private void StartBackgroundFetch <T>(string key, Func <Task <T> > func, TinyCachePolicy policy, Action <T> onUpdate)
{
if (policy.UpdateCacheTimeout > 0)
{
if (ShouldFetch(policy.UpdateCacheTimeout, key))
{
#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
Task.Delay((int)policy.UpdateCacheTimeout).ContinueWith(async(arg) =>
{
try
{
var newvalue = await TimeoutAfter <T>(func, policy.BackgroundFetchTimeout);
onUpdate?.Invoke(newvalue);
Store(key, newvalue, policy);
}
catch (Exception ex)
{
if (policy.ReportExceptionsOnBackgroundFetch)
{
OnError?.Invoke(policy, ex);
policy.ExceptionHandler?.Invoke(ex, true);
}
}
});
}
#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
}
}
/// <summary>
/// Fetch using policy
/// </summary>
/// <returns>The data from function or cache depending on policy.</returns>
/// <param name="key">Cache key.</param>
/// <param name="func">Function for populating cache</param>
/// <param name="policy">Policy.</param>
/// <param name="onUpdate">Method to call when data is updated in the background.</param>
/// <typeparam name="T">Return type of function and cache object.</typeparam>
public async Task <T> RunAsync <T>(string key, Func <Task <T> > func, TinyCachePolicy policy = null, Action <T> onUpdate = null)
{
var genericType = typeof(T);
object ret = Storage.Get(key, genericType);
if (ret == null && SecondaryStorage != null)
{
ret = SecondaryStorage.Get(key, genericType);
}
policy = policy ?? defaultPolicy;
if (ret == null)
{
ret = await func();
Store(key, ret, policy);
}
else if (policy.UseCacheFirstFunction == null || !policy.UseCacheFirstFunction())
{
if (policy.Mode == TinyCacheModeEnum.FetchFirst)
{
try
{
var realFetch = await TimeoutAfter(func, policy.FetchTimeout);
if (!(realFetch is T))
{
ret = realFetch;
Store(key, realFetch, policy);
}
}
catch (Exception ex)
{
OnError?.Invoke(policy, ex);
policy.ExceptionHandler?.Invoke(ex, true);
}
}
}
StartBackgroundFetch(key, func, policy, onUpdate);
AddLastFetch(key);
return((ret == null) ? default(T) : (T)ret);
}
private void Store(string key, object val, TinyCachePolicy policy)
{
if (val != null)
{
AddLastFetch(key);
if (Storage.Store(key, val))
{
policy?.UpdateHandler?.Invoke(key, val);
OnUpdate?.Invoke(val, new CacheUpdatedEvt(key, val));
if (SecondaryStorage != null)
{
Task.Delay(10).ContinueWith((a) =>
{
SecondaryStorage.Store(key, val, false);
});
}
}
}
}
/// <summary>
/// Sets the base policy wich will be used if not specified in each request.
/// </summary>
/// <param name="tinyCachePolicy">Tiny cache policy.</param>
public void SetBasePolicy(TinyCachePolicy tinyCachePolicy)
{
defaultPolicy = tinyCachePolicy;
}