fix lru caching test and fix reference binding to null pointer (#8326)

Summary:
Fix for https://github.com/facebook/rocksdb/issues/8315. Inhe lru caching test, 5100 is not enough to hold meta block and first block in some random case, increase to 6100. Fix the reference binding to null pointer, use template.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8326

Test Plan: make check

Reviewed By: pdillinger

Differential Revision: D28625666

Pulled By: zhichao-cao

fbshipit-source-id: 97b85306ae3d09bfb74addc7c65e57fe55a976a5

cache/lru_cache_test.cc

@@ -659,14 +659,14 @@ TEST_F(DBSecondaryCacheTest, TestSecondaryCacheCorrectness1) {
   Destroy(options);
 }
 
-// In this test, the block cache size is set to 5100, after insert 6 KV-pairs
+// In this test, the block cache size is set to 6100, after insert 6 KV-pairs
 // and flush, there are 5 blocks in this SST file, 2 data blocks and 3 meta
 // blocks. block_1 size is 4096 and block_2 size is 2056. The total size
 // of the meta blocks are about 900 to 1000. Therefore, we can successfully
 // insert and cache block_1 in the block cache (this is the different place
 // from TestSecondaryCacheCorrectness1)
 TEST_F(DBSecondaryCacheTest, TestSecondaryCacheCorrectness2) {
-  LRUCacheOptions opts(5100, 0, false, 0.5, nullptr, kDefaultToAdaptiveMutex,
+  LRUCacheOptions opts(6100, 0, false, 0.5, nullptr, kDefaultToAdaptiveMutex,
                        kDontChargeCacheMetadata);
   std::shared_ptr<TestSecondaryCache> secondary_cache(
       new TestSecondaryCache(2048 * 1024));

table/block_based/block_based_table_reader.cc

@@ -1124,9 +1124,8 @@ Status BlockBasedTable::GetDataBlockFromCache(
   Statistics* statistics = rep_->ioptions.statistics.get();
   bool using_zstd = rep_->blocks_definitely_zstd_compressed;
   const FilterPolicy* filter_policy = rep_->filter_policy;
-  Cache::CreateCallback create_cb =
-      GetCreateCallback(read_amp_bytes_per_bit, statistics, using_zstd,
-                        filter_policy, *block->GetValue());
+  Cache::CreateCallback create_cb = GetCreateCallback<TBlocklike>(
+      read_amp_bytes_per_bit, statistics, using_zstd, filter_policy);
 
   // Lookup uncompressed cache first
   if (block_cache != nullptr) {
@@ -1151,8 +1150,8 @@ Status BlockBasedTable::GetDataBlockFromCache(
 
   assert(!compressed_block_cache_key.empty());
   BlockContents contents;
-  Cache::CreateCallback create_cb_special = GetCreateCallback(
-      read_amp_bytes_per_bit, statistics, using_zstd, filter_policy, contents);
+  Cache::CreateCallback create_cb_special = GetCreateCallback<BlockContents>(
+      read_amp_bytes_per_bit, statistics, using_zstd, filter_policy);
   block_cache_compressed_handle = block_cache_compressed->Lookup(
       compressed_block_cache_key,
       BlocklikeTraits<BlockContents>::GetCacheItemHelper(block_type),

table/block_based/block_like_traits.h

@@ -23,8 +23,7 @@ Cache::CacheItemHelper* GetCacheItemHelperForRole();
 template <typename TBlocklike>
 Cache::CreateCallback GetCreateCallback(size_t read_amp_bytes_per_bit,
                                         Statistics* statistics, bool using_zstd,
-                                        const FilterPolicy* filter_policy,
-                                        const TBlocklike& /*block*/) {
+                                        const FilterPolicy* filter_policy) {
   return [read_amp_bytes_per_bit, statistics, using_zstd, filter_policy](
              void* buf, size_t size, void** out_obj, size_t* charge) -> Status {
     assert(buf != nullptr);