Merge pull request grpc#7024 from markdroth/filter_call_init_failure

Extend filter API to allow call initialization to return an error.

Makefile

@@ -6518,6 +6518,7 @@ LIBEND2END_TESTS_SRC = \
     test/core/end2end/tests/default_host.c \
     test/core/end2end/tests/disappearing_server.c \
     test/core/end2end/tests/empty_batch.c \
+    test/core/end2end/tests/filter_call_init_fails.c \
     test/core/end2end/tests/filter_causes_close.c \
     test/core/end2end/tests/graceful_server_shutdown.c \
     test/core/end2end/tests/high_initial_seqno.c \
@@ -6597,6 +6598,7 @@ LIBEND2END_NOSEC_TESTS_SRC = \
     test/core/end2end/tests/default_host.c \
     test/core/end2end/tests/disappearing_server.c \
     test/core/end2end/tests/empty_batch.c \
+    test/core/end2end/tests/filter_call_init_fails.c \
     test/core/end2end/tests/filter_causes_close.c \
     test/core/end2end/tests/graceful_server_shutdown.c \
     test/core/end2end/tests/high_initial_seqno.c \

src/core/ext/census/grpc_filter.c

@@ -127,13 +127,14 @@ static void server_start_transport_op(grpc_exec_ctx *exec_ctx,
   grpc_call_next_op(exec_ctx, elem, op);
 }
 
-static void client_init_call_elem(grpc_exec_ctx *exec_ctx,
-                                  grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+static grpc_error *client_init_call_elem(grpc_exec_ctx *exec_ctx,
+                                         grpc_call_element *elem,
+                                         grpc_call_element_args *args) {
   call_data *d = elem->call_data;
   GPR_ASSERT(d != NULL);
   memset(d, 0, sizeof(*d));
   d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
+  return GRPC_ERROR_NONE;
 }
 
 static void client_destroy_call_elem(grpc_exec_ctx *exec_ctx,
@@ -145,15 +146,16 @@ static void client_destroy_call_elem(grpc_exec_ctx *exec_ctx,
   /* TODO(hongyu): record rpc client stats and census_rpc_end_op here */
 }
 
-static void server_init_call_elem(grpc_exec_ctx *exec_ctx,
-                                  grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+static grpc_error *server_init_call_elem(grpc_exec_ctx *exec_ctx,
+                                         grpc_call_element *elem,
+                                         grpc_call_element_args *args) {
   call_data *d = elem->call_data;
   GPR_ASSERT(d != NULL);
   memset(d, 0, sizeof(*d));
   d->start_ts = gpr_now(GPR_CLOCK_REALTIME);
   /* TODO(hongyu): call census_tracing_start_op here. */
   grpc_closure_init(&d->finish_recv, server_on_done_recv, elem);
+  return GRPC_ERROR_NONE;
 }
 
 static void server_destroy_call_elem(grpc_exec_ctx *exec_ctx,

src/core/ext/client_config/client_channel.c

@@ -436,10 +436,12 @@ static int cc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *elemp,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   grpc_subchannel_call_holder_init(elem->call_data, cc_pick_subchannel, elem,
                                    args->call_stack);
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for call_data */

src/core/ext/client_config/subchannel.c

@@ -702,19 +702,26 @@ grpc_connected_subchannel *grpc_subchannel_get_connected_subchannel(
   return GET_CONNECTED_SUBCHANNEL(c, acq);
 }
 
