Perf: Improve fast find for pithy print

trunk/src/app/srs_app_pithy_print.cpp

@@ -171,6 +171,7 @@ static SrsStageManager* _srs_stages = new SrsStageManager();
 SrsPithyPrint::SrsPithyPrint(int _stage_id)
 {
     stage_id = _stage_id;
+    cache_ = NULL;
     client_id = enter_stage();
     previous_tick = srs_get_system_time();
     _age = 0;
@@ -308,7 +309,10 @@ void SrsPithyPrint::leave_stage()
 
 void SrsPithyPrint::elapse()
 {
-    SrsStageInfo* stage = _srs_stages->fetch_or_create(stage_id);
+    SrsStageInfo* stage = cache_;
+    if (!stage) {
+        stage = cache_ = _srs_stages->fetch_or_create(stage_id);
+    }
     srs_assert(stage != NULL);
     
     srs_utime_t diff = srs_get_system_time() - previous_tick;
@@ -321,7 +325,10 @@ void SrsPithyPrint::elapse()
 
 bool SrsPithyPrint::can_print()
 {
-    SrsStageInfo* stage = _srs_stages->fetch_or_create(stage_id);
+    SrsStageInfo* stage = cache_;
+    if (!stage) {
+        stage = cache_ = _srs_stages->fetch_or_create(stage_id);
+    }
     srs_assert(stage != NULL);
     
     return stage->can_print();

trunk/src/app/srs_app_pithy_print.hpp

@@ -111,6 +111,7 @@ class SrsPithyPrint
 {
 private:
     int client_id;
+    SrsStageInfo* cache_;
     int stage_id;
     srs_utime_t _age;
     srs_utime_t previous_tick;