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dataloader.cpp
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319 lines (244 loc) · 8.23 KB
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/*
Description: async stream reader, used to load repository data on startup
Author: Marco Costalba (C) 2005-2007
Copyright: See COPYING file that comes with this distribution
*/
#include <QDir>
#include <QTemporaryFile>
#include "FileHistory.h"
#include "git.h"
#include "dataloader.h"
#define GUI_UPDATE_INTERVAL 500
#define READ_BLOCK_SIZE 65535
class UnbufferedTemporaryFile : public QTemporaryFile {
public:
explicit UnbufferedTemporaryFile(QObject* p) : QTemporaryFile(p) {}
bool unbufOpen() { return open(QIODevice::ReadOnly | QIODevice::Unbuffered); }
};
DataLoader::DataLoader(Git* g, FileHistory* f) : QProcess(g), git(g), fh(f) {
canceling = parsing = false;
isProcExited = true;
halfChunk = NULL;
dataFile = NULL;
loadedBytes = 0;
guiUpdateTimer.setSingleShot(true);
connect(git, SIGNAL(cancelAllProcesses()), this, SLOT(on_cancel()));
connect(&guiUpdateTimer, SIGNAL(timeout()), this, SLOT(on_timeout()));
}
DataLoader::~DataLoader() {
// avoid a Qt warning in case we are
// destroyed while still running
waitForFinished(1000);
}
void DataLoader::on_cancel(const FileHistory* f) {
if (f == fh)
on_cancel();
}
void DataLoader::on_cancel() {
if (!canceling) { // just once
canceling = true;
kill(); // SIGKILL (Unix and Mac), TerminateProcess (Windows)
}
}
bool DataLoader::start(SCList args, SCRef wd, SCRef buf) {
if (!isProcExited) {
dbs("ASSERT in DataLoader::start(), called while processing");
return false;
}
isProcExited = false;
setWorkingDirectory(wd);
connect(this, SIGNAL(finished(int, QProcess::ExitStatus)),
this, SLOT(on_finished(int, QProcess::ExitStatus)));
if (!createTemporaryFile() || !QGit::startProcess(this, args, buf)) {
deleteLater();
return false;
}
loadTime.start();
guiUpdateTimer.start(GUI_UPDATE_INTERVAL);
return true;
}
void DataLoader::on_finished(int, QProcess::ExitStatus) {
isProcExited = true;
if (parsing && guiUpdateTimer.isActive())
dbs("ASSERT in DataLoader: timer active while parsing");
if (parsing == guiUpdateTimer.isActive() && !canceling)
dbs("ASSERT in DataLoader: inconsistent timer");
if (guiUpdateTimer.isActive()) // no need to wait anymore
guiUpdateTimer.start(1);
}
void DataLoader::on_timeout() {
if (canceling) {
deleteLater();
return; // we leave with guiUpdateTimer not active
}
parsing = true;
// process could exit while we are processing so save the flag now
bool lastBuffer = isProcExited;
loadedBytes += readNewData(lastBuffer);
emit newDataReady(fh); // inserting in list view is about 3% of total time
if (lastBuffer) {
emit loaded(fh, loadedBytes, loadTime.elapsed(), true, "", "");
deleteLater();
} else if (isProcExited) { // exited while parsing
dbs("Exited while parsing!!!!");
guiUpdateTimer.start(1);
} else
guiUpdateTimer.start(GUI_UPDATE_INTERVAL);
parsing = false;
}
void DataLoader::parseSingleBuffer(const QByteArray& ba) {
if (ba.size() == 0 || canceling)
return;
int ofs = 0, newOfs, bz = ba.size();
/* Due to unknown reasons randomly first byte
* of 'ba' is 0, this seems to happen only when
* using QFile::read(), i.e. with temporary file
* interface. Until we discover the real reason
* workaround this skipping the bogus byte
*/
if (ba.at(0) == 0 && bz > 1 && !halfChunk)
ofs++;
while (bz - ofs > 0) {
if (!halfChunk) {
newOfs = git->addChunk(fh, ba, ofs);
if (newOfs == -1)
break; // half chunk detected
ofs = newOfs;
} else { // less then 1% of cases with READ_BLOCK_SIZE = 64KB
int end = ba.indexOf('\0');
if (end == -1) // consecutives half chunks
break;
ofs = end + 1;
baAppend(&halfChunk, ba.constData(), ofs);
fh->rowData.append(halfChunk);
addSplittedChunks(halfChunk);
halfChunk = NULL;
}
}
// save any remaining half chunk
if (bz - ofs > 0)
baAppend(&halfChunk, ba.constData() + ofs, bz - ofs);
}
void DataLoader::addSplittedChunks(const QByteArray* hc) {
if (hc->at(hc->size() - 1) != 0) {
dbs("ASSERT in DataLoader, bad half chunk");
return;
}
// do not assume we have only one chunk in hc
int ofs = 0;
while (ofs != -1 && ofs != (int)hc->size())
ofs = git->addChunk(fh, *hc, ofs);
}
void DataLoader::baAppend(QByteArray** baPtr, const char* ascii, int len) {
if (*baPtr)
// we cannot use QByteArray::append(const char*)
// because 'ascii' is not '\0' terminating
(*baPtr)->append(QByteArray::fromRawData(ascii, len));
else
*baPtr = new QByteArray(ascii, len);
}
// *************** git interface facility dependant code *****************************
#ifdef USE_QPROCESS
ulong DataLoader::readNewData(bool lastBuffer) {
/*
QByteArray copy c'tor uses shallow copy, but there is a deep copy in
QProcess::readStdout(), from an internal buffers list to return value.
