ext/unicorn_http/httpdate.c

   1 #include <ruby.h>
   2 #include <time.h>
   3 #include <stdio.h>
   4
   5 static const size_t buf_capa = sizeof("Thu, 01 Jan 1970 00:00:00 GMT");
   6 static VALUE buf;
   7 static char *buf_ptr;
   8 static const char *const week[] = {
   9         "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
  10 };
  11 static const char *const months[] = {
  12         "Jan", "Feb", "Mar", "Apr", "May", "Jun",
  13         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
  14 };
  15
  16 /* for people on wonky systems only */
  17 #ifndef HAVE_GMTIME_R
  18 static struct tm * my_gmtime_r(time_t *now, struct tm *tm)
  19 {
  20         struct tm *global = gmtime(now);
  21         if (global)
  22                 *tm = *global;
  23         return tm;
  24 }
  25 #  define gmtime_r my_gmtime_r
  26 #endif
  27
  28
  29 /*
  30  * Returns a string which represents the time as rfc1123-date of HTTP-date
  31  * defined by RFC 2616:
  32  *
  33  *   day-of-week, DD month-name CCYY hh:mm:ss GMT
  34  *
  35  * Note that the result is always GMT.
  36  *
  37  * This method is identical to Time#httpdate in the Ruby standard library,
  38  * except it is implemented in C for performance.  We always saw
  39  * Time#httpdate at or near the top of the profiler output so we
  40  * decided to rewrite this in C.
  41  *
  42  * Caveats: it relies on a Ruby implementation with the global VM lock,
  43  * a thread-safe version will be provided when a Unix-only, GVL-free Ruby
  44  * implementation becomes viable.
  45  */
  46 static VALUE httpdate(VALUE self)
  47 {
  48         static time_t last;
  49         time_t now = time(NULL); /* not a syscall on modern 64-bit systems */
  50         struct tm tm;
  51
  52         if (last == now)
  53                 return buf;
  54         last = now;
  55         gmtime_r(&now, &tm);
  56
  57         /* we can make this thread-safe later if our Ruby loses the GVL */
  58         snprintf(buf_ptr, buf_capa,
  59                  "%s, %02d %s %4d %02d:%02d:%02d GMT",
  60                  week[tm.tm_wday],
  61                  tm.tm_mday,
  62                  months[tm.tm_mon],
  63                  tm.tm_year + 1900,
  64                  tm.tm_hour,
  65                  tm.tm_min,
  66                  tm.tm_sec);
  67
  68         return buf;
  69 }
  70
  71 void init_unicorn_httpdate(void)
  72 {
  73         VALUE mod = rb_const_get(rb_cObject, rb_intern("Unicorn"));
  74         mod = rb_define_module_under(mod, "HttpResponse");
  75
  76         buf = rb_str_new(0, buf_capa - 1);
  77         rb_global_variable(&buf);
  78         buf_ptr = RSTRING_PTR(buf);
  79         httpdate(Qnil);
  80
  81         rb_define_method(mod, "httpdate", httpdate, 0);
  82 }