HTTP: added a $request_time variable.

docs/changes.xml

@@ -37,6 +37,12 @@ support rack v3 in ruby applications.
 </para>
 </change>
 
+<change type="feature">
+<para>
+the $request_time variable contains the request processing time.
+</para>
+</change>
+
 <change type="bugfix">
 <para>
 fix HTTP cookie parsing when the value contains an equals sign.

src/nxt_http.h

@@ -140,6 +140,8 @@ struct nxt_http_request_s {
     nxt_buf_t                       *out;
     const nxt_http_request_state_t  *state;
 
+    nxt_nsec_t                      start_time;
+
     nxt_str_t                       host;
     nxt_str_t                       server_name;
     nxt_str_t                       target;

src/nxt_http_request.c

@@ -278,6 +278,8 @@ nxt_http_request_create(nxt_task_t *task)
     r->resp.content_length_n = -1;
     r->state = &nxt_http_request_init_state;
 
+    r->start_time = nxt_thread_monotonic_time(task->thread);
+
     task->thread->engine->requests_cnt++;
 
     return r;

src/nxt_http_variables.c

@@ -9,6 +9,8 @@
 
 static nxt_int_t nxt_http_var_dollar(nxt_task_t *task, nxt_str_t *str,
     void *ctx, uint16_t field);
+static nxt_int_t nxt_http_var_request_time(nxt_task_t *task, nxt_str_t *str,
+    void *ctx, uint16_t field);
 static nxt_int_t nxt_http_var_method(nxt_task_t *task, nxt_str_t *str,
     void *ctx, uint16_t field);
 static nxt_int_t nxt_http_var_request_uri(nxt_task_t *task, nxt_str_t *str,
@@ -45,6 +47,9 @@ static nxt_var_decl_t  nxt_http_vars[] = {
     {
         .name = nxt_string("dollar"),
         .handler = nxt_http_var_dollar,
+    }, {
+        .name = nxt_string("request_time"),
+        .handler = nxt_http_var_request_time,
     }, {
         .name = nxt_string("method"),
         .handler = nxt_http_var_method,
@@ -110,6 +115,34 @@ nxt_http_var_dollar(nxt_task_t *task, nxt_str_t *str, void *ctx, uint16_t field)
 }
 
 
+static nxt_int_t
+nxt_http_var_request_time(nxt_task_t *task, nxt_str_t *str, void *ctx,
+    uint16_t field)
+{
+    u_char              *p;
+    nxt_msec_t          ms;
+    nxt_nsec_t          now;
+    nxt_http_request_t  *r;
+
+    r = ctx;
+
+    now = nxt_thread_monotonic_time(task->thread);
+    ms = (now - r->start_time) / 1000000;
+
+    str->start = nxt_mp_nget(r->mem_pool, NXT_TIME_T_LEN + 4);
+    if (nxt_slow_path(str->start == NULL)) {
+        return NXT_ERROR;
+    }
+
+    p = nxt_sprintf(str->start, str->start + NXT_TIME_T_LEN, "%T.%03M",
+                    (nxt_time_t) ms / 1000, ms % 1000);
+
+    str->length = p - str->start;
+
+    return NXT_OK;
+}
+
+
 static nxt_int_t
 nxt_http_var_method(nxt_task_t *task, nxt_str_t *str, void *ctx, uint16_t field)
 {