Merge pull request #2403 from ctiller/no-worries-i-can-wait

Add a clock_type field to gpr_timespec

45 files changed, 252 insertions, 149 deletions

diff --git a/src/core/channel/client_channel.c b/src/core/channel/client_channel.c
index f890f99237..10e01ebbb4 100644
--- a/src/core/channel/client_channel.c
+++ b/src/core/channel/client_channel.c
@@ -132,7 +132,7 @@ static void handle_op_after_cancellation(grpc_call_element *elem,
     mdb.list.head = &calld->status;
     mdb.list.tail = &calld->details;
     mdb.garbage.head = mdb.garbage.tail = NULL;
-    mdb.deadline = gpr_inf_future;
+    mdb.deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
     grpc_sopb_add_metadata(op->recv_ops, mdb);
     *op->recv_state = GRPC_STREAM_CLOSED;
     op->on_done_recv->cb(op->on_done_recv->cb_arg, 1);
@@ -518,7 +518,7 @@ static void init_call_elem(grpc_call_element *elem,
   gpr_mu_init(&calld->mu_state);
   calld->elem = elem;
   calld->state = CALL_CREATED;
-  calld->deadline = gpr_inf_future;
+  calld->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
 /* Destructor for call_data */
diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
index 8cdad1015f..35f172683a 100644
--- a/src/core/client_config/subchannel.c
+++ b/src/core/client_config/subchannel.c
@@ -302,7 +302,7 @@ static void continue_connect(grpc_subchannel *c) {
 static void start_connect(grpc_subchannel *c) {
   gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
   c->next_attempt = now;
-  c->backoff_delta = gpr_time_from_seconds(1);
+  c->backoff_delta = gpr_time_from_seconds(1, GPR_TIMESPAN);
 
   continue_connect(c);
 }
diff --git a/src/core/iomgr/alarm.c b/src/core/iomgr/alarm.c
index 5860834de3..5b9a37e5dd 100644
--- a/src/core/iomgr/alarm.c
+++ b/src/core/iomgr/alarm.c
@@ -102,7 +102,8 @@ void grpc_alarm_list_init(gpr_timespec now) {
 
 void grpc_alarm_list_shutdown(void) {
   int i;
-  while (run_some_expired_alarms(NULL, gpr_inf_future, NULL, 0))
+  while (run_some_expired_alarms(NULL, gpr_inf_future(GPR_CLOCK_REALTIME), NULL,
+                                 0))
     ;
   for (i = 0; i < NUM_SHARDS; i++) {
     shard_type *shard = &g_shards[i];
@@ -127,6 +128,7 @@ static gpr_timespec dbl_to_ts(double d) {
   gpr_timespec ts;
   ts.tv_sec = d;
   ts.tv_nsec = 1e9 * (d - ts.tv_sec);
+  ts.clock_type = GPR_TIMESPAN;
   return ts;
 }
 
diff --git a/src/core/iomgr/iocp_windows.c b/src/core/iomgr/iocp_windows.c
index 3d3a193d00..8741241fb8 100644
--- a/src/core/iomgr/iocp_windows.c
+++ b/src/core/iomgr/iocp_windows.c
@@ -157,7 +157,7 @@ void grpc_iocp_shutdown(void) {
   BOOL success;
   gpr_event_set(&g_shutdown_iocp, (void *)1);
   grpc_iocp_kick();
-  gpr_event_wait(&g_iocp_done, gpr_inf_future);
+  gpr_event_wait(&g_iocp_done, gpr_inf_future(GPR_CLOCK_REALTIME));
   success = CloseHandle(g_iocp);
   GPR_ASSERT(success);
 }
diff --git a/src/core/iomgr/iomgr.c b/src/core/iomgr/iomgr.c
index cca92d3b32..0244f689b1 100644
--- a/src/core/iomgr/iomgr.c
+++ b/src/core/iomgr/iomgr.c
@@ -57,9 +57,9 @@ static grpc_iomgr_object g_root_object;
 static void background_callback_executor(void *ignored) {
   gpr_mu_lock(&g_mu);
   while (!g_shutdown) {
-    gpr_timespec deadline = gpr_inf_future;
-    gpr_timespec short_deadline =
-        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100));
+    gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
+    gpr_timespec short_deadline = gpr_time_add(
+        gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100, GPR_TIMESPAN));
     if (g_cbs_head) {
       grpc_iomgr_closure *closure = g_cbs_head;
       g_cbs_head = closure->next;
@@ -110,8 +110,8 @@ static size_t count_objects(void) {
 void grpc_iomgr_shutdown(void) {
   grpc_iomgr_object *obj;
   grpc_iomgr_closure *closure;
-  gpr_timespec shutdown_deadline =
-      gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_seconds(10));
+  gpr_timespec shutdown_deadline = gpr_time_add(
+      gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_seconds(10, GPR_TIMESPAN));
   gpr_timespec last_warning_time = gpr_now(GPR_CLOCK_REALTIME);
 
   gpr_mu_lock(&g_mu);
@@ -119,7 +119,7 @@ void grpc_iomgr_shutdown(void) {
   while (g_cbs_head != NULL || g_root_object.next != &g_root_object) {
     if (gpr_time_cmp(
             gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), last_warning_time),
-            gpr_time_from_seconds(1)) >= 0) {
+            gpr_time_from_seconds(1, GPR_TIMESPAN)) >= 0) {
       if (g_cbs_head != NULL && g_root_object.next != &g_root_object) {
         gpr_log(GPR_DEBUG,
                 "Waiting for %d iomgr objects to be destroyed and executing "
@@ -145,14 +145,14 @@ void grpc_iomgr_shutdown(void) {
       } while (g_cbs_head);
       continue;
     }
-    if (grpc_alarm_check(&g_mu, gpr_inf_future, NULL)) {
+    if (grpc_alarm_check(&g_mu, gpr_inf_future(GPR_CLOCK_REALTIME), NULL)) {
       gpr_log(GPR_DEBUG, "got late alarm");
       continue;
     }
     if (g_root_object.next != &g_root_object) {
       int timeout = 0;
-      gpr_timespec short_deadline =
-          gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100));
+      gpr_timespec short_deadline = gpr_time_add(
+          gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_millis(100, GPR_TIMESPAN));
       while (gpr_cv_wait(&g_rcv, &g_mu, short_deadline) && g_cbs_head == NULL) {
         if (gpr_time_cmp(gpr_now(GPR_CLOCK_REALTIME), shutdown_deadline) > 0) {
           timeout = 1;
@@ -174,7 +174,8 @@ void grpc_iomgr_shutdown(void) {
   gpr_mu_unlock(&g_mu);
 
   grpc_kick_poller();
-  gpr_event_wait(&g_background_callback_executor_done, gpr_inf_future);
+  gpr_event_wait(&g_background_callback_executor_done,
+                 gpr_inf_future(GPR_CLOCK_REALTIME));
 
   grpc_alarm_list_shutdown();
 
diff --git a/src/core/iomgr/pollset_posix.c b/src/core/iomgr/pollset_posix.c
index 85101764d2..7afff58eee 100644
--- a/src/core/iomgr/pollset_posix.c
+++ b/src/core/iomgr/pollset_posix.c
@@ -191,17 +191,17 @@ int grpc_poll_deadline_to_millis_timeout(gpr_timespec deadline,
                                          gpr_timespec now) {
   gpr_timespec timeout;
   static const int max_spin_polling_us = 10;
-  if (gpr_time_cmp(deadline, gpr_inf_future) == 0) {
+  if (gpr_time_cmp(deadline, gpr_inf_future(GPR_CLOCK_REALTIME)) == 0) {
     return -1;
   }
-  if (gpr_time_cmp(
-          deadline,
-          gpr_time_add(now, gpr_time_from_micros(max_spin_polling_us))) <= 0) {
+  if (gpr_time_cmp(deadline, gpr_time_add(now, gpr_time_from_micros(
+                                                   max_spin_polling_us,
+                                                   GPR_TIMESPAN))) <= 0) {
     return 0;
   }
   timeout = gpr_time_sub(deadline, now);
-  return gpr_time_to_millis(
-      gpr_time_add(timeout, gpr_time_from_nanos(GPR_NS_PER_SEC - 1)));
+  return gpr_time_to_millis(gpr_time_add(
+      timeout, gpr_time_from_nanos(GPR_NS_PER_SEC - 1, GPR_TIMESPAN)));
 }
 
