Add a function to return current perf level

Summary: Add a function to return the perf level. It is to allow a wrapper of DB to increase the perf level and restore the original perf level after finishing the function call.

Test Plan: Add a verification in db_test

Reviewers: yhchiang, igor, ljin

Reviewed By: ljin

Subscribers: xjin, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D19551

db/db_test.cc

@@ -2355,6 +2355,7 @@ TEST(DBTest, NumImmutableMemTable) {
     std::string big_value(1000000 * 2, 'x');
     std::string num;
     SetPerfLevel(kEnableTime);;
+    ASSERT_TRUE(GetPerfLevel() == kEnableTime);
 
     ASSERT_OK(dbfull()->Put(writeOpt, handles_[1], "k1", big_value));
     ASSERT_TRUE(dbfull()->GetProperty(handles_[1],
@@ -2417,6 +2418,7 @@ TEST(DBTest, NumImmutableMemTable) {
     // break if we change the default skiplist implementation
     ASSERT_EQ(num, "200");
     SetPerfLevel(kDisable);
+    ASSERT_TRUE(GetPerfLevel() == kDisable);
   } while (ChangeCompactOptions());
 }
 

include/rocksdb/perf_context.h

@@ -20,6 +20,9 @@ enum PerfLevel {
 // set the perf stats level
 void SetPerfLevel(PerfLevel level);
 
+// get current perf stats level
+PerfLevel GetPerfLevel();
+
 // A thread local context for gathering performance counter efficiently
 // and transparently.
 

util/perf_context.cc

@@ -22,6 +22,10 @@ void SetPerfLevel(PerfLevel level) {
   perf_level = level;
 }
 
+PerfLevel GetPerfLevel() {
+  return perf_level;
+}
+
 void PerfContext::Reset() {
 #if !defined(NPERF_CONTEXT) && !defined(IOS_CROSS_COMPILE)
   user_key_comparison_count = 0;