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Re: The age of multicore has just started for U++.... [message #8933 is a reply to message #8932]

Sun, 08 April 2007 17:14

mirek
Messages: 13980
Registered: November 2005

Ultimate Member

exolon wrote on Sun, 08 April 2007 10:33

What does this Cowork class do, and how?

Well, detailed description will come with new Core, but essentially it is a thread pool. A tool to simply paralellize loops.

E.g. this is some original loop from the uppweb:

VectorMap<String, String> reflink;

struct ScanTopicIterator : RichText::Iterator {
	String         link;

	virtual bool operator()(int pos, const RichPara& para)
	{
		if(!IsNull(para.format.label)) {
			reflink.Add(para.format.label, link);
		}
		return false;
	}
};

void GatherRefLinks(const char *upp)
{
	Progress pi;
	pi.AlignText(ALIGN_LEFT);
	for(FindFile pff(AppendFileName(upp, "*.*")); pff; pff.Next()) {
		if(pff.IsFolder()) {
			pi.Step();
			String package = pff.GetName();
			String pdir = AppendFileName(upp, package);
			TopicLink tl;
			tl.package = package;
			for(FindFile ff(AppendFileName(pdir, "*.tpp")); ff; ff.Next()) {
				if(ff.IsFolder()) {
					String group = GetFileTitle(ff.GetName());
					tl.group = group;
					String dir = AppendFileName(pdir, ff.GetName());
					for(FindFile ft(AppendFileName(dir, "*.tpp")); ft; ft.Next()) {
						if(ft.IsFile()) {
							String path = AppendFileName(dir, ft.GetName());
							tl.topic = GetFileTitle(ft.GetName());
							String link = TopicLinkString(tl);
							pi.SetText("Indexing topic " + tl.topic);
							ScanTopicIterator sti;
							sti.link = link;
							ParseQTF(ReadTopic(LoadFile(path))).Iterate(sti);
						}
					}
				}
			}
		}
	}
}

parallel version with CoWork:

StaticCriticalSection     reflink_lock;
VectorMap<String, String> reflink;

struct ScanTopicIterator : RichText::Iterator {
	String         link;

	virtual bool operator()(int pos, const RichPara& para)
	{
		if(!IsNull(para.format.label)) {
			INTERLOCKED_(reflink_lock)
				reflink.Add(para.format.label, link);
		}
		return false;
	}
};


static void sDoFile(const char *path, const char *link)
{
	ScanTopicIterator sti;
	sti.link = link;
	ParseQTF(ReadTopic(LoadFile(path))).Iterate(sti);
}

void GatherRefLinks(const char *upp)
{
	CoWork work;
	Progress pi;
	pi.AlignText(ALIGN_LEFT);
	for(FindFile pff(AppendFileName(upp, "*.*")); pff; pff.Next()) {
		if(pff.IsFolder()) {
			pi.Step();
			String package = pff.GetName();
			String pdir = AppendFileName(upp, package);
			TopicLink tl;
			tl.package = package;
			for(FindFile ff(AppendFileName(pdir, "*.tpp")); ff; ff.Next()) {
				if(ff.IsFolder()) {
					String group = GetFileTitle(ff.GetName());
					tl.group = group;
					String dir = AppendFileName(pdir, ff.GetName());
					for(FindFile ft(AppendFileName(dir, "*.tpp")); ft; ft.Next()) {
						if(ft.IsFile()) {
							String path = AppendFileName(dir, ft.GetName());
							tl.topic = GetFileTitle(ft.GetName());
							String link = TopicLinkString(tl);
							pi.SetText("Indexing topic " + tl.topic);
							work & callback2(sDoFile, path, link);
						}
					}
				}
			}
		}
	}
}

The advantage is that you do not have start/join/manage threads, in fact, CoWork starts a couple of threads ("thread pool") first time it is used and never quits them until application exists.

Mirek

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