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grpc.go
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grpc.go
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package querylimits
import (
"context"
"fmt"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
)
const (
lowerQueryLimitsHeaderName = "x-loki-query-limits"
)
func injectIntoGRPCRequest(ctx context.Context) (context.Context, error) {
limits := ExtractQueryLimitsContext(ctx)
fmt.Printf("extract limits grpc: %v", limits)
if limits == nil {
return ctx, nil
}
// inject into GRPC metadata
md, ok := metadata.FromOutgoingContext(ctx)
if !ok {
md = metadata.New(map[string]string{})
}
md = md.Copy()
headerValue, err := MarshalQueryLimits(limits)
if err != nil {
return nil, err
}
md.Set(lowerQueryLimitsHeaderName, string(headerValue))
newCtx := metadata.NewOutgoingContext(ctx, md)
return newCtx, nil
}
func ClientQueryLimitsInterceptor(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
ctx, err := injectIntoGRPCRequest(ctx)
if err != nil {
return err
}
return invoker(ctx, method, req, reply, cc, opts...)
}
func StreamClientQueryLimitsInterceptor(ctx context.Context, desc *grpc.StreamDesc, cc *grpc.ClientConn, method string, streamer grpc.Streamer, opts ...grpc.CallOption) (grpc.ClientStream, error) {
ctx, err := injectIntoGRPCRequest(ctx)
if err != nil {
return nil, err
}
return streamer(ctx, desc, cc, method, opts...)
}
func extractFromGRPCRequest(ctx context.Context) (context.Context, error) {
md, ok := metadata.FromIncomingContext(ctx)
if !ok {
// No metadata, just return as is
return ctx, nil
}
headerValues, ok := md[lowerQueryLimitsHeaderName]
if !ok {
// No QueryLimits header in metadata, just return context
return ctx, nil
}
if len(headerValues) == 0 {
return ctx, nil
}
// Pick first header
limits, err := UnmarshalQueryLimits([]byte(headerValues[0]))
if err != nil {
return ctx, err
}
return InjectQueryLimitsContext(ctx, *limits), nil
}
func ServerQueryLimitsInterceptor(ctx context.Context, req interface{}, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
ctx, err := extractFromGRPCRequest(ctx)
if err != nil {
return nil, err
}
return handler(ctx, req)
}
func StreamServerQueryLimitsInterceptor(srv interface{}, ss grpc.ServerStream, _ *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
ctx, err := extractFromGRPCRequest(ss.Context())
if err != nil {
return err
}
return handler(srv, serverStream{
ctx: ctx,
ServerStream: ss,
})
}
type serverStream struct {
ctx context.Context
grpc.ServerStream
}
func (ss serverStream) Context() context.Context {
return ss.ctx
}