Implement getfreespace for WinEnv (#6265)

Summary:
A new interface method Env::GetFreeSpace was added in https://github.com/facebook/rocksdb/issues/4164. It needs to be implemented for Windows port. Some error_handler_test cases fail on Windows because recovery cannot succeed without free space being reported.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6265

Differential Revision: D19303065

fbshipit-source-id: 1f1a83e53f334284781cf61feabc996e87b945ca

port/win/env_win.cc

@@ -1075,6 +1075,20 @@ std::string WinEnvIO::TimeToString(uint64_t secondsSince1970) {
   return result;
 }
 
+Status WinEnvIO::GetFreeSpace(const std::string& path, uint64_t* diskfree) {
+  assert(diskfree != nullptr);
+  ULARGE_INTEGER freeBytes;
+  BOOL f = RX_GetDiskFreeSpaceEx(RX_FN(path).c_str(), &freeBytes, NULL, NULL);
+  if (f) {
+    *diskfree = freeBytes.QuadPart;
+    return Status::OK();
+  } else {
+    DWORD lastError = GetLastError();
+    return IOErrorFromWindowsError("Failed to get free space: " + path,
+                                   lastError);
+  }
+}
+
 EnvOptions WinEnvIO::OptimizeForLogWrite(const EnvOptions& env_options,
                                          const DBOptions& db_options) const {
   EnvOptions optimized(env_options);
@@ -1467,6 +1481,10 @@ uint64_t WinEnv::GetThreadID() const {
   return winenv_threads_.GetThreadID();
 }
 
+Status WinEnv::GetFreeSpace(const std::string& path, uint64_t* diskfree) {
+  return winenv_io_.GetFreeSpace(path, diskfree);
+}
+
 void WinEnv::SleepForMicroseconds(int micros) {
   return winenv_threads_.SleepForMicroseconds(micros);
 }

port/win/env_win.h

@@ -164,6 +164,12 @@ public:
   virtual Status GetAbsolutePath(const std::string& db_path,
                                  std::string* output_path);
 
+  // This seems to clash with a macro on Windows, so #undef it here
+#undef GetFreeSpace
+
+  // Get the amount of free disk space
+  virtual Status GetFreeSpace(const std::string& path, uint64_t* diskfree);
+
   virtual std::string TimeToString(uint64_t secondsSince1970);
 
   virtual EnvOptions OptimizeForLogWrite(const EnvOptions& env_options,
@@ -307,6 +313,12 @@ public:
 
   uint64_t GetThreadID() const override;
 
+  // This seems to clash with a macro on Windows, so #undef it here
+#undef GetFreeSpace
+
+  // Get the amount of free disk space
+  Status GetFreeSpace(const std::string& path, uint64_t* diskfree) override;
+
   void SleepForMicroseconds(int micros) override;
 
   // Allow increasing the number of worker threads.

port/win/port_win.h

@@ -363,6 +363,7 @@ std::wstring utf8_to_utf16(const std::string& utf8);
 #define RX_CreateHardLink CreateHardLinkW
 #define RX_PathIsRelative PathIsRelativeW
 #define RX_GetCurrentDirectory GetCurrentDirectoryW
+#define RX_GetDiskFreeSpaceEx GetDiskFreeSpaceExW
 
 #else
 
@@ -386,6 +387,7 @@ std::wstring utf8_to_utf16(const std::string& utf8);
 #define RX_CreateHardLink CreateHardLinkA
 #define RX_PathIsRelative PathIsRelativeA
 #define RX_GetCurrentDirectory GetCurrentDirectoryA
+#define RX_GetDiskFreeSpaceEx GetDiskFreeSpaceExA
 
 #endif