asynchronous

问题 I'm learning about JavaScript and Node. I understand how asynchronous stuff works. I get why it could significantly speed things up. I see that other languages (like Ruby and Java?) are designed to be blocking. Why? I have a vague idea that you could use threads to handle situations where things take a long time. What are the advantages and disadvantages to this over doing things asynchronously? 回答1: Blocking, or synchronous code is easy to write, and the default single threaded behavior.

问题 Does async/await have an extra cost associated when returning early from the method compared to the synchronous method? Take these examples: public async Task<bool> TryDoSomethingAsync() { if ( Is99PercentOfTheCases() ) return false; // does this path... await DoSomethingAsync(); return true; } // versus public bool TryDoSomething() { if ( Is99PercentOfTheCases() ) return false; // ...have the same cost as this path? DoSomething(); return true; } I know async/await has an extra cost

问题 What is the idiomatically correct way to mutate a dictionary/other collection asynchronously in Swift? The following type of situation often arises while coding: func loadData(key: String, dict: inout [String: String]) { // Load some data. Use DispatchQueue to simulate async request DispatchQueue.main.async { dict[key] = "loadedData" } } var dict = [String:String]() for x in ["a", "b", "c"] { loadData(key: x, dict: &dict) } Here, I am loading some data asynchronously and adding it to a

问题 I need to be sure that a method accessed via a web API cannot be accessed by multiple call at the same time if it work on the same object with the same id I understand the use of SemaphoreSlim but a simple implemetation of that will lock the critical section for all. But I need that section locked only if it works on the same entity and not on 2 different This is my scenario, an user start to work, the entity is created and is ready to be modified, then one or more user can manipulate this

问题 Probably I have here 2 questions instead of one, but anyway. I'm implementing cooperative cancellation as here suggested. Here is my test code: type Async with static member Isolate(f : CancellationToken -> Async<'T>) : Async<'T> = async { let! ct = Async.CancellationToken let isolatedTask = Async.StartAsTask(f ct) return! Async.AwaitTask isolatedTask } let testLoop (ct: CancellationToken) = async { let rec next ix = if ct.IsCancellationRequested then () else printf "%i.." ix Thread.Sleep 10

问题 I have already seen this, but I am experiencing another problem. I have this service class for managing ASP.NET identity roles: public class RoleService : IRoleService { private readonly RoleManager<ApplicationRole> _roleManager; public RoleService(RoleManager<ApplicationRole> roleManager) { this._roleManager = roleManager; } public async Task<IdentityResult> CreateAsync(ApplicationRole role) { return await this._roleManager.CreateAsync(role); } } As suggested by this question, I use the

问题 Here is my function in songAction.js export function createSong(title, url, token) { axios.defaults.headers.common['Authorization'] = token return function (dispatch) { axios.post('http://localhost:8080/api/song/create', { title, link: url }) .then((response) => { console.log('the response was', response) if(response.data.success){ dispatch({type: "CREATE_SONG_FULFILLED", payload: response.data.song}) } else { dispatch({type: "CREATE_SONG_REJECTED", payload: response.data}) } }) .catch((err)

问题 I have already seen this, but I am experiencing another problem. I have this service class for managing ASP.NET identity roles: public class RoleService : IRoleService { private readonly RoleManager<ApplicationRole> _roleManager; public RoleService(RoleManager<ApplicationRole> roleManager) { this._roleManager = roleManager; } public async Task<IdentityResult> CreateAsync(ApplicationRole role) { return await this._roleManager.CreateAsync(role); } } As suggested by this question, I use the

问题 I am trying to use nock to intercept/mock some HTTP traffic in my application for testing purposes. Our app authenticates to another one of our sites, and I need nock to imitate an HTTP 200 (with JSON data) and an HTTP 401 (with no data) to test behaviors when the user is or isn't logged in there (respectively). I have two tests which both work correctly when run alone, but if I run the entire test suite, one of them always fails. I realize that nock is shared state because it modifies how

问题 The scenario is the following: Backend: Asp.NET Core WebAPI 2.2 Frontend: iOS and Android which consumes the API I have a function allowing the user to send messages to other users. The sending of a message is done in an asynchronous action: public async Task<IActionResult> CreateMessage This action does the following in order: Validation Awaits persistance of the message to DB Awaits the notification of relevant clients via SignalR Doesn't await the sending of push notification via Azure