micro/client/lookup.go

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package client
import (
"context"
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"sort"
"github.com/unistack-org/micro/v3/errors"
"github.com/unistack-org/micro/v3/router"
)
// LookupFunc is used to lookup routes for a service
type LookupFunc func(context.Context, Request, CallOptions) ([]string, error)
// LookupRoute for a request using the router and then choose one using the selector
func LookupRoute(ctx context.Context, req Request, opts CallOptions) ([]string, error) {
// check to see if an address was provided as a call option
if len(opts.Address) > 0 {
return opts.Address, nil
}
// construct the router query
query := []router.QueryOption{router.QueryService(req.Service())}
// if a custom network was requested, pass this to the router. By default the router will use it's
// own network, which is set during initialisation.
if len(opts.Network) > 0 {
query = append(query, router.QueryNetwork(opts.Network))
}
// lookup the routes which can be used to execute the request
routes, err := opts.Router.Lookup(query...)
if err == router.ErrRouteNotFound {
return nil, errors.InternalServerError("go.micro.client", "service %s: %s", req.Service(), err.Error())
} else if err != nil {
return nil, errors.InternalServerError("go.micro.client", "error getting next %s node: %s", req.Service(), err.Error())
}
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// sort by lowest metric first
sort.Slice(routes, func(i, j int) bool {
return routes[i].Metric < routes[j].Metric
})
addrs := make([]string, 0, len(routes))
for _, route := range routes {
addrs = append(addrs, route.Address)
}
return addrs, nil
}