func()

in xds/balancer/clusterimpl/picker.go [116:203]
68 lines of code
19 McCabe index (conditional complexity)

func (d *picker) Pick(info balancer.PickInfo) (balancer.PickResult, error) {
	// Don't drop unless the inner picker is READY. Similar to
	// https://github.com/grpc/grpc-go/issues/2622.
	if d.s.ConnectivityState == connectivity.Ready {
		// Check if this RPC should be dropped by category.
		for _, dp := range d.drops {
			if dp.drop() {
				if d.loadStore != nil {
					d.loadStore.CallDropped(dp.category)
				}
				return balancer.PickResult{}, status.Errorf(codes.Unavailable, "RPC is dropped")
			}
		}
	}

	// Check if this RPC should be dropped by circuit breaking.
	if d.counter != nil {
		if err := d.counter.StartRequest(d.countMax); err != nil {
			// Drops by circuit breaking are reported with empty category. They
			// will be reported only in total drops, but not in per category.
			if d.loadStore != nil {
				d.loadStore.CallDropped("")
			}
			return balancer.PickResult{}, status.Errorf(codes.Unavailable, err.Error())
		}
	}

	var lIDStr string
	pr, err := d.s.Picker.Pick(info)
	if scw, ok := pr.SubConn.(*scWrapper); ok {
		// This OK check also covers the case err!=nil, because SubConn will be
		// nil.
		pr.SubConn = scw.SubConn
		var e error
		// If locality ID isn't found in the wrapper, an empty locality ID will
		// be used.
		lIDStr, e = scw.localityID().ToString()
		if e != nil {
			dubbogoLogger.Infof("failed to marshal LocalityID: %#v, loads won't be reported", scw.localityID())
		}
	}

	if err != nil {
		if d.counter != nil {
			// Release one request count if this pick fails.
			d.counter.EndRequest()
		}
		return pr, err
	}

	if d.loadStore != nil {
		d.loadStore.CallStarted(lIDStr)
		oldDone := pr.Done
		pr.Done = func(info balancer.DoneInfo) {
			if oldDone != nil {
				oldDone(info)
			}
			d.loadStore.CallFinished(lIDStr, info.Err)

			load, ok := info.ServerLoad.(*orcapb.OrcaLoadReport)
			if !ok {
				return
			}
			d.loadStore.CallServerLoad(lIDStr, serverLoadCPUName, load.CpuUtilization)
			d.loadStore.CallServerLoad(lIDStr, serverLoadMemoryName, load.MemUtilization)
			for n, c := range load.RequestCost {
				d.loadStore.CallServerLoad(lIDStr, n, c)
			}
			for n, c := range load.Utilization {
				d.loadStore.CallServerLoad(lIDStr, n, c)
			}
		}
	}

	if d.counter != nil {
		// Update Done() so that when the RPC finishes, the request count will
		// be released.
		oldDone := pr.Done
		pr.Done = func(doneInfo balancer.DoneInfo) {
			d.counter.EndRequest()
			if oldDone != nil {
				oldDone(doneInfo)
			}
		}
	}

	return pr, err
}