diff options
Diffstat (limited to 'vendor/github.com/grpc-ecosystem/go-grpc-middleware/chain.go')
-rw-r--r-- | vendor/github.com/grpc-ecosystem/go-grpc-middleware/chain.go | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/chain.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/chain.go new file mode 100644 index 00000000..45a2f5f4 --- /dev/null +++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/chain.go @@ -0,0 +1,183 @@ +// Copyright 2016 Michal Witkowski. All Rights Reserved. +// See LICENSE for licensing terms. + +// gRPC Server Interceptor chaining middleware. + +package grpc_middleware + +import ( + "golang.org/x/net/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 ChainUnaryServer(interceptors ...grpc.UnaryServerInterceptor) grpc.UnaryServerInterceptor { + n := len(interceptors) + + if n > 1 { + lastI := n - 1 + return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) { + var ( + chainHandler grpc.UnaryHandler + curI int + ) + + chainHandler = func(currentCtx context.Context, currentReq interface{}) (interface{}, error) { + if curI == lastI { + return handler(currentCtx, currentReq) + } + curI++ + resp, err := interceptors[curI](currentCtx, currentReq, info, chainHandler) + curI-- + return resp, err + } + + return interceptors[0](ctx, req, info, chainHandler) + } + } + + if n == 1 { + return interceptors[0] + } + + // n == 0; Dummy interceptor maintained for backward compatibility to avoid returning nil. + return func(ctx context.Context, req interface{}, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) { + return handler(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 ChainStreamServer(interceptors ...grpc.StreamServerInterceptor) grpc.StreamServerInterceptor { + n := len(interceptors) + + if n > 1 { + lastI := n - 1 + return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error { + var ( + chainHandler grpc.StreamHandler + curI int + ) + + chainHandler = func(currentSrv interface{}, currentStream grpc.ServerStream) error { + if curI == lastI { + return handler(currentSrv, currentStream) + } + curI++ + err := interceptors[curI](currentSrv, currentStream, info, chainHandler) + curI-- + return err + } + + return interceptors[0](srv, stream, info, chainHandler) + } + } + + if n == 1 { + return interceptors[0] + } + + // n == 0; Dummy interceptor maintained for backward compatibility to avoid returning nil. + return func(srv interface{}, stream grpc.ServerStream, _ *grpc.StreamServerInfo, handler grpc.StreamHandler) error { + return handler(srv, stream) + } +} + +// ChainUnaryClient 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 ChainUnaryClient(one, two, three) will execute one before two before three. +func ChainUnaryClient(interceptors ...grpc.UnaryClientInterceptor) grpc.UnaryClientInterceptor { + n := len(interceptors) + + if n > 1 { + lastI := n - 1 + return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error { + var ( + chainHandler grpc.UnaryInvoker + curI int + ) + + chainHandler = func(currentCtx context.Context, currentMethod string, currentReq, currentRepl interface{}, currentConn *grpc.ClientConn, currentOpts ...grpc.CallOption) error { + if curI == lastI { + return invoker(currentCtx, currentMethod, currentReq, currentRepl, currentConn, currentOpts...) + } + curI++ + err := interceptors[curI](currentCtx, currentMethod, currentReq, currentRepl, currentConn, chainHandler, currentOpts...) + curI-- + return err + } + + return interceptors[0](ctx, method, req, reply, cc, chainHandler, opts...) + } + } + + if n == 1 { + return interceptors[0] + } + + // n == 0; Dummy interceptor maintained for backward compatibility to avoid returning nil. + return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error { + return invoker(ctx, method, req, reply, cc, opts...) + } +} + +// ChainStreamClient 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 ChainStreamClient(one, two, three) will execute one before two before three. +func ChainStreamClient(interceptors ...grpc.StreamClientInterceptor) grpc.StreamClientInterceptor { + n := len(interceptors) + + if n > 1 { + lastI := n - 1 + return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) { + var ( + chainHandler grpc.Streamer + curI int + ) + + chainHandler = func(currentCtx context.Context, currentDesc *grpc.StreamDesc, currentConn *grpc.ClientConn, currentMethod string, currentOpts ...grpc.CallOption) (grpc.ClientStream, error) { + if curI == lastI { + return streamer(currentCtx, currentDesc, currentConn, currentMethod, currentOpts...) + } + curI++ + stream, err := interceptors[curI](currentCtx, currentDesc, currentConn, currentMethod, chainHandler, currentOpts...) + curI-- + return stream, err + } + + return interceptors[0](ctx, desc, cc, method, chainHandler, opts...) + } + } + + if n == 1 { + return interceptors[0] + } + + // n == 0; Dummy interceptor maintained for backward compatibility to avoid returning nil. + return func(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) { + return streamer(ctx, desc, cc, method, opts...) + } +} + +// Chain creates a single interceptor out of a chain of many interceptors. +// +// WithUnaryServerChain is a grpc.Server config option that accepts multiple unary interceptors. +// Basically syntactic sugar. +func WithUnaryServerChain(interceptors ...grpc.UnaryServerInterceptor) grpc.ServerOption { + return grpc.UnaryInterceptor(ChainUnaryServer(interceptors...)) +} + +// WithStreamServerChain is a grpc.Server config option that accepts multiple stream interceptors. +// Basically syntactic sugar. +func WithStreamServerChain(interceptors ...grpc.StreamServerInterceptor) grpc.ServerOption { + return grpc.StreamInterceptor(ChainStreamServer(interceptors...)) +} |