 /*
diff --git a/src/core/iomgr/tcp_server_windows.c b/src/core/iomgr/tcp_server_windows.c
index e6e1d1499e..187009b2c8 100644
--- a/src/core/iomgr/tcp_server_windows.c
+++ b/src/core/iomgr/tcp_server_windows.c
@@ -116,7 +116,7 @@ void grpc_tcp_server_destroy(grpc_tcp_server *s,
   }
   /* This happens asynchronously. Wait while that happens. */
   while (s->active_ports) {
-    gpr_cv_wait(&s->cv, &s->mu, gpr_inf_future);
+    gpr_cv_wait(&s->cv, &s->mu, gpr_inf_future(GPR_CLOCK_REALTIME));
   }
   gpr_mu_unlock(&s->mu);
 
diff --git a/src/core/security/credentials.c b/src/core/security/credentials.c
index 230f0dfb85..fb59fa4b0e 100644
--- a/src/core/security/credentials.c
+++ b/src/core/security/credentials.c
@@ -324,7 +324,7 @@ static void jwt_reset_cache(grpc_jwt_credentials *c) {
     gpr_free(c->cached.service_url);
     c->cached.service_url = NULL;
   }
-  c->cached.jwt_expiration = gpr_inf_past;
+  c->cached.jwt_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
 }
 
 static void jwt_destroy(grpc_credentials *creds) {
@@ -347,8 +347,8 @@ static void jwt_get_request_metadata(grpc_credentials *creds,
                                      grpc_credentials_metadata_cb cb,
                                      void *user_data) {
   grpc_jwt_credentials *c = (grpc_jwt_credentials *)creds;
-  gpr_timespec refresh_threshold = {GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS,
-                                    0};
+  gpr_timespec refresh_threshold = gpr_time_from_seconds(
+      GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS, GPR_TIMESPAN);
 
   /* See if we can return a cached jwt. */
   grpc_credentials_md_store *jwt_md = NULL;
@@ -516,6 +516,7 @@ grpc_oauth2_token_fetcher_credentials_parse_server_response(
                  access_token->value);
     token_lifetime->tv_sec = strtol(expires_in->value, NULL, 10);
     token_lifetime->tv_nsec = 0;
+    token_lifetime->clock_type = GPR_TIMESPAN;
     if (*token_md != NULL) grpc_credentials_md_store_unref(*token_md);
     *token_md = grpc_credentials_md_store_create(1);
     grpc_credentials_md_store_add_cstrings(
@@ -552,7 +553,7 @@ static void on_oauth2_token_fetcher_http_response(
     r->cb(r->user_data, c->access_token_md->entries,
           c->access_token_md->num_entries, status);
   } else {
-    c->token_expiration = gpr_inf_past;
+    c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
     r->cb(r->user_data, NULL, 0, status);
   }
   gpr_mu_unlock(&c->mu);
@@ -564,8 +565,8 @@ static void oauth2_token_fetcher_get_request_metadata(
     grpc_credentials_metadata_cb cb, void *user_data) {
   grpc_oauth2_token_fetcher_credentials *c =
       (grpc_oauth2_token_fetcher_credentials *)creds;
-  gpr_timespec refresh_threshold = {GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS,
-                                    0};
+  gpr_timespec refresh_threshold = gpr_time_from_seconds(
+      GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS, GPR_TIMESPAN);
   grpc_credentials_md_store *cached_access_token_md = NULL;
   {
     gpr_mu_lock(&c->mu);
@@ -596,7 +597,7 @@ static void init_oauth2_token_fetcher(grpc_oauth2_token_fetcher_credentials *c,
   c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
   gpr_ref_init(&c->base.refcount, 1);
   gpr_mu_init(&c->mu);
-  c->token_expiration = gpr_inf_past;
+  c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
   c->fetch_func = fetch_func;
   grpc_httpcli_context_init(&c->httpcli_context);
 }
diff --git a/src/core/security/google_default_credentials.c b/src/core/security/google_default_credentials.c
index f622deff42..833484310f 100644
--- a/src/core/security/google_default_credentials.c
+++ b/src/core/security/google_default_credentials.c
@@ -91,7 +91,7 @@ static int is_stack_running_on_compute_engine(void) {
 
   /* The http call is local. If it takes more than one sec, it is for sure not
      on compute engine. */
-  gpr_timespec max_detection_delay = {1, 0};
+  gpr_timespec max_detection_delay = gpr_time_from_seconds(1, GPR_TIMESPAN);
 
   grpc_pollset_init(&detector.pollset);
   detector.is_done = 0;
@@ -112,7 +112,7 @@ static int is_stack_running_on_compute_engine(void) {
      called once for the lifetime of the process by the default credentials. */
   gpr_mu_lock(GRPC_POLLSET_MU(&detector.pollset));
   while (!detector.is_done) {
-    grpc_pollset_work(&detector.pollset, gpr_inf_future);
+    grpc_pollset_work(&detector.pollset, gpr_inf_future(GPR_CLOCK_REALTIME));
   }
   gpr_mu_unlock(GRPC_POLLSET_MU(&detector.pollset));
 
diff --git a/src/core/security/json_token.c b/src/core/security/json_token.c
index 9b1ea255ae..021912f333 100644
--- a/src/core/security/json_token.c
+++ b/src/core/security/json_token.c
@@ -49,7 +49,7 @@
 /* --- Constants. --- */
 
 /* 1 hour max. */
-const gpr_timespec grpc_max_auth_token_lifetime = {3600, 0};
+const gpr_timespec grpc_max_auth_token_lifetime = {3600, 0, GPR_TIMESPAN};
 
 #define GRPC_JWT_RSA_SHA256_ALGORITHM "RS256"
 #define GRPC_JWT_TYPE "JWT"
diff --git a/src/core/security/jwt_verifier.c b/src/core/security/jwt_verifier.c
index 9140eb2ef7..1276693da7 100644
--- a/src/core/security/jwt_verifier.c
+++ b/src/core/security/jwt_verifier.c
@@ -109,7 +109,7 @@ static const char *validate_string_field(const grpc_json *json,
 
 static gpr_timespec validate_time_field(const grpc_json *json,
                                         const char *key) {
-  gpr_timespec result = gpr_time_0;
+  gpr_timespec result = gpr_time_0(GPR_CLOCK_REALTIME);
   if (json->type != GRPC_JSON_NUMBER) {
     gpr_log(GPR_ERROR, "Invalid %s field [%s]", key, json->value);
     return result;
@@ -221,17 +221,17 @@ const char *grpc_jwt_claims_audience(const grpc_jwt_claims *claims) {
 }
 
 gpr_timespec grpc_jwt_claims_issued_at(const grpc_jwt_claims *claims) {
-  if (claims == NULL) return gpr_inf_past;
+  if (claims == NULL) return gpr_inf_past(GPR_CLOCK_REALTIME);
   return claims->iat;
 }
 
 gpr_timespec grpc_jwt_claims_expires_at(const grpc_jwt_claims *claims) {
-  if (claims == NULL) return gpr_inf_future;
+  if (claims == NULL) return gpr_inf_future(GPR_CLOCK_REALTIME);
   return claims->exp;
 }
 
 gpr_timespec grpc_jwt_claims_not_before(const grpc_jwt_claims *claims) {
-  if (claims == NULL) return gpr_inf_past;
+  if (claims == NULL) return gpr_inf_past(GPR_CLOCK_REALTIME);
   return claims->nbf;
 }
 
@@ -242,9 +242,9 @@ grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, gpr_slice buffer) {
   memset(claims, 0, sizeof(grpc_jwt_claims));
   claims->json = json;
   claims->buffer = buffer;
-  claims->iat = gpr_inf_past;
-  claims->nbf = gpr_inf_past;
-  claims->exp = gpr_inf_future;
+  claims->iat = gpr_inf_past(GPR_CLOCK_REALTIME);
+  claims->nbf = gpr_inf_past(GPR_CLOCK_REALTIME);
+  claims->exp = gpr_inf_future(GPR_CLOCK_REALTIME);
 
   /* Per the spec, all fields are optional. */
   for (cur = json->child; cur != NULL; cur = cur->next) {
@@ -262,13 +262,16 @@ grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, gpr_slice buffer) {
       if (claims->jti == NULL) goto error;
     } else if (strcmp(cur->key, "iat") == 0) {
       claims->iat = validate_time_field(cur, "iat");
-      if (gpr_time_cmp(claims->iat, gpr_time_0) == 0) goto error;
+      if (gpr_time_cmp(claims->iat, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
+        goto error;
     } else if (strcmp(cur->key, "exp") == 0) {
       claims->exp = validate_time_field(cur, "exp");
-      if (gpr_time_cmp(claims->exp, gpr_time_0) == 0) goto error;
+      if (gpr_time_cmp(claims->exp, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
+        goto error;
     } else if (strcmp(cur->key, "nbf") == 0) {
       claims->nbf = validate_time_field(cur, "nbf");
-      if (gpr_time_cmp(claims->nbf, gpr_time_0) == 0) goto error;
+      if (gpr_time_cmp(claims->nbf, gpr_time_0(GPR_CLOCK_REALTIME)) == 0)
+        goto error;
     }
   }
   return claims;
@@ -359,10 +362,10 @@ void verifier_cb_ctx_destroy(verifier_cb_ctx *ctx) {
 /* --- grpc_jwt_verifier object. --- */
 
