using System; using System.Collections.Generic; using System.Linq; using System.Reflection; using StardewModdingAPI.Events; using StardewModdingAPI.Internal; namespace StardewModdingAPI.Framework.Events { /// <summary>An event wrapper which intercepts and logs errors in handler code.</summary> /// <typeparam name="TEventArgs">The event arguments type.</typeparam> internal class ManagedEvent<TEventArgs> : IManagedEvent { /********* ** Fields *********/ /// <summary>The mod registry with which to identify mods.</summary> protected readonly ModRegistry ModRegistry; /// <summary>The underlying event handlers.</summary> private readonly List<ManagedEventHandler<TEventArgs>> Handlers = new List<ManagedEventHandler<TEventArgs>>(); /// <summary>A cached snapshot of <see cref="Handlers"/>, or <c>null</c> to rebuild it next raise.</summary> private ManagedEventHandler<TEventArgs>[] CachedHandlers = new ManagedEventHandler<TEventArgs>[0]; /// <summary>The total number of event handlers registered for this events, regardless of whether they're still registered.</summary> private int RegistrationIndex; /// <summary>Whether new handlers were added since the last raise.</summary> private bool HasNewHandlers; /********* ** Accessors *********/ /// <summary>A human-readable name for the event.</summary> public string EventName { get; } /// <summary>Whether the event is typically called at least once per second.</summary> public bool IsPerformanceCritical { get; } /********* ** Public methods *********/ /// <summary>Construct an instance.</summary> /// <param name="eventName">A human-readable name for the event.</param> /// <param name="modRegistry">The mod registry with which to identify mods.</param> /// <param name="isPerformanceCritical">Whether the event is typically called at least once per second.</param> public ManagedEvent(string eventName, ModRegistry modRegistry, bool isPerformanceCritical = false) { this.EventName = eventName; this.ModRegistry = modRegistry; this.IsPerformanceCritical = isPerformanceCritical; } /// <summary>Get whether anything is listening to the event.</summary> public bool HasListeners() { return this.Handlers.Count > 0; } /// <summary>Add an event handler.</summary> /// <param name="handler">The event handler.</param> /// <param name="mod">The mod which added the event handler.</param> public void Add(EventHandler<TEventArgs> handler, IModMetadata mod) { lock (this.Handlers) { EventPriority priority = handler.Method.GetCustomAttribute<EventPriorityAttribute>()?.Priority ?? EventPriority.Normal; var managedHandler = new ManagedEventHandler<TEventArgs>(handler, this.RegistrationIndex++, priority, mod); this.Handlers.Add(managedHandler); this.CachedHandlers = null; this.HasNewHandlers = true; } } /// <summary>Remove an event handler.</summary> /// <param name="handler">The event handler.</param> public void Remove(EventHandler<TEventArgs> handler) { lock (this.Handlers) { // match C# events: if a handler is listed multiple times, remove the last one added for (int i = this.Handlers.Count - 1; i >= 0; i--) { if (this.Handlers[i].Handler != handler) continue; this.Handlers.RemoveAt(i); this.CachedHandlers = null; break; } } } /// <summary>Raise the event and notify all handlers.</summary> /// <param name="args">The event arguments to pass.</param> /// <param name="match">A lambda which returns true if the event should be raised for the given mod.</param> public void Raise(TEventArgs args, Func<IModMetadata, bool> match = null) { // skip if no handlers if (this.Handlers.Count == 0) return; // update cached data // (This is debounced here to avoid repeatedly sorting when handlers are added/removed, // and keeping a separate cached list allows changes during enumeration.) var handlers = this.CachedHandlers; // iterate local copy in case a mod adds/removes a handler while handling the event, which will set this field to null if (handlers == null) { lock (this.Handlers) { if (this.HasNewHandlers && this.Handlers.Any(p => p.Priority != EventPriority.Normal)) this.Handlers.Sort(); this.CachedHandlers = handlers = this.Handlers.ToArray(); this.HasNewHandlers = false; } } // raise event foreach (ManagedEventHandler<TEventArgs> handler in handlers) { if (match != null && !match(handler.SourceMod)) continue; try { handler.Handler.Invoke(null, args); } catch (Exception ex) { this.LogError(handler, ex); } } } /********* ** Private methods *********/ /// <summary>Log an exception from an event handler.</summary> /// <param name="handler">The event handler instance.</param> /// <param name="ex">The exception that was raised.</param> protected void LogError(ManagedEventHandler<TEventArgs> handler, Exception ex) { handler.SourceMod.LogAsMod($"This mod failed in the {this.EventName} event. Technical details: \n{ex.GetLogSummary()}", LogLevel.Error); } } }