Set user data vtable when creating grpc_lb_addresses.

src/core/ext/client_config/lb_policy_factory.c

@@ -38,19 +38,20 @@
 
 #include "src/core/ext/client_config/lb_policy_factory.h"
 
-grpc_lb_addresses* grpc_lb_addresses_create(size_t num_addresses) {
+grpc_lb_addresses* grpc_lb_addresses_create(
+    size_t num_addresses, const grpc_lb_user_data_vtable* user_data_vtable) {
   grpc_lb_addresses* addresses = gpr_malloc(sizeof(grpc_lb_addresses));
   addresses->num_addresses = num_addresses;
+  addresses->user_data_vtable = user_data_vtable;
   const size_t addresses_size = sizeof(grpc_lb_address) * num_addresses;
   addresses->addresses = gpr_malloc(addresses_size);
   memset(addresses->addresses, 0, addresses_size);
   return addresses;
 }
 
-grpc_lb_addresses* grpc_lb_addresses_copy(grpc_lb_addresses* addresses,
-                                          void* (*user_data_copy)(void*)) {
-  grpc_lb_addresses* new_addresses =
-      grpc_lb_addresses_create(addresses->num_addresses);
+grpc_lb_addresses* grpc_lb_addresses_copy(const grpc_lb_addresses* addresses) {
+  grpc_lb_addresses* new_addresses = grpc_lb_addresses_create(
+      addresses->num_addresses, addresses->user_data_vtable);
   memcpy(new_addresses->addresses, addresses->addresses,
          sizeof(grpc_lb_address) * addresses->num_addresses);
   for (size_t i = 0; i < addresses->num_addresses; ++i) {
@@ -58,9 +59,10 @@ grpc_lb_addresses* grpc_lb_addresses_copy(grpc_lb_addresses* addresses,
       new_addresses->addresses[i].balancer_name =
           gpr_strdup(new_addresses->addresses[i].balancer_name);
     }
-    if (user_data_copy != NULL) {
+    if (new_addresses->addresses[i].user_data != NULL) {
       new_addresses->addresses[i].user_data =
-          user_data_copy(new_addresses->addresses[i].user_data);
+          addresses->user_data_vtable->copy(
+              new_addresses->addresses[i].user_data);
     }
   }
   return new_addresses;
@@ -71,6 +73,7 @@ void grpc_lb_addresses_set_address(grpc_lb_addresses* addresses, size_t index,
                                    bool is_balancer, char* balancer_name,
                                    void* user_data) {
   GPR_ASSERT(index < addresses->num_addresses);
+  if (user_data != NULL) GPR_ASSERT(addresses->user_data_vtable != NULL);
   grpc_lb_address* target = &addresses->addresses[index];
   memcpy(target->address.addr, address, address_len);
   target->address.len = address_len;
@@ -79,12 +82,42 @@ void grpc_lb_addresses_set_address(grpc_lb_addresses* addresses, size_t index,
   target->user_data = user_data;
 }
 