 /* Clock skew defaults to one minute. */
-gpr_timespec grpc_jwt_verifier_clock_skew = {60, 0};
+gpr_timespec grpc_jwt_verifier_clock_skew = {60, 0, GPR_TIMESPAN};
 
 /* Max delay defaults to one minute. */
-gpr_timespec grpc_jwt_verifier_max_delay = {60, 0};
+gpr_timespec grpc_jwt_verifier_max_delay = {60, 0, GPR_TIMESPAN};
 
 typedef struct {
   char *email_domain;
diff --git a/src/core/support/cancellable.c b/src/core/support/cancellable.c
index 3cbb318ab6..4756f1e125 100644
--- a/src/core/support/cancellable.c
+++ b/src/core/support/cancellable.c
@@ -121,8 +121,9 @@ void gpr_cancellable_cancel(gpr_cancellable *c) {
         } else {
           gpr_event ev;
           gpr_event_init(&ev);
-          gpr_event_wait(&ev, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
-                                           gpr_time_from_micros(1000)));
+          gpr_event_wait(
+              &ev, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
+                                gpr_time_from_micros(1000, GPR_TIMESPAN)));
         }
       }
     } while (failures != 0);
diff --git a/src/core/support/sync_posix.c b/src/core/support/sync_posix.c
index 0ccbd4923f..41af8ceb0a 100644
--- a/src/core/support/sync_posix.c
+++ b/src/core/support/sync_posix.c
@@ -63,7 +63,7 @@ void gpr_cv_destroy(gpr_cv *cv) { GPR_ASSERT(pthread_cond_destroy(cv) == 0); }
 
 int gpr_cv_wait(gpr_cv *cv, gpr_mu *mu, gpr_timespec abs_deadline) {
   int err = 0;
-  if (gpr_time_cmp(abs_deadline, gpr_inf_future) == 0) {
+  if (gpr_time_cmp(abs_deadline, gpr_inf_future(GPR_CLOCK_REALTIME)) == 0) {
     err = pthread_cond_wait(cv, mu);
   } else {
     struct timespec abs_deadline_ts;
diff --git a/src/core/support/sync_win32.c b/src/core/support/sync_win32.c
index 29b77fc4c2..63196d10d3 100644
--- a/src/core/support/sync_win32.c
+++ b/src/core/support/sync_win32.c
@@ -83,7 +83,7 @@ int gpr_cv_wait(gpr_cv *cv, gpr_mu *mu, gpr_timespec abs_deadline) {
   int timeout = 0;
   DWORD timeout_max_ms;
   mu->locked = 0;
-  if (gpr_time_cmp(abs_deadline, gpr_inf_future) == 0) {
+  if (gpr_time_cmp(abs_deadline, gpr_inf_future(GPR_CLOCK_REALTIME)) == 0) {
     SleepConditionVariableCS(cv, &mu->cs, INFINITE);
   } else {
     gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
diff --git a/src/core/support/time.c b/src/core/support/time.c
index d47b08b266..570f195bd1 100644
--- a/src/core/support/time.c
+++ b/src/core/support/time.c
@@ -41,6 +41,7 @@
 
 int gpr_time_cmp(gpr_timespec a, gpr_timespec b) {
   int cmp = (a.tv_sec > b.tv_sec) - (a.tv_sec < b.tv_sec);
+  GPR_ASSERT(a.clock_type == b.clock_type);
   if (cmp == 0) {
     cmp = (a.tv_nsec > b.tv_nsec) - (a.tv_nsec < b.tv_nsec);
   }
@@ -71,19 +72,40 @@ gpr_timespec gpr_time_max(gpr_timespec a, gpr_timespec b) {
   ((t)(TYPE_IS_SIGNED(t) ? (TOP_BIT_OF_TYPE(t) - 1) \
                          : ((TOP_BIT_OF_TYPE(t) - 1) << 1) + 1))
 
-const gpr_timespec gpr_time_0 = {0, 0};
-const gpr_timespec gpr_inf_future = {TYPE_MAX(time_t), 0};
-const gpr_timespec gpr_inf_past = {TYPE_MIN(time_t), 0};
+gpr_timespec gpr_time_0(gpr_clock_type type) {
+  gpr_timespec out;
+  out.tv_sec = 0;
+  out.tv_nsec = 0;
+  out.clock_type = type;
+  return out;
+}
+
+gpr_timespec gpr_inf_future(gpr_clock_type type) {
+  gpr_timespec out;
+  out.tv_sec = TYPE_MAX(time_t);
+  out.tv_nsec = 0;
+  out.clock_type = type;
+  return out;
+}
+
+gpr_timespec gpr_inf_past(gpr_clock_type type) {
+  gpr_timespec out;
+  out.tv_sec = TYPE_MIN(time_t);
+  out.tv_nsec = 0;
+  out.clock_type = type;
+  return out;
+}
 
 /* TODO(ctiller): consider merging _nanos, _micros, _millis into a single
    function for maintainability. Similarly for _seconds, _minutes, and _hours */
 
-gpr_timespec gpr_time_from_nanos(long ns) {
+gpr_timespec gpr_time_from_nanos(long ns, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (ns == LONG_MAX) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (ns == LONG_MIN) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else if (ns >= 0) {
     result.tv_sec = ns / GPR_NS_PER_SEC;
     result.tv_nsec = (int)(ns - result.tv_sec * GPR_NS_PER_SEC);
@@ -95,12 +117,13 @@ gpr_timespec gpr_time_from_nanos(long ns) {
   return result;
 }
 
-gpr_timespec gpr_time_from_micros(long us) {
+gpr_timespec gpr_time_from_micros(long us, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (us == LONG_MAX) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (us == LONG_MIN) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else if (us >= 0) {
     result.tv_sec = us / 1000000;
     result.tv_nsec = (int)((us - result.tv_sec * 1000000) * 1000);
@@ -112,12 +135,13 @@ gpr_timespec gpr_time_from_micros(long us) {
   return result;
 }
 
-gpr_timespec gpr_time_from_millis(long ms) {
+gpr_timespec gpr_time_from_millis(long ms, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (ms == LONG_MAX) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (ms == LONG_MIN) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else if (ms >= 0) {
     result.tv_sec = ms / 1000;
     result.tv_nsec = (int)((ms - result.tv_sec * 1000) * 1000000);
@@ -129,12 +153,13 @@ gpr_timespec gpr_time_from_millis(long ms) {
   return result;
 }
 
-gpr_timespec gpr_time_from_seconds(long s) {
+gpr_timespec gpr_time_from_seconds(long s, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (s == LONG_MAX) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (s == LONG_MIN) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else {
     result.tv_sec = s;
     result.tv_nsec = 0;
@@ -142,12 +167,13 @@ gpr_timespec gpr_time_from_seconds(long s) {
   return result;
 }
 
-gpr_timespec gpr_time_from_minutes(long m) {
+gpr_timespec gpr_time_from_minutes(long m, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (m >= LONG_MAX / 60) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (m <= LONG_MIN / 60) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else {
     result.tv_sec = m * 60;
     result.tv_nsec = 0;
@@ -155,12 +181,13 @@ gpr_timespec gpr_time_from_minutes(long m) {
   return result;
 }
 
