MMORPG通用成就系统两种表达式树方案求评估及替代建议

Hey fellow devs! Let me walk through my current progress on a universal achievement system for an MMORPG, and get your take on two expression tree approaches I'm weighing for filtering logic.

Project Background #

I'm building a code-free, designer-friendly achievement system for an MMORPG. The core idea is to use configuration files to define achievements, which map to event type enums and support optional filter parameters. Here's a sample config:

name: ACHIEVEMENT_NAME
event_type: ITEM_USAGE # String representation of the event enum
count: 30 # Requirement: Use an item 30 times
args: # Optional filter parameters
  item_vnum: 1127 # Target item VNum
  map_id: 1 # Only trigger on map ID 1

And here's the corresponding C# code structure:

public enum AchievementEventType { ITEM_USED, MONSTER_KILLED, }
public interface IAchievementArgument { AchievementEventType EventType { get;} }
public class MonsterKilledAchievementArgument : IAchievementArgument 
{ 
    public AchievementEventType EventType => AchievementEventType.MONSTER_KILLED; 
    public long MonsterVnum { get; set; } 
    public short? MapId { get; set; } 
}
public class AchievementConfiguration 
{ 
    public string Name { get; set; } 
    public string EventType { get; set; } 
    public long Count { get; set; } 
    public Dictionary<string, object>? Args { get; set; } 
}
public delegate bool AchievementFilter(IAchievementArgument achievementArgument);

Core Problem: Choosing Expression Tree Approach for AchievementFilter #

I plan to generate expression trees to build the AchievementFilter delegate, which determines whether a player's achievement counter should increment. I've got two competing approaches, each with tradeoffs, and I'm looking for external input on which to pick—or if there's a better middle ground.

Approach 1: One Expression Tree Per Achievement #

• How it works: Generate a custom expression tree for every single achievement. The tree directly compares the incoming IAchievementArgument against that achievement's specific config parameters.
• Pros: Blazing fast execution. Each achievement has a tailored delegate with no extra iteration overhead—just direct condition checks.
• Cons: Higher memory footprint. If the game ends up with hundreds or thousands of achievements, each holding its own delegate instance, memory usage can add up over time.

Approach 2: One Expression Tree Per IAchievementArgument Type #

• How it works: Create a single, generic expression tree for each event argument type (e.g., MonsterKilledAchievementArgument). At runtime, it iterates through all key-value pairs in the achievement's Args config and checks if they match the incoming argument's properties.
• Pros: Minimal memory usage. All achievements sharing the same event type reuse the same delegate, cutting down on instance count drastically.
• Cons: Slower execution. Every filter check requires looping through all configured parameters, which adds overhead—especially if an achievement has many optional args.

Looking for Community Input #

I'd love to hear your thoughts:

1. For a typical MMORPG scenario (lots of achievements, but not ultra-high frequency of filter checks), which approach makes more sense?
2. Is there a hybrid optimization that balances memory and performance? For example, caching expression trees for common parameter combinations?

内容的提问来源于stack exchange，提问作者Blowa