-void grpc_lb_addresses_destroy(grpc_lb_addresses* addresses,
-                               void (*user_data_destroy)(void*)) {
+int grpc_lb_addresses_cmp(const grpc_lb_addresses* addresses1,
+                          const grpc_lb_addresses* addresses2) {
+  if (addresses1->num_addresses > addresses2->num_addresses) return 1;
+  if (addresses1->num_addresses < addresses2->num_addresses) return -1;
+  if (addresses1->user_data_vtable > addresses2->user_data_vtable) return 1;
+  if (addresses1->user_data_vtable < addresses2->user_data_vtable) return -1;
+  for (size_t i = 0; i < addresses1->num_addresses; ++i) {
+    const grpc_lb_address* target1 = &addresses1->addresses[i];
+    const grpc_lb_address* target2 = &addresses2->addresses[i];
+    if (target1->address.len > target2->address.len) return 1;
+    if (target1->address.len < target2->address.len) return -1;
+    int retval = memcmp(
+        target1->address.addr, target2->address.addr, target1->address.len);
+    if (retval != 0) return retval;
+    if (target1->is_balancer > target2->is_balancer) return 1;
+    if (target1->is_balancer < target2->is_balancer) return -1;
+    const char* balancer_name1 = target1->balancer_name != NULL
+                                     ? target1->balancer_name : "";
+    const char* balancer_name2 = target2->balancer_name != NULL
+                                     ? target2->balancer_name : "";
+    retval = strcmp(balancer_name1, balancer_name2);
+    if (retval != 0) return retval;
+    if (addresses1->user_data_vtable != NULL) {
+      retval = addresses1->user_data_vtable->cmp(target1->user_data,
+                                                 target2->user_data);
+      if (retval != 0) return retval;
+    }
+  }
+  return 0;
+}
+
+void grpc_lb_addresses_destroy(grpc_lb_addresses* addresses) {
   for (size_t i = 0; i < addresses->num_addresses; ++i) {
     gpr_free(addresses->addresses[i].balancer_name);
-    if (user_data_destroy != NULL) {
-      user_data_destroy(addresses->addresses[i].user_data);
+    if (addresses->addresses[i].user_data != NULL) {
+      addresses->user_data_vtable->destroy(addresses->addresses[i].user_data);
     }
   }
   gpr_free(addresses->addresses);

src/core/ext/client_config/lb_policy_factory.h

@@ -59,19 +59,27 @@ typedef struct grpc_lb_address {
   void *user_data;
 } grpc_lb_address;
 
+typedef struct grpc_lb_user_data_vtable {
+  void* (*copy)(void*);
+  void (*destroy)(void*);
+  int (*cmp)(void*, void*);
+} grpc_lb_user_data_vtable;
+
 typedef struct grpc_lb_addresses {
   size_t num_addresses;
   grpc_lb_address *addresses;
+  const grpc_lb_user_data_vtable *user_data_vtable;
 } grpc_lb_addresses;
 
 /** Returns a grpc_addresses struct with enough space for
- * \a num_addresses addresses. */
-grpc_lb_addresses *grpc_lb_addresses_create(size_t num_addresses);
+    \a num_addresses addresses.  The \a user_data_vtable argument may be
+    NULL if no user data will be added. */
+grpc_lb_addresses *grpc_lb_addresses_create(
+    size_t num_addresses, const grpc_lb_user_data_vtable* user_data_vtable);
 
 /** Creates a copy of \a addresses.  If \a user_data_copy is not NULL,
  * it will be invoked to copy the \a user_data field of each address. */
-grpc_lb_addresses *grpc_lb_addresses_copy(grpc_lb_addresses *addresses,
-                                          void *(*user_data_copy)(void *));
+grpc_lb_addresses *grpc_lb_addresses_copy(const grpc_lb_addresses *addresses);
 
 /** Sets the value of the address at index \a index of \a addresses.
  * \a address is a socket address of length \a address_len.
@@ -81,10 +89,13 @@ void grpc_lb_addresses_set_address(grpc_lb_addresses *addresses, size_t index,
                                    bool is_balancer, char *balancer_name,
                                    void *user_data);
 
+/** Compares \a addresses1 and \a addresses2. */
+int grpc_lb_addresses_cmp(const grpc_lb_addresses *addresses1,
+                          const grpc_lb_addresses *addresses2);
+
 /** Destroys \a addresses.  If \a user_data_destroy is not NULL, it will
  * be invoked to destroy the \a user_data field of each address. */
-void grpc_lb_addresses_destroy(grpc_lb_addresses *addresses,
-                               void (*user_data_destroy)(void *));
+void grpc_lb_addresses_destroy(grpc_lb_addresses *addresses);
 
 /** Arguments passed to LB policies. */
 /* TODO(roth, ctiller): Consider replacing this struct with

src/core/ext/client_config/resolver_result.c

@@ -67,7 +67,7 @@ void grpc_resolver_result_unref(grpc_exec_ctx* exec_ctx,
                                 grpc_resolver_result* result) {
   if (gpr_unref(&result->refs)) {
     gpr_free(result->server_name);
-    grpc_lb_addresses_destroy(result->addresses, NULL /* user_data_destroy */);
+    grpc_lb_addresses_destroy(result->addresses);
     gpr_free(result->lb_policy_name);
     grpc_channel_args_destroy(result->channel_args);
     gpr_free(result);

