Make alarm initialization take a timespec now.

This will allow combining of gpr_now() calls, and make it easier to test the
alarm code in the future.
	Change on 2014/12/16 by ctiller <ctiller@google.com>
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82246768

src/core/channel/client_setup.c

@@ -212,11 +212,11 @@ void grpc_client_setup_request_finish(grpc_client_setup_request *r,
     /* TODO(klempner): Replace these values with further consideration. 2x is
        probably too aggressive of a backoff. */
     gpr_timespec max_backoff = gpr_time_from_minutes(2);
-    gpr_timespec deadline =
-        gpr_time_add(s->current_backoff_interval, gpr_now());
+    gpr_timespec now = gpr_now();
+    gpr_timespec deadline = gpr_time_add(s->current_backoff_interval, now);
     GPR_ASSERT(!s->in_alarm);
     s->in_alarm = 1;
-    grpc_alarm_init(&s->backoff_alarm, deadline, backoff_alarm_done, s);
+    grpc_alarm_init(&s->backoff_alarm, deadline, backoff_alarm_done, s, now);
     s->current_backoff_interval =
         gpr_time_add(s->current_backoff_interval, s->current_backoff_interval);
     if (gpr_time_cmp(s->current_backoff_interval, max_backoff) > 0) {

src/core/iomgr/alarm.h

@@ -53,7 +53,8 @@ typedef struct grpc_alarm grpc_alarm;
    information about when to free up any user-level state.
    Returns 1 on success, 0 on failure. */
 int grpc_alarm_init(grpc_alarm *alarm, gpr_timespec deadline,
-                    grpc_iomgr_cb_func alarm_cb, void *alarm_cb_arg);
+                    grpc_iomgr_cb_func alarm_cb, void *alarm_cb_arg,
+                    gpr_timespec now);
 
 /* Note that there is no alarm destroy function. This is because the
    alarm is a one-time occurrence with a guarantee that the callback will

src/core/iomgr/iomgr_libevent.c

@@ -363,10 +363,11 @@ static void libevent_alarm_cb(int fd, short what, void *arg /*=alarm*/) {
 }
 
 int grpc_alarm_init(grpc_alarm *alarm, gpr_timespec deadline,
-                    grpc_iomgr_cb_func alarm_cb, void *alarm_cb_arg) {
+                    grpc_iomgr_cb_func alarm_cb, void *alarm_cb_arg,
+                    gpr_timespec now) {
   grpc_libevent_activation_data *adata =
       &alarm->task.activation[GRPC_EM_TA_ONLY];
-  gpr_timespec delay_timespec = gpr_time_sub(deadline, gpr_now());
+  gpr_timespec delay_timespec = gpr_time_sub(deadline, now);
   struct timeval delay = gpr_timeval_from_timespec(delay_timespec);
   alarm->task.type = GRPC_EM_TASK_ALARM;
   gpr_atm_rel_store(&alarm->triggered, ALARM_TRIGGER_INIT);

src/core/surface/call.c

@@ -877,5 +877,5 @@ void grpc_call_set_deadline(grpc_call_element *elem, gpr_timespec deadline) {
   }
   grpc_call_internal_ref(call);
   call->have_alarm = 1;
-  grpc_alarm_init(&call->alarm, deadline, call_alarm, call);
+  grpc_alarm_init(&call->alarm, deadline, call_alarm, call, gpr_now());
 }

test/core/iomgr/alarm_test.c

@@ -116,7 +116,8 @@ static void test_grpc_alarm() {
   gpr_cv_init(&arg.cv);
   gpr_event_init(&arg.fcb_arg);
 
-  grpc_alarm_init(&alarm, gpr_time_add(tv0, gpr_now()), alarm_cb, &arg);
+  grpc_alarm_init(&alarm, gpr_time_add(tv0, gpr_now()), alarm_cb, &arg,
+                  gpr_now());
 
   alarm_deadline = gpr_time_add(gpr_now(), tv1);
   gpr_mu_lock(&arg.mu);
@@ -162,7 +163,7 @@ static void test_grpc_alarm() {
   gpr_event_init(&arg2.fcb_arg);
 
   grpc_alarm_init(&alarm_to_cancel, gpr_time_add(tv2, gpr_now()), alarm_cb,
-                  &arg2);
+                  &arg2, gpr_now());
   grpc_alarm_cancel(&alarm_to_cancel);
 
   alarm_deadline = gpr_time_add(gpr_now(), tv1);