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Refactor QIODevice::read()

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Move device-dependent part of the code into the private function for
further reusing by peek() procedure.

Task-number: QTBUG-56032
Change-Id: Iedceafe4b0bab109ca5c64ad274d779efe87c27b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
This commit is contained in:
Alex Trotsenko 2016-10-21 18:52:54 +03:00
parent b052d0cffd
commit 60563855e5
2 changed files with 51 additions and 36 deletions
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86
src/corelib/io/qiodevice.cpp
View File

@ -1007,10 +1007,9 @@ qint64 QIODevice::read(char *data, qint64 maxSize)
#endif
const bool sequential = d->isSequential();
const bool keepDataInBuffer = sequential && d->transactionStarted;
// Short circuit for getChar()
if (maxSize == 1 && !keepDataInBuffer) {
// Short-cut for getChar(), unless we need to keep the data in the buffer.
if (maxSize == 1 && !(sequential && d->transactionStarted)) {
int chint;
while ((chint = d->buffer.getChar()) != -1) {
if (!sequential)
@ -1031,6 +1030,30 @@ qint64 QIODevice::read(char *data, qint64 maxSize)
}
CHECK_MAXLEN(read, qint64(-1));
CHECK_READABLE(read, qint64(-1));
const qint64 readBytes = d->read(data, maxSize);
#if defined QIODEVICE_DEBUG
printf("%p \treturning %lld, d->pos == %lld, d->buffer.size() == %lld\n", this,
readBytes, d->pos, d->buffer.size());
if (readBytes > 0)
debugBinaryString(data - readBytes, readBytes);
#endif
return readBytes;
}
/*!
\internal
*/
qint64 QIODevicePrivate::read(char *data, qint64 maxSize)
{
Q_Q(QIODevice);
const bool buffered = (openMode & QIODevice::Unbuffered) == 0;
const bool sequential = isSequential();
const bool keepDataInBuffer = sequential && transactionStarted;
qint64 readSoFar = 0;
bool madeBufferReadsOnly = true;
bool deviceAtEof = false;
@ -1038,36 +1061,33 @@ qint64 QIODevice::read(char *data, qint64 maxSize)
forever {
// Try reading from the buffer.
qint64 bufferReadChunkSize = keepDataInBuffer
? d->buffer.peek(data, maxSize, d->transactionPos)
: d->buffer.read(data, maxSize);
? buffer.peek(data, maxSize, transactionPos)
: buffer.read(data, maxSize);
if (bufferReadChunkSize > 0) {
if (keepDataInBuffer)
d->transactionPos += bufferReadChunkSize;
transactionPos += bufferReadChunkSize;
else if (!sequential)
d->pos += bufferReadChunkSize;
pos += bufferReadChunkSize;
#if defined QIODEVICE_DEBUG
printf("%p \treading %lld bytes from buffer into position %lld\n", q,
bufferReadChunkSize, readSoFar);
#endif
readSoFar += bufferReadChunkSize;
data += bufferReadChunkSize;
maxSize -= bufferReadChunkSize;
#if defined QIODEVICE_DEBUG
printf("%p \treading %lld bytes from buffer into position %lld\n", this,
bufferReadChunkSize, readSoFar - bufferReadChunkSize);
#endif
} else {
CHECK_READABLE(read, qint64(-1));
}
if (maxSize > 0 && !deviceAtEof) {
qint64 readFromDevice = 0;
// Make sure the device is positioned correctly.
if (sequential || d->pos == d->devicePos || seek(d->pos)) {
if (sequential || pos == devicePos || q->seek(pos)) {
madeBufferReadsOnly = false; // fix readData attempt
if ((maxSize >= d->readBufferChunkSize || (d->openMode & Unbuffered))
&& !keepDataInBuffer) {
if ((!buffered || maxSize >= readBufferChunkSize) && !keepDataInBuffer) {
// Read big chunk directly to output buffer
readFromDevice = readData(data, maxSize);
readFromDevice = q->readData(data, maxSize);
deviceAtEof = (readFromDevice != maxSize);
#if defined QIODEVICE_DEBUG
printf("%p \treading %lld bytes from device (total %lld)\n", this,
printf("%p \treading %lld bytes from device (total %lld)\n", q,
readFromDevice, readSoFar);
#endif
if (readFromDevice > 0) {
@ -1075,24 +1095,24 @@ qint64 QIODevice::read(char *data, qint64 maxSize)
data += readFromDevice;
maxSize -= readFromDevice;
if (!sequential) {
d->pos += readFromDevice;
d->devicePos += readFromDevice;
pos += readFromDevice;
devicePos += readFromDevice;
}
}
} else {
// Do not read more than maxSize on unbuffered devices
const qint64 bytesToBuffer = (d->openMode & Unbuffered)
? qMin(maxSize, qint64(d->readBufferChunkSize))
: qint64(d->readBufferChunkSize);
const qint64 bytesToBuffer = (buffered || readBufferChunkSize < maxSize)
? qint64(readBufferChunkSize)
: maxSize;
// Try to fill QIODevice buffer by single read
readFromDevice = readData(d->buffer.reserve(bytesToBuffer), bytesToBuffer);
readFromDevice = q->readData(buffer.reserve(bytesToBuffer), bytesToBuffer);
deviceAtEof = (readFromDevice != bytesToBuffer);
d->buffer.chop(bytesToBuffer - qMax(Q_INT64_C(0), readFromDevice));
buffer.chop(bytesToBuffer - qMax(Q_INT64_C(0), readFromDevice));
if (readFromDevice > 0) {
if (!sequential)
d->devicePos += readFromDevice;
devicePos += readFromDevice;
#if defined QIODEVICE_DEBUG
printf("%p \treading %lld from device into buffer\n", this,
printf("%p \treading %lld from device into buffer\n", q,
readFromDevice);
#endif
continue;
@ -1108,7 +1128,7 @@ qint64 QIODevice::read(char *data, qint64 maxSize)
}
}
if ((d->openMode & Text) && readPtr < data) {
if ((openMode & QIODevice::Text) && readPtr < data) {
const char *endPtr = data;
// optimization to avoid initial self-assignment
@ -1140,14 +1160,8 @@ qint64 QIODevice::read(char *data, qint64 maxSize)
break;
}
#if defined QIODEVICE_DEBUG
printf("%p \treturning %lld, d->pos == %lld, d->buffer.size() == %lld\n", this,
readSoFar, d->pos, d->buffer.size());
debugBinaryString(data - readSoFar, readSoFar);
#endif
if (madeBufferReadsOnly && d->isBufferEmpty())
readData(data, 0);
if (madeBufferReadsOnly && isBufferEmpty())
q->readData(data, 0);
return readSoFar;
}

1
src/corelib/io/qiodevice_p.h
View File

@ -171,6 +171,7 @@ public:
void setReadChannelCount(int count);
void setWriteChannelCount(int count);
qint64 read(char *data, qint64 maxSize);
virtual qint64 peek(char *data, qint64 maxSize);
virtual QByteArray peek(qint64 maxSize);