是否有一种方法可以重构两个方法,一个调用等待方法,另一个调用普通方法

本文关键字:方法 调用 一个 另一个 两个 等待 重构 一种 是否 | 更新日期: 2023-09-27 17:54:34

我正在为一个网站构建一个缓存服务,我想提供一个公共接口,可以采用Func<TKey,TValue>Func<TKey,Task<TValue>>方法a,可以由服务调用缓存miss

在处理这两种委托类型时,我最终重复了代码。有办法合并吗?我特别担心'Func'方法不是线程安全的,并且不适合包装在'Task.Run'中。

下面是我的代码:
public interface ICacheServiceEngine
{
    Task<CacheResult<TValue>> TryGetValueAsync<TValue>(string key);
    Task<CacheResult<TValue>> 
        TryGetValueAsync<TKey,TValue>(TKey key, Func<TKey,string> keyFunc);
    Task<TValue> GetValueAsync<TValue>(string key, 
        Func<string, TValue> valueSourceFunc);
    Task<TValue> GetValueAsync<TKey,TValue>(TKey key, 
        Func<TKey,string> keyFunc, Func<TKey, TValue> valueSourceFunc);
    Task<TValue> GetValueAsync<TValue>(string key, 
        Func<string, Task<TValue>> valueSourceFuncAsync);
    Task<TValue> GetValueAsync<TKey, TValue>(TKey key, 
        Func<TKey,string> keyFunc, Func<TKey, Task<TValue>> valueSourceFuncAsync);
}
public interface ICacheServiceDataAccessor
{
    Task<CacheResult<TValue>> TryGetAsync<TValue>(string key);
    Task PutAsync<TValue>(string key , TValue result);
}

public class CacheServiceEngine : ICacheServiceEngine
{
    private ICacheServiceDataAccessor cacheDataAccessor;

    public CacheServiceEngine(ICacheServiceDataAccessor cacheDataAccessor)
    {   
        // add guard
        this.cacheDataAccessor = cacheDataAccessor;
    }

    public async Task<CacheResult<TValue>> TryGetValueAsync<TValue>(string key)
    {
        return await this.cacheDataAccessor.TryGetAsync<TValue>(key);
    }
    public async Task<CacheResult<TValue>> TryGetValueAsync<TKey,TValue>(TKey key, 
        Func<TKey,string> keyFunc)
    {
        string keyString = keyFunc(key);
        return await this.cacheDataAccessor.TryGetAsync<TValue>(keyString);
    }   
    public async Task<TValue> GetValueAsync<TValue>(string key, 
        Func<string, TValue> valueSourceFunc)
    {
        return await this.InnerGetValueAsync(key, () => valueSourceFunc(key));
    }
    public async Task<TValue> GetValueAsync<TKey,TValue>(TKey key, 
        Func<TKey,string> keyFunc, Func<TKey, TValue> valueSourceFunc)
    {
        string keyString = keyFunc(key);
        return await this.InnerGetValueAsync(keyString, () => valueSourceFunc(key));
    }
    public async Task<TValue> GetValueAsync<TValue>(string key, 
        Func<string, Task<TValue>> valueSourceFuncAsync)
    {
        return await this.InnerGetValueAsync(key, () => valueSourceFuncAsync(key));
    }
    public async Task<TValue> GetValueAsync<TKey, TValue>(TKey key, 
        Func<TKey,string> keyFunc, Func<TKey, Task<TValue>> valueSourceFuncAsync)
    {
        string keyString = keyFunc(key);
        return await this.InnerGetValueAsync(keyString, 
            () => valueSourceFuncAsync(key));
    }

    // the two private methods are very close to each other
    // can I pull out the similarities, if I assume that 'valueSourceFunc'
    // is not thread-safe?
    private async Task<TValue> InnerGetValueAsync<TValue>(string key, 
        Func<TValue> valueSourceFunc)
    {
        TValue value;
        CacheResult<TValue> cacheResult = 
            await this.cacheDataAccessor.TryGetAsync<TValue>(key);
        if (cacheResult.InCache)
        {
            value  = cacheResult.Value;
        }
        else
        {
            // this call is normal (synchronous)
            value = valueSourceFunc();
            await this.cacheDataAccessor.PutAsync(key, value);
        }
        return value;   
    }
    private async Task<TValue> InnerGetValueAsync<TValue>(string key, 
        Func<Task<TValue>> valueSourceFuncAsync)
    {
        TValue value;
        CacheResult<TValue> cacheResult = 
            await this.cacheDataAccessor.TryGetAsync<TValue>(key);
        if (cacheResult.InCache)
        {
            value  = cacheResult.Value;
        }
        else 
        {
            // this call has to be awaited
            value = await valueSourceFuncAsync();
            await this.cacheDataAccessor.PutAsync(key, value);
        }
        return value;
    }
}

是否有一种方法可以重构两个方法,一个调用等待方法,另一个调用普通方法

首先,您应该重新考虑您的ICacheServiceDataAccessor。当键不在缓存中时,完全有可能计算不必要的值。我建议这样写:

public interface ICacheServiceDataAccessor
{
  Task<CacheResult<TValue>> TryGetAsync<TValue>(string key);
  Task<CacheResult<TValue>> GetOrPutAsync<TValue>(string key, Func<Task<TValue>> result);
}

但是——暂时忽略这个问题——有一种方法可以将同步调用视为异步调用:Task.FromResult .

public Task<CacheResult<TValue>> TryGetValueAsync<TValue>(string key)
{
    return cacheDataAccessor.TryGetAsync<TValue>(key);
}
public Task<CacheResult<TValue>> TryGetValueAsync<TKey,TValue>(TKey key, 
    Func<TKey, string> keyFunc)
{
    string keyString = keyFunc(key);
    return cacheDataAccessor.TryGetAsync<TValue>(keyString);
}   
public Task<TValue> GetValueAsync<TValue>(string key, 
    Func<string, TValue> valueSourceFunc)
{
    return InnerGetValueAsync(key, () => Task.FromResult(valueSourceFunc(key)));
}
public Task<TValue> GetValueAsync<TKey,TValue>(TKey key, 
    Func<TKey,string> keyFunc, Func<TKey, TValue> valueSourceFunc)
{
    string keyString = keyFunc(key);
    return InnerGetValueAsync(keyString, () => Task.FromResult(valueSourceFunc(key)));
}
public Task<TValue> GetValueAsync<TValue>(string key, 
    Func<string, Task<TValue>> valueSourceFuncAsync)
{
    return InnerGetValueAsync(key, () => valueSourceFuncAsync(key));
}
public async Task<TValue> GetValueAsync<TKey, TValue>(TKey key, 
    Func<TKey,string> keyFunc, Func<TKey, Task<TValue>> valueSourceFuncAsync)
{
    string keyString = keyFunc(key);
    return InnerGetValueAsync(keyString, () => valueSourceFuncAsync(key));
}

作为最后的设计注意事项,我会考虑只将这些最通用的元素作为ICacheServiceEngine的实际成员。由于其他方法实际上只是该方法的重载(并且无论派生类如何都将具有相同的实现),因此可以将它们定义为ICacheServiceEngine上的扩展方法。