logging: reduce the amount of code emitted for log statements

[folly.git] / folly / File.h

diff --git a/folly/File.h b/folly/File.h
index 26d158e11f9b1fb5dca80ce228f24211077ad05e..af6620960b6e3bb36e354a6f4417a9392f9ca25d 100644 (file)
--- a/folly/File.h
+++ b/folly/File.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,10 @@
 #include <sys/types.h>
 
 #include <string>
+#include <system_error>
 
+#include <folly/ExceptionWrapper.h>
+#include <folly/Expected.h>
 #include <folly/Portability.h>
 #include <folly/Range.h>
 #include <folly/portability/Unistd.h>
@@ -36,13 +39,13 @@ class File {
   /**
    * Creates an empty File object, for late initialization.
    */
-  File();
+  File() noexcept;
 
   /**
    * Create a File object from an existing file descriptor.
    * Takes ownership of the file descriptor if ownsFd is true.
    */
-  explicit File(int fd, bool ownsFd = false);
+  explicit File(int fd, bool ownsFd = false) noexcept;
 
   /**
    * Open and create a file object.  Throws on error.
@@ -52,6 +55,20 @@ class File {
       const std::string& name, int flags = O_RDONLY, mode_t mode = 0666);
   explicit File(StringPiece name, int flags = O_RDONLY, mode_t mode = 0666);
 
+  /**
+   * All the constructors that are not noexcept can throw std::system_error.
+   * This is a helper method to use folly::Expected to chain a file open event
+   * to something else you want to do with the open fd.
+   */
+  template <typename... Args>
+  static Expected<File, exception_wrapper> makeFile(Args&&... args) noexcept {
+    try {
+      return File(std::forward<Args>(args)...);
+    } catch (const std::system_error& se) {
+      return makeUnexpected(exception_wrapper(std::current_exception(), se));
+    }
+  }
+
   ~File();
 
   /**