Refcounting fixes and debugging, empty batch stability fixes

src/core/channel/client_channel.c

@@ -77,6 +77,7 @@ typedef struct {
 
 typedef enum {
   CALL_CREATED,
+  CALL_WAITING_FOR_SEND,
   CALL_WAITING_FOR_CONFIG,
   CALL_WAITING_FOR_PICK,
   CALL_WAITING_FOR_CALL,
@@ -101,6 +102,9 @@ struct call_data {
   grpc_linked_mdelem details;
 };
 
+static grpc_iomgr_closure *merge_into_waiting_op(grpc_call_element *elem,
+                                  grpc_transport_stream_op *new_op) GRPC_MUST_USE_RESULT;
+
 static void handle_op_after_cancellation(grpc_call_element *elem,
                                          grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
@@ -241,12 +245,13 @@ static void pick_target(grpc_lb_policy *lb_policy, call_data *calld) {
                       &calld->picked_channel, &calld->async_setup_task);
 }
 
-static void merge_into_waiting_op(grpc_call_element *elem,
+static grpc_iomgr_closure *merge_into_waiting_op(grpc_call_element *elem,
                                   grpc_transport_stream_op *new_op) {
   call_data *calld = elem->call_data;
+  grpc_iomgr_closure *consumed_op = NULL;
   grpc_transport_stream_op *waiting_op = &calld->waiting_op;
-  GPR_ASSERT((waiting_op->send_ops == NULL) != (new_op->send_ops == NULL));
-  GPR_ASSERT((waiting_op->recv_ops == NULL) != (new_op->recv_ops == NULL));
+  GPR_ASSERT((waiting_op->send_ops == NULL) != (new_op->send_ops == NULL) || waiting_op->send_ops == NULL);
+  GPR_ASSERT((waiting_op->recv_ops == NULL) != (new_op->recv_ops == NULL) || waiting_op->recv_ops == NULL);
   if (new_op->send_ops != NULL) {
     waiting_op->send_ops = new_op->send_ops;
     waiting_op->is_last_send = new_op->is_last_send;
@@ -257,13 +262,16 @@ static void merge_into_waiting_op(grpc_call_element *elem,
     waiting_op->recv_state = new_op->recv_state;
     waiting_op->on_done_recv = new_op->on_done_recv;
   }
-  if (waiting_op->on_consumed == NULL) {
+  if (new_op->on_consumed != NULL) {
+    if (waiting_op->on_consumed != NULL) {
+      consumed_op = waiting_op->on_consumed;
+    }
     waiting_op->on_consumed = new_op->on_consumed;
-    new_op->on_consumed = NULL;
   }
   if (new_op->cancel_with_status != GRPC_STATUS_OK) {
     waiting_op->cancel_with_status = new_op->cancel_with_status;
   }
+  return consumed_op;
 }
 
 static void perform_transport_stream_op(grpc_call_element *elem,
@@ -274,6 +282,7 @@ static void perform_transport_stream_op(grpc_call_element *elem,
   grpc_subchannel_call *subchannel_call;
   grpc_lb_policy *lb_policy;
   grpc_transport_stream_op op2;
+  grpc_iomgr_closure *consumed_op = NULL;
   GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
 
@@ -289,6 +298,17 @@ static void perform_transport_stream_op(grpc_call_element *elem,
       gpr_mu_unlock(&calld->mu_state);
       handle_op_after_cancellation(elem, op);
       break;
+    case CALL_WAITING_FOR_SEND:
+      GPR_ASSERT(!continuation);
+      consumed_op = merge_into_waiting_op(elem, op);
+      if (!calld->waiting_op.send_ops && calld->waiting_op.cancel_with_status == GRPC_STATUS_OK) {
+        gpr_mu_unlock(&calld->mu_state);
+        break;
+      }
+      *op = calld->waiting_op;
+      memset(&calld->waiting_op, 0, sizeof(calld->waiting_op));
+      continuation = 1;
+      /* fall through */
     case CALL_WAITING_FOR_CONFIG:
     case CALL_WAITING_FOR_PICK:
     case CALL_WAITING_FOR_CALL:
@@ -308,7 +328,7 @@ static void perform_transport_stream_op(grpc_call_element *elem,
           handle_op_after_cancellation(elem, op);
           handle_op_after_cancellation(elem, &op2);
         } else {
-          merge_into_waiting_op(elem, op);
+          consumed_op = merge_into_waiting_op(elem, op);
           gpr_mu_unlock(&calld->mu_state);
           if (op->on_consumed != NULL) {
             op->on_consumed->cb(op->on_consumed->cb_arg, 0);
@@ -325,26 +345,37 @@ static void perform_transport_stream_op(grpc_call_element *elem,
       } else {
         calld->waiting_op = *op;
 
