CSHARP-941: Change default GridFS chunk size from 256KiB to 255KiB.

Author: rstam

MongoDB.Driver/GridFS/MongoGridFSSettings.cs

@@ -47,7 +47,7 @@ static MongoGridFSSettings()
         {
             __defaults = new MongoGridFSSettings
             {
-                ChunkSize = 256 * 1024, // 256KiB
+                ChunkSize = 255 * 1024, // 255KiB
                 Root = "fs",
                 UpdateMD5 = true,
                 VerifyMD5 = true

MongoDB.DriverUnitTests/GridFS/MongoGridFSSettingsTests.cs

@@ -35,7 +35,7 @@ public void TestFixtureSetup()
         public void TestDefaults()
         {
             var settings = MongoGridFSSettings.Defaults;
-            Assert.AreEqual(256 * 1024, settings.ChunkSize);
+            Assert.AreEqual(255 * 1024, settings.ChunkSize);
             Assert.AreEqual("fs", settings.Root);
             Assert.AreEqual(true, settings.UpdateMD5);
             Assert.AreEqual(true, settings.VerifyMD5);

MongoDB.DriverUnitTests/GridFS/MongoGridFSTests.cs

@@ -185,7 +185,7 @@ public void TestDownloadDontVerifyMD5()
         public void TestDownloadTwoChunks()
         {
             _gridFS.Delete(Query.Null);
-            var contents = new string('x', 256 * 1024) + new string('y', 256 * 1024);
+            var contents = new string('x', 255 * 1024) + new string('y', 255 * 1024);
             var bytes = Encoding.UTF8.GetBytes(contents);
             var stream = new MemoryStream(bytes);
             var fileInfo = _gridFS.Upload(stream, "TwoChunks.txt");