-gpr_timespec gpr_time_from_hours(long h) {
+gpr_timespec gpr_time_from_hours(long h, gpr_clock_type type) {
   gpr_timespec result;
+  result.clock_type = type;
   if (h >= LONG_MAX / 3600) {
-    result = gpr_inf_future;
+    result = gpr_inf_future(type);
   } else if (h <= LONG_MIN / 3600) {
-    result = gpr_inf_past;
+    result = gpr_inf_past(type);
   } else {
     result.tv_sec = h * 3600;
     result.tv_nsec = 0;
@@ -171,6 +198,8 @@ gpr_timespec gpr_time_from_hours(long h) {
 gpr_timespec gpr_time_add(gpr_timespec a, gpr_timespec b) {
   gpr_timespec sum;
   int inc = 0;
+  GPR_ASSERT(b.clock_type == GPR_TIMESPAN);
+  sum.clock_type = a.clock_type;
   sum.tv_nsec = a.tv_nsec + b.tv_nsec;
   if (sum.tv_nsec >= GPR_NS_PER_SEC) {
     sum.tv_nsec -= GPR_NS_PER_SEC;
@@ -180,14 +209,14 @@ gpr_timespec gpr_time_add(gpr_timespec a, gpr_timespec b) {
     sum = a;
   } else if (b.tv_sec == TYPE_MAX(time_t) ||
              (b.tv_sec >= 0 && a.tv_sec >= TYPE_MAX(time_t) - b.tv_sec)) {
-    sum = gpr_inf_future;
+    sum = gpr_inf_future(sum.clock_type);
   } else if (b.tv_sec == TYPE_MIN(time_t) ||
              (b.tv_sec <= 0 && a.tv_sec <= TYPE_MIN(time_t) - b.tv_sec)) {
-    sum = gpr_inf_past;
+    sum = gpr_inf_past(sum.clock_type);
   } else {
     sum.tv_sec = a.tv_sec + b.tv_sec;
     if (inc != 0 && sum.tv_sec == TYPE_MAX(time_t) - 1) {
-      sum = gpr_inf_future;
+      sum = gpr_inf_future(sum.clock_type);
     } else {
       sum.tv_sec += inc;
     }
@@ -198,6 +227,12 @@ gpr_timespec gpr_time_add(gpr_timespec a, gpr_timespec b) {
 gpr_timespec gpr_time_sub(gpr_timespec a, gpr_timespec b) {
   gpr_timespec diff;
   int dec = 0;
+  if (b.clock_type == GPR_TIMESPAN) {
+    diff.clock_type = a.clock_type;
+  } else {
+    GPR_ASSERT(a.clock_type == b.clock_type);
+    diff.clock_type = GPR_TIMESPAN;
+  }
   diff.tv_nsec = a.tv_nsec - b.tv_nsec;
   if (diff.tv_nsec < 0) {
     diff.tv_nsec += GPR_NS_PER_SEC;
@@ -207,14 +242,14 @@ gpr_timespec gpr_time_sub(gpr_timespec a, gpr_timespec b) {
     diff = a;
   } else if (b.tv_sec == TYPE_MIN(time_t) ||
              (b.tv_sec <= 0 && a.tv_sec >= TYPE_MAX(time_t) + b.tv_sec)) {
-    diff = gpr_inf_future;
+    diff = gpr_inf_future(GPR_CLOCK_REALTIME);
   } else if (b.tv_sec == TYPE_MAX(time_t) ||
              (b.tv_sec >= 0 && a.tv_sec <= TYPE_MIN(time_t) + b.tv_sec)) {
-    diff = gpr_inf_past;
+    diff = gpr_inf_past(GPR_CLOCK_REALTIME);
   } else {
     diff.tv_sec = a.tv_sec - b.tv_sec;
     if (dec != 0 && diff.tv_sec == TYPE_MIN(time_t) + 1) {
-      diff = gpr_inf_past;
+      diff = gpr_inf_past(GPR_CLOCK_REALTIME);
     } else {
       diff.tv_sec -= dec;
     }
@@ -225,6 +260,9 @@ gpr_timespec gpr_time_sub(gpr_timespec a, gpr_timespec b) {
 int gpr_time_similar(gpr_timespec a, gpr_timespec b, gpr_timespec threshold) {
   int cmp_ab;
 
+  GPR_ASSERT(a.clock_type == b.clock_type);
+  GPR_ASSERT(threshold.clock_type == GPR_TIMESPAN);
+
   cmp_ab = gpr_time_cmp(a, b);
   if (cmp_ab == 0) return 1;
   if (cmp_ab < 0) {
diff --git a/src/core/support/time_posix.c b/src/core/support/time_posix.c
index f9b7958783..258b2e640e 100644
--- a/src/core/support/time_posix.c
+++ b/src/core/support/time_posix.c
@@ -38,6 +38,7 @@
 #include <stdlib.h>
 #include <time.h>
 #include <unistd.h>
+#include <grpc/support/log.h>
 #include <grpc/support/time.h>
 
 static struct timespec timespec_from_gpr(gpr_timespec gts) {
@@ -48,10 +49,12 @@ static struct timespec timespec_from_gpr(gpr_timespec gts) {
 }
 
 #if _POSIX_TIMERS > 0
-static gpr_timespec gpr_from_timespec(struct timespec ts) {
+static gpr_timespec gpr_from_timespec(struct timespec ts,
+                                      gpr_clock_type clock) {
   gpr_timespec rv;
   rv.tv_sec = ts.tv_sec;
   rv.tv_nsec = (int)ts.tv_nsec;
+  rv.clock_type = clock;
   return rv;
 }
 
@@ -62,8 +65,9 @@ void gpr_time_init(void) {}
 
 gpr_timespec gpr_now(gpr_clock_type clock) {
   struct timespec now;
+  GPR_ASSERT(clock != GPR_TIMESPAN);
   clock_gettime(clockid_for_gpr_clock[clock], &now);
-  return gpr_from_timespec(now);
+  return gpr_from_timespec(now, clock);
 }
 #else
 /* For some reason Apple's OSes haven't implemented clock_gettime. */
@@ -88,6 +92,7 @@ gpr_timespec gpr_now(gpr_clock_type clock) {
   struct timeval now_tv;
   double now_dbl;
 
+  now.clock_type = clock;
   switch (clock) {
     case GPR_CLOCK_REALTIME:
       gettimeofday(&now_tv, NULL);
@@ -99,6 +104,8 @@ gpr_timespec gpr_now(gpr_clock_type clock) {
       now.tv_sec = now_dbl * 1e-9;
       now.tv_nsec = now_dbl - now.tv_sec * 1e9;
       break;
+    case GPR_TIMESPAN:
+      abort();
   }
 
   return now;
diff --git a/src/core/support/time_win32.c b/src/core/support/time_win32.c
index fa77c74eeb..238cd07ebc 100644
--- a/src/core/support/time_win32.c
+++ b/src/core/support/time_win32.c
@@ -55,6 +55,7 @@ gpr_timespec gpr_now(gpr_clock_type clock) {
   struct _timeb now_tb;
   LARGE_INTEGER timestamp;
   double now_dbl;
+  now_tv.clock_type = clock;
   switch (clock) {
     case GPR_CLOCK_REALTIME:
       _ftime_s(&now_tb);
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index 71f4235571..1146d83982 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -347,7 +347,7 @@ grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
   }
   grpc_call_stack_init(channel_stack, server_transport_data, initial_op_ptr,
                        CALL_STACK_FROM_CALL(call));
-  if (gpr_time_cmp(send_deadline, gpr_inf_future) != 0) {
+  if (gpr_time_cmp(send_deadline, gpr_inf_future(GPR_CLOCK_REALTIME)) != 0) {
     set_deadline_alarm(call, send_deadline);
   }
   return call;
@@ -985,7 +985,7 @@ static int fill_send_ops(grpc_call *call, grpc_transport_stream_op *op) {
           mdb.list = chain_metadata_from_app(call, data.send_metadata.count,
                                              data.send_metadata.metadata);
           mdb.garbage.head = mdb.garbage.tail = NULL;
-          mdb.deadline = gpr_inf_future;
+          mdb.deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
           /* send status */
           /* TODO(ctiller): cache common status values */
           data = call->request_data[GRPC_IOREQ_SEND_STATUS];
@@ -1338,7 +1338,7 @@ static void recv_metadata(grpc_call *call, grpc_metadata_batch *md) {
       l->md = 0;
     }
   }
-  if (gpr_time_cmp(md->deadline, gpr_inf_future) != 0) {
+  if (gpr_time_cmp(md->deadline, gpr_inf_future(GPR_CLOCK_REALTIME)) != 0) {
     set_deadline_alarm(call, md->deadline);
   }
   if (!is_trailing) {
diff --git a/src/core/surface/completion_queue.c b/src/core/surface/completion_queue.c
index f3630b31dd..8484418247 100644
--- a/src/core/surface/completion_queue.c
+++ b/src/core/surface/completion_queue.c
@@ -260,8 +260,9 @@ grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cc) {
 void grpc_cq_hack_spin_pollset(grpc_completion_queue *cc) {
   gpr_mu_lock(GRPC_POLLSET_MU(&cc->pollset));
   grpc_pollset_kick(&cc->pollset);
-  grpc_pollset_work(&cc->pollset, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
-                                               gpr_time_from_millis(100)));
+  grpc_pollset_work(&cc->pollset,
+                    gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
+                                 gpr_time_from_millis(100, GPR_TIMESPAN)));
   gpr_mu_unlock(GRPC_POLLSET_MU(&cc->pollset));
 }
 
diff --git a/src/core/surface/lame_client.c b/src/core/surface/lame_client.c
index 3dd56fe5a9..3f2bb5c8a9 100644
--- a/src/core/surface/lame_client.c
+++ b/src/core/surface/lame_client.c
@@ -72,7 +72,7 @@ static void lame_start_transport_stream_op(grpc_call_element *elem,
     mdb.list.head = &calld->status;
     mdb.list.tail = &calld->details;
     mdb.garbage.head = mdb.garbage.tail = NULL;
-    mdb.deadline = gpr_inf_future;
+    mdb.deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
     grpc_sopb_add_metadata(op->recv_ops, mdb);
     *op->recv_state = GRPC_STREAM_CLOSED;
     op->on_done_recv->cb(op->on_done_recv->cb_arg, 1);
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index 4dc51bf031..37f0c3c005 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -487,9 +487,9 @@ static void maybe_finish_shutdown(grpc_server *server) {
 
