Merge pull request #2643 from chenBright/scope_exit

Support SCOPE_EXIT macro

src/butil/endpoint.cpp

@@ -467,11 +467,11 @@ int pthread_timed_connect(int sockfd, const struct sockaddr* serv_addr,
  butil::make_non_blocking(sockfd);
  }
  // Scoped non-blocking.
- auto guard = butil::MakeScopeGuard([is_blocking, sockfd]() {
+ BRPC_SCOPE_EXIT {
  if (is_blocking) {
  butil::make_blocking(sockfd);
  }
- });
+ };
 
  const int rc = ::connect(sockfd, serv_addr, addrlen);
  if (rc == 0 || errno != EINPROGRESS) {

src/butil/memory/scope_guard.h

@@ -19,6 +19,7 @@
 #define BRPC_SCOPED_GUARD_H
 
 #include <type_traits>
+#include "butil/macros.h"
 
 namespace butil {
 
@@ -83,6 +84,31 @@ ScopeGuard<Callback> MakeScopeGuard(Callback&& callback) noexcept {
  return ScopeGuard<Callback>{ std::forward<Callback>(callback)};
 }
 
+namespace internal {
+// for BAIDU_SCOPE_EXIT.
+enum class ScopeExitHelper {};
+
+template<typename Callback>
+ScopeGuard<Callback>
+operator+(ScopeExitHelper, Callback&& callback) {
+ return MakeScopeGuard(std::forward<Callback>(callback));
 }
+} // namespace internal
+} // namespace butil
+
+#define BRPC_ANONYMOUS_VARIABLE(prefix) BAIDU_CONCAT(prefix, __COUNTER__)
+
+// The code in the braces of BAIDU_SCOPE_EXIT always executes at the end of the scope.
+// Variables used within BAIDU_SCOPE_EXIT are captured by reference.
+// Example:
+// int fd = open(...);
+// BAIDU_SCOPE_EXIT {
+// close(fd);
+// };
+// use fd ...
+//
+#define BRPC_SCOPE_EXIT \
+ auto BRPC_ANONYMOUS_VARIABLE(SCOPE_EXIT) = \
+ ::butil::internal::ScopeExitHelper() + [&]() noexcept
 
 #endif // BRPC_SCOPED_GUARD_H

test/scope_guard_unittest.cc

@@ -28,6 +28,25 @@ TEST(ScopedGuardTest, sanity) {
  }
  ASSERT_TRUE(flag);
 
+ flag = false;
+ {
+ BRPC_SCOPE_EXIT {
+ flag = true;
+ };
+ }
+ ASSERT_TRUE(flag);
+
+ {
+ BRPC_SCOPE_EXIT {
+ flag = true;
+ };
+
+ BRPC_SCOPE_EXIT {
+ flag = false;
+ };
+ }
+ ASSERT_TRUE(flag);
+
  flag = false;
  {
  auto guard = butil::MakeScopeGuard([&flag] {