Extend thread safety annotations.

This CL makes it easier to reason about thread safety by:

1) Adding Clang thread safety annotations according to comments.
2) Expanding a couple of variable names, without adding extra lines of code.
3) Adding const in a couple of places.
4) Replacing an always-non-null const pointer with a reference.
5) Fixing style warnings in the modified files.

This CL does not annotate the DBImpl members that claim to be protected
by the instance mutex, but are accessed without the mutex being held.
Those members (and their unprotected accesses) will be addressed in
future CLs.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189354657

1 files changed, 3 insertions, 3 deletions

diff --git a/db/table_cache.cc b/db/table_cache.cc
index e3d82cd..6cf005b 100644
--- a/db/table_cache.cc
+++ b/db/table_cache.cc
@@ -30,9 +30,9 @@ static void UnrefEntry(void* arg1, void* arg2) {
 }
 
 TableCache::TableCache(const std::string& dbname,
-                       const Options* options,
+                       const Options& options,
                        int entries)
-    : env_(options->env),
+    : env_(options.env),
       dbname_(dbname),
       options_(options),
       cache_(NewLRUCache(entries)) {
@@ -61,7 +61,7 @@ Status TableCache::FindTable(uint64_t file_number, uint64_t file_size,
       }
     }
     if (s.ok()) {
-      s = Table::Open(*options_, file, file_size, &table);
+      s = Table::Open(options_, file, file_size, &table);
     }
 
     if (!s.ok()) {