   if (server->root_channel_data.next != &server->root_channel_data ||
       server->listeners_destroyed < num_listeners(server)) {
-    if (gpr_time_cmp(
-            gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME), server->last_shutdown_message_time),
-            gpr_time_from_seconds(1)) >= 0) {
+    if (gpr_time_cmp(gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME),
+                                  server->last_shutdown_message_time),
+                     gpr_time_from_seconds(1, GPR_TIMESPAN)) >= 0) {
       server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
       gpr_log(GPR_DEBUG,
               "Waiting for %d channels and %d/%d listeners to be destroyed"
@@ -536,7 +536,8 @@ static void server_on_recv(void *ptr, int success) {
       grpc_stream_op *op = &ops[i];
       if (op->type != GRPC_OP_METADATA) continue;
       grpc_metadata_batch_filter(&op->data.metadata, server_filter, elem);
-      if (0 != gpr_time_cmp(op->data.metadata.deadline, gpr_inf_future)) {
+      if (0 != gpr_time_cmp(op->data.metadata.deadline,
+                            gpr_inf_future(GPR_CLOCK_REALTIME))) {
         calld->deadline = op->data.metadata.deadline;
       }
       calld->got_initial_metadata = 1;
@@ -610,7 +611,7 @@ static void accept_stream(void *cd, grpc_transport *transport,
   channel_data *chand = cd;
   /* create a call */
   grpc_call_create(chand->channel, NULL, transport_server_data, NULL, 0,
-                   gpr_inf_future);
+                   gpr_inf_future(GPR_CLOCK_REALTIME));
 }
 
 static void channel_connectivity_changed(void *cd, int iomgr_status_ignored) {
@@ -638,7 +639,7 @@ static void init_call_elem(grpc_call_element *elem,
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   memset(calld, 0, sizeof(call_data));
-  calld->deadline = gpr_inf_future;
+  calld->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
   calld->call = grpc_call_from_top_element(elem);
   gpr_mu_init(&calld->mu_state);
 
diff --git a/src/core/transport/chttp2/incoming_metadata.c b/src/core/transport/chttp2/incoming_metadata.c
index 77162a6864..974b864ffb 100644
--- a/src/core/transport/chttp2/incoming_metadata.c
+++ b/src/core/transport/chttp2/incoming_metadata.c
@@ -42,7 +42,7 @@
 
 void grpc_chttp2_incoming_metadata_buffer_init(
     grpc_chttp2_incoming_metadata_buffer *buffer) {
-  buffer->deadline = gpr_inf_future;
+  buffer->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
 void grpc_chttp2_incoming_metadata_buffer_destroy(
@@ -87,7 +87,7 @@ void grpc_chttp2_incoming_metadata_buffer_place_metadata_batch_into(
   b.list.tail = (void *)(gpr_intptr)buffer->count;
   b.garbage.head = b.garbage.tail = NULL;
   b.deadline = buffer->deadline;
-  buffer->deadline = gpr_inf_future;
+  buffer->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 
   grpc_sopb_add_metadata(sopb, b);
 }
diff --git a/src/core/transport/chttp2/parsing.c b/src/core/transport/chttp2/parsing.c
index 82362544d5..aa32f2e44a 100644
--- a/src/core/transport/chttp2/parsing.c
+++ b/src/core/transport/chttp2/parsing.c
@@ -601,7 +601,7 @@ static void on_header(void *tp, grpc_mdelem *md) {
                                       cached_timeout)) {
         gpr_log(GPR_ERROR, "Ignoring bad timeout value '%s'",
                 grpc_mdstr_as_c_string(md->value));
-        *cached_timeout = gpr_inf_future;
+        *cached_timeout = gpr_inf_future(GPR_CLOCK_REALTIME);
       }
       grpc_mdelem_set_user_data(md, free_timeout, cached_timeout);
     }
diff --git a/src/core/transport/chttp2/stream_encoder.c b/src/core/transport/chttp2/stream_encoder.c
index d553d80085..d7fc2da5d3 100644
--- a/src/core/transport/chttp2/stream_encoder.c
+++ b/src/core/transport/chttp2/stream_encoder.c
@@ -585,7 +585,8 @@ void grpc_chttp2_encode(grpc_stream_op *ops, size_t ops_count, int eof,
           l->md = hpack_enc(compressor, l->md, &st);
           need_unref |= l->md != NULL;
         }
-        if (gpr_time_cmp(op->data.metadata.deadline, gpr_inf_future) != 0) {
+        if (gpr_time_cmp(op->data.metadata.deadline,
+                         gpr_inf_future(GPR_CLOCK_REALTIME)) != 0) {
           deadline_enc(compressor, op->data.metadata.deadline, &st);
         }
         curop++;
diff --git a/src/core/transport/chttp2/timeout_encoding.c b/src/core/transport/chttp2/timeout_encoding.c
index 33915c4039..1dd768ada4 100644
--- a/src/core/transport/chttp2/timeout_encoding.c
+++ b/src/core/transport/chttp2/timeout_encoding.c
@@ -147,7 +147,7 @@ int grpc_chttp2_decode_timeout(const char *buffer, gpr_timespec *timeout) {
     gpr_uint32 xp = x * 10 + *p - '0';
     have_digit = 1;
     if (xp < x) {
-      *timeout = gpr_inf_future;
+      *timeout = gpr_inf_future(GPR_CLOCK_REALTIME);
       return 1;
     }
     x = xp;
@@ -159,22 +159,22 @@ int grpc_chttp2_decode_timeout(const char *buffer, gpr_timespec *timeout) {
   /* decode unit specifier */
   switch (*p) {
     case 'n':
-      *timeout = gpr_time_from_nanos(x);
+      *timeout = gpr_time_from_nanos(x, GPR_TIMESPAN);
       break;
     case 'u':
-      *timeout = gpr_time_from_micros(x);
+      *timeout = gpr_time_from_micros(x, GPR_TIMESPAN);
       break;
     case 'm':
-      *timeout = gpr_time_from_millis(x);
+      *timeout = gpr_time_from_millis(x, GPR_TIMESPAN);
       break;
     case 'S':
-      *timeout = gpr_time_from_seconds(x);
+      *timeout = gpr_time_from_seconds(x, GPR_TIMESPAN);
       break;
     case 'M':
-      *timeout = gpr_time_from_minutes(x);
+      *timeout = gpr_time_from_minutes(x, GPR_TIMESPAN);
       break;
     case 'H':
-      *timeout = gpr_time_from_hours(x);
+      *timeout = gpr_time_from_hours(x, GPR_TIMESPAN);
       break;
     default:
       return 0;
diff --git a/src/core/transport/stream_op.c b/src/core/transport/stream_op.c
index fdb50c6b71..71061fe0c7 100644
--- a/src/core/transport/stream_op.c
+++ b/src/core/transport/stream_op.c
@@ -205,7 +205,7 @@ void grpc_metadata_batch_assert_ok(grpc_metadata_batch *batch) {
 void grpc_metadata_batch_init(grpc_metadata_batch *batch) {
   batch->list.head = batch->list.tail = batch->garbage.head = batch->garbage.tail =
       NULL;
-  batch->deadline = gpr_inf_future;
+  batch->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
 void grpc_metadata_batch_destroy(grpc_metadata_batch *batch) {
diff --git a/src/core/transport/transport_op_string.c b/src/core/transport/transport_op_string.c
index 862eb40c4b..9d127c5472 100644
--- a/src/core/transport/transport_op_string.c
+++ b/src/core/transport/transport_op_string.c
@@ -61,7 +61,7 @@ static void put_metadata_list(gpr_strvec *b, grpc_metadata_batch md) {
     if (m != md.list.head) gpr_strvec_add(b, gpr_strdup(", "));
     put_metadata(b, m->md);
   }
-  if (gpr_time_cmp(md.deadline, gpr_inf_future) != 0) {
+  if (gpr_time_cmp(md.deadline, gpr_inf_future(GPR_CLOCK_REALTIME)) != 0) {
     char *tmp;
     gpr_asprintf(&tmp, " deadline=%d.%09d", md.deadline.tv_sec,
                  md.deadline.tv_nsec);
diff --git a/src/cpp/client/client_context.cc b/src/cpp/client/client_context.cc
index c68f6dd9f8..372f3e27ec 100644
--- a/src/cpp/client/client_context.cc
+++ b/src/cpp/client/client_context.cc
@@ -44,7 +44,7 @@ ClientContext::ClientContext()
     : initial_metadata_received_(false),
       call_(nullptr),
       cq_(nullptr),
-      deadline_(gpr_inf_future) {}
+      deadline_(gpr_inf_future(GPR_CLOCK_REALTIME)) {}
 
