD&& f) : fd_(f.fd_) { f.fd_ = NullFD; }
+
+  UniqueFD& operator=(const UniqueFD&) = delete;
+  UniqueFD& operator=(UniqueFD&& f) {
+    fd_ = f.fd_;
+    f.fd_ = NullFD;
+    return *this;
+  }
+
+  int Release() {
+    int fd = fd_;
+    fd_ = NullFD;
+    return fd;
+  }
+
+  void Reset(int fd = NullFD) {
+    int old_fd = fd_;
+    fd_ = fd;
+    if (old_fd != NullFD) close(old_fd);
+  }
+
+  void Close() {
+    Reset();
+  }
+
+  void Swap(UniqueFD& other) {
+    std::swap(fd_, other.fd_);
+  }
+
+  int Get() const { return fd_; }
+  int operator*() const { return fd_; }
+  explicit operator bool() const { return fd_ != NullFD; }
+
+  bool operator==(const UniqueFD& f) const {
+    return fd_ == f.fd_;
+  }
+
+  bool operator!=(const UniqueFD& f) const {
+    return !(*this == f);
+  }
+
+ private:
+  int fd_;
+};
+
+
+// ref to https://en.cppreference.com/w/cpp/experimental/scope_exit
+template <typename F>
+struct ScopeExit {

Review Comment:
   Is `ScopeExit` an `fd` related utility?



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