Directly refernce perf_context internally.

Summary:
After 7f6c02dda1, the same get_perf_context() is called both of internally and externally. However, I found internally this is not got inlined. I don't know why this is the case, but directly referencing perf_context is the logical way to do.
Closes https://github.com/facebook/rocksdb/pull/2892

Differential Revision: D5843789

Pulled By: siying

fbshipit-source-id: b49777d8809f35847699291bb7f8ea2754c3af49

monitoring/iostats_context.cc

@@ -6,7 +6,6 @@
 #include <sstream>
 #include "monitoring/iostats_context_imp.h"
 #include "rocksdb/env.h"
-#include "util/thread_local.h"
 
 namespace rocksdb {
 

monitoring/iostats_context_imp.h

@@ -8,35 +8,33 @@
 #include "rocksdb/iostats_context.h"
 
 #ifdef ROCKSDB_SUPPORT_THREAD_LOCAL
+namespace rocksdb {
+extern __thread IOStatsContext iostats_context;
+}  // namespace rocksdb
 
 // increment a specific counter by the specified value
-#define IOSTATS_ADD(metric, value)     \
-  (get_iostats_context()->metric += value)
+#define IOSTATS_ADD(metric, value) (iostats_context.metric += value)
 
 // Increase metric value only when it is positive
 #define IOSTATS_ADD_IF_POSITIVE(metric, value)   \
   if (value > 0) { IOSTATS_ADD(metric, value); }
 
 // reset a specific counter to zero
-#define IOSTATS_RESET(metric)          \
-  (get_iostats_context()->metric = 0)
+#define IOSTATS_RESET(metric) (iostats_context.metric = 0)
 
 // reset all counters to zero
-#define IOSTATS_RESET_ALL()                        \
-  (get_iostats_context()->Reset())
+#define IOSTATS_RESET_ALL() (iostats_context.Reset())
 
 #define IOSTATS_SET_THREAD_POOL_ID(value) \
-  (get_iostats_context()->thread_pool_id = value)
+  (iostats_context.thread_pool_id = value)
 
-#define IOSTATS_THREAD_POOL_ID()               \
-  (get_iostats_context()->thread_pool_id)
+#define IOSTATS_THREAD_POOL_ID() (iostats_context.thread_pool_id)
 
-#define IOSTATS(metric)                        \
-  (get_iostats_context()->metric)
+#define IOSTATS(metric) (iostats_context.metric)
 
 // Declare and set start time of the timer
 #define IOSTATS_TIMER_GUARD(metric)                                     \
-  PerfStepTimer iostats_step_timer_##metric(&(get_iostats_context()->metric)); \
+  PerfStepTimer iostats_step_timer_##metric(&(iostats_context.metric)); \
   iostats_step_timer_##metric.Start();
 
 #else  // ROCKSDB_SUPPORT_THREAD_LOCAL

monitoring/perf_context_imp.h

@@ -9,6 +9,16 @@
 #include "util/stop_watch.h"
 
 namespace rocksdb {
+#if defined(NPERF_CONTEXT) || !defined(ROCKSDB_SUPPORT_THREAD_LOCAL)
+extern PerfContext perf_context;
+#else
+#if defined(OS_SOLARIS)
+extern __thread PerfContext perf_context_;
+#define perf_context (*get_perf_context());
+#else
+extern __thread PerfContext perf_context;
+#endif
+#endif
 
 #if defined(NPERF_CONTEXT)
 
@@ -28,11 +38,11 @@ namespace rocksdb {
 
 // Declare and set start time of the timer
 #define PERF_TIMER_GUARD(metric)                                  \
-  PerfStepTimer perf_step_timer_##metric(&(get_perf_context()->metric)); \
+  PerfStepTimer perf_step_timer_##metric(&(perf_context.metric)); \
   perf_step_timer_##metric.Start();
 
 #define PERF_CONDITIONAL_TIMER_FOR_MUTEX_GUARD(metric, condition)       \
-  PerfStepTimer perf_step_timer_##metric(&(get_perf_context()->metric), true); \
+  PerfStepTimer perf_step_timer_##metric(&(perf_context.metric), true); \
   if ((condition)) {                                                    \
     perf_step_timer_##metric.Start();                                   \
   }
@@ -44,7 +54,7 @@ namespace rocksdb {
 // Increase metric value
 #define PERF_COUNTER_ADD(metric, value)        \
   if (perf_level >= PerfLevel::kEnableCount) { \
-    get_perf_context()->metric += value;       \
+    perf_context.metric += value;              \
   }
 
 #endif