 ClientContext::~ClientContext() {
   if (call_) {
@@ -53,8 +53,8 @@ ClientContext::~ClientContext() {
   if (cq_) {
     // Drain cq_.
     grpc_completion_queue_shutdown(cq_);
-    while (grpc_completion_queue_next(cq_, gpr_inf_future).type !=
-           GRPC_QUEUE_SHUTDOWN)
+    while (grpc_completion_queue_next(cq_, gpr_inf_future(GPR_CLOCK_REALTIME))
+               .type != GRPC_QUEUE_SHUTDOWN)
       ;
     grpc_completion_queue_destroy(cq_);
   }
diff --git a/src/cpp/client/secure_credentials.cc b/src/cpp/client/secure_credentials.cc
index 4d200908fb..01c7f14f1a 100644
--- a/src/cpp/client/secure_credentials.cc
+++ b/src/cpp/client/secure_credentials.cc
@@ -92,7 +92,8 @@ std::shared_ptr<Credentials> ServiceAccountCredentials(
             "with non-positive lifetime");
     return WrapCredentials(nullptr);
   }
-  gpr_timespec lifetime = gpr_time_from_seconds(token_lifetime_seconds);
+  gpr_timespec lifetime =
+      gpr_time_from_seconds(token_lifetime_seconds, GPR_TIMESPAN);
   return WrapCredentials(grpc_service_account_credentials_create(
       json_key.c_str(), scope.c_str(), lifetime));
 }
@@ -105,7 +106,8 @@ std::shared_ptr<Credentials> JWTCredentials(const grpc::string& json_key,
             "Trying to create JWTCredentials with non-positive lifetime");
     return WrapCredentials(nullptr);
   }
-  gpr_timespec lifetime = gpr_time_from_seconds(token_lifetime_seconds);
+  gpr_timespec lifetime =
+      gpr_time_from_seconds(token_lifetime_seconds, GPR_TIMESPAN);
   return WrapCredentials(
       grpc_jwt_credentials_create(json_key.c_str(), lifetime));
 }
diff --git a/src/cpp/common/completion_queue.cc b/src/cpp/common/completion_queue.cc
index b2dd1acdca..593963f672 100644
--- a/src/cpp/common/completion_queue.cc
+++ b/src/cpp/common/completion_queue.cc
@@ -70,7 +70,8 @@ CompletionQueue::NextStatus CompletionQueue::AsyncNextInternal(
 }
 
 bool CompletionQueue::Pluck(CompletionQueueTag* tag) {
-  auto ev = grpc_completion_queue_pluck(cq_, tag, gpr_inf_future);
+  auto ev =
+      grpc_completion_queue_pluck(cq_, tag, gpr_inf_future(GPR_CLOCK_REALTIME));
   bool ok = ev.success != 0;
   void* ignored = tag;
   GPR_ASSERT(tag->FinalizeResult(&ignored, &ok));
@@ -80,7 +81,8 @@ bool CompletionQueue::Pluck(CompletionQueueTag* tag) {
 }
 
 void CompletionQueue::TryPluck(CompletionQueueTag* tag) {
-  auto ev = grpc_completion_queue_pluck(cq_, tag, gpr_time_0);
+  auto ev =
+      grpc_completion_queue_pluck(cq_, tag, gpr_time_0(GPR_CLOCK_REALTIME));
   if (ev.type == GRPC_QUEUE_TIMEOUT) return;
   bool ok = ev.success != 0;
   void* ignored = tag;
diff --git a/src/cpp/util/time.cc b/src/cpp/util/time.cc
index fd94d00b32..a814cad452 100644
--- a/src/cpp/util/time.cc
+++ b/src/cpp/util/time.cc
@@ -51,13 +51,15 @@ void Timepoint2Timespec(const system_clock::time_point& from,
   system_clock::duration deadline = from.time_since_epoch();
   seconds secs = duration_cast<seconds>(deadline);
   if (from == system_clock::time_point::max() ||
-      secs.count() >= gpr_inf_future.tv_sec || secs.count() < 0) {
-    *to = gpr_inf_future;
+      secs.count() >= gpr_inf_future(GPR_CLOCK_REALTIME).tv_sec ||
+      secs.count() < 0) {
+    *to = gpr_inf_future(GPR_CLOCK_REALTIME);
     return;
   }
   nanoseconds nsecs = duration_cast<nanoseconds>(deadline - secs);
   to->tv_sec = secs.count();
   to->tv_nsec = nsecs.count();
+  to->clock_type = GPR_CLOCK_REALTIME;
 }
 
 void TimepointHR2Timespec(const high_resolution_clock::time_point& from,
@@ -65,17 +67,19 @@ void TimepointHR2Timespec(const high_resolution_clock::time_point& from,
   high_resolution_clock::duration deadline = from.time_since_epoch();
   seconds secs = duration_cast<seconds>(deadline);
   if (from == high_resolution_clock::time_point::max() ||
-      secs.count() >= gpr_inf_future.tv_sec || secs.count() < 0) {
-    *to = gpr_inf_future;
+      secs.count() >= gpr_inf_future(GPR_CLOCK_REALTIME).tv_sec ||
+      secs.count() < 0) {
+    *to = gpr_inf_future(GPR_CLOCK_REALTIME);
     return;
   }
   nanoseconds nsecs = duration_cast<nanoseconds>(deadline - secs);
   to->tv_sec = secs.count();
   to->tv_nsec = nsecs.count();
+  to->clock_type = GPR_CLOCK_REALTIME;
 }
 
 system_clock::time_point Timespec2Timepoint(gpr_timespec t) {
-  if (gpr_time_cmp(t, gpr_inf_future) == 0) {
+  if (gpr_time_cmp(t, gpr_inf_future(GPR_CLOCK_REALTIME)) == 0) {
     return system_clock::time_point::max();
   }
   system_clock::time_point tp;
diff --git a/src/csharp/Grpc.Core.Tests/TimespecTest.cs b/src/csharp/Grpc.Core.Tests/TimespecTest.cs
index f5bae6d935..5831121add 100644
--- a/src/csharp/Grpc.Core.Tests/TimespecTest.cs
+++ b/src/csharp/Grpc.Core.Tests/TimespecTest.cs
@@ -61,28 +61,28 @@ namespace Grpc.Core.Internal.Tests
         [Test]
         public void Add()
         {
-            var t = new Timespec { tv_sec = new IntPtr(12345), tv_nsec = new IntPtr(123456789) };
+            var t = new Timespec { tv_sec = new IntPtr(12345), tv_nsec = 123456789 };
             var result = t.Add(TimeSpan.FromTicks(TimeSpan.TicksPerSecond * 10));
             Assert.AreEqual(result.tv_sec, new IntPtr(12355));
-            Assert.AreEqual(result.tv_nsec, new IntPtr(123456789));
+            Assert.AreEqual(result.tv_nsec, 123456789);
         }
 
         [Test]
         public void Add_Nanos()
         {
-            var t = new Timespec { tv_sec = new IntPtr(12345), tv_nsec = new IntPtr(123456789) };
+            var t = new Timespec { tv_sec = new IntPtr(12345), tv_nsec = 123456789 };
             var result = t.Add(TimeSpan.FromTicks(10));
             Assert.AreEqual(result.tv_sec, new IntPtr(12345));
-            Assert.AreEqual(result.tv_nsec, new IntPtr(123456789 + 1000));
+            Assert.AreEqual(result.tv_nsec, 123456789 + 1000);
         }
 
         [Test]
         public void Add_NanosOverflow()
         {
-            var t = new Timespec { tv_sec = new IntPtr(12345), tv_nsec = new IntPtr(999999999) };
+            var t = new Timespec { tv_sec = new IntPtr(12345), tv_nsec = 999999999 };
             var result = t.Add(TimeSpan.FromTicks(TimeSpan.TicksPerSecond * 10 + 10));
             Assert.AreEqual(result.tv_sec, new IntPtr(12356));
-            Assert.AreEqual(result.tv_nsec, new IntPtr(999));
+            Assert.AreEqual(result.tv_nsec, 999);
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Internal/Enums.cs b/src/csharp/Grpc.Core/Internal/Enums.cs
index af11b5b9f3..185098160b 100644
--- a/src/csharp/Grpc.Core/Internal/Enums.cs
+++ b/src/csharp/Grpc.Core/Internal/Enums.cs
@@ -90,4 +90,19 @@ namespace Grpc.Core.Internal
         /* operation completion */
         OpComplete
     }
+
+    /// <summary>
+    /// gpr_clock_type from grpc/support/time.h
+    /// </summary>
+    internal enum GPRClockType
+    {
+        /* Monotonic clock */
+        Monotonic,
+
+        /* Realtime clock */
+        Realtime,
+
+        /* Timespan - the distance between two time points */
+        Timespan
+    }
 }
diff --git a/src/csharp/Grpc.Core/Internal/Timespec.cs b/src/csharp/Grpc.Core/Internal/Timespec.cs
index 775af27db9..de783f5a4b 100644
--- a/src/csharp/Grpc.Core/Internal/Timespec.cs
+++ b/src/csharp/Grpc.Core/Internal/Timespec.cs
@@ -55,7 +55,8 @@ namespace Grpc.Core.Internal
         // NOTE: on linux 64bit  sizeof(gpr_timespec) = 16, on windows 32bit sizeof(gpr_timespec) = 8
         // so IntPtr seems to have the right size to work on both.
         public System.IntPtr tv_sec;
-        public System.IntPtr tv_nsec;
+        public int tv_nsec;
+        public GPRClockType clock_type;
 
