1 files changed, 258 insertions, 0 deletions
diff --git a/src/core/lib/channel/channel_stack_builder.c b/src/core/lib/channel/channel_stack_builder.c
new file mode 100644
index 0000000000..1ce0c4e07f
--- /dev/null
+++ b/src/core/lib/channel/channel_stack_builder.c
@@ -0,0 +1,258 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/channel/channel_stack_builder.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+
+int grpc_trace_channel_stack_builder = 0;
+
+typedef struct filter_node {
+  struct filter_node *next;
+  struct filter_node *prev;
+  const grpc_channel_filter *filter;
+  grpc_post_filter_create_init_func init;
+  void *init_arg;
+} filter_node;
+
+struct grpc_channel_stack_builder {
+  // sentinel nodes for filters that have been added
+  filter_node begin;
+  filter_node end;
+  // various set/get-able parameters
+  const grpc_channel_args *args;
+  grpc_transport *transport;
+  const char *name;
+};
+
+struct grpc_channel_stack_builder_iterator {
+  grpc_channel_stack_builder *builder;
+  filter_node *node;
+};
+
+grpc_channel_stack_builder *grpc_channel_stack_builder_create(void) {
+  grpc_channel_stack_builder *b = gpr_malloc(sizeof(*b));
+  memset(b, 0, sizeof(*b));
+
+  b->begin.filter = NULL;
+  b->end.filter = NULL;
+  b->begin.next = &b->end;
+  b->begin.prev = &b->end;
+  b->end.next = &b->begin;
+  b->end.prev = &b->begin;
+
+  return b;
+}
+
+static grpc_channel_stack_builder_iterator *create_iterator_at_filter_node(
+    grpc_channel_stack_builder *builder, filter_node *node) {
+  grpc_channel_stack_builder_iterator *it = gpr_malloc(sizeof(*it));
+  it->builder = builder;
+  it->node = node;
+  return it;
+}
+
+void grpc_channel_stack_builder_iterator_destroy(
+    grpc_channel_stack_builder_iterator *it) {
+  gpr_free(it);
+}
+
+grpc_channel_stack_builder_iterator *
+grpc_channel_stack_builder_create_iterator_at_first(
+    grpc_channel_stack_builder *builder) {
+  return create_iterator_at_filter_node(builder, &builder->begin);
+}
+
+grpc_channel_stack_builder_iterator *
+grpc_channel_stack_builder_create_iterator_at_last(
+    grpc_channel_stack_builder *builder) {
+  return create_iterator_at_filter_node(builder, &builder->end);
+}
+
+bool grpc_channel_stack_builder_move_next(
+    grpc_channel_stack_builder_iterator *iterator) {
+  if (iterator->node == &iterator->builder->end) return false;
+  iterator->node = iterator->node->next;
+  return true;
+}
+
+bool grpc_channel_stack_builder_move_prev(
+    grpc_channel_stack_builder_iterator *iterator) {
+  if (iterator->node == &iterator->builder->begin) return false;
+  iterator->node = iterator->node->prev;
+  return true;
+}
+
+bool grpc_channel_stack_builder_move_prev(
+    grpc_channel_stack_builder_iterator *iterator);
+
+void grpc_channel_stack_builder_set_name(grpc_channel_stack_builder *builder,
+                                         const char *name) {
+  GPR_ASSERT(builder->name == NULL);
+  builder->name = name;
+}
+
+void grpc_channel_stack_builder_set_channel_arguments(
+    grpc_channel_stack_builder *builder, const grpc_channel_args *args) {
+  GPR_ASSERT(builder->args == NULL);
+  builder->args = args;
+}
+
+void grpc_channel_stack_builder_set_transport(
+    grpc_channel_stack_builder *builder, grpc_transport *transport) {
+  GPR_ASSERT(builder->transport == NULL);
+  builder->transport = transport;
+}
+
+grpc_transport *grpc_channel_stack_builder_get_transport(
+    grpc_channel_stack_builder *builder) {
+  return builder->transport;
+}
+
+const grpc_channel_args *grpc_channel_stack_builder_get_channel_arguments(
+    grpc_channel_stack_builder *builder) {
+  return builder->args;
+}
+
+bool grpc_channel_stack_builder_append_filter(
+    grpc_channel_stack_builder *builder, const grpc_channel_filter *filter,
+    grpc_post_filter_create_init_func post_init_func, void *user_data) {
+  grpc_channel_stack_builder_iterator *it =
+      grpc_channel_stack_builder_create_iterator_at_last(builder);
