public void OnCompletion(FileAsyncIOResult asyncIOResult)
{
m_result = asyncIOResult;
Contract.Assume(m_pinningHandle.IsAllocated);
m_pinningHandle.Free();
m_event.Set();
}
/// <inheritdoc />
public unsafe Overlapped *ReadFileOverlapped(
IIOCompletionTarget target,
SafeFileHandle handle,
byte *pinnedBuffer,
int bytesToRead,
long fileOffset)
{
Contract.Requires(target != null);
Contract.Requires(handle != null && !handle.IsInvalid);
Contract.Requires(pinnedBuffer != null);
TaggedOverlapped *overlapped = m_overlappedPool.ReserveOverlappedWithTarget(target);
TraceStartIfEnabled(overlapped, target);
bool needOverlappedRelease = true;
bool overlappedHasBeenReleased = false;
try
{
FileAsyncIOResult result = FileSystemWin.ReadFileOverlapped(
handle,
pinnedBuffer,
bytesToRead,
fileOffset,
(Overlapped *)overlapped);
if (result.Status != FileAsyncIOStatus.Pending)
{
Contract.Assert(
result.Status == FileAsyncIOStatus.Succeeded ||
result.Status == FileAsyncIOStatus.Failed);
// We could call the target directly.
// However, since the target may itself issue more I/O, we need to prevent unbounded stack growth.
// TODO: We could set a recursion-limit to allow some fraction of repeated IOs to complete synchronously, without
// queueing to the threadpool. Sync completions are the common case for files cached in memory.
ReleaseOvelappedAndQueueCompletionNotification(overlapped, result);
overlappedHasBeenReleased = true;
}
// At this point overlapped is either needed (pending status)
// or already released by ReleaseOvelappedAndQueueCompletionNotification
needOverlappedRelease = false;
return(!overlappedHasBeenReleased ? (Overlapped *)overlapped : null);
}
finally
{
if (needOverlappedRelease)
{
IIOCompletionTarget releasedTarget = ReleaseOverlappedAndGetTarget(overlapped);
Contract.Assume(releasedTarget == target);
}
}
}
private unsafe void QueueCompletionNotification(IIOCompletionTarget target, FileAsyncIOResult result)
{
var notificationArgs = new IOCompletionNotificationArgs
{
Result = result,
Target = target,
};
ThreadPool.QueueUserWorkItem(
state =>
{
var stateArgs = (IOCompletionNotificationArgs)state;
stateArgs.Target.OnCompletion(stateArgs.Result);
},
notificationArgs);
}
/// <inheritdoc />
public unsafe Overlapped *ReadOverlapped(
IIOCompletionTarget target,
byte *pinnedBuffer,
int bytesToRead,
long fileOffset)
{
FileAsyncIOResult result;
if (GetCurrentLength() == 0 || fileOffset >= GetCurrentLength())
{
result = new FileAsyncIOResult(FileAsyncIOStatus.Failed, bytesTransferred: 0, error: NativeIOConstants.ErrorHandleEof);
}
else
{
lock (m_fileStream)
{
try
{
byte[] buffer = new byte[bytesToRead];
m_fileStream.Seek(fileOffset, SeekOrigin.Begin);
int bytesRead = m_fileStream.Read(buffer, 0, bytesToRead);
for (int i = 0; i < bytesRead; i++)
{
pinnedBuffer[i] = buffer[i];
}
result = new FileAsyncIOResult(FileAsyncIOStatus.Succeeded, bytesTransferred: bytesRead, error: NativeIOConstants.ErrorSuccess);
}
catch (Exception ex)
{
int errorCode = (int)NativeErrorCodeForException(ex);
result = new FileAsyncIOResult(FileAsyncIOStatus.Failed, bytesTransferred: 0, error: errorCode);
}
}
}
QueueCompletionNotification(target, result);
return(null);
}
public async Task ReadEmptyFile()
{
string path = GetFullPath("file");
using (File.Create(path))
{
}
