1 files changed, 111 insertions, 0 deletions
diff --git a/src/rocksdb/table/persistent_cache_helper.cc b/src/rocksdb/table/persistent_cache_helper.cc
new file mode 100644
index 000000000..eece8100e
--- /dev/null
+++ b/src/rocksdb/table/persistent_cache_helper.cc
@@ -0,0 +1,111 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  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 "table/persistent_cache_helper.h"
+
+#include "table/block_based/block_based_table_reader.h"
+#include "table/format.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+const PersistentCacheOptions PersistentCacheOptions::kEmpty;
+
+void PersistentCacheHelper::InsertSerialized(
+    const PersistentCacheOptions& cache_options, const BlockHandle& handle,
+    const char* data, const size_t size) {
+  assert(cache_options.persistent_cache);
+  assert(cache_options.persistent_cache->IsCompressed());
+
+  CacheKey key =
+      BlockBasedTable::GetCacheKey(cache_options.base_cache_key, handle);
+
+  cache_options.persistent_cache->Insert(key.AsSlice(), data, size)
+      .PermitUncheckedError();
+}
+
+void PersistentCacheHelper::InsertUncompressed(
+    const PersistentCacheOptions& cache_options, const BlockHandle& handle,
+    const BlockContents& contents) {
+  assert(cache_options.persistent_cache);
+  assert(!cache_options.persistent_cache->IsCompressed());
+  // Precondition:
+  // (1) content is cacheable
+  // (2) content is not compressed
+
+  CacheKey key =
+      BlockBasedTable::GetCacheKey(cache_options.base_cache_key, handle);
+
+  cache_options.persistent_cache
+      ->Insert(key.AsSlice(), contents.data.data(), contents.data.size())
+      .PermitUncheckedError();
+  ;
+}
+
+Status PersistentCacheHelper::LookupSerialized(
+    const PersistentCacheOptions& cache_options, const BlockHandle& handle,
+    std::unique_ptr<char[]>* out_data, const size_t expected_data_size) {
+#ifdef NDEBUG
+  (void)expected_data_size;
+#endif
+  assert(cache_options.persistent_cache);
+  assert(cache_options.persistent_cache->IsCompressed());
+
+  CacheKey key =
+      BlockBasedTable::GetCacheKey(cache_options.base_cache_key, handle);
+
+  size_t size;
+  Status s =
+      cache_options.persistent_cache->Lookup(key.AsSlice(), out_data, &size);
+  if (!s.ok()) {
+    // cache miss
+    RecordTick(cache_options.statistics, PERSISTENT_CACHE_MISS);
+    return s;
+  }
+
+  // cache hit
+  // Block-based table is assumed
+  assert(expected_data_size ==
+         handle.size() + BlockBasedTable::kBlockTrailerSize);
+  assert(size == expected_data_size);
+  RecordTick(cache_options.statistics, PERSISTENT_CACHE_HIT);
+  return Status::OK();
+}
+
+Status PersistentCacheHelper::LookupUncompressed(
+    const PersistentCacheOptions& cache_options, const BlockHandle& handle,
+    BlockContents* contents) {
+  assert(cache_options.persistent_cache);
+  assert(!cache_options.persistent_cache->IsCompressed());
+  if (!contents) {
+    // We shouldn't lookup in the cache. Either
+    // (1) Nowhere to store
+    return Status::NotFound();
+  }
+
+  CacheKey key =
+      BlockBasedTable::GetCacheKey(cache_options.base_cache_key, handle);
+
+  std::unique_ptr<char[]> data;
+  size_t size;
+  Status s =
+      cache_options.persistent_cache->Lookup(key.AsSlice(), &data, &size);
+  if (!s.ok()) {
+    // cache miss
+    RecordTick(cache_options.statistics, PERSISTENT_CACHE_MISS);
+    return s;
+  }
+
+  // please note we are potentially comparing compressed data size with
+  // uncompressed data size
+  assert(handle.size() <= size);
+
+  // update stats
+  RecordTick(cache_options.statistics, PERSISTENT_CACHE_HIT);
+  // construct result and return
+  *contents = BlockContents(std::move(data), size);
+  return Status::OK();
+}
+
+}  // namespace ROCKSDB_NAMESPACE