1 files changed, 228 insertions, 120 deletions

diff --git a/src/corelib/io/qwindowspipewriter.cpp b/src/corelib/io/qwindowspipewriter.cpp
index e374034a06..5ed584c6e3 100644
--- a/src/corelib/io/qwindowspipewriter.cpp
+++ b/src/corelib/io/qwindowspipewriter.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 Alex Trotsenko <alex1973tr@gmail.com>
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -38,189 +39,296 @@
 ****************************************************************************/
 
 #include "qwindowspipewriter_p.h"
-#include "qiodevice_p.h"
 #include <qscopedvaluerollback.h>
+#include <qcoreapplication.h>
+#include <QMutexLocker>
 
 QT_BEGIN_NAMESPACE
 
-QWindowsPipeWriter::Overlapped::Overlapped(QWindowsPipeWriter *pipeWriter)
-    : pipeWriter(pipeWriter)
-{
-}
-
-void QWindowsPipeWriter::Overlapped::clear()
-{
-    ZeroMemory(this, sizeof(OVERLAPPED));
-}
-
-
 QWindowsPipeWriter::QWindowsPipeWriter(HANDLE pipeWriteEnd, QObject *parent)
     : QObject(parent),
       handle(pipeWriteEnd),
-      overlapped(this),
+      eventHandle(CreateEvent(NULL, FALSE, FALSE, NULL)),
+      syncHandle(CreateEvent(NULL, FALSE, FALSE, NULL)),
+      waitObject(NULL),
       pendingBytesWrittenValue(0),
+      lastError(ERROR_SUCCESS),
       stopped(true),
       writeSequenceStarted(false),
-      notifiedCalled(false),
       bytesWrittenPending(false),
+      winEventActPosted(false),
       inBytesWritten(false)
 {
-    connect(this, &QWindowsPipeWriter::_q_queueBytesWritten,
-            this, &QWindowsPipeWriter::emitPendingBytesWrittenValue, Qt::QueuedConnection);
+    ZeroMemory(&overlapped, sizeof(OVERLAPPED));
+    overlapped.hEvent = eventHandle;
+    waitObject = CreateThreadpoolWait(waitCallback, this, NULL);
+    if (waitObject == NULL)
+        qErrnoWarning("QWindowsPipeWriter: CreateThreadpollWait failed.");
 }
 
 QWindowsPipeWriter::~QWindowsPipeWriter()
 {
     stop();
+    CloseThreadpoolWait(waitObject);
+    CloseHandle(eventHandle);
+    CloseHandle(syncHandle);
 }
 
-bool QWindowsPipeWriter::waitForWrite(int msecs)
+/*!
+    Stops the asynchronous write sequence.
+    If the write sequence is running then the I/O operation is canceled.
+ */
+void QWindowsPipeWriter::stop()
 {
-    if (bytesWrittenPending) {
-        emitPendingBytesWrittenValue();
-        return true;
-    }
-
-    if (!writeSequenceStarted)
-        return false;
-
-    if (!waitForNotification(msecs))
-        return false;
+    if (stopped)
+        return;
 
-    if (bytesWrittenPending) {
-        emitPendingBytesWrittenValue();
-        return true;
+    mutex.lock();
+    stopped = true;
+    if (writeSequenceStarted) {
+        // Trying to disable callback before canceling the operation.
+        // Callback invocation is unnecessary here.
+        SetThreadpoolWait(waitObject, NULL, NULL);
+        if (!CancelIoEx(handle, &overlapped)) {
+            const DWORD dwError = GetLastError();
+            if (dwError != ERROR_NOT_FOUND) {
+                qErrnoWarning(dwError, "QWindowsPipeWriter: CancelIoEx on handle %p failed.",
+                              handle);
+            }
+        }
+        writeSequenceStarted = false;
     }
+    mutex.unlock();
 