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

@@ -338,6 +338,21 @@ static bool is_server_valid(const grpc_grpclb_server *server, size_t idx,
   return true;
 }
 
+/* vtable for LB tokens in grpc_lb_addresses. */
+static void* lb_token_copy(void *token) {
+  return token == NULL ? NULL : GRPC_MDELEM_REF(token);
+}
+static void lb_token_destroy(void *token) {
+  if (token != NULL) GRPC_MDELEM_UNREF(token);
+}
+static int lb_token_cmp(void* token1, void* token2) {
+  if (token1 > token2) return 1;
+  if (token1 < token2) return -1;
+  return 0;
+}
+static const grpc_lb_user_data_vtable lb_token_vtable = {
+    lb_token_copy, lb_token_destroy, lb_token_cmp};
+
 /* Returns addresses extracted from \a serverlist. */
 static grpc_lb_addresses *process_serverlist(
     const grpc_grpclb_serverlist *serverlist) {
@@ -349,7 +364,8 @@ static grpc_lb_addresses *process_serverlist(
   }
   if (num_valid == 0) return NULL;
 
-  grpc_lb_addresses *lb_addresses = grpc_lb_addresses_create(num_valid);
+  grpc_lb_addresses *lb_addresses =
+      grpc_lb_addresses_create(num_valid, &lb_token_vtable);
 
   /* second pass: actually populate the addresses and LB tokens (aka user data
    * to the outside world) to be read by the RR policy during its creation.
@@ -410,11 +426,6 @@ static grpc_lb_addresses *process_serverlist(
   return lb_addresses;
 }
 
-/* A plugin for grpc_lb_addresses_destroy that unrefs the LB token metadata. */
-static void lb_token_destroy(void *token) {
-  if (token != NULL) GRPC_MDELEM_UNREF(token);
-}
-
 /* perform a pick over \a rr_policy. Given that a pick can return immediately
  * (ignoring its completion callback) we need to perform the cleanups this
  * callback would be otherwise resposible for */
@@ -465,7 +476,7 @@ static grpc_lb_policy *create_rr_locked(
 
   if (glb_policy->addresses != NULL) {
     /* dispose of the previous version */
-    grpc_lb_addresses_destroy(glb_policy->addresses, lb_token_destroy);
+    grpc_lb_addresses_destroy(glb_policy->addresses);
   }
   glb_policy->addresses = args.addresses;
 
@@ -662,7 +673,7 @@ static void glb_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
     grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
   }
   gpr_mu_destroy(&glb_policy->mu);
-  grpc_lb_addresses_destroy(glb_policy->addresses, lb_token_destroy);
+  grpc_lb_addresses_destroy(glb_policy->addresses);
   gpr_free(glb_policy);
 }
 

src/core/ext/resolver/dns/native/dns_resolver.c

@@ -170,8 +170,8 @@ static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
   GPR_ASSERT(r->resolving);
   r->resolving = false;
   if (r->addresses != NULL) {
-    grpc_lb_addresses *addresses =
-        grpc_lb_addresses_create(r->addresses->naddrs);
+    grpc_lb_addresses *addresses = grpc_lb_addresses_create(
+        r->addresses->naddrs, NULL /* user_data_vtable */);
     for (size_t i = 0; i < r->addresses->naddrs; ++i) {
       grpc_lb_addresses_set_address(
           addresses, i, &r->addresses->addrs[i].addr,

