Add is_resolver bit to grpc_resolved_address.

src/core/ext/lb_policy/grpclb/grpclb.c

@@ -309,6 +309,11 @@ static grpc_lb_policy *create_rr(grpc_exec_ctx *exec_ctx,
     if (parse_ipv4(&uri, &sa, &sa_len)) { /* TODO(dgq): add support for ipv6 */
       memcpy(args.addresses->addrs[out_addrs_idx].addr, &sa, sa_len);
       args.addresses->addrs[out_addrs_idx].len = sa_len;
+      // These are, of course, actually balancer addresses.  However, we
+      // want the round_robin LB policy to treat them as normal backend
+      // addresses, since we don't need to talk to balancers in order to
+      // find the balancers themselves.
+      args.addresses->addrs[out_addrs_idx].is_balancer = false;
       ++out_addrs_idx;
     } else {
       gpr_log(GPR_ERROR, "Invalid LB service address '%s', ignoring.",
@@ -414,6 +419,20 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
 static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
                                   grpc_lb_policy_factory *factory,
                                   grpc_lb_policy_args *args) {
+  // Count the number of gRPC-LB addresses.  There must be at least one.
+  // TODO(roth): For now, we ignore non-balancer addresses, so there must be
+  // at least one balancer address.  In the future, we may change the
+  // behavior such that we fall back to using the non-balancer addresses
+  // if we cannot reach any balancers.  At that time, this should be
+  // changed to allow a list with no balancer addresses, since the
+  // resolver might fail to return a balancer address even when this is
+  // the right LB policy to use.
+  size_t num_grpclb_addrs = 0;
+  for (size_t i = 0; i < args->addresses->naddrs; ++i) {
+    if (args->addresses->addrs[i].is_balancer) ++num_grpclb_addrs;
+  }
+  if (num_grpclb_addrs == 0) return NULL;
+
   glb_lb_policy *glb_policy = gpr_malloc(sizeof(*glb_policy));
   memset(glb_policy, 0, sizeof(*glb_policy));
 
@@ -424,25 +443,25 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
    * Create a client channel over them to communicate with a LB service */
   glb_policy->cc_factory = args->client_channel_factory;
   GPR_ASSERT(glb_policy->cc_factory != NULL);
-  if (args->addresses->naddrs == 0) {
-    return NULL;
-  }
 
   /* construct a target from the args->addresses, in the form
    * ipvX://ip1:port1,ip2:port2,...
    * TODO(dgq): support mixed ip version */
-  char **addr_strs = gpr_malloc(sizeof(char *) * args->addresses->naddrs);
+  char **addr_strs = gpr_malloc(sizeof(char *) * num_grpclb_addrs);
   addr_strs[0] =
       grpc_sockaddr_to_uri((const struct sockaddr *)&args->addresses->addrs[0]);
+  size_t addr_index = 1;
   for (size_t i = 1; i < args->addresses->naddrs; i++) {
+    if (args->addresses->addrs[i].is_balancer) {
       GPR_ASSERT(grpc_sockaddr_to_string(
-                   &addr_strs[i],
+                     &addr_strs[addr_index++],
                      (const struct sockaddr *)&args->addresses->addrs[i],
                      true) == 0);
     }
+  }
   size_t uri_path_len;
   char *target_uri_str = gpr_strjoin_sep(
-      (const char **)addr_strs, args->addresses->naddrs, ",", &uri_path_len);
+      (const char **)addr_strs, num_grpclb_addrs, ",", &uri_path_len);
 
   /* will pick using pick_first */
   glb_policy->lb_channel = grpc_client_channel_factory_create_channel(
@@ -450,7 +469,7 @@ static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx,
       GRPC_CLIENT_CHANNEL_TYPE_LOAD_BALANCING, NULL);
 
   gpr_free(target_uri_str);
-  for (size_t i = 0; i < args->addresses->naddrs; i++) {
+  for (size_t i = 0; i < num_grpclb_addrs; i++) {
     gpr_free(addr_strs[i]);
   }
   gpr_free(addr_strs);

src/core/ext/lb_policy/pick_first/pick_first.c

@@ -443,17 +443,26 @@ static grpc_lb_policy *create_pick_first(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(args->addresses != NULL);
   GPR_ASSERT(args->client_channel_factory != NULL);
 
-  if (args->addresses->naddrs == 0) return NULL;
+  // Find the number of backend addresses.  We ignore balancer
+  // addresses, since we don't know how to handle them.
+  size_t num_addrs = 0;
+  for (size_t i = 0; i < args->addresses->naddrs; i++) {
+    if (!args->addresses->addrs[i].is_balancer) ++num_addrs;
+  }
+  if (num_addrs == 0) return NULL;
 
   pick_first_lb_policy *p = gpr_malloc(sizeof(*p));
   memset(p, 0, sizeof(*p));
 
   p->subchannels =
-      gpr_malloc(sizeof(grpc_subchannel *) * args->addresses->naddrs);
-  memset(p->subchannels, 0, sizeof(*p->subchannels) * args->addresses->naddrs);
+      gpr_malloc(sizeof(grpc_subchannel *) * num_addrs);
+  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->naddrs; i++) {
+    // Skip balancer addresses, since we only know how to handle backends.
+    if (args->addresses->addrs[i].is_balancer) continue;
+
     memset(&sc_args, 0, sizeof(grpc_subchannel_args));
     sc_args.addr = (struct sockaddr *)(args->addresses->addrs[i].addr);
     sc_args.addr_len = (size_t)args->addresses->addrs[i].len;

src/core/ext/lb_policy/round_robin/round_robin.c

@@ -571,16 +571,27 @@ static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
   GPR_ASSERT(args->addresses != NULL);
   GPR_ASSERT(args->client_channel_factory != NULL);
 