-    return false;
+    WaitForThreadpoolWaitCallbacks(waitObject, TRUE);
 }
 
+/*!
+    Returns \c true if async operation is in progress or a bytesWritten
+    signal is pending.
+ */
+bool QWindowsPipeWriter::isWriteOperationActive() const
+{
+    QMutexLocker locker(&mutex);
+    return writeSequenceStarted || bytesWrittenPending;
+}
+
+/*!
+    Returns the number of bytes that are waiting to be written.
+ */
 qint64 QWindowsPipeWriter::bytesToWrite() const
 {
-    return buffer.size() + pendingBytesWrittenValue;
+    QMutexLocker locker(&mutex);
+    return writeBuffer.size() + pendingBytesWrittenValue;
 }
 
-void QWindowsPipeWriter::emitPendingBytesWrittenValue()
+/*!
+    Writes data to the pipe.
+ */
+bool QWindowsPipeWriter::write(const QByteArray &ba)
 {
-    if (bytesWrittenPending) {
-        // Reset the state even if we don't emit bytesWritten().
-        // It's a defined behavior to not re-emit this signal recursively.
-        bytesWrittenPending = false;
-        const qint64 bytes = pendingBytesWrittenValue;
-        pendingBytesWrittenValue = 0;
-
-        emit canWrite();
-        if (!inBytesWritten) {
-            QScopedValueRollback<bool> guard(inBytesWritten, true);
-            emit bytesWritten(bytes);
-        }
+    QMutexLocker locker(&mutex);
+
+    if (lastError != ERROR_SUCCESS)
+        return false;
+
+    writeBuffer.append(ba);
+    if (writeSequenceStarted)
+        return true;
+
+    stopped = false;
+    startAsyncWriteLocked();
+
+    // Do not post the event, if the write operation will be completed asynchronously.
+    if (!bytesWrittenPending)
+        return true;
+
+    if (!winEventActPosted) {
+        winEventActPosted = true;
+        locker.unlock();
+        QCoreApplication::postEvent(this, new QEvent(QEvent::WinEventAct));
+    } else {
+        locker.unlock();
     }
+
+    SetEvent(syncHandle);
+    return true;
 }
 
-void QWindowsPipeWriter::writeFileCompleted(DWORD errorCode, DWORD numberOfBytesTransfered,
-                                            OVERLAPPED *overlappedBase)
+/*!
+    Starts a new write sequence. Thread-safety should be ensured by the caller.
+ */
+void QWindowsPipeWriter::startAsyncWriteLocked()
 {
-    Overlapped *overlapped = static_cast<Overlapped *>(overlappedBase);
-    overlapped->pipeWriter->notified(errorCode, numberOfBytesTransfered);
+    while (!writeBuffer.isEmpty()) {
+        // WriteFile() returns true, if the write operation completes synchronously.
+        // We don't need to call GetOverlappedResult() additionally, because
+        // 'numberOfBytesWritten' is valid in this case.
+        DWORD numberOfBytesWritten;
+        DWORD errorCode = ERROR_SUCCESS;
+        if (!WriteFile(handle, writeBuffer.readPointer(), writeBuffer.nextDataBlockSize(),
+                       &numberOfBytesWritten, &overlapped)) {
+            errorCode = GetLastError();
+            if (errorCode == ERROR_IO_PENDING) {
+                // Operation has been queued and will complete in the future.
+                writeSequenceStarted = true;
+                SetThreadpoolWait(waitObject, eventHandle, NULL);
+                return;
+            }
+        }
+
+        if (!writeCompleted(errorCode, numberOfBytesWritten))
+            return;
+    }
 }
 
