From be086cf0056294bc5643bde3bb5b7b73aa4b362f Mon Sep 17 00:00:00 2001
From: Jesse Plamondon-Willard <Pathoschild@users.noreply.github.com>
Date: Wed, 22 Jun 2022 01:53:37 -0400
Subject: [PATCH] avoid unneeded overhead of ConcurrentQueue

---
 docs/release-notes.md               |  3 ++
 src/SMAPI/Framework/CommandQueue.cs | 47 +++++++++++++++++++++++++++++
 src/SMAPI/Framework/SCore.cs        | 43 +++++++++++++-------------
 3 files changed, 72 insertions(+), 21 deletions(-)
 create mode 100644 src/SMAPI/Framework/CommandQueue.cs

diff --git a/docs/release-notes.md b/docs/release-notes.md
index 16b47670..622a146a 100644
--- a/docs/release-notes.md
+++ b/docs/release-notes.md
@@ -8,6 +8,9 @@
 -->
 
 ## Upcoming release
+* For players:
+  * Minor optimizations.
+
 * For the web UI:
   * Fixed the mod count in the log parser metadata.
 
diff --git a/src/SMAPI/Framework/CommandQueue.cs b/src/SMAPI/Framework/CommandQueue.cs
new file mode 100644
index 00000000..c51016ad
--- /dev/null
+++ b/src/SMAPI/Framework/CommandQueue.cs
@@ -0,0 +1,47 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+
+namespace StardewModdingAPI.Framework
+{
+    /// <summary>A thread-safe command queue optimized for infrequent changes.</summary>
+    internal class CommandQueue
+    {
+        /********
+        ** Fields
+        ********/
+        /// <summary>The underlying list of queued commands to parse and execute.</summary>
+        private readonly List<string> RawCommandQueue = new();
+
+
+        /********
+        ** Public methods
+        ********/
+        /// <summary>Add a command to the queue.</summary>
+        /// <param name="command">The command to add.</param>
+        public void Add(string command)
+        {
+            lock (this.RawCommandQueue)
+                this.RawCommandQueue.Add(command);
+        }
+
+        /// <summary>Remove and return all queued commands, if any.</summary>
+        /// <param name="queued">The commands that were dequeued, in the order they were originally queued.</param>
+        /// <returns>Returns whether any values were dequeued.</returns>
+        [SuppressMessage("ReSharper", "InconsistentlySynchronizedField", Justification = "Deliberately check if it's empty before locking unnecessarily.")]
+        public bool TryDequeue([NotNullWhen(true)] out string[]? queued)
+        {
+            if (this.RawCommandQueue.Count is 0)
+            {
+                queued = null;
+                return false;
+            }
+
+            lock (this.RawCommandQueue)
+            {
+                queued = this.RawCommandQueue.ToArray();
+                this.RawCommandQueue.Clear();
+                return queued.Length > 0;
+            }
+        }
+    }
+}
diff --git a/src/SMAPI/Framework/SCore.cs b/src/SMAPI/Framework/SCore.cs
index ff3eadf5..cc332225 100644
--- a/src/SMAPI/Framework/SCore.cs
+++ b/src/SMAPI/Framework/SCore.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
@@ -147,8 +146,7 @@ namespace StardewModdingAPI.Framework
 #endif
 
         /// <summary>A list of queued commands to parse and execute.</summary>
-        /// <remarks>This property must be thread-safe, since it's accessed from a separate console input thread.</remarks>
-        private readonly ConcurrentQueue<string> RawCommandQueue = new();
+        private readonly CommandQueue RawCommandQueue = new();
 
         /// <summary>A list of commands to execute on each screen.</summary>
         private readonly PerScreen<List<QueuedCommand>> ScreenCommandQueue = new(() => new List<QueuedCommand>());
@@ -437,7 +435,7 @@ namespace StardewModdingAPI.Framework
                 () => this.LogManager.RunConsoleInputLoop(
                     commandManager: this.CommandManager,
                     reloadTranslations: this.ReloadTranslations,
-                    handleInput: input => this.RawCommandQueue.Enqueue(input),
+                    handleInput: input => this.RawCommandQueue.Add(input),
                     continueWhile: () => this.IsGameRunning && !this.CancellationToken.IsCancellationRequested
                 )
             ).Start();
@@ -525,29 +523,32 @@ namespace StardewModdingAPI.Framework
                 /*********
                 ** Parse commands
                 *********/
-                while (this.RawCommandQueue.TryDequeue(out string? rawInput))
+                if (this.RawCommandQueue.TryDequeue(out string[]? rawCommands))
                 {
-                    // parse command
-                    string? name;
-                    string[]? args;
-                    Command? command;
-                    int screenId;
-                    try
+                    foreach (string rawInput in rawCommands)
                     {
-                        if (!this.CommandManager.TryParse(rawInput, out name, out args, out command, out screenId))
+                        // parse command
+                        string? name;
+                        string[]? args;
+                        Command? command;
+                        int screenId;
+                        try
                         {
-                            this.Monitor.Log("Unknown command; type 'help' for a list of available commands.", LogLevel.Error);
+                            if (!this.CommandManager.TryParse(rawInput, out name, out args, out command, out screenId))
+                            {
+                                this.Monitor.Log("Unknown command; type 'help' for a list of available commands.", LogLevel.Error);
+                                continue;
+                            }
+                        }
+                        catch (Exception ex)
+                        {
+                            this.Monitor.Log($"Failed parsing that command:\n{ex.GetLogSummary()}", LogLevel.Error);
                             continue;
                         }
-                    }
-                    catch (Exception ex)
-                    {
-                        this.Monitor.Log($"Failed parsing that command:\n{ex.GetLogSummary()}", LogLevel.Error);
-                        continue;
-                    }
 
-                    // queue command for screen
-                    this.ScreenCommandQueue.GetValueForScreen(screenId).Add(new(command, name, args));
+                        // queue command for screen
+                        this.ScreenCommandQueue.GetValueForScreen(screenId).Add(new(command, name, args));
+                    }
                 }