-grpc_subchannel_call *grpc_connected_subchannel_create_call(
+grpc_error *grpc_connected_subchannel_create_call(
     grpc_exec_ctx *exec_ctx, grpc_connected_subchannel *con,
-    grpc_polling_entity *pollent) {
+    grpc_polling_entity *pollent, grpc_subchannel_call **call) {
   grpc_channel_stack *chanstk = CHANNEL_STACK_FROM_CONNECTION(con);
-  grpc_subchannel_call *call =
-      gpr_malloc(sizeof(grpc_subchannel_call) + chanstk->call_stack_size);
-  grpc_call_stack *callstk = SUBCHANNEL_CALL_TO_CALL_STACK(call);
-  call->connection = con;
+  *call = gpr_malloc(sizeof(grpc_subchannel_call) + chanstk->call_stack_size);
+  grpc_call_stack *callstk = SUBCHANNEL_CALL_TO_CALL_STACK(*call);
+  (*call)->connection = con;  // Ref is added below.
+  grpc_error *error =
+      grpc_call_stack_init(exec_ctx, chanstk, 1, subchannel_call_destroy, *call,
+                           NULL, NULL, callstk);
+  if (error != GRPC_ERROR_NONE) {
+    const char *error_string = grpc_error_string(error);
+    gpr_log(GPR_ERROR, "error: %s", error_string);
+    grpc_error_free_string(error_string);
+    gpr_free(*call);
+    return error;
+  }
   GRPC_CONNECTED_SUBCHANNEL_REF(con, "subchannel_call");
-  grpc_call_stack_init(exec_ctx, chanstk, 1, subchannel_call_destroy, call,
-                       NULL, NULL, callstk);
   grpc_call_stack_set_pollset_or_pollset_set(exec_ctx, callstk, pollent);
-  return call;
+  return GRPC_ERROR_NONE;
 }
 
 grpc_call_stack *grpc_subchannel_call_get_call_stack(

src/core/ext/client_config/subchannel.h

@@ -108,9 +108,9 @@ void grpc_subchannel_call_unref(grpc_exec_ctx *exec_ctx,
                                     GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
 
 /** construct a subchannel call */
-grpc_subchannel_call *grpc_connected_subchannel_create_call(
+grpc_error *grpc_connected_subchannel_create_call(
     grpc_exec_ctx *exec_ctx, grpc_connected_subchannel *connected_subchannel,
-    grpc_polling_entity *pollent);
+    grpc_polling_entity *pollent, grpc_subchannel_call **subchannel_call);
 
 /** process a transport level op */
 void grpc_connected_subchannel_process_transport_op(

src/core/ext/client_config/subchannel_call_holder.c

@@ -84,6 +84,11 @@ void grpc_subchannel_call_holder_destroy(grpc_exec_ctx *exec_ctx,
   gpr_free(holder->waiting_ops);
 }
 
+// The logic here is fairly complicated, due to (a) the fact that we
+// need to handle the case where we receive the send op before the
+// initial metadata op, and (b) the need for efficiency, especially in
+// the streaming case.
+// TODO(ctiller): Explain this more thoroughly.
 void grpc_subchannel_call_holder_perform_op(grpc_exec_ctx *exec_ctx,
                                             grpc_subchannel_call_holder *holder,
                                             grpc_transport_stream_op *op) {
@@ -121,7 +126,8 @@ void grpc_subchannel_call_holder_perform_op(grpc_exec_ctx *exec_ctx,
   }
   /* if this is a cancellation, then we can raise our cancelled flag */
   if (op->cancel_error != GRPC_ERROR_NONE) {
-    if (!gpr_atm_rel_cas(&holder->subchannel_call, 0, 1)) {
+    if (!gpr_atm_rel_cas(&holder->subchannel_call, 0,
+                         (gpr_atm)(uintptr_t)CANCELLED_CALL)) {
       goto retry;
     } else {
       switch (holder->creation_phase) {
@@ -158,10 +164,17 @@ void grpc_subchannel_call_holder_perform_op(grpc_exec_ctx *exec_ctx,
   /* if we've got a subchannel, then let's ask it to create a call */
   if (holder->creation_phase == GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING &&
       holder->connected_subchannel != NULL) {
-    gpr_atm_rel_store(
-        &holder->subchannel_call,
-        (gpr_atm)(uintptr_t)grpc_connected_subchannel_create_call(
-            exec_ctx, holder->connected_subchannel, holder->pollent));
+    grpc_subchannel_call *subchannel_call = NULL;
+    grpc_error *error = grpc_connected_subchannel_create_call(
+        exec_ctx, holder->connected_subchannel, holder->pollent,
+        &subchannel_call);
+    if (error != GRPC_ERROR_NONE) {
+      subchannel_call = CANCELLED_CALL;
+      fail_locked(exec_ctx, holder, GRPC_ERROR_REF(error));
+      grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
+    }
+    gpr_atm_rel_store(&holder->subchannel_call,
+                      (gpr_atm)(uintptr_t)subchannel_call);
     retry_waiting_locked(exec_ctx, holder);
     goto retry;
   }
@@ -189,10 +202,17 @@ static void subchannel_ready(grpc_exec_ctx *exec_ctx, void *arg,
                 GRPC_ERROR_CREATE_REFERENCING(
                     "Cancelled before creating subchannel", &error, 1));
   } else {
-    gpr_atm_rel_store(
-        &holder->subchannel_call,
-        (gpr_atm)(uintptr_t)grpc_connected_subchannel_create_call(
-            exec_ctx, holder->connected_subchannel, holder->pollent));
+    grpc_subchannel_call *subchannel_call = NULL;
+    grpc_error *new_error = grpc_connected_subchannel_create_call(
+        exec_ctx, holder->connected_subchannel, holder->pollent,
+        &subchannel_call);
+    if (new_error != GRPC_ERROR_NONE) {
+      new_error = grpc_error_add_child(new_error, error);
+      subchannel_call = CANCELLED_CALL;
+      fail_locked(exec_ctx, holder, new_error);
+    }
+    gpr_atm_rel_store(&holder->subchannel_call,
+                      (gpr_atm)(uintptr_t)subchannel_call);
     retry_waiting_locked(exec_ctx, holder);
   }
   gpr_mu_unlock(&holder->mu);

