1 files changed, 121 insertions, 0 deletions
diff --git a/src/rocksdb/cache/charged_cache.h b/src/rocksdb/cache/charged_cache.h
new file mode 100644
index 000000000..1739e4088
--- /dev/null
+++ b/src/rocksdb/cache/charged_cache.h
@@ -0,0 +1,121 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include <string>
+
+#include "port/port.h"
+#include "rocksdb/cache.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class ConcurrentCacheReservationManager;
+
+// A cache interface which wraps around another cache and takes care of
+// reserving space in block cache towards a single global memory limit, and
+// forwards all the calls to the underlying cache.
+class ChargedCache : public Cache {
+ public:
+  ChargedCache(std::shared_ptr<Cache> cache,
+               std::shared_ptr<Cache> block_cache);
+  ~ChargedCache() override = default;
+
+  Status Insert(const Slice& key, void* value, size_t charge, DeleterFn deleter,
+                Handle** handle, Priority priority) override;
+  Status Insert(const Slice& key, void* value, const CacheItemHelper* helper,
+                size_t charge, Handle** handle = nullptr,
+                Priority priority = Priority::LOW) override;
+
+  Cache::Handle* Lookup(const Slice& key, Statistics* stats) override;
+  Cache::Handle* Lookup(const Slice& key, const CacheItemHelper* helper,
+                        const CreateCallback& create_cb, Priority priority,
+                        bool wait, Statistics* stats = nullptr) override;
+
+  bool Release(Cache::Handle* handle, bool useful,
+               bool erase_if_last_ref = false) override;
+  bool Release(Cache::Handle* handle, bool erase_if_last_ref = false) override;
+
+  void Erase(const Slice& key) override;
+  void EraseUnRefEntries() override;
+
+  static const char* kClassName() { return "ChargedCache"; }
+  const char* Name() const override { return kClassName(); }
+
+  uint64_t NewId() override { return cache_->NewId(); }
+
+  void SetCapacity(size_t capacity) override;
+
+  void SetStrictCapacityLimit(bool strict_capacity_limit) override {
+    cache_->SetStrictCapacityLimit(strict_capacity_limit);
+  }
+
+  bool HasStrictCapacityLimit() const override {
+    return cache_->HasStrictCapacityLimit();
+  }
+
+  void* Value(Cache::Handle* handle) override { return cache_->Value(handle); }
+
+  bool IsReady(Cache::Handle* handle) override {
+    return cache_->IsReady(handle);
+  }
+
+  void Wait(Cache::Handle* handle) override { cache_->Wait(handle); }
+
+  void WaitAll(std::vector<Handle*>& handles) override {
+    cache_->WaitAll(handles);
+  }
+
+  bool Ref(Cache::Handle* handle) override { return cache_->Ref(handle); }
+
+  size_t GetCapacity() const override { return cache_->GetCapacity(); }
+
+  size_t GetUsage() const override { return cache_->GetUsage(); }
+
+  size_t GetUsage(Cache::Handle* handle) const override {
+    return cache_->GetUsage(handle);
+  }
+
+  size_t GetPinnedUsage() const override { return cache_->GetPinnedUsage(); }
+
+  size_t GetCharge(Cache::Handle* handle) const override {
+    return cache_->GetCharge(handle);
+  }
+
+  Cache::DeleterFn GetDeleter(Cache::Handle* handle) const override {
+    return cache_->GetDeleter(handle);
+  }
+
+  void ApplyToAllEntries(
+      const std::function<void(const Slice& key, void* value, size_t charge,
+                               Cache::DeleterFn deleter)>& callback,
+      const Cache::ApplyToAllEntriesOptions& opts) override {
+    cache_->ApplyToAllEntries(callback, opts);
+  }
+
+  void ApplyToAllCacheEntries(void (*callback)(void* value, size_t charge),
+                              bool thread_safe) override {
+    cache_->ApplyToAllCacheEntries(callback, thread_safe);
+  }
+
+  std::string GetPrintableOptions() const override {
+    return cache_->GetPrintableOptions();
+  }
+
+  void DisownData() override { return cache_->DisownData(); }
+
+  inline Cache* GetCache() const { return cache_.get(); }
+
+  inline ConcurrentCacheReservationManager* TEST_GetCacheReservationManager()
+      const {
+    return cache_res_mgr_.get();
+  }
+
+ private:
+  std::shared_ptr<Cache> cache_;
+  std::shared_ptr<ConcurrentCacheReservationManager> cache_res_mgr_;
+};
+
+}  // namespace ROCKSDB_NAMESPACE