Struct xdsResolver

internal/xds/resolver/xds_resolver.go:225–267

xdsResolver implements the resolver.Resolver interface. It manages the dependency manager which in turn manages all xDS resource watches. It receives the xDS resource config and passes them to ClientConn.

// It manages the dependency manager which in turn manages all xDS resource
// watches. It receives the xDS resource config and passes them to ClientConn.
type xdsResolver struct {
	// The following fields are initialized at creation time and are read-only
	// after that.
	cc              resolver.ClientConn
	logger          *grpclog.PrefixLogger
	ldsResourceName string
	dm              *xdsdepmgr.DependencyManager
	xdsClient       xdsclient.XDSClient
	xdsClientClose  func()
	channelID       uint64 // Unique random ID for the channel owning this resolver.
	// All methods on the xdsResolver type except for the ones invoked by gRPC,
	// i.e ResolveNow() and Close(), are guaranteed to execute in the context of
	// this serializer's callback. We use the serializer because these shared
	// states are accessed by each RPC when it is committed, and so
	// serializer is preffered over a mutex.
	serializer       *grpcsync.CallbackSerializer
	serializerCancel context.CancelFunc

	// The following fields are accessed only from within the serializer
	// callbacks.
	xdsConfig *xdsresource.XDSConfig
	// activeClusters is a map from cluster name to information about the
	// weighted cluster that includes a reference count and load balancing
	// configuration. These counts are used only by the resolver. The current
	// configSelector holds one reference, and each ongoing RPC holds an
	// additional reference. When the count hits zero, the resolver removes the
	// cluster from this map and calls unsubscribe. This signals the dependency
	// manager to stop the xDS watch once its own reference count reaches zero.
	activeClusters map[string]*clusterInfo
	// activePlugins is a map from cluster specifier plugin name to information
	// about the cluster specifier plugin that includes a ref count and load
	// balancing configuration. These counts are used only by the resolver. The
	// current configSelector holds one reference, and each ongoing RPC holds an
	// additional reference. When the count hits zero, the resolver removes the
	// plugin name from this map.
	activePlugins     map[string]*clusterInfo
	curConfigSelector stoppableConfigSelector
	// httpFilters is a map from client filter key to client filter instance. It
	// lives here so that the resolver can reuse filter instances across config
	// updates when the same filter is specified, and to be able to clean up
	// filter instances that are no longer used.
	httpFilters map[clientFilterKey]httpfilter.ClientFilter
}

// ResolveNow calls RequestDNSReresolution on the dependency manager.
func (r *xdsResolver) ResolveNow(opts resolver.ResolveNowOptions) {