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// Copyright 2016 Michal Witkowski. All Rights Reserved.
// See LICENSE for licensing terms.
// gRPC Server Interceptor chaining middleware.
package grpc
import (
"context"
"google.golang.org/grpc"
)
// ChainUnaryServer creates a single interceptor out of a chain of many interceptors.
//
// Execution is done in left-to-right order, including passing of context.
// For example ChainUnaryServer(one, two, three) will execute one before two before three, and three
// will see context changes of one and two.
func grpc_middleware_ChainUnaryServer(interceptors ...grpc.UnaryServerInterceptor) grpc.UnaryServerInterceptor {
n := len(interceptors)
return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
chainer := func(currentInter grpc.UnaryServerInterceptor, currentHandler grpc.UnaryHandler) grpc.UnaryHandler {
return func(currentCtx context.Context, currentReq interface{}) (interface{}, error) {
return currentInter(currentCtx, currentReq, info, currentHandler)
}
}
chainedHandler := handler
for i := n - 1; i >= 0; i-- {
chainedHandler = chainer(interceptors[i], chainedHandler)
}
return chainedHandler(ctx, req)
}
}
// ChainStreamServer creates a single interceptor out of a chain of many interceptors.
//
// Execution is done in left-to-right order, including passing of context.
// For example ChainUnaryServer(one, two, three) will execute one before two before three.
// If you want to pass context between interceptors, use WrapServerStream.
func grpc_middleware_ChainStreamServer(interceptors ...grpc.StreamServerInterceptor) grpc.StreamServerInterceptor {
n := len(interceptors)
return func(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
chainer := func(currentInter grpc.StreamServerInterceptor, currentHandler grpc.StreamHandler) grpc.StreamHandler {
return func(currentSrv interface{}, currentStream grpc.ServerStream) error {
return currentInter(currentSrv, currentStream, info, currentHandler)
}
}
chainedHandler := handler
for i := n - 1; i >= 0; i-- {
chainedHandler = chainer(interceptors[i], chainedHandler)
}
return chainedHandler(srv, ss)
}
}
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