Re: [RFC \ WISH] Add -o option to git-rev-list

On 12/10/06, Linus Torvalds [off-list ref] wrote:

looks about right.

Yes it's right. Thanks!

But it's still slow. Almost one second (985ms) to read the little qgit repo:

$ ./qgit HEAD
Found GNU source-highlight 2.5
count is <-1>
count is <60169>
count is <-1>
count is <60505>
count is <-1>
count is <61462>
count is <-1>
count is <61911>
count is <-1>
count is <61392>
count is <-1>
count is <61880>
count is <-1>
count is <62009>
count is <-1>
count is <62549>
count is <-1>
count is <21354>
count is <0>
$

As a compare the temporary file version needs a mere 105ms (1030 revs).

This is the code under test:

bool DataLoader::start(const QStringList& args, const QString& workDir) {

	QDir::setCurrent(workDir);
	_file = popen(args.join(" ").ascii(), "r");
	if (!_file)
		return false;

	fcntl(fileno(_file), F_SETFL, O_NONBLOCK);
	
	loadTime.start();
	guiUpdateTimer.start(10, true);
	return true;
}

void DataLoader::on_timeout() {

	if (canceling) {
		deleteLater();
		return;
	}

	int count;
	for (;;) {

		QByteArray* ba = new QByteArray(FILE_BLOCK_SIZE); // 64KB

		// this is the ONLY deep copy involved in the whole loading
		count = read(fileno(_file), ba->data(), ba->size());

		dbg(count); // DEBUG print

		if (count == 0) {
			/* All done, no more to read */
			delete ba;
			break;
		}
		if (count < 0) {
			delete ba;
			if (errno == EAGAIN)
				break;
			if (errno == EINTR)
				continue;

                      /* Anything else is fatal - report error */
                      dbg("Fatal error");
                      on_cancel();
                      deleteLater();
                      return;
		}
		if (count < (int)ba->size()) // very rare
			ba->resize(count);

		loadedBytes += count;
		fh->rowData.append(ba);
		parseSingleBuffer(*ba);
	}

	if (count == 0) {
		emit loaded(fh, loadedBytes, loadTime.elapsed(), true, "", "");
		pclose(_file);
		_file = NULL;
		deleteLater();
	} else
		guiUpdateTimer.start(100, true);