Remove Net5CompatFileStreamStrategy. (#57735)

Author: teo-tsirpanis

src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs

@@ -312,12 +312,6 @@ private static Version GetICUVersion()
                               version & 0xFF);
         }
 
-        private static readonly Lazy<bool> _net5CompatFileStream = new Lazy<bool>(() => GetStaticNonPublicBooleanPropertyValue("System.IO.Strategies.FileStreamHelpers", "UseNet5CompatStrategy"));
-
-        public static bool IsNet5CompatFileStreamEnabled => _net5CompatFileStream.Value;
-
-        public static bool IsNet5CompatFileStreamDisabled => !IsNet5CompatFileStreamEnabled;
-
         private static readonly Lazy<bool> s_fileLockingDisabled = new Lazy<bool>(() => GetStaticNonPublicBooleanPropertyValue("Microsoft.Win32.SafeHandles.SafeFileHandle", "DisableFileLocking"));
 
         public static bool IsFileLockingEnabled => IsWindows || !s_fileLockingDisabled.Value;

src/libraries/System.IO.FileSystem/System.IO.FileSystem.sln

@@ -21,8 +21,6 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.FileSystem.Disabl
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.FileSystem.Manual.Tests", "tests\ManualTests\System.IO.FileSystem.Manual.Tests.csproj", "{534152EB-14A8-4EF4-B181-342A555337F1}"
 EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.FileSystem.Net5Compat.Tests", "tests\Net5CompatTests\System.IO.FileSystem.Net5Compat.Tests.csproj", "{48E07F12-8597-40DE-8A37-CCBEB9D54012}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.FileSystem.Tests", "tests\System.IO.FileSystem.Tests.csproj", "{3A8E16D3-8A22-4076-BB48-2CD1FBFAF81B}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.Runtime.CompilerServices.Unsafe", "..\System.Runtime.CompilerServices.Unsafe\ref\System.Runtime.CompilerServices.Unsafe.csproj", "{79A74577-C550-4264-B352-51D304796B89}"

src/libraries/System.IO.FileSystem/tests/FileStream/ReadAsync.cs

@@ -101,7 +101,7 @@ public async Task ReadAsyncCanceledFile(int bufferSize, bool isAsync)
             }
         }
 
-        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported), nameof(PlatformDetection.IsNet5CompatFileStreamDisabled))]
+        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
         [InlineData(FileShare.None, FileOptions.Asynchronous)] // FileShare.None: exclusive access
         [InlineData(FileShare.ReadWrite, FileOptions.Asynchronous)] // FileShare.ReadWrite: others can write to the file, the length can't be cached
         [InlineData(FileShare.None, FileOptions.None)]

