PluralKit/PluralKit.Bot/Utils/MiscUtils.cs

using System.Net.Sockets;

using Myriad.Rest.Exceptions;

using Newtonsoft.Json;

using Npgsql;

using PluralKit.Core;

using Polly.Timeout;

namespace PluralKit.Bot;

public static class MiscUtils
{
    public static string ProxyTagsString(this PKMember member, string separator = ", ") =>
        string.Join(separator, member.ProxyTags.Select(t => t.ProxyString.AsCode()));

    public static bool IsOurProblem(this Exception e)
    {
        // This function filters out sporadic errors out of our control from being reported to Sentry
        // otherwise we'd blow out our error reporting budget as soon as Discord takes a dump, or something.

        // Occasionally Discord's API will Have A Bad Time and return a bunch of CloudFlare errors (in HTML format).
        // The library tries to parse these HTML responses as JSON and crashes with a consistent exception message.
        if (e is JsonReaderException jre && jre.Message ==
            "Unexpected character encountered while parsing value: <. Path '', line 0, position 0.") return false;

        // And now (2020-05-12), apparently Discord returns these weird responses occasionally. Also not our problem.
        if (e is BadRequestException bre && bre.ResponseBody.Contains("<center>nginx</center>")) return false;
        if (e is NotFoundException ne && ne.ResponseBody.Contains("<center>nginx</center>")) return false;
        if (e is UnauthorizedException ue && ue.ResponseBody.Contains("<center>nginx</center>")) return false;

        // Filter out timeout/ratelimit related stuff
        if (e is TooManyRequestsException) return false;
        if (e is RatelimitBucketExhaustedException) return false;
        if (e is TimeoutRejectedException) return false;

        // 5xxs? also not our problem :^)
        if (e is UnknownDiscordRequestException udre && (int)udre.StatusCode >= 500) return false;

        // Webhook server errors are also *not our problem*
        // (this includes rate limit errors, WebhookRateLimited is a subclass)
        if (e is WebhookExecutionErrorOnDiscordsEnd) return false;

        // Socket errors are *not our problem*
        if (e.GetBaseException() is SocketException) return false;

        // Tasks being cancelled for whatver reason are, you guessed it, also not our problem.
        if (e is TaskCanceledException) return false;

        // Sometimes Discord just times everything out.
        if (e is TimeoutException) return false;

        // HTTP/2 streams are complicated and break sometimes.
        if (e is HttpRequestException) return false;

        // Ignore "Database is shutting down" error
        if (e is PostgresException pe && pe.SqlState == "57P03") return false;

        // Ignore database timing out as well.
        if (e is NpgsqlException tpe && tpe.InnerException is TimeoutException)
            return false;

        // Ignore thread pool exhaustion errors
        if (e is NpgsqlException npe && npe.Message.Contains("The connection pool has been exhausted"))
            return false;

        // This may expanded at some point.
        return true;
    }
}