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QProcess/Win: get rid of incremental wait

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Introduce QProcessPoller helper class on Windows that implements
waiting for any activity from a child process.

Change-Id: I99414db4424b4342e0fa3d7a3789f85cad76d190
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
This commit is contained in:
Alex Trotsenko 2021-03-19 18:29:50 +02:00
parent d4fd996363
commit 82c67623db
5 changed files with 87 additions and 85 deletions
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112
src/corelib/io/qprocess_win.cpp
View File

@ -85,6 +85,46 @@ QProcessEnvironment QProcessEnvironment::systemEnvironment()
#if QT_CONFIG(process)
namespace {
struct QProcessPoller
{
QProcessPoller(const QProcessPrivate &proc);
int poll(const QDeadlineTimer &deadline);
enum { maxHandles = 4 };
HANDLE handles[maxHandles];
DWORD handleCount = 0;
};
QProcessPoller::QProcessPoller(const QProcessPrivate &proc)
{
if (proc.stdinChannel.writer)
handles[handleCount++] = proc.stdinChannel.writer->syncEvent();
if (proc.stdoutChannel.reader)
handles[handleCount++] = proc.stdoutChannel.reader->syncEvent();
if (proc.stderrChannel.reader)
handles[handleCount++] = proc.stderrChannel.reader->syncEvent();
handles[handleCount++] = proc.pid->hProcess;
}
int QProcessPoller::poll(const QDeadlineTimer &deadline)
{
DWORD waitRet;
do {
waitRet = WaitForMultipleObjectsEx(handleCount, handles, FALSE,
deadline.remainingTime(), TRUE);
} while (waitRet == WAIT_IO_COMPLETION);
if (waitRet - WAIT_OBJECT_0 < handleCount)
return 1;
return (waitRet == WAIT_TIMEOUT) ? 0 : -1;
}
} // anonymous namespace
static bool qt_create_pipe(Q_PIPE *pipe, bool isInputPipe, BOOL defInheritFlag)
{
// Anomymous pipes do not support asynchronous I/O. Thus we
@ -658,16 +698,22 @@ bool QProcessPrivate::drainOutputPipes()
bool QProcessPrivate::waitForReadyRead(const QDeadlineTimer &deadline)
{
QIncrementalSleepTimer timer(deadline.remainingTime());
forever {
if (!writeBuffer.isEmpty() && !_q_canWrite())
return false;
if (stdinChannel.writer && stdinChannel.writer->waitForWrite(0))
timer.resetIncrements();
if ((stdoutChannel.reader && stdoutChannel.reader->waitForReadyRead(0))
|| (stderrChannel.reader && stderrChannel.reader->waitForReadyRead(0)))
QProcessPoller poller(*this);
int ret = poller.poll(deadline);
if (ret < 0)
return false;
if (ret == 0)
break;
if (stdinChannel.writer)
stdinChannel.writer->checkForWrite();
if ((stdoutChannel.reader && stdoutChannel.reader->checkForReadyRead())
|| (stderrChannel.reader && stderrChannel.reader->checkForReadyRead()))
return true;
if (!pid)
@ -678,10 +724,6 @@ bool QProcessPrivate::waitForReadyRead(const QDeadlineTimer &deadline)
processFinished();
return readyReadEmitted;
}
Sleep(timer.nextSleepTime());
if (timer.hasTimedOut())
break;
}
setError(QProcess::Timedout);
@ -690,8 +732,6 @@ bool QProcessPrivate::waitForReadyRead(const QDeadlineTimer &deadline)
bool QProcessPrivate::waitForBytesWritten(const QDeadlineTimer &deadline)
{
QIncrementalSleepTimer timer(deadline.remainingTime());
forever {
// If no write is pending, try to start one. However, at entry into
// the loop the write buffer can be empty to start with, in which
@ -699,17 +739,24 @@ bool QProcessPrivate::waitForBytesWritten(const QDeadlineTimer &deadline)
if (pipeWriterBytesToWrite() == 0 && !_q_canWrite())
return false;
QProcessPoller poller(*this);
int ret = poller.poll(deadline);
if (ret < 0)
return false;
if (ret == 0)
break;
Q_ASSERT(stdinChannel.writer);
if (stdinChannel.writer->waitForWrite(0))
if (stdinChannel.writer->checkForWrite())
return true;
// If we wouldn't write anything, check if we can read stdout.
if (stdoutChannel.reader && stdoutChannel.reader->waitForReadyRead(0))
timer.resetIncrements();
if (stdoutChannel.reader)
stdoutChannel.reader->checkForReadyRead();
// Check if we can read stderr.
if (stderrChannel.reader && stderrChannel.reader->waitForReadyRead(0))
timer.resetIncrements();
if (stderrChannel.reader)
stderrChannel.reader->checkForReadyRead();
// Check if the process died while reading.
if (!pid)
@ -723,10 +770,6 @@ bool QProcessPrivate::waitForBytesWritten(const QDeadlineTimer &deadline)
processFinished();
return false;
}
// Only wait for as long as we've been asked.
if (timer.hasTimedOut())
break;
}
setError(QProcess::Timedout);
@ -739,30 +782,33 @@ bool QProcessPrivate::waitForFinished(const QDeadlineTimer &deadline)
qDebug("QProcessPrivate::waitForFinished(%lld)", deadline.remainingTime());
#endif
QIncrementalSleepTimer timer(deadline.remainingTime());
forever {
if (!writeBuffer.isEmpty() && !_q_canWrite())
return false;
if (stdinChannel.writer && stdinChannel.writer->waitForWrite(0))
timer.resetIncrements();
if (stdoutChannel.reader && stdoutChannel.reader->waitForReadyRead(0))
timer.resetIncrements();
if (stderrChannel.reader && stderrChannel.reader->waitForReadyRead(0))
timer.resetIncrements();
QProcessPoller poller(*this);
int ret = poller.poll(deadline);
if (ret < 0)
return false;
if (ret == 0)
break;
if (stdinChannel.writer)
stdinChannel.writer->checkForWrite();
if (stdoutChannel.reader)
stdoutChannel.reader->checkForReadyRead();
if (stderrChannel.reader)
stderrChannel.reader->checkForReadyRead();
if (!pid)
return true;
if (WaitForSingleObject(pid->hProcess, timer.nextSleepTime()) == WAIT_OBJECT_0) {
if (WaitForSingleObject(pid->hProcess, 0) == WAIT_OBJECT_0) {
drainOutputPipes();
if (pid)
processFinished();
return true;
}
if (timer.hasTimedOut())
break;
}
setError(QProcess::Timedout);

