fix db get/write stats

Summary:
we were passing `record_read_stats` (a bool) as the `hist_type` argument, which meant we were updating either `rocksdb.db.get.micros` (`hist_type == 0`) or `rocksdb.db.write.micros` (`hist_type == 1`) with wrong data.
Closes https://github.com/facebook/rocksdb/pull/2666

Differential Revision: D5520384

Pulled By: ajkr

fbshipit-source-id: 2f7c956aec32f8b58c5c18845ac478e0230c9516

HISTORY.md

@@ -4,6 +4,9 @@
 * Add Iterator::Refresh(), which allows users to update the iterator state so that they can avoid some initialization costs of recreating iterators.
 * Replace dynamic_cast<> (except unit test) so people can choose to build with RTTI off. With make, release mode is by default built with -fno-rtti and debug mode is built without it. Users can override it by setting USE_RTTI=0 or 1.
 
+### Bug Fixes
+* Fix wrong latencies in `rocksdb.db.get.micros`, `rocksdb.db.write.micros`, and `rocksdb.sst.read.micros`.
+
 ## 5.7.0 (07/13/2017)
 ### Public API Change
 * DB property "rocksdb.sstables" now prints keys in hex form.

db/table_cache.cc

@@ -106,10 +106,10 @@ Status TableCache::GetTableReader(
     }
     StopWatch sw(ioptions_.env, ioptions_.statistics, TABLE_OPEN_IO_MICROS);
     std::unique_ptr<RandomAccessFileReader> file_reader(
-        new RandomAccessFileReader(std::move(file), fname, ioptions_.env,
-                                   ioptions_.statistics, record_read_stats,
-                                   file_read_hist, ioptions_.rate_limiter,
-                                   for_compaction));
+        new RandomAccessFileReader(
+            std::move(file), fname, ioptions_.env,
+            record_read_stats ? ioptions_.statistics : nullptr, SST_READ_MICROS,
+            file_read_hist, ioptions_.rate_limiter, for_compaction));
     s = ioptions_.table_factory->NewTableReader(
         TableReaderOptions(ioptions_, env_options, internal_comparator,
                            skip_filters, level),