         /// <summary>
         /// Timespec a long time in the future.
@@ -99,12 +100,13 @@ namespace Grpc.Core.Internal
 
         public Timespec Add(TimeSpan timeSpan)
         {
-            long nanos = tv_nsec.ToInt64() + (timeSpan.Ticks % TimeSpan.TicksPerSecond) * NanosPerTick;
+            long nanos = (long)tv_nsec + (timeSpan.Ticks % TimeSpan.TicksPerSecond) * NanosPerTick;
             long overflow_sec = (nanos > NanosPerSecond) ? 1 : 0;
 
             Timespec result;
-            result.tv_nsec = new IntPtr(nanos % NanosPerSecond);
+            result.tv_nsec = (int)(nanos % NanosPerSecond);
             result.tv_sec = new IntPtr(tv_sec.ToInt64() + (timeSpan.Ticks / TimeSpan.TicksPerSecond) + overflow_sec);
+            result.clock_type = GPRClockType.Realtime;
             return result;
         }
     }
diff --git a/src/csharp/ext/grpc_csharp_ext.c b/src/csharp/ext/grpc_csharp_ext.c
index a55cc9e247..7dd1959a5f 100644
--- a/src/csharp/ext/grpc_csharp_ext.c
+++ b/src/csharp/ext/grpc_csharp_ext.c
@@ -302,12 +302,13 @@ grpcsharp_completion_queue_destroy(grpc_completion_queue *cq) {
 
 GPR_EXPORT grpc_event GPR_CALLTYPE
 grpcsharp_completion_queue_next(grpc_completion_queue *cq) {
-  return grpc_completion_queue_next(cq, gpr_inf_future);
+  return grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME));
 }
 
 GPR_EXPORT grpc_event GPR_CALLTYPE
 grpcsharp_completion_queue_pluck(grpc_completion_queue *cq, void *tag) {
-  return grpc_completion_queue_pluck(cq, tag, gpr_inf_future);
+  return grpc_completion_queue_pluck(cq, tag,
+                                     gpr_inf_future(GPR_CLOCK_REALTIME));
 }
 
 /* Channel */
@@ -382,7 +383,7 @@ grpcsharp_channel_args_destroy(grpc_channel_args *args) {
 GPR_EXPORT gpr_timespec GPR_CALLTYPE gprsharp_now(void) { return gpr_now(GPR_CLOCK_REALTIME); }
 
 GPR_EXPORT gpr_timespec GPR_CALLTYPE gprsharp_inf_future(void) {
-  return gpr_inf_future;
+  return gpr_inf_future(GPR_CLOCK_REALTIME);
 }
 
 GPR_EXPORT gpr_int32 GPR_CALLTYPE gprsharp_sizeof_timespec(void) {
diff --git a/src/node/ext/completion_queue_async_worker.cc b/src/node/ext/completion_queue_async_worker.cc
index 4be208c82d..1215c97e19 100644
--- a/src/node/ext/completion_queue_async_worker.cc
+++ b/src/node/ext/completion_queue_async_worker.cc
@@ -62,7 +62,8 @@ CompletionQueueAsyncWorker::CompletionQueueAsyncWorker()
 CompletionQueueAsyncWorker::~CompletionQueueAsyncWorker() {}
 
 void CompletionQueueAsyncWorker::Execute() {
-  result = grpc_completion_queue_next(queue, gpr_inf_future);
+  result =
+      grpc_completion_queue_next(queue, gpr_inf_future(GPR_CLOCK_REALTIME));
   if (!result.success) {
     SetErrorMessage("The batch encountered an error");
   }
diff --git a/src/node/ext/server.cc b/src/node/ext/server.cc
index 51c55ba965..34cde9ffab 100644
--- a/src/node/ext/server.cc
+++ b/src/node/ext/server.cc
@@ -161,7 +161,8 @@ void Server::ShutdownServer() {
     grpc_server_shutdown_and_notify(this->wrapped_server,
                                     this->shutdown_queue,
                                     NULL);
-    grpc_completion_queue_pluck(this->shutdown_queue, NULL, gpr_inf_future);
+    grpc_completion_queue_pluck(this->shutdown_queue, NULL,
+                                gpr_inf_future(GPR_CLOCK_REALTIME));
     this->wrapped_server = NULL;
   }
 }
diff --git a/src/node/ext/timeval.cc b/src/node/ext/timeval.cc
index bc3237f7a6..60de4d816d 100644
--- a/src/node/ext/timeval.cc
+++ b/src/node/ext/timeval.cc
@@ -42,18 +42,19 @@ namespace node {
 
 gpr_timespec MillisecondsToTimespec(double millis) {
   if (millis == std::numeric_limits<double>::infinity()) {
-    return gpr_inf_future;
+    return gpr_inf_future(GPR_CLOCK_REALTIME);
   } else if (millis == -std::numeric_limits<double>::infinity()) {
-    return gpr_inf_past;
+    return gpr_inf_past(GPR_CLOCK_REALTIME);
   } else {
-    return gpr_time_from_micros(static_cast<int64_t>(millis * 1000));
+    return gpr_time_from_micros(static_cast<int64_t>(millis * 1000),
+                                GPR_CLOCK_REALTIME);
   }
 }
 
 double TimespecToMilliseconds(gpr_timespec timespec) {
-  if (gpr_time_cmp(timespec, gpr_inf_future) == 0) {
+  if (gpr_time_cmp(timespec, gpr_inf_future(GPR_CLOCK_REALTIME)) == 0) {
     return std::numeric_limits<double>::infinity();
-  } else if (gpr_time_cmp(timespec, gpr_inf_past) == 0) {
+  } else if (gpr_time_cmp(timespec, gpr_inf_past(GPR_CLOCK_REALTIME)) == 0) {
     return -std::numeric_limits<double>::infinity();
   } else {
     return (static_cast<double>(timespec.tv_sec) * 1000 +
diff --git a/src/php/ext/grpc/call.c b/src/php/ext/grpc/call.c
index 10a4946ea6..b67bae7568 100644
--- a/src/php/ext/grpc/call.c
+++ b/src/php/ext/grpc/call.c
@@ -408,7 +408,7 @@ PHP_METHOD(Call, startBatch) {
     goto cleanup;
   }
   event = grpc_completion_queue_pluck(completion_queue, call->wrapped,
-                                      gpr_inf_future);
+                                      gpr_inf_future(GPR_CLOCK_REALTIME));
   if (!event.success) {
     zend_throw_exception(spl_ce_LogicException,
                          "The batch failed for some reason",
diff --git a/src/php/ext/grpc/completion_queue.c b/src/php/ext/grpc/completion_queue.c
index b24c83757c..c653a592ef 100644
--- a/src/php/ext/grpc/completion_queue.c
+++ b/src/php/ext/grpc/completion_queue.c
@@ -43,8 +43,9 @@ void grpc_php_init_completion_queue(TSRMLS_D) {
 
 void grpc_php_shutdown_completion_queue(TSRMLS_D) {
   grpc_completion_queue_shutdown(completion_queue);
-  while (grpc_completion_queue_next(completion_queue, gpr_inf_future).type !=
-         GRPC_QUEUE_SHUTDOWN)
+  while (grpc_completion_queue_next(completion_queue,
+                                    gpr_inf_future(GPR_CLOCK_REALTIME))
+             .type != GRPC_QUEUE_SHUTDOWN)
     ;
   grpc_completion_queue_destroy(completion_queue);
 }
diff --git a/src/php/ext/grpc/server.c b/src/php/ext/grpc/server.c
index 02c886c715..c319526e42 100644
--- a/src/php/ext/grpc/server.c
+++ b/src/php/ext/grpc/server.c
@@ -64,7 +64,8 @@ void free_wrapped_grpc_server(void *object TSRMLS_DC) {
   wrapped_grpc_server *server = (wrapped_grpc_server *)object;
   if (server->wrapped != NULL) {
     grpc_server_shutdown_and_notify(server->wrapped, completion_queue, NULL);
-    grpc_completion_queue_pluck(completion_queue, NULL, gpr_inf_future);
+    grpc_completion_queue_pluck(completion_queue, NULL,
+                                gpr_inf_future(GPR_CLOCK_REALTIME));
     grpc_server_destroy(server->wrapped);
   }
   efree(server);
@@ -143,7 +144,8 @@ PHP_METHOD(Server, requestCall) {
                          (long)error_code TSRMLS_CC);
     goto cleanup;
   }
-  event = grpc_completion_queue_pluck(completion_queue, NULL, gpr_inf_future);
+  event = grpc_completion_queue_pluck(completion_queue, NULL,
+                                      gpr_inf_future(GPR_CLOCK_REALTIME));
   if (!event.success) {
     zend_throw_exception(spl_ce_LogicException,
                          "Failed to request a call for some reason",
diff --git a/src/php/ext/grpc/timeval.c b/src/php/ext/grpc/timeval.c
index ccf7f0f81a..4fd069e19a 100644
--- a/src/php/ext/grpc/timeval.c
+++ b/src/php/ext/grpc/timeval.c
@@ -98,7 +98,7 @@ PHP_METHOD(Timeval, __construct) {
                          "Timeval expects a long", 1 TSRMLS_CC);
     return;
   }
-  gpr_timespec time = gpr_time_from_micros(microseconds);
+  gpr_timespec time = gpr_time_from_micros(microseconds, GPR_TIMESPAN);
   memcpy(&timeval->wrapped, &time, sizeof(gpr_timespec));
 }
 