+  bool ok = grpc_channel_stack_builder_add_filter_before(
+      it, filter, post_init_func, user_data);
+  grpc_channel_stack_builder_iterator_destroy(it);
+  return ok;
+}
+
+bool grpc_channel_stack_builder_prepend_filter(
+    grpc_channel_stack_builder *builder, const grpc_channel_filter *filter,
+    grpc_post_filter_create_init_func post_init_func, void *user_data) {
+  grpc_channel_stack_builder_iterator *it =
+      grpc_channel_stack_builder_create_iterator_at_first(builder);
+  bool ok = grpc_channel_stack_builder_add_filter_after(
+      it, filter, post_init_func, user_data);
+  grpc_channel_stack_builder_iterator_destroy(it);
+  return ok;
+}
+
+static void add_after(filter_node *before, const grpc_channel_filter *filter,
+                      grpc_post_filter_create_init_func post_init_func,
+                      void *user_data) {
+  filter_node *new = gpr_malloc(sizeof(*new));
+  new->next = before->next;
+  new->prev = before;
+  new->next->prev = new->prev->next = new;
+  new->filter = filter;
+  new->init = post_init_func;
+  new->init_arg = user_data;
+}
+
+bool grpc_channel_stack_builder_add_filter_before(
+    grpc_channel_stack_builder_iterator *iterator,
+    const grpc_channel_filter *filter,
+    grpc_post_filter_create_init_func post_init_func, void *user_data) {
+  if (iterator->node == &iterator->builder->begin) return false;
+  add_after(iterator->node->prev, filter, post_init_func, user_data);
+  return true;
+}
+
+bool grpc_channel_stack_builder_add_filter_after(
+    grpc_channel_stack_builder_iterator *iterator,
+    const grpc_channel_filter *filter,
+    grpc_post_filter_create_init_func post_init_func, void *user_data) {
+  if (iterator->node == &iterator->builder->end) return false;
+  add_after(iterator->node, filter, post_init_func, user_data);
+  return true;
+}
+
+void grpc_channel_stack_builder_destroy(grpc_channel_stack_builder *builder) {
+  filter_node *p = builder->begin.next;
+  while (p != &builder->end) {
+    filter_node *next = p->next;
+    gpr_free(p);
+    p = next;
+  }
+  gpr_free(builder);
+}
+
+void *grpc_channel_stack_builder_finish(grpc_exec_ctx *exec_ctx,
+                                        grpc_channel_stack_builder *builder,
+                                        size_t prefix_bytes, int initial_refs,
+                                        grpc_iomgr_cb_func destroy,
+                                        void *destroy_arg) {
+  // count the number of filters
+  size_t num_filters = 0;
+  for (filter_node *p = builder->begin.next; p != &builder->end; p = p->next) {
+    num_filters++;
+  }
+
+  // create an array of filters
+  const grpc_channel_filter **filters =
+      gpr_malloc(sizeof(*filters) * num_filters);
+  size_t i = 0;
+  for (filter_node *p = builder->begin.next; p != &builder->end; p = p->next) {
+    filters[i++] = p->filter;
+  }
+
+  // calculate the size of the channel stack
+  size_t channel_stack_size = grpc_channel_stack_size(filters, num_filters);
+
+  // allocate memory, with prefix_bytes followed by channel_stack_size
+  char *result = gpr_malloc(prefix_bytes + channel_stack_size);
+  // fetch a pointer to the channel stack
+  grpc_channel_stack *channel_stack =
+      (grpc_channel_stack *)(result + prefix_bytes);
+  // and initialize it
+  grpc_channel_stack_init(exec_ctx, initial_refs, destroy,
+                          destroy_arg == NULL ? result : destroy_arg, filters,
+                          num_filters, builder->args, builder->name,
+                          channel_stack);
+
+  // run post-initialization functions
+  i = 0;
+  for (filter_node *p = builder->begin.next; p != &builder->end; p = p->next) {
+    if (p->init != NULL) {
+      p->init(channel_stack, grpc_channel_stack_element(channel_stack, i),
+              p->init_arg);
+    }
+    i++;
+  }
+
+  grpc_channel_stack_builder_destroy(builder);
+  gpr_free((grpc_channel_filter **)filters);
+
+  return result;
+}