1 files changed, 117 insertions, 0 deletions
diff --git a/src/rocksdb/cache/charged_cache.cc b/src/rocksdb/cache/charged_cache.cc
new file mode 100644
index 000000000..a9ff969b8
--- /dev/null
+++ b/src/rocksdb/cache/charged_cache.cc
@@ -0,0 +1,117 @@
+//  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).
+
+#include "cache/charged_cache.h"
+
+#include "cache/cache_reservation_manager.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+ChargedCache::ChargedCache(std::shared_ptr<Cache> cache,
+                           std::shared_ptr<Cache> block_cache)
+    : cache_(cache),
+      cache_res_mgr_(std::make_shared<ConcurrentCacheReservationManager>(
+          std::make_shared<
+              CacheReservationManagerImpl<CacheEntryRole::kBlobCache>>(
+              block_cache))) {}
+
+Status ChargedCache::Insert(const Slice& key, void* value, size_t charge,
+                            DeleterFn deleter, Handle** handle,
+                            Priority priority) {
+  Status s = cache_->Insert(key, value, charge, deleter, handle, priority);
+  if (s.ok()) {
+    // Insert may cause the cache entry eviction if the cache is full. So we
+    // directly call the reservation manager to update the total memory used
+    // in the cache.
+    assert(cache_res_mgr_);
+    cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+        .PermitUncheckedError();
+  }
+  return s;
+}
+
+Status ChargedCache::Insert(const Slice& key, void* value,
+                            const CacheItemHelper* helper, size_t charge,
+                            Handle** handle, Priority priority) {
+  Status s = cache_->Insert(key, value, helper, charge, handle, priority);
+  if (s.ok()) {
+    // Insert may cause the cache entry eviction if the cache is full. So we
+    // directly call the reservation manager to update the total memory used
+    // in the cache.
+    assert(cache_res_mgr_);
+    cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+        .PermitUncheckedError();
+  }
+  return s;
+}
+
+Cache::Handle* ChargedCache::Lookup(const Slice& key, Statistics* stats) {
+  return cache_->Lookup(key, stats);
+}
+
+Cache::Handle* ChargedCache::Lookup(const Slice& key,
+                                    const CacheItemHelper* helper,
+                                    const CreateCallback& create_cb,
+                                    Priority priority, bool wait,
+                                    Statistics* stats) {
+  auto handle = cache_->Lookup(key, helper, create_cb, priority, wait, stats);
+  // Lookup may promote the KV pair from the secondary cache to the primary
+  // cache. So we directly call the reservation manager to update the total
+  // memory used in the cache.
+  assert(cache_res_mgr_);
+  cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+      .PermitUncheckedError();
+  return handle;
+}
+
+bool ChargedCache::Release(Cache::Handle* handle, bool useful,
+                           bool erase_if_last_ref) {
+  size_t memory_used_delta = cache_->GetUsage(handle);
+  bool erased = cache_->Release(handle, useful, erase_if_last_ref);
+  if (erased) {
+    assert(cache_res_mgr_);
+    cache_res_mgr_
+        ->UpdateCacheReservation(memory_used_delta, /* increase */ false)
+        .PermitUncheckedError();
+  }
+  return erased;
+}
+
+bool ChargedCache::Release(Cache::Handle* handle, bool erase_if_last_ref) {
+  size_t memory_used_delta = cache_->GetUsage(handle);
+  bool erased = cache_->Release(handle, erase_if_last_ref);
+  if (erased) {
+    assert(cache_res_mgr_);
+    cache_res_mgr_
+        ->UpdateCacheReservation(memory_used_delta, /* increase */ false)
+        .PermitUncheckedError();
+  }
+  return erased;
+}
+
+void ChargedCache::Erase(const Slice& key) {
+  cache_->Erase(key);
+  assert(cache_res_mgr_);
+  cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+      .PermitUncheckedError();
+}
+
+void ChargedCache::EraseUnRefEntries() {
+  cache_->EraseUnRefEntries();
+  assert(cache_res_mgr_);
+  cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+      .PermitUncheckedError();
+}
+
+void ChargedCache::SetCapacity(size_t capacity) {
+  cache_->SetCapacity(capacity);
+  // SetCapacity can result in evictions when the cache capacity is decreased,
+  // so we would want to update the cache reservation here as well.
+  assert(cache_res_mgr_);
+  cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+      .PermitUncheckedError();
+}
+
+}  // namespace ROCKSDB_NAMESPACE