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

@@ -121,8 +121,7 @@ static void sockaddr_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
   if (r->next_completion != NULL && !r->published) {
     r->published = true;
     *r->target_result = grpc_resolver_result_create(
-        r->target_name,
-        grpc_lb_addresses_copy(r->addresses, NULL /* user_data_copy */),
+        r->target_name, grpc_lb_addresses_copy(r->addresses),
         NULL /* lb_policy_name */, grpc_channel_args_copy(r->channel_args));
     grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL);
     r->next_completion = NULL;
@@ -133,7 +132,7 @@ static void sockaddr_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
   sockaddr_resolver *r = (sockaddr_resolver *)gr;
   gpr_mu_destroy(&r->mu);
   gpr_free(r->target_name);
-  grpc_lb_addresses_destroy(r->addresses, NULL /* user_data_destroy */);
+  grpc_lb_addresses_destroy(r->addresses);
   grpc_channel_args_destroy(r->channel_args);
   gpr_free(r);
 }
@@ -178,7 +177,8 @@ static grpc_resolver *sockaddr_create(grpc_resolver_args *args,
   gpr_slice_buffer path_parts;
   gpr_slice_buffer_init(&path_parts);
   gpr_slice_split(path_slice, ",", &path_parts);
-  grpc_lb_addresses *addresses = grpc_lb_addresses_create(path_parts.count);
+  grpc_lb_addresses *addresses = grpc_lb_addresses_create(
+      path_parts.count, NULL /* user_data_vtable */);
   bool errors_found = false;
   for (size_t i = 0; i < addresses->num_addresses; i++) {
     grpc_uri ith_uri = *args->uri;
@@ -196,7 +196,7 @@ static grpc_resolver *sockaddr_create(grpc_resolver_args *args,
   gpr_slice_buffer_destroy(&path_parts);
   gpr_slice_unref(path_slice);
   if (errors_found) {
-    grpc_lb_addresses_destroy(addresses, NULL /* user_data_destroy */);
+    grpc_lb_addresses_destroy(addresses);
     return NULL;
   }
   /* Instantiate resolver. */

test/core/end2end/fake_resolver.c

@@ -78,7 +78,7 @@ static void fake_resolver_destroy(grpc_exec_ctx* exec_ctx, grpc_resolver* gr) {
   fake_resolver* r = (fake_resolver*)gr;
   gpr_mu_destroy(&r->mu);
   gpr_free(r->target_name);
-  grpc_lb_addresses_destroy(r->addresses, NULL /* user_data_destroy */);
+  grpc_lb_addresses_destroy(r->addresses);
   gpr_free(r->lb_policy_name);
   grpc_method_config_table_unref(r->method_config_table);
   gpr_free(r);
@@ -107,8 +107,7 @@ static void fake_resolver_maybe_finish_next_locked(grpc_exec_ctx* exec_ctx,
       lb_policy_args = grpc_channel_args_copy_and_add(NULL /* src */, &arg, 1);
     }
     *r->target_result = grpc_resolver_result_create(
-        r->target_name,
-        grpc_lb_addresses_copy(r->addresses, NULL /* user_data_copy */),
+        r->target_name, grpc_lb_addresses_copy(r->addresses),
         r->lb_policy_name, lb_policy_args);
     grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL);
     r->next_completion = NULL;
@@ -168,7 +167,8 @@ static grpc_resolver* fake_resolver_create(grpc_resolver_factory* factory,
   gpr_slice_buffer path_parts;
   gpr_slice_buffer_init(&path_parts);
   gpr_slice_split(path_slice, ",", &path_parts);
-  grpc_lb_addresses* addresses = grpc_lb_addresses_create(path_parts.count);
+  grpc_lb_addresses* addresses = grpc_lb_addresses_create(
+      path_parts.count, NULL /* user_data_vtable */);
   bool errors_found = false;
   for (size_t i = 0; i < addresses->num_addresses; i++) {
     grpc_uri ith_uri = *args->uri;
@@ -187,7 +187,7 @@ static grpc_resolver* fake_resolver_create(grpc_resolver_factory* factory,
   gpr_slice_buffer_destroy(&path_parts);
   gpr_slice_unref(path_slice);
   if (errors_found) {
-    grpc_lb_addresses_destroy(addresses, NULL /* user_data_destroy */);
+    grpc_lb_addresses_destroy(addresses);
     return NULL;
   }
   // Construct method config table.