You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: stats.go
    path of file: ./repos/dendrite/userapi/util
    
    the code of the file until where you have to start completion: // Copyright 2022 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//go:
    
func getMemoryStats(p *phoneHomeStats) error {
	oldUsage := p.prevData
	newUsage := syscall.Rusage{}
	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &newUsage); err != nil {
		logrus.WithError(err).Error("unable to get usage")
		return err
	}
	newData := timestampToRUUsage{timestamp: time.Now().Unix(), usage: newUsage}
	p.prevData = newData

	usedCPUTime := (newUsage.Utime.Sec + newUsage.Stime.Sec) - (oldUsage.usage.Utime.Sec + oldUsage.usage.Stime.Sec)

	if usedCPUTime == 0 || newData.timestamp == oldUsage.timestamp {
		p.stats["cpu_average"] = 0
	} else {
		// conversion to int64 required for GOARCH=386
		p.stats["cpu_average"] = int64(usedCPUTime) / (newData.timestamp - oldUsage.timestamp) * 100
	}
	p.stats["memory_rss"] = newUsage.Maxrss
	return nil
}