firebase函数获取密钥名称列表

我刚接触Nodejs,我想做两天。我想获取存储在特定节点下的密钥名列表(这是喜欢此用户的用户ID)。但我的代码没有继续执行以下日志: "getting key names for user: NRtRoPEh4HUYUc0Hz6unMCsTBSn1"

然后,我的代码使用此日志超时: Function execution took 60002 ms, finished with status: 'timeout'

我的代码:

const functions = require('firebase-functions');

const admin = require('firebase-admin');

const serviceAccount = require('./service-account.json');
admin.initializeApp({
    credential: admin.credential.cert(serviceAccount),
    databaseURL: 'MY-URL',
});

var events = require('events');

exports.getLikedUsers = functions.database.ref('/users_to_test/{pushID}').onCreate(snapshot => {
    let UID = snapshot.val();
    let likeList = new Array();
        console.log('getting key names for user: ', UID);


        return admin.database().ref(`/user_likes/${UID}/{likedUser}`)
            .once('child_added').then(snap =>
            {          
                snap.forEach((childSnap) =>{
                    likeList.push(childsnap.key);
                });

                console.log('liked users list: ' + likeList.entries());

                return;

            }).then(function (functionReturn)    
        {
        return;
        });
    });
`