Add cleanup

CMakeLists.txt

@@ -103,6 +103,7 @@ set(fpindexlib_SOURCES
 	src/fpindex/io/memory_directory.cpp
 	src/fpindex/io/memory_file.h
 	src/fpindex/io/memory_file.cpp
+	src/fpindex/util/cleanup.h
 	src/fpindex/proto/internal.pb.h
 	src/fpindex/proto/internal.pb.cc
 )
@@ -241,6 +242,7 @@ set(tests_SOURCES
 	src/index/op_test.cpp
 	src/fpindex/segment_test.cpp
 	src/fpindex/segment_builder_test.cpp
+	src/fpindex/util/cleanup_test.cpp
 	src/store/buffered_input_stream_test.cpp
 	src/store/input_stream_test.cpp
 	src/store/output_stream_test.cpp

src/fpindex/util/cleanup.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <optional>
+
+namespace fpindex {
+namespace util {
+
+template <typename Callback = void()>
+class Cleanup {
+ public:
+    Cleanup(Callback callback) : callback_(std::move(callback)) {}
+    ~Cleanup() { Invoke(); }
+
+    void Cancel() { callback_.reset(); }
+    void Invoke() {
+        if (callback_) {
+            auto cb = std::move(*callback_);
+            callback_.reset();
+            cb();
+        }
+    }
+
+ private:
+    std::optional<Callback> callback_;
+};
+
+template <typename Callback>
+Cleanup<Callback> MakeCleanup(Callback callback) {
+    return {std::move(callback)};
+}
+
+}  // namespace util
+}  // namespace fpindex

src/fpindex/util/cleanup_test.cpp

@@ -0,0 +1,42 @@
+#include "fpindex/util/cleanup.h"
+
+#include <gtest/gtest.h>
+
+using namespace fpindex;
+
+TEST(CleanupTest, Cleanup) {
+    std::string s = "initial";
+    {
+        auto cleanup = util::MakeCleanup([&s]() {
+            s = "cleaned";
+        });
+        EXPECT_EQ(s, "initial");
+    }
+    EXPECT_EQ(s, "cleaned");
+}
+
+TEST(CleanupTest, Invoke) {
+    std::string s = "initial";
+    {
+        auto cleanup = util::MakeCleanup([&s]() {
+            s = "cleaned";
+        });
+        EXPECT_EQ(s, "initial");
+        cleanup.Invoke();
+        EXPECT_EQ(s, "cleaned");
+        s = "updated";
+    }
+    EXPECT_EQ(s, "updated");
+}
+
+TEST(CleanupTest, Cancel) {
+    std::string s = "initial";
+    {
+        auto cleanup = util::MakeCleanup([&s]() {
+            s = "cleaned";
+        });
+        cleanup.Cancel();
+        EXPECT_EQ(s, "initial");
+    }
+    EXPECT_EQ(s, "initial");
+}