Change LB policies to get their input from channel args.

1 files changed, 21 insertions, 10 deletions

diff --git a/src/core/ext/lb_policy/pick_first/pick_first.c b/src/core/ext/lb_policy/pick_first/pick_first.c
index 3683079cf4..d95f0310b6 100644
--- a/src/core/ext/lb_policy/pick_first/pick_first.c
+++ b/src/core/ext/lb_policy/pick_first/pick_first.c
@@ -34,7 +34,9 @@
 #include <string.h>
 
 #include <grpc/support/alloc.h>
+
 #include "src/core/ext/client_config/lb_policy_registry.h"
+#include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/transport/connectivity_state.h"
 
 typedef struct pending_pick {
@@ -432,14 +434,23 @@ static void pick_first_factory_unref(grpc_lb_policy_factory *factory) {}
 static grpc_lb_policy *create_pick_first(grpc_exec_ctx *exec_ctx,
                                          grpc_lb_policy_factory *factory,
                                          grpc_lb_policy_args *args) {
-  GPR_ASSERT(args->addresses != NULL);
   GPR_ASSERT(args->client_channel_factory != NULL);
 
+  /* Get server name. */
+  const grpc_arg* arg =
+      grpc_channel_args_find(args->args, GRPC_ARG_SERVER_NAME);
+  const char* server_name =
+      arg != NULL && arg->type == GRPC_ARG_STRING
+          ? arg->value.string : NULL;
+
   /* Find the number of backend addresses. We ignore balancer
    * addresses, since we don't know how to handle them. */
+  arg = grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
+  GPR_ASSERT(arg != NULL && arg->type == GRPC_ARG_POINTER);
+  grpc_lb_addresses* addresses = arg->value.pointer.p;
   size_t num_addrs = 0;
-  for (size_t i = 0; i < args->addresses->num_addresses; i++) {
-    if (!args->addresses->addresses[i].is_balancer) ++num_addrs;
+  for (size_t i = 0; i < addresses->num_addresses; i++) {
+    if (!addresses->addresses[i].is_balancer) ++num_addrs;
   }
   if (num_addrs == 0) return NULL;
 
@@ -450,22 +461,22 @@ static grpc_lb_policy *create_pick_first(grpc_exec_ctx *exec_ctx,
   memset(p->subchannels, 0, sizeof(*p->subchannels) * num_addrs);
   grpc_subchannel_args sc_args;
   size_t subchannel_idx = 0;
-  for (size_t i = 0; i < args->addresses->num_addresses; i++) {
+  for (size_t i = 0; i < addresses->num_addresses; i++) {
     /* Skip balancer addresses, since we only know how to handle backends. */
-    if (args->addresses->addresses[i].is_balancer) continue;
+    if (addresses->addresses[i].is_balancer) continue;
 
-    if (args->addresses->addresses[i].user_data != NULL) {
+    if (addresses->addresses[i].user_data != NULL) {
       gpr_log(GPR_ERROR,
               "This LB policy doesn't support user data. It will be ignored");
     }
 
     memset(&sc_args, 0, sizeof(grpc_subchannel_args));
     /* server_name will be copied as part of the subchannel creation. This makes
-     * the copying of args->server_name (a borrowed pointer) OK. */
-    sc_args.server_name = args->server_name;
+     * the copying of server_name (a borrowed pointer) OK. */
+    sc_args.server_name = server_name;
     sc_args.addr =
-        (struct sockaddr *)(&args->addresses->addresses[i].address.addr);
-    sc_args.addr_len = args->addresses->addresses[i].address.len;
+        (struct sockaddr *)(&addresses->addresses[i].address.addr);
+    sc_args.addr_len = addresses->addresses[i].address.len;
     sc_args.args = args->args;
 
     grpc_subchannel *subchannel = grpc_client_channel_factory_create_subchannel(