Hint temperature of bottommost level files to FileSystem (#8222)

Summary:
As the first part of the effort of having placing different files on different storage types, this change introduces several things:
(1) An experimental interface in FileSystem that specify temperature to a new file created.
(2) A test FileSystemWrapper,  SimulatedHybridFileSystem, that simulates HDD for a file of "warm" temperature.
(3) A simple experimental feature ColumnFamilyOptions.bottommost_temperature. RocksDB would pass this value to FileSystem when creating any bottommost file.
(4) A db_bench parameter that applies the (2) and (3) to db_bench.

The motivation of the change is to introduce minimal changes that allow us to evolve tiered storage development.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8222

Test Plan:
./db_bench --benchmarks=fillrandom --write_buffer_size=2000000 -max_bytes_for_level_base=20000000  -level_compaction_dynamic_level_bytes --reads=100 -compaction_readahead_size=20000000 --reads=100000 -num=10000000

followed by

./db_bench --benchmarks=readrandom,stats --write_buffer_size=2000000 -max_bytes_for_level_base=20000000 -simulate_hybrid_fs_file=/tmp/warm_file_list -level_compaction_dynamic_level_bytes -compaction_readahead_size=20000000 --reads=500 --threads=16 -use_existing_db --num=10000000

and see results as expected.

Reviewed By: ajkr

Differential Revision: D28003028

fbshipit-source-id: 4724896d5205730227ba2f17c3fecb11261744ce

1 files changed, 1 insertions, 0 deletions

diff --git a/TARGETS b/TARGETS
index ea89b657f..d6b14caa2 100644
--- a/TARGETS
+++ b/TARGETS
@@ -780,6 +780,7 @@ cpp_library(
         "test_util/testutil.cc",
         "tools/block_cache_analyzer/block_cache_trace_analyzer.cc",
         "tools/db_bench_tool.cc",
+        "tools/simulated_hybrid_file_system.cc",
         "tools/trace_analyzer_tool.cc",
     ],
     auto_headers = AutoHeaders.RECURSIVE_GLOB,