node.js - GCF "No Such Object"当相关对象刚刚创建时

Question

我正在设置一个 Google Cloud Functions (GCF) 函数，该函数被频繁触发，以至于有多个实例同时运行。

我从 readStream 中收到错误，该流的源文件不存在，但此时在我的程序中我实际上刚刚创建了它。

我已通过console.log() 处理文件 JSON 确保该文件在流开始之前存在，因此该文件确实存在。我还确保我尝试访问的文件已由先前的流通过等待完成写入，但没有骰子。

编辑:代码现在包含整个脚本。似乎引发错误的部分是函数columnDelete()。

var parse = require('fast-csv');
var Storage = require('@google-cloud/storage');
var Transform = require('readable-stream').Transform;

var storage = new Storage();
var bucket = storage.bucket('<BUCKET>');
const DMSs = ['PBS','CDK','One_Eighty','InfoBahn'];


class DeleteColumns extends Transform{
    constructor(){
        super({objectMode:true})
    }
    _transform(row, enc, done){
        //create an array 2 elements shorter than received
        let newRow = new Array(row.length - 2);

        //write all data but the first two columns
        for(let i = 0; i < newRow.length; i++){
            newRow[i] = row[i+2];
        }

        this.push(newRow.toString() + '\n');
        done();
    }
}


function rename(file, originalFile, DMS){
    return new Promise((resolve, reject) => {
        var dealer;
        var date;
        var header = true;
        var parser = parse({delimiter : ",", quote:'\\'});

        //for each row of data
        var stream = originalFile.createReadStream();
        stream.pipe(parser)
        .on('data', (row)=>{


            //if this is the first line do nothing
            if(header){
                header = false;
            }
            //otherwise record the contents of the first two columns and then destroy the stream
            else {
                dealer = row[0].toString().replace('"', '').replace('"', '');
                date = row[1].toString().replace('"', '').replace('"', '');

                stream.end();
            }
        })
        .on('finish', function(){
            var newName = dealer + ' ' + date + '_' + DMS + 'temp.csv';
            //if this was not triggered by the renaming of a file
            if(!file.name.includes(dealer)&&!file.name.includes(':')){
                console.log('Renamed ' + file.name);
                originalFile.copy(newName);
                originalFile.copy(newName.replace('temp',''));
            }else{
                newName = 'Not Renamed';
                console.log('Oops, triggered by the rename');
            }
            resolve(newName);

        });
    });

}
function columnDelete(fileName){
    return new Promise((resolve, reject) =>{
        console.log('Deleting Columns...');
        console.log(bucket.file(fileName));
        var parser = parse({delimiter : ",", quote:'\\'});
        var del = new DeleteColumns();
        var temp = bucket.file(fileName);
        var final = bucket.file(fileName.replace('temp', ''));

        //for each row of data
        temp.createReadStream()
        //parse the csv
        .pipe(parser)
        //delete first two columns
        .pipe(del)
        //write to new file
        .pipe(final.createWriteStream()
            .on('finish', function(){
                console.log('Columns Deleted');
                temp.delete();
                resolve();
            })
        );
    });

}

exports.triggerRename = async(data, context) => {
    var DMS = 'Triple';
    var file = data;
    //if not a temporary file
    if(!file.name.includes('temp')){

        //create a new File object from the name of the data passed
        const originalFile = bucket.file(file.name);

        //identify which database this data is from
        DMSs.forEach(function(database){
            if(file.name.includes(database)){
                DMS = database;
            }
        });
        //rename the file
        var tempName = await rename(file, originalFile, DMS);
        //if it was renamed, delete the extra columns
        if (!tempName.includes('Not Renamed')){
            await columnDelete(tempName);
        }

    } else if(file.name.includes('undefined')){
        console.log(file.name + ' is invalid. Deleted.');
        bucket.file(file.name).delete();
    }
     else {
        console.log( file.name + ' is a temporary file. Did not rename.');
    }
};

我期望的输出如下:

Deleting Columns...
Columns Deleted

很好又简单，让我们知道它何时开始和结束。

但是，我得到的是这个:

Deleting Columns...
ApiError: No such object: <file> at at Object.parseHttpRespMessage(......)
finished with status: 'crash'

由于显而易见的原因，这不是想要的。我的下一个想法是确保该文件没有被脚本的另一个实例中途删除，但要做到这一点，我必须检查该文件是否正在被另一个流使用，据我所知，这是不可能的。

有什么想法吗？

Answer 1

当我创建文件时，我调用了异步函数copy()并继续，这意味着当尝试访问该文件时，它尚未完成复制。我不知道的是，文件对象是一个引用变量，实际上并不包含文件本身。复制文件时，指针存在，但指向未完成的文件。

因此，“没有这样的对象”。为了解决这个问题，我只是使用了一个回调来确保在访问文件之前复制已完成。

感谢 Doug Stevenson 让我了解指针!