+  // Find the number of backend addresses.  We ignore balancer
+  // addresses, since we don't know how to handle them.
+  size_t num_addrs = 0;
+  for (size_t i = 0; i < args->addresses->naddrs; i++) {
+    if (!args->addresses->addrs[i].is_balancer) ++num_addrs;
+  }
+  if (num_addrs == 0) return NULL;
+
   round_robin_lb_policy *p = gpr_malloc(sizeof(*p));
   memset(p, 0, sizeof(*p));
 
   p->subchannels =
-      gpr_malloc(sizeof(*p->subchannels) * args->addresses->naddrs);
-  memset(p->subchannels, 0, sizeof(*p->subchannels) * args->addresses->naddrs);
+      gpr_malloc(sizeof(*p->subchannels) * num_addrs);
+  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->naddrs; i++) {
+    // Skip balancer addresses, since we only know how to handle backends.
+    if (args->addresses->addrs[i].is_balancer) continue;
+
     memset(&sc_args, 0, sizeof(grpc_subchannel_args));
     sc_args.addr = (struct sockaddr *)(args->addresses->addrs[i].addr);
     sc_args.addr_len = (size_t)args->addresses->addrs[i].len;

src/core/ext/resolver/sockaddr/sockaddr_resolver.c

@@ -63,7 +63,7 @@ typedef struct {
   /** mutex guarding the rest of the state */
   gpr_mu mu;
   /** have we published? */
-  int published;
+  bool published;
   /** pending next completion, or NULL */
   grpc_closure *next_completion;
   /** target result address for next completion */
@@ -102,7 +102,7 @@ static void sockaddr_channel_saw_error(grpc_exec_ctx *exec_ctx,
                                        grpc_resolver *resolver) {
   sockaddr_resolver *r = (sockaddr_resolver *)resolver;
   gpr_mu_lock(&r->mu);
-  r->published = 0;
+  r->published = false;
   sockaddr_maybe_finish_next_locked(exec_ctx, r);
   gpr_mu_unlock(&r->mu);
 }
@@ -131,7 +131,7 @@ static void sockaddr_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
         grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);
     grpc_resolver_result_set_lb_policy(result, lb_policy);
     GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "sockaddr");
-    r->published = 1;
+    r->published = true;
     *r->target_result = result;
     grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL);
     r->next_completion = NULL;
@@ -175,7 +175,7 @@ static void do_nothing(void *ignored) {}
 static grpc_resolver *sockaddr_create(
     grpc_resolver_args *args, const char *default_lb_policy_name,
     int parse(grpc_uri *uri, struct sockaddr_storage *dst, size_t *len)) {
-  int errors_found = 0; /* GPR_FALSE */
+  bool errors_found = false;
   sockaddr_resolver *r;
   gpr_slice path_slice;
   gpr_slice_buffer path_parts;
@@ -228,9 +228,10 @@ static grpc_resolver *sockaddr_create(
     if (!parse(&ith_uri,
                (struct sockaddr_storage *)(&r->addresses->addrs[i].addr),
                &r->addresses->addrs[i].len)) {
-      errors_found = 1; /* GPR_TRUE */
+      errors_found = true;
     }
     gpr_free(part_str);
+    r->addresses->addrs[i].is_balancer = lb_enabled;
     if (errors_found) break;
   }
 

src/core/lib/iomgr/resolve_address.h

@@ -34,6 +34,7 @@
 #ifndef GRPC_CORE_LIB_IOMGR_RESOLVE_ADDRESS_H
 #define GRPC_CORE_LIB_IOMGR_RESOLVE_ADDRESS_H
 
+#include <stdbool.h>
 #include <stddef.h>
 #include "src/core/lib/iomgr/exec_ctx.h"
 #include "src/core/lib/iomgr/iomgr.h"
@@ -43,6 +44,7 @@
 typedef struct {
   char addr[GRPC_MAX_SOCKADDR_SIZE];
   size_t len;
+  bool is_balancer;
 } grpc_resolved_address;
 
 typedef struct {

src/core/lib/iomgr/resolve_address_posix.c

@@ -132,6 +132,7 @@ static grpc_error *blocking_resolve_address_impl(
   for (resp = result; resp != NULL; resp = resp->ai_next) {
     memcpy(&(*addresses)->addrs[i].addr, resp->ai_addr, resp->ai_addrlen);
     (*addresses)->addrs[i].len = resp->ai_addrlen;
+    (*addresses)->addrs[i].is_balancer = false;
     i++;
   }
   err = GRPC_ERROR_NONE;

src/core/lib/iomgr/resolve_address_windows.c

@@ -118,6 +118,7 @@ static grpc_error *blocking_resolve_address_impl(
   for (resp = result; resp != NULL; resp = resp->ai_next) {
     memcpy(&(*addresses)->addrs[i].addr, resp->ai_addr, resp->ai_addrlen);
     (*addresses)->addrs[i].len = resp->ai_addrlen;
+    (*addresses)->addrs[i].is_balancer = false;
     i++;
   }
 

src/core/lib/iomgr/unix_sockets_posix.c

@@ -58,6 +58,7 @@ grpc_error *grpc_resolve_unix_domain_address(const char *name,
   un->sun_family = AF_UNIX;
   strcpy(un->sun_path, name);
   (*addrs)->addrs->len = strlen(un->sun_path) + sizeof(un->sun_family) + 1;
+  (*addrs)->addrs->is_balancer = false;
   return GRPC_ERROR_NONE;
 }