NodeJs中的瀑布似乎是異步的。爲什麼？

Question

我正在爲循環中的每個配置文件運行瀑布。在瀑布的第一個功能中，我從SFTP下載文件。從我讀到的關於瀑布的內容來看，它應該等到一個函數完成後纔開始下一個函數。

發生在我身上的事情恰恰相反。

呼籲在一個循環的每個配置文件中的瀑布功能：

for (var i=0; i<configFiles.length; i++) { 
    waterfallMain(configFiles[i],i); 
} 

瀑布功能：

function waterfallMain(configFile, i) { 
    async.waterfall([ 
    function(callback) { 
     // If there is no such file error is thrown and next iteration of the loop starts 
     util.log("Downloading config files."+i); 
     sftpHandler.downloadFile(credentials.sftpPathToImportFiles+configFile.importFileName, callback); 
       }, 
    function(callback) { 
     // Change file encoding to UTF8 
     util.log("Going to change file name of the file on SFTP prepending in_progress."); 
     sftpHandler.renameFileOnSftp(); 
    }, 
    function(callback) { 
     // Change file encoding to UTF8 
     util.log("Going to change file encoding to UTF8."); 
     readFileSync_encoding(configFile.importFileName, "ISO-8859-1", callback); 
    }, 
    function(fileData, callback) { 
     util.log("Parsing the file data."); 
     parseFileData(fileData, configFile, callback); 
    }], 
    // the bonus final callback function 
    function(err, status) { 
     if (err) { 
     // app has crashed 
     util.log(err); 
     return; 
     } 
     // keep looping with 1 min delay 
     util.log(status); 
     setTimeout(function() { 
     mainProcess(); 
     }, 60000); 
     return; 
    }); 
} 

而且downloadFile功能：

SftpHandler.prototype.downloadFile = function (path, callback) { 
    // Download swush file from SFTP 
    client.scp({ 
     'host': this.host, 
     'username': this.username, 
     'password': this.password, 
     'path': path 
     },'./', function(err) { 
     if (err) { 
      return callback("File: "+path+" "+err); 
     } else { 
      return callback(null); 
     } 
     }); 
}; 

和輸出：

29 Jul 11:58:01 - Main process started. 
29 Jul 11:58:01 - Running through all config files. Count: 3 
29 Jul 11:58:01 - Downloading config files.0 
29 Jul 11:58:01 - Downloading config files.1 
29 Jul 11:58:01 - Downloading config files.2 
29 Jul 11:58:02 - File: /E-drive/sftp/VismaReports/Test/QueueSystem/test2.csv Er 
ror: file does not exist 
29 Jul 11:58:03 - File: /E-drive/sftp/VismaReports/Test/QueueSystem/test5.csv Er 
ror: file does not exist 
29 Jul 11:58:03 - Going to change file name of the file on SFTP prepending in_pr 
ogress. 

我不希望看到Downloading config files.+i在實際下載發生之前看到那裏3次。在我看來，這是異步的，我不希望它是異步的。

Answer 1

for (var i=0; i<configFiles.length;i++){ 
     waterfallMain(configFiles[i],i); 
} 

您將異步代碼作爲同步運行。像下面這樣嘗試

async.eachSeries(configFiles, waterfallMain, function(err) { // sequence run 
    console.log((err) ? err.message : 'Done')}; 

    // Process error here 
}) 
... 
function waterfallMain(configFile, callback){ 
    async.waterfall([ 
      function(callback){ 
       util.log("Downloading config files.", configFiles); 
       sftpHandler.downloadFile(credentials.sftpPathToImportFiles+configFile.importFileName, callback); 
      }, 
      function(callback) { 
       util.log("Going to change file name of the file on SFTP prepending in_progress."); 
       sftpHandler.renameFileOnSftp(callback); // !!! You must call callback function to move next 
      }, 
      function(callback) { 
       util.log("Going to change file encoding to UTF8."); 
       readFileSync_encoding(configFile.importFileName, "ISO-8859-1", callback); // !!! Smth wrong readFileSync_encoding like sync-function. Why it call callback? 
      }, 
      function(fileData, callback) { 
       util.log("Parsing the file data."); 
       parseFileData(fileData, configFile, callback); 
      }], 
      callback // !!! simple call callback. Errors processing above. 
/* This function is not good 
     // the bonus final callback function 
     function(err, status) { // !!! what is status? Where it's set? 
      // app has crashed 
      if (err) 
       return util.log(err); // !!! shortly 

      // !!! WTF?! 
      // keep looping with 1 min delay 
      util.log(status); 
      setTimeout(function(){ 
       mainProcess(); 
      }, 60000); 
     } 
*/  
     ); 
}