-        gpr_mu_lock(&chand->mu_config);
-        lb_policy = chand->lb_policy;
-        if (lb_policy) {
-          GRPC_LB_POLICY_REF(lb_policy, "pick");
-          gpr_mu_unlock(&chand->mu_config);
-          calld->state = CALL_WAITING_FOR_PICK;
+        if (op->send_ops == NULL) {
+          /* need to have some send ops before we can select the
+             lb target */
+          calld->state = CALL_WAITING_FOR_SEND;
           gpr_mu_unlock(&calld->mu_state);
-
-          pick_target(lb_policy, calld);
-
-          GRPC_LB_POLICY_UNREF(lb_policy, "pick");
         } else {
-          calld->state = CALL_WAITING_FOR_CONFIG;
-          add_to_lb_policy_wait_queue_locked_state_config(elem);
-          gpr_mu_unlock(&chand->mu_config);
-          gpr_mu_unlock(&calld->mu_state);
+          gpr_mu_lock(&chand->mu_config);
+          lb_policy = chand->lb_policy;
+          if (lb_policy) {
+            GRPC_LB_POLICY_REF(lb_policy, "pick");
+            gpr_mu_unlock(&chand->mu_config);
+            calld->state = CALL_WAITING_FOR_PICK;
+            gpr_mu_unlock(&calld->mu_state);
+
+            pick_target(lb_policy, calld);
+
+            GRPC_LB_POLICY_UNREF(lb_policy, "pick");
+          } else {
+            calld->state = CALL_WAITING_FOR_CONFIG;
+            add_to_lb_policy_wait_queue_locked_state_config(elem);
+            gpr_mu_unlock(&chand->mu_config);
+            gpr_mu_unlock(&calld->mu_state);
+          }
         }
       }
       break;
   }
+
+  if (consumed_op != NULL) {
+    consumed_op->cb(consumed_op->cb_arg, 1);
+  }
 }
 
 static void cc_start_transport_stream_op(grpc_call_element *elem,
@@ -503,6 +534,7 @@ static void destroy_call_elem(grpc_call_element *elem) {
     case CALL_WAITING_FOR_PICK:
     case CALL_WAITING_FOR_CONFIG:
     case CALL_WAITING_FOR_CALL:
+    case CALL_WAITING_FOR_SEND:
       gpr_log(GPR_ERROR, "should never reach here");
       abort();
       break;

src/core/httpcli/httpcli.c

@@ -198,7 +198,7 @@ static void on_connected(void *arg, grpc_endpoint *tcp) {
                GRPC_SECURITY_OK);
     grpc_setup_secure_transport(&sc->base, tcp, on_secure_transport_setup_done,
                                 req);
-    grpc_security_connector_unref(&sc->base);
+    GRPC_SECURITY_CONNECTOR_UNREF(&sc->base, "httpcli");
   } else {
     start_write(req);
   }

src/core/security/client_auth_filter.c

@@ -297,7 +297,7 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
   /* initialize members */
   GPR_ASSERT(sc->is_client_side);
   chand->security_connector =
-      (grpc_channel_security_connector *)grpc_security_connector_ref(sc);
+      (grpc_channel_security_connector *)GRPC_SECURITY_CONNECTOR_REF(sc, "client_auth_filter");
   chand->md_ctx = metadata_context;
   chand->authority_string = grpc_mdstr_from_string(chand->md_ctx, ":authority");
   chand->path_string = grpc_mdstr_from_string(chand->md_ctx, ":path");
@@ -310,7 +310,7 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
   grpc_channel_security_connector *ctx = chand->security_connector;
-  if (ctx != NULL) grpc_security_connector_unref(&ctx->base);
+  if (ctx != NULL) GRPC_SECURITY_CONNECTOR_UNREF(&ctx->base, "client_auth_filter");
   if (chand->authority_string != NULL) {
     grpc_mdstr_unref(chand->authority_string);
   }