 /*!
-    \internal
-    Will be called whenever the write operation completes.
+    Thread pool callback procedure.
  */
-void QWindowsPipeWriter::notified(DWORD errorCode, DWORD numberOfBytesWritten)
+void QWindowsPipeWriter::waitCallback(PTP_CALLBACK_INSTANCE instance, PVOID context,
+                                      PTP_WAIT wait, TP_WAIT_RESULT waitResult)
 {
-    notifiedCalled = true;
-    writeSequenceStarted = false;
-    Q_ASSERT(errorCode != ERROR_SUCCESS || numberOfBytesWritten == DWORD(buffer.size()));
-    buffer.clear();
-
-    switch (errorCode) {
-    case ERROR_SUCCESS:
-        break;
-    case ERROR_OPERATION_ABORTED:
-        if (stopped)
-            break;
-        Q_FALLTHROUGH();
-    default:
-        qErrnoWarning(errorCode, "QWindowsPipeWriter: asynchronous write failed.");
-        break;
-    }
+    Q_UNUSED(instance);
+    Q_UNUSED(wait);
+    Q_UNUSED(waitResult);
+    QWindowsPipeWriter *pipeWriter = reinterpret_cast<QWindowsPipeWriter *>(context);
+
+    // Get the result of the asynchronous operation.
+    DWORD numberOfBytesTransfered = 0;
+    DWORD errorCode = ERROR_SUCCESS;
+    if (!GetOverlappedResult(pipeWriter->handle, &pipeWriter->overlapped,
+                             &numberOfBytesTransfered, FALSE))
+        errorCode = GetLastError();
+
+    QMutexLocker locker(&pipeWriter->mutex);
 
     // After the writer was stopped, the only reason why this function can be called is the
-    // completion of a cancellation. No signals should be emitted, and no new write sequence should
-    // be started in this case.
-    if (stopped)
+    // completion of a cancellation. No signals should be emitted, and no new write sequence
+    // should be started in this case.
+    if (pipeWriter->stopped)
         return;
 
-    pendingBytesWrittenValue += qint64(numberOfBytesWritten);
-    if (!bytesWrittenPending) {
-        bytesWrittenPending = true;
-        emit _q_queueBytesWritten(QWindowsPipeWriter::QPrivateSignal());
+    pipeWriter->writeSequenceStarted = false;
+
+    if (pipeWriter->writeCompleted(errorCode, numberOfBytesTransfered))
+        pipeWriter->startAsyncWriteLocked();
+
+    if (pipeWriter->lastError == ERROR_SUCCESS && !pipeWriter->winEventActPosted) {
+        pipeWriter->winEventActPosted = true;
+        locker.unlock();
+        QCoreApplication::postEvent(pipeWriter, new QEvent(QEvent::WinEventAct));
+    } else {
+        locker.unlock();
     }
+
+    // We set the event only after unlocking to avoid additional context
+    // switches due to the released thread immediately running into the lock.
+    SetEvent(pipeWriter->syncHandle);
 }
 
-bool QWindowsPipeWriter::waitForNotification(int timeout)
+/*!
+    Will be called whenever the write operation completes. Returns \c true if
+    no error occurred; otherwise returns \c false.
+ */
+bool QWindowsPipeWriter::writeCompleted(DWORD errorCode, DWORD numberOfBytesWritten)
 {
-    QElapsedTimer t;
-    t.start();
-    notifiedCalled = false;
-    int msecs = timeout;
-    while (SleepEx(msecs == -1 ? INFINITE : msecs, TRUE) == WAIT_IO_COMPLETION) {
-        if (notifiedCalled)
-            return true;
+    if (errorCode == ERROR_SUCCESS) {
+        Q_ASSERT(numberOfBytesWritten == DWORD(writeBuffer.nextDataBlockSize()));
 
-        // Some other I/O completion routine was called. Wait some more.
-        msecs = qt_subtract_from_timeout(timeout, t.elapsed());
-        if (!msecs)
-            break;
+        bytesWrittenPending = true;
+        pendingBytesWrittenValue += numberOfBytesWritten;
+        writeBuffer.free(numberOfBytesWritten);
+        return true;
     }
-    return notifiedCalled;
+
+    lastError = errorCode;
+    writeBuffer.clear();
+    // The other end has closed the pipe. This can happen in QLocalSocket. Do not warn.
+    if (errorCode != ERROR_OPERATION_ABORTED && errorCode != ERROR_NO_DATA)
+        qErrnoWarning(errorCode, "QWindowsPipeWriter: write failed.");
+    return false;
 }
 
