O_DIRECT alone only promises that the kernel will avoid copying data from user space to kernel space, and will instead write it directly via DMA (Direct memory access; if possible). Data does not go into caches. There is no strict guarantee that the function will return only after all data has been transferred. O_SYNC guarantees … Read more
The only time that you can wrap an async method in a synchronous one is when you don’t need to get a return value. For example if you want to disable the save button, save results to the server asynchronously and re-enable the save button when the job is done you can write it like … Read more
We modified midos answer to get it to work the following: function readFile(file){ return new Promise((resolve, reject) => { var fr = new FileReader(); fr.onload = () => { resolve(fr.result ) }; fr.onerror = reject; fr.readAsText(file.blob); }); }
The goal with node is not to care what order things happen in. This can complicate some scenarios. There is no shame in nesting callbacks. Once you are used to how it looks, you may find that you actually prefer that style. I do; it is very clear what order callbacks will fire. You can … Read more
deasync turns async function into sync, implemented with a blocking mechanism by calling Node.js event loop at JavaScript layer. As a result, deasync only blocks subsequent code from running without blocking entire thread, nor incuring busy wait. With this module, here is the answer to the jsFiddle challenge: function AnticipatedSyncFunction(){ var ret; setTimeout(function(){ ret = … Read more
To block the execution of the main thread until the operation completes, you could do [operation waitUntilFinished] after it’s added to the operation queue. In this case, you wouldn’t need the return in the block; setting the __block variable would be enough. That said, I’d strongly discourage forcing asynchronous operations to synchronous methods. It’s tricky … Read more
Use Promises. var mongoose = require(‘mongoose’); mongoose.connect(‘your MongoDB connection string’); var conn = mongoose.connection; var promises = [‘aaa’, ‘bbb’, ‘ccc’].map(function(name) { return new Promise(function(resolve, reject) { var collection = conn.collection(name); collection.drop(function(err) { if (err) { return reject(err); } console.log(‘dropped ‘ + name); resolve(); }); }); }); Promise.all(promises) .then(function() { console.log(‘all dropped)’); }) .catch(console.error); This drops … Read more
In many circumstances they are different names for the same thing, but in some contexts they are quite different. So it depends. Terminology is not applied in a totally consistent way across the whole software industry. For example in the classic sockets API, a non-blocking socket is one that simply returns immediately with a special … Read more
Try the WshShell object instead of the native Shell function. Dim wsh As Object Set wsh = VBA.CreateObject(“WScript.Shell”) Dim waitOnReturn As Boolean: waitOnReturn = True Dim windowStyle As Integer: windowStyle = 1 Dim errorCode As Long errorCode = wsh.Run(“notepad.exe”, windowStyle, waitOnReturn) If errorCode = 0 Then MsgBox “Done! No error to report.” Else MsgBox “Program … Read more
I’m curious as to whether all javascript callbacks are asynchronous No. For instance, the callback used by Array#sort is not asynchronous, nor is the one used by String#replace. The only way you know whether a callback is asynchronous is from its documentation. Typically, ones involving requests for external resources (ajax calls, for instance) are asynchronous, … Read more