src/libraries/System.IO.FileSystem/tests/FileStream/SafeFileHandle.cs

@@ -65,89 +65,5 @@ public void AccessFlushesFileClosesHandle()
                 Assert.Equal(TestBuffer.Length, fsr.Length);
             }
         }
-
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNet5CompatFileStreamEnabled))]
-        public async Task ThrowWhenHandlePositionIsChanged_sync()
-        {
-            await ThrowWhenHandlePositionIsChanged(useAsync: false);
-        }
-
-        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported), nameof(PlatformDetection.IsNet5CompatFileStreamEnabled))]
-        public async Task ThrowWhenHandlePositionIsChanged_async()
-        {
-            await ThrowWhenHandlePositionIsChanged(useAsync: true);
-        }
-
-        private async Task ThrowWhenHandlePositionIsChanged(bool useAsync)
-        {
-            string fileName = GetTestFilePath();
-
-            using (FileStream fs = new FileStream(fileName, FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite, 0x100, useAsync))
-            {
-                // write some data to move the position, flush to ensure OS position is updated
-                fs.Write(TestBuffer, 0, TestBuffer.Length);
-                fs.Flush();
-
-                if (fs.SafeFileHandle.IsInvalid)
-                {
-                    // nothing to test
-                    return;
-                }
-
-                using (FileStream fsr = new FileStream(fs.SafeFileHandle, FileAccess.Read, TestBuffer.Length, useAsync))
-                {
-                    Assert.Equal(TestBuffer.Length, fs.Position);
-                    Assert.Equal(TestBuffer.Length, fsr.Position);
-
-                    // Operations on original filestream will fail if data is in buffer and position changes.
-
-                    // Put data in FS write buffer and update position from FSR
-                    fs.WriteByte(0);
-                    fsr.Position = 0;
-
-                    if (useAsync
-                        // Async I/O behaviors differ due to kernel-based implementation on Windows
-                        && OperatingSystem.IsWindows()
-                        // ReadAsync which in this case (single byte written to buffer) calls FlushAsync is now 100% async
-                        // so it does not complete synchronously anymore
-                        && PlatformDetection.IsNet5CompatFileStreamEnabled) 
-                    {
-                        Assert.Throws<IOException>(() => FSAssert.CompletesSynchronously(fs.ReadAsync(new byte[1], 0, 1)));
-                    }
-                    else
-                    {
-                        await Assert.ThrowsAsync<IOException>(() => fs.ReadAsync(new byte[1], 0, 1));
-                    }
-
-                    fs.WriteByte(0);
-                    fsr.Position++;
-                    Assert.Throws<IOException>(() => fs.Read(new byte[1], 0, 1));
-
-                    fs.WriteByte(0);
-                    fsr.Position++;
-                    await Assert.ThrowsAsync<IOException>(() => fs.ReadAsync(new byte[1], 0, 1));
-
-                    fs.WriteByte(0);
-                    fsr.Position++;
-                    Assert.Throws<IOException>(() => fs.ReadByte());
-
-                    fs.WriteByte(0);
-                    fsr.Position++;
-                    Assert.Throws<IOException>(() => fs.Seek(0, SeekOrigin.End));
-
-                    fs.WriteByte(0);
-                    fsr.Position++;
-                    Assert.Throws<IOException>(() => fs.SetLength(2));
-
-                    fs.WriteByte(0);
-                    fsr.Position++;
-                    Assert.Throws<IOException>(() => fs.Flush());
-
-                    fs.WriteByte(0);
-                    fsr.Position++;
-                    Assert.Throws<IOException>(() => fs.Dispose());
-                }
-            }
-        }
     }
 }

src/libraries/System.IO.FileSystem/tests/FileStream/WriteAsync.cs

@@ -229,18 +229,6 @@ public async Task ManyConcurrentWriteAsyncs_OuterLoop(
                 {
                     writes[i] = WriteAsync(fs, expectedData, i * writeSize, writeSize, cancellationToken);
                     Assert.Null(writes[i].Exception);
-                    if (useAsync)
-                    {
-                        // To ensure that the buffer of a FileStream opened for async IO is flushed
-                        // by FlushAsync in asynchronous way, we aquire a lock for every buffered WriteAsync.
-                        // The side effect of this is that the Position of FileStream is not updated until
-                        // the lock is released by a previous operation.
-                        // So now all WriteAsync calls should be awaited before starting another async file operation.
-                        if (PlatformDetection.IsNet5CompatFileStreamEnabled)
-                        {
-                            Assert.Equal((i + 1) * writeSize, fs.Position);
-                        }
-                    }
                 }
 
                 await Task.WhenAll(writes);

src/libraries/System.IO.FileSystem/tests/Net5CompatTests/Net5CompatSwitchTests.cs

@@ -7,8 +7,6 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO", "ref\System.IO.
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO", "src\System.IO.csproj", "{0769544B-1A5D-4D74-94FD-899DF6C39D62}"
 EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.Net5Compat.Tests", "tests\Net5CompatTests\System.IO.Net5Compat.Tests.csproj", "{0217540D-FA86-41B3-9754-7BB5096ABA3E}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.Tests", "tests\System.IO.Tests.csproj", "{72923407-7B7B-44A8-BCA6-2DB562835A8F}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.Runtime.CompilerServices.Unsafe", "..\System.Runtime.CompilerServices.Unsafe\ref\System.Runtime.CompilerServices.Unsafe.csproj", "{602525FF-EE47-4938-8979-32DC962109E4}"