[date_time_scanner] try to optimize

Author: tstack

src/base/date_time_scanner.cc

@@ -36,6 +36,7 @@
 #include "config.h"
 #include "date_time_scanner.cfg.hh"
 #include "injector.hh"
+#include "math_util.hh"
 #include "ptimec.hh"
 #include "scn/scn.h"
 
@@ -336,6 +337,19 @@ date_time_scanner::scan(const char* time_dest,
     return retval;
 }
 
+void
+date_time_scanner::clear()
+{
+    this->dts_base_time = 0;
+    this->dts_base_tm = exttm{};
+    this->dts_fmt_lock = -1;
+    this->dts_fmt_len = -1;
+    this->dts_last_tv = timeval{};
+    this->dts_last_tm = exttm{};
+    this->dts_localtime_cached_gmt = 0;
+    this->dts_localtime_cached_tm = tm{};
+}
+
 void
 date_time_scanner::set_base_time(time_t base_time, const tm& local_tm)
 {
@@ -371,7 +385,29 @@ date_time_scanner::to_localtime(time_t t, exttm& tm_out)
             -= this->dts_local_offset_expiry % EXPIRE_TIME;
     } else {
         time_t adjust_gmt = t + this->dts_local_offset_cache;
-        secs2tm(adjust_gmt, &tm_out.et_tm);
+        auto adjust_gmt_min = adjust_gmt / 60;
+        if (this->dts_localtime_cached_gmt == adjust_gmt_min)
+        {
+            tm_out.et_tm = this->dts_localtime_cached_tm;
+            tm_out.et_tm.tm_sec = adjust_gmt % 60;
+        } else {
+            secs2tm(adjust_gmt, &tm_out.et_tm);
+            this->dts_localtime_cached_gmt = adjust_gmt_min;
+            this->dts_localtime_cached_tm = tm_out.et_tm;
+            this->dts_localtime_cached_tm.tm_sec = 0;
+        }
+#if 0
+        {
+            tm verify_tm;
+            secs2tm(adjust_gmt, &verify_tm);
+            require(tm_out.et_tm.tm_year == verify_tm.tm_year);
+            require(tm_out.et_tm.tm_mon == verify_tm.tm_mon);
+            require(tm_out.et_tm.tm_mday == verify_tm.tm_mday);
+            require(tm_out.et_tm.tm_hour == verify_tm.tm_hour);
+            require(tm_out.et_tm.tm_min == verify_tm.tm_min);
+            require(tm_out.et_tm.tm_sec == verify_tm.tm_sec);
+        }
+#endif
     }
     tm_out.et_gmtoff = 0;
 #ifdef HAVE_STRUCT_TM_TM_ZONE

src/base/date_time_scanner.hh

@@ -50,15 +50,7 @@
 struct date_time_scanner {
     date_time_scanner() { this->clear(); }
 
-    void clear()
-    {
-        this->dts_base_time = 0;
-        this->dts_base_tm = exttm{};
-        this->dts_fmt_lock = -1;
-        this->dts_fmt_len = -1;
-        this->dts_last_tv = timeval{};
-        this->dts_last_tm = exttm{};
-    }
+    void clear();
 
     struct lock_state {
         int ls_fmt_index{-1};
@@ -106,6 +98,8 @@ struct date_time_scanner {
     time_t dts_local_offset_cache{0};
     time_t dts_local_offset_valid{0};
     time_t dts_local_offset_expiry{0};
+    time_t dts_localtime_cached_gmt{0};
+    tm dts_localtime_cached_tm{};
     const date::time_zone* dts_default_zone{nullptr};
 
     static const int EXPIRE_TIME = 15 * 60;

src/logfile.cc

@@ -1207,6 +1207,13 @@ logfile::rebuild_index(std::optional<ui_clock::time_point> deadline)
         } else {
             retval = rebuild_result_t::NEW_LINES;
         }
+
+        {
+            auto est_rem = this->estimated_remaining_lines();
+            if (est_rem > 0) {
+                this->lf_index.reserve(this->lf_index.size() + est_rem);
+            }
+        }
     } else if (this->lf_sort_needed) {
         retval = rebuild_result_t::NEW_ORDER;
         this->lf_sort_needed = false;