1 /* 2 * 3 * Copyright 2016 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 // Package tap defines the function handles which are executed on the transport 20 // layer of gRPC-Go and related information. 21 // 22 // # Experimental 23 // 24 // Notice: This API is EXPERIMENTAL and may be changed or removed in a 25 // later release. 26 package tap 27 28 import ( 29 "context" 30 31 "google.golang.org/grpc/metadata" 32 ) 33 34 // Info defines the relevant information needed by the handles. 35 type Info struct { 36 // FullMethodName is the string of grpc method (in the format of 37 // /package.service/method). 38 FullMethodName string 39 40 // Header contains the header metadata received. 41 Header metadata.MD 42 43 // TODO: More to be added. 44 } 45 46 // ServerInHandle defines the function which runs before a new stream is 47 // created on the server side. If it returns a non-nil error, the stream will 48 // not be created and an error will be returned to the client. If the error 49 // returned is a status error, that status code and message will be used, 50 // otherwise PermissionDenied will be the code and err.Error() will be the 51 // message. 52 // 53 // It's intended to be used in situations where you don't want to waste the 54 // resources to accept the new stream (e.g. rate-limiting). For other general 55 // usages, please use interceptors. 56 // 57 // Note that it is executed in the per-connection I/O goroutine(s) instead of 58 // per-RPC goroutine. Therefore, users should NOT have any 59 // blocking/time-consuming work in this handle. Otherwise all the RPCs would 60 // slow down. Also, for the same reason, this handle won't be called 61 // concurrently by gRPC. 62 type ServerInHandle func(ctx context.Context, info *Info) (context.Context, error) 63