src/core/ext/load_reporting/load_reporting_filter.c

@@ -107,8 +107,9 @@ static void on_initial_md_ready(grpc_exec_ctx *exec_ctx, void *user_data,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   memset(calld, 0, sizeof(call_data));
 
@@ -125,6 +126,8 @@ static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                                                 NULL,
                                                 NULL};
   */
+
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for call_data */

src/core/lib/channel/channel_stack.c

@@ -157,12 +157,13 @@ void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,
   }
 }
 
-void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
-                          grpc_channel_stack *channel_stack, int initial_refs,
-                          grpc_iomgr_cb_func destroy, void *destroy_arg,
-                          grpc_call_context_element *context,
-                          const void *transport_server_data,
-                          grpc_call_stack *call_stack) {
+grpc_error *grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
+                                 grpc_channel_stack *channel_stack,
+                                 int initial_refs, grpc_iomgr_cb_func destroy,
+                                 void *destroy_arg,
+                                 grpc_call_context_element *context,
+                                 const void *transport_server_data,
+                                 grpc_call_stack *call_stack) {
   grpc_channel_element *channel_elems = CHANNEL_ELEMS_FROM_STACK(channel_stack);
   grpc_call_element_args args;
   size_t count = channel_stack->count;
@@ -178,17 +179,27 @@ void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
               ROUND_UP_TO_ALIGNMENT_SIZE(count * sizeof(grpc_call_element));
 
   /* init per-filter data */
+  grpc_error *first_error = GRPC_ERROR_NONE;
   for (i = 0; i < count; i++) {
     args.call_stack = call_stack;
     args.server_transport_data = transport_server_data;
     args.context = context;
     call_elems[i].filter = channel_elems[i].filter;
     call_elems[i].channel_data = channel_elems[i].channel_data;
     call_elems[i].call_data = user_data;
-    call_elems[i].filter->init_call_elem(exec_ctx, &call_elems[i], &args);
+    grpc_error *error =
+        call_elems[i].filter->init_call_elem(exec_ctx, &call_elems[i], &args);
+    if (error != GRPC_ERROR_NONE) {
+      if (first_error == GRPC_ERROR_NONE) {
+        first_error = error;
+      } else {
+        GRPC_ERROR_UNREF(error);
+      }
+    }
     user_data +=
         ROUND_UP_TO_ALIGNMENT_SIZE(call_elems[i].filter->sizeof_call_data);
   }
+  return first_error;
 }
 