3
src/corelib/io/qwindowspipereader.cpp
View File

@ -51,7 +51,7 @@ QWindowsPipeReader::QWindowsPipeReader(QObject *parent)
: QObject(parent),
handle(INVALID_HANDLE_VALUE),
eventHandle(CreateEvent(NULL, FALSE, FALSE, NULL)),
syncHandle(CreateEvent(NULL, FALSE, FALSE, NULL)),
syncHandle(CreateEvent(NULL, TRUE, FALSE, NULL)),
waitObject(NULL),
readBufferMaxSize(0),
actualReadBufferSize(0),
@ -396,6 +396,7 @@ bool QWindowsPipeReader::event(QEvent *e)
*/
bool QWindowsPipeReader::consumePendingAndEmit(bool allowWinActPosting)
{
ResetEvent(syncHandle);
mutex.lock();
// Enable QEvent::WinEventAct posting.

2
src/corelib/io/qwindowspipereader_p.h
View File

@ -81,9 +81,11 @@ public:
qint64 read(char *data, qint64 maxlen);
bool canReadLine() const;
bool waitForReadyRead(int msecs);
bool checkForReadyRead() { return consumePendingAndEmit(false); }
bool waitForPipeClosed(int msecs);
bool isReadOperationActive() const;
HANDLE syncEvent() const { return syncHandle; }
Q_SIGNALS:
void winError(ulong, const QString &);

3
src/corelib/io/qwindowspipewriter.cpp
View File

@ -49,7 +49,7 @@ QWindowsPipeWriter::QWindowsPipeWriter(HANDLE pipeWriteEnd, QObject *parent)
: QObject(parent),
handle(pipeWriteEnd),
eventHandle(CreateEvent(NULL, FALSE, FALSE, NULL)),
syncHandle(CreateEvent(NULL, FALSE, FALSE, NULL)),
syncHandle(CreateEvent(NULL, TRUE, FALSE, NULL)),
waitObject(NULL),
pendingBytesWrittenValue(0),
lastError(ERROR_SUCCESS),
@ -267,6 +267,7 @@ bool QWindowsPipeWriter::event(QEvent *e)
*/
bool QWindowsPipeWriter::consumePendingAndEmit(bool allowWinActPosting)
{
ResetEvent(syncHandle);
QMutexLocker locker(&mutex);
// Enable QEvent::WinEventAct posting.

52
src/corelib/io/qwindowspipewriter_p.h
View File

@ -52,8 +52,6 @@
// We mean it.
//
#include <QtCore/private/qglobal_p.h>
#include <qelapsedtimer.h>
#include <qobject.h>
#include <qdeadlinetimer.h>
#include <qmutex.h>
@ -63,54 +61,6 @@
QT_BEGIN_NAMESPACE
#define SLEEPMIN 10
#define SLEEPMAX 500
class QIncrementalSleepTimer
{
public:
QIncrementalSleepTimer(int msecs)
: totalTimeOut(msecs)
, nextSleep(qMin(SLEEPMIN, totalTimeOut))
{
if (totalTimeOut == -1)
nextSleep = SLEEPMIN;
timer.start();
}
int nextSleepTime()
{
int tmp = nextSleep;
nextSleep = qMin(nextSleep * 2, qMin(SLEEPMAX, timeLeft()));
return tmp;
}
int timeLeft() const
{
if (totalTimeOut == -1)
return SLEEPMAX;
return qMax(int(totalTimeOut - timer.elapsed()), 0);
}
bool hasTimedOut() const
{
if (totalTimeOut == -1)
return false;
return timer.elapsed() >= totalTimeOut;
}
void resetIncrements()
{
nextSleep = qMin(SLEEPMIN, timeLeft());
}
private:
QElapsedTimer timer;
int totalTimeOut;
int nextSleep;
};
class Q_CORE_EXPORT QWindowsPipeWriter : public QObject
{
Q_OBJECT
@ -121,8 +71,10 @@ public:
bool write(const QByteArray &ba);
void stop();
bool waitForWrite(int msecs);
bool checkForWrite() { return consumePendingAndEmit(false); }
bool isWriteOperationActive() const;
qint64 bytesToWrite() const;
HANDLE syncEvent() const { return syncHandle; }
Q_SIGNALS:
void canWrite();