src/core/security/secure_transport_setup.c

@@ -74,7 +74,7 @@ static void secure_transport_setup_done(grpc_secure_transport_setup *s,
   if (s->handshaker != NULL) tsi_handshaker_destroy(s->handshaker);
   if (s->handshake_buffer != NULL) gpr_free(s->handshake_buffer);
   gpr_slice_buffer_destroy(&s->left_overs);
-  grpc_security_connector_unref(s->connector);
+  GRPC_SECURITY_CONNECTOR_UNREF(s->connector, "secure_transport_setup");
   gpr_free(s);
 }
 
@@ -275,7 +275,7 @@ void grpc_setup_secure_transport(grpc_security_connector *connector,
     secure_transport_setup_done(s, 0);
     return;
   }
-  s->connector = grpc_security_connector_ref(connector);
+  s->connector = GRPC_SECURITY_CONNECTOR_REF(connector, "secure_transport_setup");
   s->handshake_buffer_size = GRPC_INITIAL_HANDSHAKE_BUFFER_SIZE;
   s->handshake_buffer = gpr_malloc(s->handshake_buffer_size);
   s->endpoint = nonsecure_endpoint;

src/core/security/security_connector.c

@@ -124,24 +124,42 @@ grpc_security_status grpc_channel_security_connector_check_call_host(
   return sc->check_call_host(sc, host, cb, user_data);
 }
 
-void grpc_security_connector_unref(grpc_security_connector *sc) {
-  if (sc == NULL) return;
-  if (gpr_unref(&sc->refcount)) sc->vtable->destroy(sc);
-}
-
-grpc_security_connector *grpc_security_connector_ref(
-    grpc_security_connector *sc) {
+#ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
+grpc_security_connector *grpc_security_connector_ref(grpc_security_connector *sc,
+                                         const char *file, int line,
+                                         const char *reason) {
+  if (sc == NULL) return NULL;
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
+          "SECURITY_CONNECTOR:%p   ref %d -> %d %s", sc, (int)sc->refcount.count,
+          (int)sc->refcount.count + 1, reason);
+#else
+grpc_security_connector *grpc_security_connector_ref(grpc_security_connector *sc) {
   if (sc == NULL) return NULL;
+#endif
   gpr_ref(&sc->refcount);
   return sc;
 }
 
+#ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
+void grpc_security_connector_unref(grpc_security_connector *sc, const char *file, int line,
+                             const char *reason) {
+  if (sc == NULL) return;
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
+          "SECURITY_CONNECTOR:%p unref %d -> %d %s", sc, (int)sc->refcount.count,
+          (int)sc->refcount.count - 1, reason);
+#else
+void grpc_security_connector_unref(grpc_security_connector *sc) {
+  if (sc == NULL) return;
+#endif
+  if (gpr_unref(&sc->refcount)) sc->vtable->destroy(sc);
+}
+
 static void connector_pointer_arg_destroy(void *p) {
-  grpc_security_connector_unref(p);
+  GRPC_SECURITY_CONNECTOR_UNREF(p, "connector_pointer_arg");
 }
 
 static void *connector_pointer_arg_copy(void *p) {
-  return grpc_security_connector_ref(p);
+  return GRPC_SECURITY_CONNECTOR_REF(p, "connector_pointer_arg");
 }
 
 grpc_arg grpc_security_connector_to_arg(grpc_security_connector *sc) {

src/core/security/security_connector.h

@@ -80,12 +80,23 @@ struct grpc_security_connector {
   grpc_auth_context *auth_context; /* Populated after the peer is checked. */
 };
 