Qt uses a select() to detect new data is ready, copies immediately the
data to the heap with a read() and stores the pointer to new data in a
pointer list, from qprocess_unix.cpp:
const int basize = 4096;
QByteArray *ba = new QByteArray(basize);
n = ::read(fd, ba->data(), basize);
buffer->append(ba); // added to a QPtrList<QByteArray> pointer list
When we call QProcess::readStdout() data from buffers pointed by the
pointer list is memcpy() to the function return value, from qprocess.cpp:
....
return buf->readAll(); // memcpy() here
*/
QByteArray* ba = new QByteArray(readAllStandardOutput());
if (lastBuffer)
ba->append('\0'); // be sure stream is null terminated
if (ba->size() == 0) {
delete ba;
return 0;
}
fh->rowData.append(ba);
parseSingleBuffer(*ba);
return ba->size();
}
bool DataLoader::createTemporaryFile() { return true; }
#else // temporary file as data exchange facility
ulong DataLoader::readNewData(bool lastBuffer) {
bool ok = dataFile &&
(dataFile->isOpen() || (dataFile->exists() && dataFile->unbufOpen()));
if (!ok)
return 0;
ulong cnt = 0;
qint64 readPos = dataFile->pos();
while (true) {
// this is the ONLY deep copy involved in the whole loading
// QFile::read() calls standard C read() function when
// file is open with Unbuffered flag, or fread() otherwise
QByteArray* ba = new QByteArray();
ba->resize(READ_BLOCK_SIZE);
int len = dataFile->read(ba->data(), READ_BLOCK_SIZE);
if (len <= 0) {
delete ba;
break;
} else if (len < ba->size()) // unlikely
ba->resize(len);
// current read position must be updated manually, it's
// not correctly incremented by read() if the producer
// process has already finished
readPos += len;
dataFile->seek(readPos);
cnt += len;
fh->rowData.append(ba);
parseSingleBuffer(*ba);
// avoid reading small chunks if data producer is still running
if (len < READ_BLOCK_SIZE && !lastBuffer)
break;
}
if (lastBuffer) { // be sure stream is null terminated
QByteArray* zb = new QByteArray(1, '\0');
fh->rowData.append(zb);
parseSingleBuffer(*zb);
}
return cnt;
}
bool DataLoader::createTemporaryFile() {
// redirect 'git log' output to a temporary file
dataFile = new UnbufferedTemporaryFile(this);
#ifndef Q_OS_WIN32
/*
For performance reasons we would like to use a tmpfs filesystem
if available, this is normally mounted under '/tmp' in Linux.
According to Qt docs, a temporary file is placed in QDir::tempPath(),
that should be system's temporary directory. On Unix/Linux systems this
is usually /tmp; on Windows this is usually the path in the TEMP or TMP
environment variable.
But due to a bug in Qt 4.2 QDir::tempPath() is instead set to $HOME/tmp
under Unix/Linux, that is not a tmpfs filesystem.
So try to manually set the best directory for our temporary file.
*/
QDir dir("/tmp");
bool foundTmpDir = (dir.exists() && dir.isReadable());
if (foundTmpDir && dir.absolutePath() != QDir::tempPath()) {
dataFile->setFileTemplate(dir.absolutePath() + "/qt_temp");
if (!dataFile->open()) { // test for write access
delete dataFile;
dataFile = new UnbufferedTemporaryFile(this);
dbs("WARNING: directory '/tmp' is not writable, "
"fallback on Qt default one, there could "
"be a performance penalty.");
} else
dataFile->close();
}
#endif
if (!dataFile->open()) // to read the file name
return false;
setStandardOutputFile(dataFile->fileName());
dataFile->close();
return true;
}
#endif // USE_QPROCESS