2
我正在上傳圖像網址的數組以保存到S3。代碼有效，但不會異步執行。給控制檯打上時間標記似乎表明首先所有圖像都被提取並緩衝，然後它們被順序保存到s3。我跑了100張圖片，第一張圖片沒有提交給s3，直到第100張被提取。至少它看起來像這樣，因爲我從圖像請求回調中獲得了控制檯中的時間戳流，並且直到最後一次圖像回調已經加了時間戳纔會啓動「保存到s3」時間戳。我對節點相當陌生，在經過兩天的實驗後，我還沒有破解這個。如何使用node.js獲取圖像URL數組並異步保存到s3？
我也試過直接調出它，但那需要所有文件都有內容長度設置，有些不會。我原本在一個函數中使用了getImageFromUrl，但將其分解爲三個單獨的小函數，以幫助找出問題所在。我正在使用request，對於s3使用knox，對於async.each迭代器使用caolan的異步庫。代碼如下：
var images2get = req.body.images2get; // an array of image urls to be fetched and saved to s3
var startTime = (new Date()).getTime();
//iterate over the array and get each image, save to S3
var imageNumber = 0; // this needs to come before the iterator so it's defined
async.each(images2get, getImageFromUrl, function(err){
if(err) {
console.log('async each failed for images2get');
} else {
res.send(200);
}
});
function getImageFromUrl(url2fetch, nextImage){
var options = {encoding: null,
url: url2fetch,
method: 'GET',
timeout: 10*1000
}
request(options, function(err, fetchResponse, body){
if(!err && fetchResponse && fetchResponse.statusCode == 200) {
nextImage(); //we've got the image, call the iterator to fetch the next one
var s3Config = prepareImageForS3(fetchResponse, url2fetch);
saveToS3(body, s3Config);
} else {
//there was a problem fetching the url
console.log('Error ' + fetchResponse.statusCode + ' Failed to get image from ', url2fetch.absolute);
nextImage();
}
});
};
function prepareImageForS3(fetchResponse, url2fetch) {
console.log('preparing image ' + imageNumber + ' at ', (Date.now() - startTime));
imageNumber += 1;
var filename = '/' + userId + '/' + pageId + '/image' + imageNumber;
var headers = {
'Content-Type': fetchResponse.headers['content-type'],
'x-amz-acl': 'public-read'
};
return{
'filename': filename,
'filetype': 'image',
'filenumber': imageNumber,
'headers': headers,
'replaceSrc': true,
'url': url2fetch
};
};
function saveToS3(file, s3Config) {
s3Client.putBuffer(file, s3Config.filename, s3Config.headers, function(err, res){
console.log('image ' + imageNumber + ' submitting to s3 at ', (Date.now() - startTime));
//console.log('response from s3 save from url, status:', res.statusCode, 'url:', res.req.url);
if(!err && res.statusCode === 200 && s3Config.replaceSrc) {
console.log('image ' + imageNumber + ' saved to s3 at ', (Date.now() - startTime));
} else {
console.log('failed to save image to S3 from ' + res.req.url)
}
});
};