src/hotspot/os/posix/os_posix.cpp

rev 56978 : 8234397: add OS uptime information to os::print_os_info output

@@ -45,10 +45,11 @@
 #include <sys/mman.h>
 #include <sys/resource.h>
 #include <sys/utsname.h>
 #include <time.h>
 #include <unistd.h>
+#include <utmpx.h>
 
 // Todo: provide a os::get_max_process_id() or similar. Number of processes
 // may have been configured, can be read more accurately from proc fs etc.
 #ifndef MAX_PID
 #define MAX_PID INT_MAX

@@ -375,10 +376,31 @@
     st->print(" Unavailable");
   }
   st->cr();
 }
 
+// boot/uptime information;
+// unfortunately it does not work on macOS because the utx chain has no entry
+// for reboot at least on my test machines
+void os::Posix::print_uptime_info(outputStream* st) {
+  int bootsec = -1;
+  int currsec = time(NULL);
+  struct utmpx* ent;
+  setutxent();
+  while ((ent = getutxent())) {
+    if (!strcmp("system boot", ent->ut_line)) {
+      bootsec = ent->ut_tv.tv_sec;
+      break;
+    }
+  }
+
+  if (bootsec != -1) {
+    st->print_cr("OS uptime (in days): %.2lf", (double) (currsec-bootsec)/(60*60*24));
+  }
+}
+
+
 void os::Posix::print_rlimit_info(outputStream* st) {
   st->print("rlimit:");
   struct rlimit rlim;
 
   st->print(" STACK ");