-bool QWindowsPipeWriter::write(const QByteArray &ba)
+/*!
+    Receives notification that the write operation has completed.
+ */
+bool QWindowsPipeWriter::event(QEvent *e)
 {
-    if (writeSequenceStarted)
+    if (e->type() == QEvent::WinEventAct) {
+        consumePendingAndEmit(true);
+        return true;
+    }
+    return QObject::event(e);
+}
+
+/*!
+    Updates the state and emits pending signals in the main thread.
+    Returns \c true, if bytesWritten() was emitted.
+ */
+bool QWindowsPipeWriter::consumePendingAndEmit(bool allowWinActPosting)
+{
+    QMutexLocker locker(&mutex);
+
+    // Enable QEvent::WinEventAct posting.
+    if (allowWinActPosting)
+        winEventActPosted = false;
+
+    if (!bytesWrittenPending)
         return false;
 
-    overlapped.clear();
-    buffer = ba;
-    stopped = false;
-    writeSequenceStarted = true;
-    if (!WriteFileEx(handle, buffer.constData(), buffer.size(),
-                     &overlapped, &writeFileCompleted)) {
-        writeSequenceStarted = false;
-        buffer.clear();
-
-        const DWORD errorCode = GetLastError();
-        switch (errorCode) {
-        case ERROR_NO_DATA:     // "The pipe is being closed."
-            // The other end has closed the pipe. This can happen in QLocalSocket. Do not warn.
-            break;
-        default:
-            qErrnoWarning(errorCode, "QWindowsPipeWriter::write failed.");
-        }
+    // Reset the state even if we don't emit bytesWritten().
+    // It's a defined behavior to not re-emit this signal recursively.
+    bytesWrittenPending = false;
+    qint64 numberOfBytesWritten = pendingBytesWrittenValue;
+    pendingBytesWrittenValue = 0;
+
+    locker.unlock();
+
+    // Disable any further processing, if the pipe was stopped.
+    if (stopped)
         return false;
+
+    emit canWrite();
+    if (!inBytesWritten) {
+        QScopedValueRollback<bool> guard(inBytesWritten, true);
+        emit bytesWritten(numberOfBytesWritten);
     }
 
     return true;
 }
 
-void QWindowsPipeWriter::stop()
+bool QWindowsPipeWriter::waitForNotification(const QDeadlineTimer &deadline)
 {
-    stopped = true;
-    bytesWrittenPending = false;
-    pendingBytesWrittenValue = 0;
-    if (writeSequenceStarted) {
-        if (!CancelIoEx(handle, &overlapped)) {
-            const DWORD dwError = GetLastError();
-            if (dwError != ERROR_NOT_FOUND) {
-                qErrnoWarning(dwError, "QWindowsPipeWriter: CancelIoEx on handle %p failed.",
-                              handle);
-            }
-        }
-        waitForNotification(-1);
+    do {
+        DWORD waitRet = WaitForSingleObjectEx(syncHandle, deadline.remainingTime(), TRUE);
+        if (waitRet == WAIT_OBJECT_0)
+            return true;
+
+        if (waitRet != WAIT_IO_COMPLETION)
+            return false;
+
+        // Some I/O completion routine was called. Wait some more.
+    } while (!deadline.hasExpired());
+
+    return false;
+}
+
+/*!
+    Waits for the completion of the asynchronous write operation.
+    Returns \c true, if we've emitted the bytesWritten signal (non-recursive case)
+    or bytesWritten will be emitted by the event loop (recursive case).
+ */
+bool QWindowsPipeWriter::waitForWrite(int msecs)
+{
+    QDeadlineTimer timer(msecs);
+
+    // Make sure that 'syncHandle' was triggered by the thread pool callback.
+    while (isWriteOperationActive() && waitForNotification(timer)) {
+        if (consumePendingAndEmit(false))
+            return true;
     }
+
+    return false;
 }
 
 QT_END_NAMESPACE