From d5eb850f8c2524aa5573bb4e672b195724e5b5ad Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jo=C3=A3o=20Abecasis?= Date: Mon, 16 Nov 2009 12:48:06 +0100 Subject: Remove needless loop in QIODevice::seek Either the buffer has more data than is being skipped and it can be cleared or it doesn't and we must skip it. If the total size of QRingBuffer exceeds INT_MAX there'll be bigger problems (e.g., QRingBuffer::size() will overflow) that can only be handled there and there's no point trying to work around them here. Reviewed-by: Markus Goetz --- src/corelib/io/qiodevice.cpp | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) diff --git a/src/corelib/io/qiodevice.cpp b/src/corelib/io/qiodevice.cpp index 4494d2a..856d737 100644 --- a/src/corelib/io/qiodevice.cpp +++ b/src/corelib/io/qiodevice.cpp @@ -619,7 +619,8 @@ qint64 QIODevice::size() const */ bool QIODevice::seek(qint64 pos) { - if (d_func()->openMode == NotOpen) { + Q_D(QIODevice); + if (d->openMode == NotOpen) { qWarning("QIODevice::seek: The device is not open"); return false; } @@ -628,7 +629,6 @@ bool QIODevice::seek(qint64 pos) return false; } - Q_D(QIODevice); #if defined QIODEVICE_DEBUG printf("%p QIODevice::seek(%d), before: d->pos = %d, d->buffer.size() = %d\n", this, int(pos), int(d->pos), d->buffer.size()); @@ -640,21 +640,16 @@ bool QIODevice::seek(qint64 pos) d->devicePos = pos; } - if (offset > 0 && !d->buffer.isEmpty()) { - // When seeking forwards, we need to pop bytes off the front of the - // buffer. - do { - int bytesToSkip = int(qMin(offset, INT_MAX)); - d->buffer.skip(bytesToSkip); - offset -= bytesToSkip; - } while (offset > 0); - } else if (offset < 0) { + if (offset < 0 + || offset >= qint64(d->buffer.size())) // When seeking backwards, an operation that is only allowed for // random-access devices, the buffer is cleared. The next read // operation will then refill the buffer. We can optimize this, if we // find that seeking backwards becomes a significant performance hit. d->buffer.clear(); - } + else if (!d->buffer.isEmpty()) + d->buffer.skip(int(offset)); + #if defined QIODEVICE_DEBUG printf("%p \tafter: d->pos == %d, d->buffer.size() == %d\n", this, int(d->pos), d->buffer.size()); -- cgit v0.12