#if NET_FRAMEWORK
using (var io = new IOCompletionManager())
#else
IIOCompletionManager io = null;
#endif
{
using (
IAsyncFile file = AsyncFileFactory.CreateOrOpen(
path,
FileDesiredAccess.GenericRead,
FileShare.Read | FileShare.Delete,
FileMode.Open,
FileFlagsAndAttributes.None,
io))
{
XAssert.IsTrue(file.CanRead);
XAssert.IsFalse(file.CanWrite);
var buffer = new byte[10];
FileAsyncIOResult result = await file.ReadAsync(buffer, buffer.Length, 0);
XAssert.AreEqual(FileAsyncIOStatus.Failed, result.Status);
XAssert.IsTrue(result.ErrorIndicatesEndOfFile);
result = await file.ReadAsync(buffer, buffer.Length, 16);
XAssert.AreEqual(FileAsyncIOStatus.Failed, result.Status);
XAssert.IsTrue(result.ErrorIndicatesEndOfFile);
}
}
}
public void ReadFileToEnd()
{
const int NumberOfWords = 1024 * 1024;
const int TotalSize = NumberOfWords * 4;
string path = GetFullPath("file");
using (var fs = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.Delete))
using (var writer = new BinaryWriter(fs, Encoding.UTF8, leaveOpen: true))
{
for (int i = 0; i < NumberOfWords; i++)
{
writer.Write((int)i);
}
}
using (var memoryStream = new MemoryStream(capacity: NumberOfWords * 4))
{
using (var io = new IOCompletionManager())
using (var target = new BlockingCompletionTarget(bufferSize: 64 * 1024))
using (
SafeFileHandle handle = CreateOrOpenFile(
path,
FileDesiredAccess.GenericRead,
FileShare.Read | FileShare.Delete,
FileMode.Open))
{
io.BindFileHandle(handle);
while (true)
{
unsafe
{
io.ReadFileOverlapped(target, handle, target.PinBuffer(), target.Buffer.Length, fileOffset: memoryStream.Length);
}
FileAsyncIOResult result = target.Wait();
if (result.Status == FileAsyncIOStatus.Failed)
{
XAssert.IsTrue(result.ErrorIndicatesEndOfFile, "Unexpected non-EOF read failure.");
break;
}
else
{
XAssert.AreEqual(FileAsyncIOStatus.Succeeded, result.Status);
}
XAssert.AreNotEqual(0, result.BytesTransferred);
XAssert.IsTrue(
memoryStream.Length + result.BytesTransferred <= TotalSize,
"Too many bytes read; Read {0} so far and just got another {1} bytes",
memoryStream.Length,
result.BytesTransferred);
memoryStream.Write(target.Buffer, 0, result.BytesTransferred);
}
}
memoryStream.Position = 0;
using (var reader = new BinaryReader(memoryStream, Encoding.UTF8, leaveOpen: true))
{
for (int i = 0; i < NumberOfWords; i++)
{
XAssert.AreEqual(i, reader.ReadInt32(), "File contents read incorrectly; offset {0}", i * 4);
}
}
}
}
public void ConcurrentReadsSingleBatch()
{
const int NumberOfConcurrentReads = 128; // This should be larger than the batch size at which we allocate OVERLAPPED structures.
WithPipePair(
(server, client) =>
{
using (var io = new IOCompletionManager())
{
io.BindFileHandle(client);
var targets = new BlockingCompletionTarget[NumberOfConcurrentReads];
var completions = new bool[NumberOfConcurrentReads];
var bufferToWrite = new byte[NumberOfConcurrentReads * 4];
using (var writeBufferStream = new MemoryStream(bufferToWrite, writable: true))
{
using (var writer = new BinaryWriter(writeBufferStream))
{
for (int i = 0; i < NumberOfConcurrentReads; i++)
{
writer.Write((int)i);
}
}
}
try
{
for (int i = 0; i < targets.Length; i++)
{
targets[i] = new BlockingCompletionTarget(bufferSize: 8);
unsafe
{
// Note that non-seekable streams mandate an offset of 0 for all requests.