@@ -217,7 +217,8 @@ PHP_METHOD(Timeval, now) {
  * @return Timeval Zero length time interval
  */
 PHP_METHOD(Timeval, zero) {
-  zval *grpc_php_timeval_zero = grpc_php_wrap_timeval(gpr_time_0);
+  zval *grpc_php_timeval_zero =
+      grpc_php_wrap_timeval(gpr_time_0(GPR_CLOCK_REALTIME));
   RETURN_ZVAL(grpc_php_timeval_zero,
               false, /* Copy original before returning? */
               true /* Destroy original before returning */);
@@ -228,7 +229,8 @@ PHP_METHOD(Timeval, zero) {
  * @return Timeval Infinite future time value
  */
 PHP_METHOD(Timeval, infFuture) {
-  zval *grpc_php_timeval_inf_future = grpc_php_wrap_timeval(gpr_inf_future);
+  zval *grpc_php_timeval_inf_future =
+      grpc_php_wrap_timeval(gpr_inf_future(GPR_CLOCK_REALTIME));
   RETURN_DESTROY_ZVAL(grpc_php_timeval_inf_future);
 }
 
@@ -237,7 +239,8 @@ PHP_METHOD(Timeval, infFuture) {
  * @return Timeval Infinite past time value
  */
 PHP_METHOD(Timeval, infPast) {
-  zval *grpc_php_timeval_inf_past = grpc_php_wrap_timeval(gpr_inf_past);
+  zval *grpc_php_timeval_inf_past =
+      grpc_php_wrap_timeval(gpr_inf_past(GPR_CLOCK_REALTIME));
   RETURN_DESTROY_ZVAL(grpc_php_timeval_inf_past);
 }
 
diff --git a/src/python/src/grpc/_adapter/_c/utility.c b/src/python/src/grpc/_adapter/_c/utility.c
index 480a720c21..000c8d0c38 100644
--- a/src/python/src/grpc/_adapter/_c/utility.c
+++ b/src/python/src/grpc/_adapter/_c/utility.c
@@ -385,10 +385,12 @@ static int pygrpc_isinf(double x) {
 gpr_timespec pygrpc_cast_double_to_gpr_timespec(double seconds) {
   gpr_timespec result;
   if (pygrpc_isinf(seconds)) {
-    result = seconds > 0.0 ? gpr_inf_future : gpr_inf_past;
+    result = seconds > 0.0 ? gpr_inf_future(GPR_CLOCK_REALTIME)
+                           : gpr_inf_past(GPR_CLOCK_REALTIME);
   } else {
     result.tv_sec = (time_t)seconds;
     result.tv_nsec = ((seconds - result.tv_sec) * 1e9);
+    result.clock_type = GPR_CLOCK_REALTIME;
   }
   return result;
 }
diff --git a/src/ruby/ext/grpc/rb_completion_queue.c b/src/ruby/ext/grpc/rb_completion_queue.c
index 2d52d96dc8..f89439f4c1 100644
--- a/src/ruby/ext/grpc/rb_completion_queue.c
+++ b/src/ruby/ext/grpc/rb_completion_queue.c
@@ -82,7 +82,7 @@ static void grpc_rb_completion_queue_shutdown_drain(grpc_completion_queue *cq) {
   next_call.cq = cq;
   next_call.event.type = GRPC_QUEUE_TIMEOUT;
   /* TODO: the timeout should be a module level constant that defaults
-   * to gpr_inf_future.
+   * to gpr_inf_future(GPR_CLOCK_REALTIME).
    *
    * - at the moment this does not work, it stalls.  Using a small timeout like
    *   this one works, and leads to fast test run times; a longer timeout was
@@ -91,7 +91,8 @@ static void grpc_rb_completion_queue_shutdown_drain(grpc_completion_queue *cq) {
    * - investigate further, this is probably another example of C-level cleanup
    * not working consistently in all cases.
    */
-  next_call.timeout = gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), gpr_time_from_micros(5e3));
+  next_call.timeout = gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
+                                   gpr_time_from_micros(5e3, GPR_TIMESPAN));
   do {
     rb_thread_call_without_gvl(grpc_rb_completion_queue_next_no_gil,
                                (void *)&next_call, NULL, NULL);
@@ -143,7 +144,7 @@ grpc_event grpc_rb_completion_queue_pluck_event(VALUE self, VALUE tag,
   TypedData_Get_Struct(self, grpc_completion_queue,
                        &grpc_rb_completion_queue_data_type, next_call.cq);
   if (TYPE(timeout) == T_NIL) {
-    next_call.timeout = gpr_inf_future;
+    next_call.timeout = gpr_inf_future(GPR_CLOCK_REALTIME);
   } else {
     next_call.timeout = grpc_rb_time_timeval(timeout, /* absolute time*/ 0);
   }
diff --git a/src/ruby/ext/grpc/rb_grpc.c b/src/ruby/ext/grpc/rb_grpc.c
index 699548b940..f138bf6dd5 100644
--- a/src/ruby/ext/grpc/rb_grpc.c
+++ b/src/ruby/ext/grpc/rb_grpc.c
@@ -98,6 +98,7 @@ gpr_timespec grpc_rb_time_timeval(VALUE time, int interval) {
   const char *tstr = interval ? "time interval" : "time";
   const char *want = " want <secs from epoch>|<Time>|<GRPC::TimeConst.*>";
 
+  t.clock_type = GPR_CLOCK_REALTIME;
   switch (TYPE(time)) {
     case T_DATA:
       if (CLASS_OF(time) == grpc_rb_cTimeVal) {
@@ -222,24 +223,31 @@ static VALUE grpc_rb_time_val_to_s(VALUE self) {
   return rb_funcall(grpc_rb_time_val_to_time(self), id_to_s, 0);
 }
 
+static gpr_timespec zero_realtime;
+static gpr_timespec inf_future_realtime;
+static gpr_timespec inf_past_realtime;
+
 /* Adds a module with constants that map to gpr's static timeval structs. */
 static void Init_grpc_time_consts() {
   VALUE grpc_rb_mTimeConsts =
       rb_define_module_under(grpc_rb_mGrpcCore, "TimeConsts");
   grpc_rb_cTimeVal =
       rb_define_class_under(grpc_rb_mGrpcCore, "TimeSpec", rb_cObject);
+  zero_realtime = gpr_time_0(GPR_CLOCK_REALTIME);
+  inf_future_realtime = gpr_inf_future(GPR_CLOCK_REALTIME);
+  inf_past_realtime = gpr_inf_past(GPR_CLOCK_REALTIME);
   rb_define_const(
       grpc_rb_mTimeConsts, "ZERO",
       TypedData_Wrap_Struct(grpc_rb_cTimeVal, &grpc_rb_timespec_data_type,
-                            (void *)&gpr_time_0));
+                            (void *)&zero_realtime));
   rb_define_const(
       grpc_rb_mTimeConsts, "INFINITE_FUTURE",
       TypedData_Wrap_Struct(grpc_rb_cTimeVal, &grpc_rb_timespec_data_type,
-                            (void *)&gpr_inf_future));
+                            (void *)&inf_future_realtime));
   rb_define_const(
       grpc_rb_mTimeConsts, "INFINITE_PAST",
       TypedData_Wrap_Struct(grpc_rb_cTimeVal, &grpc_rb_timespec_data_type,
-                            (void *)&gpr_inf_past));
+                            (void *)&inf_past_realtime));
   rb_define_method(grpc_rb_cTimeVal, "to_time", grpc_rb_time_val_to_time, 0);
   rb_define_method(grpc_rb_cTimeVal, "inspect", grpc_rb_time_val_inspect, 0);
   rb_define_method(grpc_rb_cTimeVal, "to_s", grpc_rb_time_val_to_s, 0);