From aa34eb201c6ac3cbc7b40c1d507cd420ccfb6bb1 Mon Sep 17 00:00:00 2001
From: Dmitri Petrov <dmitri.petrov@rockset.com>
Date: Thu, 21 Dec 2023 23:44:08 +0000
Subject: [PATCH] Use virtual inheritance in FileSystem hierarchy.

---
 include/rocksdb/cloud/cloud_file_system.h      | 2 +-
 include/rocksdb/cloud/cloud_file_system_impl.h | 3 +--
 include/rocksdb/file_system.h                  | 2 +-
 3 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/rocksdb/cloud/cloud_file_system.h b/include/rocksdb/cloud/cloud_file_system.h
index 42aa07c8aaef..7cae24f4b3e1 100644
--- a/include/rocksdb/cloud/cloud_file_system.h
+++ b/include/rocksdb/cloud/cloud_file_system.h
@@ -494,7 +494,7 @@ struct CloudManifestDelta {
 // NOTE: The AWS SDK must be initialized before the CloudFileSystem is
 // constructed, and remain active (Aws::ShutdownAPI() not called) as long as any
 // CloudFileSystem objects exist.
-class CloudFileSystem : public FileSystem {
+class CloudFileSystem : public virtual FileSystem {
  protected:
   CloudFileSystemOptions cloud_fs_options;
   std::shared_ptr<FileSystem> base_fs_;  // The underlying file system
diff --git a/include/rocksdb/cloud/cloud_file_system_impl.h b/include/rocksdb/cloud/cloud_file_system_impl.h
index dcd9ffc44522..6eada2608559 100644
--- a/include/rocksdb/cloud/cloud_file_system_impl.h
+++ b/include/rocksdb/cloud/cloud_file_system_impl.h
@@ -22,7 +22,7 @@ class CloudFileDeletionScheduler;
 //
 // The Cloud file system
 //
-class CloudFileSystemImpl : public CloudFileSystem {
+class CloudFileSystemImpl : public virtual CloudFileSystem {
   friend class CloudFileSystem;
 
  public:
@@ -236,7 +236,6 @@ class CloudFileSystemImpl : public CloudFileSystem {
         "CloudFileSystemImpl::IsDirectory() not supported.");
   }
 
-
   IOStatus Poll(std::vector<void*>& io_handles,
                 size_t /*min_completions*/) override {
     for (auto* handle : io_handles) {
diff --git a/include/rocksdb/file_system.h b/include/rocksdb/file_system.h
index 05ac40b41a89..22e07bb3536b 100644
--- a/include/rocksdb/file_system.h
+++ b/include/rocksdb/file_system.h
@@ -1380,7 +1380,7 @@ class FSDirectory {
 // An implementation of Env that forwards all calls to another Env.
 // May be useful to clients who wish to override just part of the
 // functionality of another Env.
-class FileSystemWrapper : public FileSystem {
+class FileSystemWrapper : public virtual FileSystem {
  public:
   // Initialize an EnvWrapper that delegates all calls to *t
   explicit FileSystemWrapper(const std::shared_ptr<FileSystem>& t);