From 75ecd9c6920c55d48295fad65fcc3a7da481f4a4 Mon Sep 17 00:00:00 2001
From: levlam <levlam@telegram.org>
Date: Fri, 3 Jan 2020 02:41:57 +0300
Subject: [PATCH] Optimize FileFd.get_size/get_real_size on Windows.

GitOrigin-RevId: e39efbecdd6882bf4465b17dad556b585633b56e
---
 tdutils/td/utils/port/FileFd.cpp | 63 +++++++++++++++++++++++---------
 1 file changed, 45 insertions(+), 18 deletions(-)

diff --git a/tdutils/td/utils/port/FileFd.cpp b/tdutils/td/utils/port/FileFd.cpp
index 2f65df61..df55b90a 100644
--- a/tdutils/td/utils/port/FileFd.cpp
+++ b/tdutils/td/utils/port/FileFd.cpp
@@ -22,6 +22,7 @@
 #include <cstring>
 #include <mutex>
 #include <unordered_set>
+#include <utility>
 
 #if TD_PORT_POSIX
 #include <fcntl.h>
@@ -475,23 +476,57 @@ NativeFd FileFd::move_as_native_fd() {
   return res;
 }
 
+#if TD_PORT_WINDOWS
+namespace {
+
+uint64 filetime_to_unix_time_nsec(LONGLONG filetime) {
+  const auto FILETIME_UNIX_TIME_DIFF = 116444736000000000ll;
+  return static_cast<uint64>((filetime - FILETIME_UNIX_TIME_DIFF) * 100);
+}
+
+struct FileSize {
+  int64 size_;
+  int64 real_size_;
+};
+
+Result<FileSize> get_file_size(const FileFd &file_fd) {
+  FILE_STANDARD_INFO standard_info;
+  if (!GetFileInformationByHandleEx(file_fd.get_native_fd().fd(), FileStandardInfo, &standard_info,
+                                    sizeof(standard_info))) {
+    return OS_ERROR("Get FileStandardInfo failed");
+  }
+  FileSize res;
+  res.size_ = standard_info.EndOfFile.QuadPart;
+  res.real_size_ = standard_info.AllocationSize.QuadPart;
+
+  if (res.size_ > 0 && res.real_size_ <= 0) {
+    res.real_size_ = res.size_;  // just in case
+  }
+
+  return res;
+}
+
+}  // namespace
+#endif
+
 Result<int64> FileFd::get_size() const {
+#if TD_PORT_POSIX
   TRY_RESULT(s, stat());
+#else if TD_PORT_WINDOWS
+  TRY_RESULT(s, get_file_size(*this));
+#endif
   return s.size_;
 }
 
 Result<int64> FileFd::get_real_size() const {
+#if TD_PORT_POSIX
   TRY_RESULT(s, stat());
+#else if TD_PORT_WINDOWS
+  TRY_RESULT(s, get_file_size(*this));
+#endif
   return s.real_size_;
 }
 
-#if TD_PORT_WINDOWS
-static uint64 filetime_to_unix_time_nsec(LONGLONG filetime) {
-  const auto FILETIME_UNIX_TIME_DIFF = 116444736000000000ll;
-  return static_cast<uint64>((filetime - FILETIME_UNIX_TIME_DIFF) * 100);
-}
-#endif
-
 Result<Stat> FileFd::stat() const {
   CHECK(!empty());
 #if TD_PORT_POSIX
@@ -509,17 +544,9 @@ Result<Stat> FileFd::stat() const {
   res.is_dir_ = (basic_info.FileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
   res.is_reg_ = !res.is_dir_;  // TODO this is still wrong
 
-  FILE_STANDARD_INFO standard_info;
-  status = GetFileInformationByHandleEx(get_native_fd().fd(), FileStandardInfo, &standard_info, sizeof(standard_info));
-  if (!status) {
-    return OS_ERROR("Get FileStandardInfo failed");
-  }
-  res.size_ = standard_info.EndOfFile.QuadPart;
-  res.real_size_ = standard_info.AllocationSize.QuadPart;
-
-  if (res.size_ != 0 && res.real_size_ <= 0 ) {
-    res.real_size_ = res.size_; // just in case
-  }
+  TRY_RESULT(file_size, get_file_size(*this));
+  res.size_ = file_size.size_;
+  res.real_size_ = file_size.real_size_;
 
   return res;
 #endif