Fix NewRandomRWFile and ReuseWritableFile in KeyManagedEncryptedEnv (#…

…167) (#168)

Summary:
Fix NewRandomRWFile and ReuseWritableFile misuse of `GetFile()` and `NewFile()`. See inline comments.

Test Plan:
manual test with tikv

Signed-off-by: Yi Wu <yiwu@pingcap.com>

encryption/encryption.cc

@@ -352,7 +352,10 @@ Status KeyManagedEncryptedEnv::ReuseWritableFile(
  const std::string& fname, const std::string& old_fname,
  std::unique_ptr<WritableFile>* result, const EnvOptions& options) {
  FileEncryptionInfo file_info;
- Status s = key_manager_->GetFile(fname, &file_info);
+ // ReuseWritableFile is only used in the context of rotating WAL file and
+ // reuse them. Old content is discardable and new WAL records are to
+ // overwrite the file. So NewFile() should be called.
+ Status s = key_manager_->NewFile(fname, &file_info);
  if (!s.ok()) {
  return s;
  }
@@ -379,7 +382,10 @@ Status KeyManagedEncryptedEnv::NewRandomRWFile(
  const std::string& fname, std::unique_ptr<RandomRWFile>* result,
  const EnvOptions& options) {
  FileEncryptionInfo file_info;
- Status s = key_manager_->NewFile(fname, &file_info);
+ // NewRandomRWFile is only used in the context of external file ingestion,
+ // for rewriting global seqno. So it should call GetFile() instead of
+ // NewFile().
+ Status s = key_manager_->GetFile(fname, &file_info);
  if (!s.ok()) {
  return s;
  }