Enable persistent cache for rocksdb-cloud.

Summary:
The persistent-cache is a lookaside cache that can be
used to store data from cloud storage on local disk.

Test Plan: Added unit test

Reviewers: hieu, haneeshr, kw, joe, igor

Reviewed By: hieu, igor

Subscribers: #platform

Differential Revision: https://rockset.phacility.com/D6378

Author: dhruba

cloud/cloud_storage_provider.cc

@@ -109,7 +109,7 @@ size_t CloudStorageReadableFileImpl::GetUniqueId(char* id,
   WalFileType log_type;
   ParseFileName(RemoveEpoch(basename(fname_)), &file_number, &file_type,
                 &log_type);
-  if (max_size < kMaxVarint64Length && file_number > 0) {
+  if (max_size >= kMaxVarint64Length && file_number > 0) {
     char* rid = id;
     rid = EncodeVarint64(rid, file_number);
     return static_cast<size_t>(rid - id);

cloud/db_cloud_impl.cc

@@ -24,6 +24,7 @@
 #include "rocksdb/status.h"
 #include "rocksdb/table.h"
 #include "util/xxhash.h"
+#include "utilities/persistent_cache/block_cache_tier.h"
 
 namespace rocksdb {
 
@@ -140,11 +141,11 @@ Status DBCloud::Open(const Options& opt, const std::string& local_dbname,
       BlockBasedTableOptions* tableopt =
           static_cast<BlockBasedTableOptions*>(bopt);
       if (!tableopt->persistent_cache) {
-        std::shared_ptr<PersistentCache> pcache;
-        st =
-            NewPersistentCache(options.env, persistent_cache_path,
-                               persistent_cache_size_gb * 1024L * 1024L * 1024L,
-                               options.info_log, false, &pcache);
+        PersistentCacheConfig config(
+            local_env, persistent_cache_path,
+            persistent_cache_size_gb * 1024L * 1024L * 1024L, options.info_log);
+        auto pcache = std::make_shared<BlockCacheTier>(config);
+        st = pcache->Open();
         if (st.ok()) {
           tableopt->persistent_cache = pcache;
           Log(InfoLogLevel::INFO_LEVEL, options.info_log,

cloud/db_cloud_test.cc

@@ -1460,7 +1460,6 @@ TEST_F(CloudTest, CopyObjectTest) {
   CloseDB();
 }
 
-#ifdef AWS_DO_NOT_RUN
 //
 // Verify that we can cache data from S3 in persistent cache.
 //
@@ -1483,7 +1482,6 @@ TEST_F(CloudTest, PersistentCache) {
   ASSERT_EQ(value, "World");
   CloseDB();
 }
-#endif /* AWS_DO_NOT_RUN */
 
 }  //  namespace rocksdb