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catalog_services.go
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/
catalog_services.go
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package cachetype
import (
"fmt"
"github.com/hashicorp/consul/agent/cache"
"github.com/hashicorp/consul/agent/structs"
)
// Recommended name for registration.
const CatalogServicesName = "catalog-services"
// CatalogServices supports fetching discovering service instances via the
// catalog.
type CatalogServices struct {
RPC RPC
}
func (c *CatalogServices) Fetch(opts cache.FetchOptions, req cache.Request) (cache.FetchResult, error) {
var result cache.FetchResult
// The request should be a DCSpecificRequest.
reqReal, ok := req.(*structs.ServiceSpecificRequest)
if !ok {
return result, fmt.Errorf(
"Internal cache failure: request wrong type: %T", req)
}
// Set the minimum query index to our current index so we block
reqReal.QueryOptions.MinQueryIndex = opts.MinIndex
reqReal.QueryOptions.MaxQueryTime = opts.Timeout
// Always allow stale - there's no point in hitting leader if the request is
// going to be served from cache and end up arbitrarily stale anyway. This
// allows cached service-discover to automatically read scale across all
// servers too.
reqReal.AllowStale = true
// Fetch
var reply structs.IndexedServiceNodes
if err := c.RPC.RPC("Catalog.ServiceNodes", reqReal, &reply); err != nil {
return result, err
}
result.Value = &reply
result.Index = reply.QueryMeta.Index
return result, nil
}
func (c *CatalogServices) SupportsBlocking() bool {
return true
}