-/* Increments the refcount. */
-grpc_security_connector *grpc_security_connector_ref(
-    grpc_security_connector *sc);
-
-/* Decrements the refcount and destroys the object if it reaches 0. */
-void grpc_security_connector_unref(grpc_security_connector *sc);
+/* Refcounting. */
+#ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
+#define GRPC_SECURITY_CONNECTOR_REF(p, r) \
+  grpc_security_connector_ref((p), __FILE__, __LINE__, (r))
+#define GRPC_SECURITY_CONNECTOR_UNREF(p, r) \
+  grpc_security_connector_unref((p), __FILE__, __LINE__, (r))
+grpc_security_connector *grpc_security_connector_ref(grpc_security_connector *policy,
+                                         const char *file, int line,
+                                         const char *reason);
+void grpc_security_connector_unref(grpc_security_connector *policy, const char *file,
+                             int line, const char *reason);
+#else
+#define GRPC_SECURITY_CONNECTOR_REF(p, r) grpc_security_connector_ref((p))
+#define GRPC_SECURITY_CONNECTOR_UNREF(p, r) grpc_security_connector_unref((p))
+grpc_security_connector *grpc_security_connector_ref(grpc_security_connector *policy);
+void grpc_security_connector_unref(grpc_security_connector *policy);
+#endif
 
 /* Handshake creation. */
 grpc_security_status grpc_security_connector_create_handshaker(

src/core/security/server_auth_filter.c

@@ -107,14 +107,14 @@ static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
 
   /* initialize members */
   GPR_ASSERT(!sc->is_client_side);
-  chand->security_connector = grpc_security_connector_ref(sc);
+  chand->security_connector = GRPC_SECURITY_CONNECTOR_REF(sc, "server_auth_filter");
 }
 
 /* Destructor for channel data */
 static void destroy_channel_elem(grpc_channel_element *elem) {
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
-  grpc_security_connector_unref(chand->security_connector);
+  GRPC_SECURITY_CONNECTOR_UNREF(chand->security_connector, "server_auth_filter");
 }
 
 const grpc_channel_filter grpc_server_auth_filter = {

src/core/security/server_secure_chttp2.c

@@ -70,7 +70,7 @@ static void state_unref(grpc_server_secure_state *state) {
     gpr_mu_lock(&state->mu);
     gpr_mu_unlock(&state->mu);
     /* clean up */
-    grpc_security_connector_unref(state->sc);
+    GRPC_SECURITY_CONNECTOR_UNREF(state->sc, "server");
     gpr_free(state);
   }
 }
@@ -220,7 +220,7 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
 /* Error path: cleanup and return */
 error:
   if (sc) {
-    grpc_security_connector_unref(sc);
+    GRPC_SECURITY_CONNECTOR_UNREF(sc, "server");
   }
   if (resolved) {
     grpc_resolved_addresses_destroy(resolved);

src/core/surface/secure_channel_create.c

@@ -142,6 +142,7 @@ static void subchannel_factory_ref(grpc_subchannel_factory *scf) {
 static void subchannel_factory_unref(grpc_subchannel_factory *scf) {
   subchannel_factory *f = (subchannel_factory *)scf;
   if (gpr_unref(&f->refs)) {
+    GRPC_SECURITY_CONNECTOR_UNREF(&f->security_connector->base, "subchannel_factory");
     grpc_channel_args_destroy(f->merge_args);
     grpc_mdctx_unref(f->mdctx);
     gpr_free(f);
@@ -218,6 +219,7 @@ grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
   gpr_ref_init(&f->refs, 1);
   grpc_mdctx_ref(mdctx);
   f->mdctx = mdctx;
+  GRPC_SECURITY_CONNECTOR_REF(&connector->base, "subchannel_factory");
   f->security_connector = connector;
   f->merge_args = grpc_channel_args_copy(args_copy);
   resolver = grpc_resolver_create(target, &f->base);
@@ -229,6 +231,8 @@ grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
   grpc_client_channel_set_resolver(grpc_channel_get_channel_stack(channel),
                                    resolver);
   GRPC_RESOLVER_UNREF(resolver, "create");
+  grpc_subchannel_factory_unref(&f->base);
+  GRPC_SECURITY_CONNECTOR_UNREF(&connector->base, "channel_create");
 
   grpc_channel_args_destroy(args_copy);
   if (new_args_from_connector != NULL) {