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diff --git a/src/core/lib/gpr/avl.h b/src/core/lib/gpr/avl.h
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+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_GPR_AVL_H
+#define GRPC_CORE_LIB_GPR_AVL_H
+
+#include <grpc/support/sync.h>
+
+/** internal node of an AVL tree */
+typedef struct gpr_avl_node {
+  gpr_refcount refs;
+  void* key;
+  void* value;
+  struct gpr_avl_node* left;
+  struct gpr_avl_node* right;
+  long height;
+} gpr_avl_node;
+
+/** vtable for the AVL tree
+ * The optional user_data is propagated from the top level gpr_avl_XXX API.
+ * From the same API call, multiple vtable functions may be called multiple
+ * times.
+ */
+typedef struct gpr_avl_vtable {
+  /** destroy a key */
+  void (*destroy_key)(void* key, void* user_data);
+  /** copy a key, returning new value */
+  void* (*copy_key)(void* key, void* user_data);
+  /** compare key1, key2; return <0 if key1 < key2,
+      >0 if key1 > key2, 0 if key1 == key2 */
+  long (*compare_keys)(void* key1, void* key2, void* user_data);
+  /** destroy a value */
+  void (*destroy_value)(void* value, void* user_data);
+  /** copy a value */
+  void* (*copy_value)(void* value, void* user_data);
+} gpr_avl_vtable;
+
+/** "pointer" to an AVL tree - this is a reference
+    counted object - use gpr_avl_ref to add a reference,
+    gpr_avl_unref when done with a reference */
+typedef struct gpr_avl {
+  const gpr_avl_vtable* vtable;
+  gpr_avl_node* root;
+} gpr_avl;
+
+/** Create an immutable AVL tree. */
+gpr_avl gpr_avl_create(const gpr_avl_vtable* vtable);
+/** Add a reference to an existing tree - returns
+    the tree as a convenience. The optional user_data will be passed to vtable
+    functions. */
+gpr_avl gpr_avl_ref(gpr_avl avl, void* user_data);
+/** Remove a reference to a tree - destroying it if there
+    are no references left. The optional user_data will be passed to vtable
+    functions. */
+void gpr_avl_unref(gpr_avl avl, void* user_data);
+/** Return a new tree with (key, value) added to avl.
+    implicitly unrefs avl to allow easy chaining.
+    if key exists in avl, the new tree's key entry updated
+    (i.e. a duplicate is not created). The optional user_data will be passed to
+    vtable functions. */
+gpr_avl gpr_avl_add(gpr_avl avl, void* key, void* value, void* user_data);
+/** Return a new tree with key deleted
+    implicitly unrefs avl to allow easy chaining. The optional user_data will be
+    passed to vtable functions. */
+gpr_avl gpr_avl_remove(gpr_avl avl, void* key, void* user_data);
+/** Lookup key, and return the associated value.
+    Does not mutate avl.
+    Returns NULL if key is not found. The optional user_data will be passed to
+    vtable functions.*/
+void* gpr_avl_get(gpr_avl avl, void* key, void* user_data);
+/** Return 1 if avl contains key, 0 otherwise; if it has the key, sets *value to
+    its value. The optional user_data will be passed to vtable functions. */
+int gpr_avl_maybe_get(gpr_avl avl, void* key, void** value, void* user_data);
+/** Return 1 if avl is empty, 0 otherwise */
+int gpr_avl_is_empty(gpr_avl avl);
+
+#endif /* GRPC_CORE_LIB_GPR_AVL_H */