// https://msdn.microsoft.com/en-us/library/windows/desktop/ms684342%28v=vs.85%29.aspx
io.ReadFileOverlapped(targets[i], client, targets[i].PinBuffer(), 4, fileOffset: 0);
}
}
server.Write(bufferToWrite, 0, bufferToWrite.Length);
server.Flush();
for (int i = 0; i < targets.Length; i++)
{
FileAsyncIOResult result = targets[i].Wait();
XAssert.AreEqual(FileAsyncIOStatus.Succeeded, result.Status);
XAssert.AreEqual(result.BytesTransferred, 4);
int completedValue = BitConverter.ToInt32(targets[i].Buffer, 0);
XAssert.IsTrue(completedValue >= 0 && completedValue < completions.Length);
XAssert.IsFalse(completions[completedValue], "Value {0} completed multiple times", completedValue);
completions[completedValue] = true;
}
}
finally
{
foreach (BlockingCompletionTarget target in targets)
{
if (target != null)
{
target.Dispose();
}
}
}
}
});
}
/// <summary>
/// This is the async callback function. Only one thread could/should call this.
/// </summary>
void IIOCompletionTarget.OnCompletion(FileAsyncIOResult asyncIOResult)
{
Contract.Assume(asyncIOResult.Status != FileAsyncIOStatus.Pending);
bool cancel = false;
lock (m_lock)
{
switch (m_state)
{
case State.Initialized:
Contract.Assume(false, "Read completion can only happen once in the Reading state");
throw new InvalidOperationException("Unreachable");
case State.Reading:
break;
case State.Stopping:
// If Stopping, we had to defer reaching Stopped until an outstanding read completed - which is now.
// We throw away remaining data in the pipe (call WaitForEofAsync if all data is needed before dispose).
// Any current waiters for WaitForEofAsync will also resume (though possibly with an exception, due to this pre-EOF cancelation).
OnStopped();
// Signaling cancelation needs to happen outside of the lock (otherwise continuations on the completion source
// may run synchronously, and have the lock by accident).
cancel = true;
break;
case State.Stopped:
Contract.Assume(false, "The Stopped state should not be reached while a read is outstanding");
throw new InvalidOperationException("Unreachable");
default:
throw Contract.AssertFailure("Unhandled state");
}
}
if (cancel)
{
SignalCompletion(reachedEof: false);
return;
}
int byteLen;
if (asyncIOResult.Status == FileAsyncIOStatus.Failed)
{
// Treat failures as EOF.
// TODO: This is a bad thing to do, but is what the original AsyncStreamReader was doing.
byteLen = 0;
}
else
{
Contract.Assume(!asyncIOResult.ErrorIndicatesEndOfFile, "End-of-file appears as a failure status");
byteLen = asyncIOResult.BytesTransferred;
Contract.Assume(byteLen > 0);
}
if (byteLen == 0)
{
// We're at EOF, we won't call this function again from here on.
lock (m_lock)
{
if (StringBuilderInstace.Length != 0)
{
m_messageQueue.Enqueue(StringBuilderInstace.ToString());
StringBuilderInstace.Length = 0;
}
m_messageQueue.Enqueue(null);
}
try
{
// UserCallback could throw, but we should still signal EOF
try
{
FlushMessageQueue();
}
#pragma warning disable ERP022 // Unobserved exception in generic exception handler
catch
{
// We are in an invalid state (maybe the process got killed or crashed).
// As the comment above says the could throw.
// Make sure we are catching the exception without crashing.
}
#pragma warning restore ERP022 // Unobserved exception in generic exception handler
}
finally
{
lock (m_lock)
{
// No more reads or callbacks will occur, so enter the Stopped state and clean up.