 void grpc_call_stack_set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,

src/core/lib/channel/channel_stack.h

@@ -115,8 +115,9 @@ typedef struct {
      on a client; if it is non-NULL, then it points to memory owned by the
      transport and is on the server. Most filters want to ignore this
      argument. */
-  void (*init_call_elem)(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                         grpc_call_element_args *args);
+  grpc_error *(*init_call_elem)(grpc_exec_ctx *exec_ctx,
+                                grpc_call_element *elem,
+                                grpc_call_element_args *args);
   void (*set_pollset_or_pollset_set)(grpc_exec_ctx *exec_ctx,
                                      grpc_call_element *elem,
                                      grpc_polling_entity *pollent);
@@ -215,12 +216,13 @@ void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,
 /* Initialize a call stack given a channel stack. transport_server_data is
    expected to be NULL on a client, or an opaque transport owned pointer on the
    server. */
-void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
-                          grpc_channel_stack *channel_stack, int initial_refs,
-                          grpc_iomgr_cb_func destroy, void *destroy_arg,
-                          grpc_call_context_element *context,
-                          const void *transport_server_data,
-                          grpc_call_stack *call_stack);
+grpc_error *grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
+                                 grpc_channel_stack *channel_stack,
+                                 int initial_refs, grpc_iomgr_cb_func destroy,
+                                 void *destroy_arg,
+                                 grpc_call_context_element *context,
+                                 const void *transport_server_data,
+                                 grpc_call_stack *call_stack);
 /* Set a pollset or a pollset_set for a call stack: must occur before the first
  * op is started */
 void grpc_call_stack_set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,

src/core/lib/channel/compress_filter.c

@@ -256,8 +256,9 @@ static void compress_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
 
@@ -266,6 +267,8 @@ static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   calld->has_compression_algorithm = 0;
   grpc_closure_init(&calld->got_slice, got_slice, elem);
   grpc_closure_init(&calld->send_done, send_done, elem);
+
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for call_data */

src/core/lib/channel/connected_channel.c

@@ -81,16 +81,16 @@ static void con_start_transport_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
-  int r;
-
-  r = grpc_transport_init_stream(
+  int r = grpc_transport_init_stream(
       exec_ctx, chand->transport, TRANSPORT_STREAM_FROM_CALL_DATA(calld),
       &args->call_stack->refcount, args->server_transport_data);
-  GPR_ASSERT(r == 0);
+  return r == 0 ? GRPC_ERROR_NONE
+                : GRPC_ERROR_CREATE("transport stream initialization failed");
 }
 
 static void set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,

src/core/lib/channel/http_client_filter.c

@@ -175,11 +175,13 @@ static void hc_start_transport_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   calld->on_done_recv = NULL;
   grpc_closure_init(&calld->hc_on_recv, hc_on_recv, elem);
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for call_data */

src/core/lib/channel/http_server_filter.c

@@ -224,13 +224,15 @@ static void hs_start_transport_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   /* initialize members */
   memset(calld, 0, sizeof(*calld));
   grpc_closure_init(&calld->hs_on_recv, hs_on_recv, elem);
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for call_data */

src/core/lib/iomgr/error.h

@@ -171,6 +171,8 @@ grpc_error *grpc_error_set_time(grpc_error *src, grpc_error_times which,
                                 gpr_timespec value) GRPC_MUST_USE_RESULT;
 grpc_error *grpc_error_set_str(grpc_error *src, grpc_error_strs which,
                                const char *value) GRPC_MUST_USE_RESULT;
+/// Returns NULL if the specified string is not set.
+/// Caller does NOT own return value.
 const char *grpc_error_get_str(grpc_error *error, grpc_error_strs which);
 /// Add a child error: an error that is believed to have contributed to this
 /// error occurring. Allows root causing high level errors from lower level

src/core/lib/security/transport/client_auth_filter.c

@@ -267,10 +267,12 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   memset(calld, 0, sizeof(*calld));
+  return GRPC_ERROR_NONE;
 }
 
 static void set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,