hook delete dir in encrypted env (facebook#334) (facebook#12)

apache/incubator-pegasus#1575

Cherry-pick from
tikv@acc624f

* hook delete dir in encrypted env
* add a comment

Signed-off-by: tabokie <xy.tao@outlook.com>
Co-authored-by: Xinye Tao <xy.tao@outlook.com>

Author: acelyc111

encryption/encryption.cc

@@ -539,6 +539,16 @@ Status KeyManagedEncryptedEnv::RenameFile(const std::string& src_fname,
   return s;
 }
 
+Status KeyManagedEncryptedEnv::DeleteDir(const std::string& dname) {
+  Status s = target()->DeleteDir(dname);
+  if (!s.ok()) {
+    return s;
+  }
+  // We don't use a dedicated `DeleteDir` function, because RocksDB already uses
+  // `RenameFile` for both file and directory.
+  return key_manager_->DeleteFile(dname);
+}
+
 Env* NewKeyManagedEncryptedEnv(Env* base_env,
                                std::shared_ptr<KeyManager>& key_manager) {
   std::shared_ptr<AESEncryptionProvider> provider(

include/rocksdb/encryption.h

@@ -97,6 +97,8 @@ class KeyManagedEncryptedEnv : public EnvWrapper {
   Status RenameFile(const std::string& src_fname,
                     const std::string& dst_fname) override;
 
+  Status DeleteDir(const std::string& dname) override;
+
  private:
   const std::shared_ptr<KeyManager> key_manager_;
   const std::shared_ptr<AESEncryptionProvider> provider_;