Convert method config to a struct for use in the fast path.

3 files changed, 66 insertions, 12 deletions

diff --git a/src/core/ext/client_config/client_channel.c b/src/core/ext/client_config/client_channel.c
index beaa9637c3..613e98922b 100644
--- a/src/core/ext/client_config/client_channel.c
+++ b/src/core/ext/client_config/client_channel.c
@@ -855,8 +855,7 @@ static void read_service_config(grpc_exec_ctx *exec_ctx, void *arg,
     // If the method config table was present, use it.
     if (method_config_table != NULL) {
       const grpc_method_config *method_config =
-          grpc_method_config_table_get_method_config(method_config_table,
-                                                     calld->path);
+          grpc_method_config_table_get(method_config_table, calld->path);
       if (method_config != NULL) {
         const gpr_timespec *per_method_timeout =
             grpc_method_config_get_timeout(method_config);
@@ -922,8 +921,7 @@ static grpc_error *cc_init_call_elem(grpc_exec_ctx *exec_ctx,
           grpc_method_config_table_ref(chand->method_config_table);
       gpr_mu_unlock(&chand->mu);
       grpc_method_config *method_config =
-          grpc_method_config_table_get_method_config(method_config_table,
-                                                     args->path);
+          grpc_method_config_table_get(method_config_table, args->path);
       if (method_config != NULL) {
         const gpr_timespec *per_method_timeout =
             grpc_method_config_get_timeout(method_config);
diff --git a/src/core/ext/client_config/method_config.c b/src/core/ext/client_config/method_config.c
index f8a82323e7..a42fe2bfd9 100644
--- a/src/core/ext/client_config/method_config.c
+++ b/src/core/ext/client_config/method_config.c
@@ -254,12 +254,12 @@ int grpc_method_config_table_cmp(const grpc_method_config_table* table1,
   return grpc_mdstr_hash_table_cmp(table1, table2);
 }
 
-grpc_method_config* grpc_method_config_table_get_method_config(
-    const grpc_method_config_table* table, const grpc_mdstr* path) {
-  grpc_method_config* method_config = grpc_mdstr_hash_table_get(table, path);
+void* grpc_method_config_table_get(const grpc_mdstr_hash_table* table,
+                                   const grpc_mdstr* path) {
+  void* value = grpc_mdstr_hash_table_get(table, path);
   // If we didn't find a match for the path, try looking for a wildcard
   // entry (i.e., change "/service/method" to "/service/*").
-  if (method_config == NULL) {
+  if (value == NULL) {
     const char* path_str = grpc_mdstr_as_c_string(path);
     const char* sep = strrchr(path_str, '/') + 1;
     const size_t len = (size_t)(sep - path_str);
@@ -269,10 +269,10 @@ grpc_method_config* grpc_method_config_table_get_method_config(
     buf[len + 1] = '\0';
     grpc_mdstr* wildcard_path = grpc_mdstr_from_string(buf);
     gpr_free(buf);
-    method_config = grpc_mdstr_hash_table_get(table, wildcard_path);
+    value = grpc_mdstr_hash_table_get(table, wildcard_path);
     GRPC_MDSTR_UNREF(wildcard_path);
   }
-  return method_config;
+  return value;
 }
 
 static void* copy_arg(void* p) { return grpc_method_config_table_ref(p); }
@@ -294,3 +294,47 @@ grpc_arg grpc_method_config_table_create_channel_arg(
   arg.value.pointer.vtable = &arg_vtable;
   return arg;
 }
+
+// State used by convert_entry() below.
+typedef struct conversion_state {
+  void* (*convert_value)(const grpc_method_config* method_config);
+  const grpc_mdstr_hash_table_vtable* vtable;
+  size_t num_entries;
+  grpc_mdstr_hash_table_entry* entries;
+} conversion_state;
+
+// A function to be passed to grpc_mdstr_hash_table_iterate() to create
+// a copy of the entries.
+static void convert_entry(const grpc_mdstr_hash_table_entry* entry,
+                          void* user_data) {
+  conversion_state* state = user_data;
+  state->entries[state->num_entries].key = GRPC_MDSTR_REF(entry->key);
+  state->entries[state->num_entries].value = state->convert_value(entry->value);
+  state->entries[state->num_entries].vtable = state->vtable;
+  ++state->num_entries;
+}
+
+grpc_mdstr_hash_table* grpc_method_config_table_convert(
+    const grpc_method_config_table* table,
+    void* (*convert_value)(const grpc_method_config* method_config),
+    const grpc_mdstr_hash_table_vtable* vtable) {
+  // Create an array of the entries in the table with converted values.
+  conversion_state state;
+  state.convert_value = convert_value;
+  state.vtable = vtable;
+  state.num_entries = 0;
+  state.entries = gpr_malloc(sizeof(grpc_mdstr_hash_table_entry) *
+                             grpc_mdstr_hash_table_num_entries(table));
+  grpc_mdstr_hash_table_iterate(table, convert_entry, &state);
+  // Create a new table based on the array we just constructed.
+  grpc_mdstr_hash_table* new_table =
+      grpc_mdstr_hash_table_create(state.num_entries, state.entries);
+  // Clean up the array.
+  for (size_t i = 0; i < state.num_entries; ++i) {
+    GRPC_MDSTR_UNREF(state.entries[i].key);
+    vtable->destroy_value(state.entries[i].value);
+  }
+  gpr_free(state.entries);
+  // Return the new table.
+  return new_table;
+}
diff --git a/src/core/ext/client_config/method_config.h b/src/core/ext/client_config/method_config.h
index 1302ac425d..87c72ec064 100644
--- a/src/core/ext/client_config/method_config.h
+++ b/src/core/ext/client_config/method_config.h
@@ -106,11 +106,23 @@ int grpc_method_config_table_cmp(const grpc_method_config_table* table1,
 /// the form "/service/method".
 /// Returns NULL if the method has no config.
 /// Caller does NOT own a reference to the result.
-grpc_method_config* grpc_method_config_table_get_method_config(
-    const grpc_method_config_table* table, const grpc_mdstr* path);
+///
+/// Note: This returns a void* instead of a grpc_method_config* so that
+/// it can also be used for tables constructed via
+/// grpc_method_config_table_convert().
+void* grpc_method_config_table_get(const grpc_mdstr_hash_table* table,
+                                   const grpc_mdstr* path);
 
 /// Returns a channel arg containing \a table.
 grpc_arg grpc_method_config_table_create_channel_arg(
     grpc_method_config_table* table);
 
+/// Generates a new table from \a table whose values are converted to a
+/// new form via the \a convert_value function.  The new table will use
+/// \a vtable for its values.
+grpc_mdstr_hash_table* grpc_method_config_table_convert(
+    const grpc_method_config_table* table,
+    void* (*convert_value)(const grpc_method_config* method_config),
+    const grpc_mdstr_hash_table_vtable* vtable);
+
 #endif /* GRPC_CORE_EXT_CLIENT_CONFIG_METHOD_CONFIG_H */