1 /* 2 * 3 * Copyright 2017 gRPC authors. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 */ 18 19 #ifndef GRPC_LOAD_REPORTING_H 20 #define GRPC_LOAD_REPORTING_H 21 22 #include <grpc/impl/codegen/port_platform.h> 23 24 #ifdef __cplusplus 25 extern "C" { 26 #endif 27 28 /** Metadata key for the gRPC LB load balancer token. 29 * 30 * The value corresponding to this key is an opaque token that is given to the 31 * frontend as part of each pick; the frontend sends this token to the backend 32 * in each request it sends when using that pick. The token is used by the 33 * backend to verify the request and to allow the backend to report load to the 34 * gRPC LB system. */ 35 #define GRPC_LB_TOKEN_MD_KEY "lb-token" 36 37 /** Metadata key for gRPC LB cost reporting. 38 * 39 * The value corresponding to this key is an opaque binary blob reported by the 40 * backend as part of its trailing metadata containing cost information for the 41 * call. */ 42 #define GRPC_LB_COST_MD_KEY "lb-cost-bin" 43 44 #ifdef __cplusplus 45 } 46 #endif 47 48 #endif /* GRPC_LOAD_REPORTING_H */ 49