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diff --git a/src/core/lib/client_config/subchannel_index.h b/src/core/lib/client_config/subchannel_index.h
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+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_CLIENT_CONFIG_SUBCHANNEL_INDEX_H
+#define GRPC_CORE_LIB_CLIENT_CONFIG_SUBCHANNEL_INDEX_H
+
+#include "src/core/lib/client_config/connector.h"
+#include "src/core/lib/client_config/subchannel.h"
+
+/** \file Provides an index of active subchannels so that they can be
+    shared amongst channels */
+
+typedef struct grpc_subchannel_key grpc_subchannel_key;
+
+/** Create a key that can be used to uniquely identify a subchannel */
+grpc_subchannel_key *grpc_subchannel_key_create(grpc_connector *con,
+                                                grpc_subchannel_args *args);
+
+/** Destroy a subchannel key */
+void grpc_subchannel_key_destroy(grpc_exec_ctx *exec_ctx,
+                                 grpc_subchannel_key *key);
+
+/** Given a subchannel key, find the subchannel registered for it.
+    Returns NULL if no such channel exists.
+    Thread-safe. */
+grpc_subchannel *grpc_subchannel_index_find(grpc_exec_ctx *exec_ctx,
+                                            grpc_subchannel_key *key);
+
+/** Register a subchannel against a key.
+    Takes ownership of \a constructed.
+    Returns the registered subchannel. This may be different from
+    \a constructed in the case of a registration race. */
+grpc_subchannel *grpc_subchannel_index_register(grpc_exec_ctx *exec_ctx,
+                                                grpc_subchannel_key *key,
+                                                grpc_subchannel *constructed);
+
+/** Remove \a constructed as the registered subchannel for \a key. */
+void grpc_subchannel_index_unregister(grpc_exec_ctx *exec_ctx,
+                                      grpc_subchannel_key *key,
+                                      grpc_subchannel *constructed);
+
+/** Initialize the subchannel index (global) */
+void grpc_subchannel_index_init(void);
+/** Shutdown the subchannel index (global) */
+void grpc_subchannel_index_shutdown(void);
+
+#endif /* GRPC_CORE_LIB_CLIENT_CONFIG_SUBCHANNEL_INDEX_H */