OnStopped();
}
m_messageQueue = null;
SignalCompletion(reachedEof: true);
}
}
else
{
int charLen = m_decoder.GetChars(ByteBuffer, 0, byteLen, CharBuffer, 0);
GetLinesFromCharBuffers(charLen);
// File offset is ignored since we're reading a pipe.
m_file.ReadOverlapped(this, m_byteBufferPtr, m_byteBufferSize, fileOffset: 0);
}
}
public async Task ReadFileRandomAccess()
{
const int NumberOfReads = 16;
const int NumberOfWordsPerRead = 64 * 1024;
const int NumberOfBytesPerRead = NumberOfWordsPerRead * 4;
const int NumberOfWords = NumberOfWordsPerRead * NumberOfReads;
const int TotalSize = NumberOfWords * 4;
string path = GetFullPath("file");
using (var fs = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.Delete))
{
using (var writer = new BinaryWriter(fs, Encoding.UTF8, leaveOpen: true))
{
for (int i = 0; i < NumberOfWords; i++)
{
writer.Write((int)i);
}
}
}
#if NET_FRAMEWORK
using (var io = new IOCompletionManager())
#else
IIOCompletionManager io = null;
#endif
{
using (
IAsyncFile file = AsyncFileFactory.CreateOrOpen(
path,
FileDesiredAccess.GenericRead,
FileShare.Read | FileShare.Delete,
FileMode.Open,
FileFlagsAndAttributes.None,
io))
{
XAssert.IsTrue(file.CanRead);
XAssert.IsFalse(file.CanWrite);
var readBuffer = new byte[TotalSize];
var readTasks = new Task[NumberOfReads];
for (int i = 0; i < readTasks.Length; i++)
{
int offset = NumberOfBytesPerRead * i;
readTasks[i] = Task.Run(
async() =>
{
byte[] localBuffer = new byte[NumberOfBytesPerRead];
int readSoFar = 0;
while (readSoFar < NumberOfBytesPerRead)
{
FileAsyncIOResult result =
await file.ReadAsync(localBuffer, bytesToRead: NumberOfBytesPerRead - readSoFar, fileOffset: offset + readSoFar);
XAssert.AreEqual(FileAsyncIOStatus.Succeeded, result.Status);
XAssert.IsTrue(result.BytesTransferred > 0);
XAssert.IsTrue(readSoFar + result.BytesTransferred <= NumberOfBytesPerRead);
Buffer.BlockCopy(localBuffer, 0, readBuffer, offset + readSoFar, result.BytesTransferred);
readSoFar += result.BytesTransferred;
}
Contract.Assert(readSoFar == NumberOfBytesPerRead);
});
}
for (int i = 0; i < readTasks.Length; i++)
{
await readTasks[i];
}
using (var reader = new BinaryReader(new MemoryStream(readBuffer, writable: false), Encoding.UTF8, leaveOpen: false))
{
for (int i = 0; i < NumberOfWords; i++)
{
XAssert.AreEqual(i, reader.ReadInt32());
}
}
}
}
}
private unsafe void ReleaseOvelappedAndQueueCompletionNotification(TaggedOverlapped *overlapped, FileAsyncIOResult result)
{
// We can now find the external-code callback that needs notification for this request.
// We can't allow it to block this thread, which is dedicated to servicing the completion port.
// Were it to block, we could starve I/O completion; blocking on other I/O completions could be a deadlock.
// So, we guarantee that IIOCompletionTargets run on thread-pool threads - they suffer no special restrictions.
IIOCompletionTarget target = ReleaseOverlappedAndGetTarget(overlapped);
var notificationArgs = new IOCompletionNotificationArgs
{
Result = result,
Target = target,
};
ThreadPool.QueueUserWorkItem(
state =>
{
var stateArgs = (IOCompletionNotificationArgs)state;
stateArgs.Target.OnCompletion(stateArgs.Result);
},
notificationArgs);
}