async-await

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 I want to return the consolidated results from calling many async/await functions. Consider my (wrong) pseudocode below const getRemoteData = async function(uri) { // get result from remote server via XMLHttpRequest return result; } const finalResult {}; const result1 = getRemoteData('http://…'); result1.forEach(async record => { // each record has a key for another URI const result2 = await getRemoteData(record["uri"]); // result2 has a key for yet another URI const result3 = await

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 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 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 want to create a simple websocket server. I want to process the incoming messages and send a response, but I get an error: error: captured variable cannot escape `FnMut` closure body --> src\main.rs:32:27 | 32 | incoming.for_each(|m| async { | _________________________-_^ | | | | | inferred to be a `FnMut` closure 33 | | match m { 34 | | // Error here... 35 | | Ok(message) => do_something(message, db, &mut outgoing).await, 36 | | Err(e) => panic!(e) 37 | | } 38 | | }).await; | |_____^

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

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

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

问题 I'm using Polly to make parallel API calls. The server however can't process more than 25 calls per second and so I'm wondering if there is a way to add a 1s delay after each batch of 25 calls? var policy = Policy .Handle<HttpRequestException>() .RetryAsync(3); foreach (var mediaItem in uploadedMedia) { var mediaRequest = new HttpRequestMessage { *** } async Task<string> func() { var response = await client.SendAsync(mediaRequest); return await response.Content.ReadAsStringAsync(); } tasks