/// <summary>
/// Gets the <see cref="IWebAgent"/> corresponding to the current user, or creates one if it doesn't exist.
/// </summary>
/// <param name="username">Username of Reddit user of <see cref="IWebAgent"/></param>
/// <param name="createAsync">Async function to return a new <see cref="RefreshTokenPoolEntry"/>. Parameters (<see cref="string"/> username, <see cref="string"/> default useragent, <see cref="RateLimitMode"/> default rate limit mode)</param>
/// <returns></returns>
public async Task <IWebAgent> GetOrCreateWebAgentAsync(string username, Func <string, string, RateLimitMode, Task <RefreshTokenPoolEntry> > createAsync, int requestsPerMinuteWithOAuth = 60, int requestsPerMinuteWithoutOAuth = 30)
{
if (string.IsNullOrWhiteSpace(username))
{
throw new ArgumentException("username cannot be null or empty");
}
var poolEnt = poolEntries.SingleOrDefault(a => a.Username.ToLower() == username.ToLower());
if (poolEnt == null)
{
await cacheLock.WaitAsync();
RefreshTokenWebAgent agent = null;
try
{
//check if someone else wrote it while waiting for lock.
poolEnt = poolEntries.SingleOrDefault(a => a.Username.ToLower() == username.ToLower());
if (poolEnt != null)
{
return(await GetWebAgentAsync(poolEnt, requestsPerMinuteWithOAuth, requestsPerMinuteWithoutOAuth));
}
poolEnt = await createAsync(username, DefaultUserAgent, DefaultRateLimitMode);
poolEntries.Add(poolEnt);
var opts = new MemoryCacheEntryOptions()
{
AbsoluteExpiration = null, SlidingExpiration = new TimeSpan(0, SlidingExpirationMinutes, 0)
};
opts.RegisterPostEvictionCallback(UpdateAgentInfoOnCacheRemove);
agent = new RefreshTokenWebAgent(poolEnt.RefreshToken, ClientID, ClientSecret, RedirectURI, poolEnt.UserAgentString, poolEnt.AccessToken, poolEnt.TokenExpires, new RateLimitManager(poolEnt.RateLimiterMode));
activeAgentsCache.Set(poolEnt.WebAgentID, agent, opts);
return(agent);
}
finally
{
cacheLock.Release();
}
}
return(await GetWebAgentAsync(poolEnt, requestsPerMinuteWithOAuth, requestsPerMinuteWithoutOAuth));
}
private void UpdateAgentInfoOnCacheRemove(object key, object value, EvictionReason reason, object state)
{
Guid webAgentID = (Guid)key;
var poolEnt = poolEntries.SingleOrDefault(a => a.WebAgentID == webAgentID);
RefreshTokenWebAgent agent = value as RefreshTokenWebAgent;
if (agent == null || poolEnt == null)
{
return;
}
poolEnt.TokenExpires = agent.TokenValidTo;
poolEnt.AccessToken = agent.AccessToken;
poolEnt.UserAgentString = agent.UserAgent;
poolEnt.RefreshToken = agent.RefreshToken;
poolEnt.RateLimiterMode = agent.RateLimiter.Mode;
}
private async Task <IWebAgent> GetWebAgentAsync(RefreshTokenPoolEntry poolEnt, int requestsPerMinuteWithOAuth, int requestsPerMinuteWithoutOAuth)
{
IWebAgent toReturn = null;
if (poolEnt != null)
{
toReturn = activeAgentsCache.Get <IWebAgent>(poolEnt.WebAgentID);
if (toReturn == null)
{
await cacheLock.WaitAsync();
RefreshTokenWebAgent agent = null;
try
{
//check if someone else wrote it while waiting for lock.
agent = activeAgentsCache.Get <RefreshTokenWebAgent>(poolEnt.WebAgentID);
if (agent != null)
{
return(agent);
}
var opts = new MemoryCacheEntryOptions()
{
AbsoluteExpiration = null, SlidingExpiration = new TimeSpan(0, SlidingExpirationMinutes, 0)
};
opts.RegisterPostEvictionCallback(UpdateAgentInfoOnCacheRemove);
agent = new RefreshTokenWebAgent(poolEnt.RefreshToken, ClientID, ClientSecret, RedirectURI, poolEnt.UserAgentString, poolEnt.AccessToken, poolEnt.TokenExpires, new RateLimitManager(poolEnt.RateLimiterMode, requestsPerMinuteWithOAuth, requestsPerMinuteWithoutOAuth));
activeAgentsCache.Set(poolEnt.WebAgentID, agent, opts);
return(agent);
}
finally
{
cacheLock.Release();
}
}
}
return(toReturn);
}