Instead of exposing ExpectContinue set it automatically based on a threshold

Author: reversefold

src/BizHawk.Client.Common/Api/HttpCommunication.cs

@@ -20,7 +20,7 @@ public sealed class HttpCommunication
 
 		public int Timeout { get; set; }
 
-		public bool ExpectContinue { get; set; } = true;
+		public int ExpectContinueThreshold { get; set; } = 1024 * 1024; // 1MB
 
 		public HttpCommunication(Func<byte[]> takeScreenshotCallback, string getURL, string postURL)
 		{
@@ -32,10 +32,14 @@ public HttpCommunication(Func<byte[]> takeScreenshotCallback, string getURL, str
 
 		public string ExecGet(string url = null) => Get(url ?? GetUrl).Result;
 
-		public string ExecPost(string url = null, string payload = "") => Post(
-			url ?? PostUrl,
-			new FormUrlEncodedContent(new Dictionary<string, string> { ["payload"] = payload })
-		).Result;
+		public string ExecPost(string url = null, string payload = "")
+		{
+			_client.DefaultRequestHeaders.ExpectContinue = payload.Length > ExpectContinueThreshold;
+			return Post(
+				url ?? PostUrl,
+				new FormUrlEncodedContent(new Dictionary<string, string> { ["payload"] = payload })
+			).Result;
+		}
 
 		public async Task<string> Get(string url)
 		{
@@ -51,7 +55,6 @@ public async Task<string> Get(string url)
 		public async Task<string> Post(string url, FormUrlEncodedContent content)
 		{
 			_client.DefaultRequestHeaders.ConnectionClose = true;
-			_client.DefaultRequestHeaders.ExpectContinue = ExpectContinue;
 			HttpResponseMessage response;
 			try
 			{

src/BizHawk.Client.Common/lua/CommonLibs/CommLuaLibrary.cs

@@ -231,13 +231,6 @@ public void HttpSetGetUrl(string url)
 			APIs.Comm.HTTP.GetUrl = url;
 		}
 
-		[LuaMethod("httpSetExpectContinue", "Set ExpectContinue boolean to an explicit value")]
-		public void HttpSetExpectContinue(bool value)
-		{
-			CheckHttp();
-			APIs.Comm.HTTP.ExpectContinue = value;
-		}
-
 		[LuaMethod("httpGetPostUrl", "Gets HTTP POST URL")]
 		public string HttpGetPostUrl()
 		{
@@ -252,13 +245,6 @@ public string HttpGetGetUrl()
 			return APIs.Comm.HTTP?.GetUrl;
 		}
 
-		[LuaMethod("httpGetExpectContinue", "Get ExpectContinue value")]
-		public bool HttpGetExpectContinue()
-		{
-			CheckHttp();
-			return APIs.Comm.HTTP.ExpectContinue;
-		}
-
 		private void CheckHttp()
 		{
 			if (APIs.Comm.HTTP == null)