async-await method (Wait for response)

Question

I use async method follow this code:

    public string TryForGetToken()
    {
        cache = getCache;
        if (!cache.Contains(keyToken))
        {
            CacheItemPolicy cacheItemPolicy = new CacheItemPolicy();
            TryForLogin();
            cacheItemPolicy.AbsoluteExpiration = DateTime.Now.AddSeconds(expiredTime - 60);
            CacheItem item = new CacheItem(keyToken, publicToken);
            //cache.Add(item, cacheItemPolicy);
            return publicToken;
        }
        else
            return cache.Get(keyToken).ToString();
    }

and

    public async Task TryForLogin()
    {
        await _semaphore.WaitAsync();
        try
        {
            AuthenticationData authenticationData = new AuthenticationData() { email = "zzzzzz", password = "zzzzzzzz" };
            ResponseResult result = await httpServiceCaller.PostJsonAsync<AuthenticationData, ResponseResult>("http://sample.com/agent/login", authenticationData, new CancellationToken(), "Login");
            publicToken = result.data.token.access_token;
            expiredTime = result.data.token.expires_in;
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
            throw;
        }
        finally
        {
            _semaphore.Release();
        }
    }

So after call postJsonAsync method and after that don`t fill publicToken if I use wait for this vs crash and closed. Do you have idea for this ?

vs crashed in unrelated: instead, result is filled correctly? — Emanuele, May 11 '20 at 08:02
You may find this question interesting: [Async threadsafe Get from MemoryCache](https://stackoverflow.com/questions/31831860/async-threadsafe-get-from-memorycache) — Theodor Zoulias, May 11 '20 at 10:32

score 6 · Accepted Answer · edited May 13 '20 at 20:55

6

Simply because the TryForGetToken finishes before TryForLogin assign value to publicToken variable. You are not awaiting Task that is returned from TryForLogin method.

You should rewrite TryForGetToken to be async Task<string> and then await TryForLogin()

edited May 13 '20 at 20:55

Theodor Zoulias

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answered May 11 '20 at 08:03

Tomas Chabada

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score 3 · Answer 2 · answered May 11 '20 at 08:03

I'm not completely sure what are you asking for but it seems you miss awaiting the TryForLogin method.

 public async Task<string> TryForGetToken()
    {
        cache = getCache;
        if (!cache.Contains(keyToken))
        {
            CacheItemPolicy cacheItemPolicy = new CacheItemPolicy();
            await TryForLogin();
            cacheItemPolicy.AbsoluteExpiration = DateTime.Now.AddSeconds(expiredTime - 60);
            CacheItem item = new CacheItem(keyToken, publicToken);
            //cache.Add(item, cacheItemPolicy);
            return publicToken;
        }
        else
            return cache.Get(keyToken).ToString();
    }

async-await method (Wait for response)

2 Answers2