private Page fetchNextPage(BackQueue backQueue, Uri currentUrl)
{
String host = currentUrl.GetLeftPart(UriPartial.Authority);
while (backQueue.EnoughTimeHasPassed(host, DateTime.Now) == false)
{
Thread.Yield();
}
Page newPage = new Page(currentUrl);
parser.AddHtmlToPage(newPage);
if (String.IsNullOrEmpty(newPage.Html))
{
return(null);
}
parser.AddBodyToPage(newPage);
if (String.IsNullOrEmpty(newPage.SiteText))
{
return(null);
}
parser.AddPathsToPage(newPage);
return(newPage);
}
private void initialiseSeed()
{
foreach (Uri seed in initialSeeds)
{
String domain = seed.GetLeftPart(UriPartial.Authority);
BackQueue backQueue = new BackQueue(domain);
backQueue.Enqueue(seed);
BackQueues.TryAdd(Interlocked.Increment(ref i), backQueue);
}
}
private void NewMethod()
{
var random = new Random();
while (_webGraph.Count() < _numberOfPages)
{
BackQueue b = new BackQueue(null); //dummy
Uri nextUrl = new Uri("https://www.aau.dk"); // dummy
if (BackQueues.Count() == 0)
{
continue;
}
b = BackQueues[random.Next(0, BackQueues.Count)];
if (b.Count == 0 || !b.TryPeek(out nextUrl))
{
continue;
}
if (_webGraph.ToList().Where(x => x.Url == nextUrl).Count() > 0)
{
continue;
}
//2. Fetch next page from URL in queue
Page newPage = fetchNextPage(b, nextUrl);
if (newPage is null)
{
continue;
}
addToWebGraph(newPage);
//For each extracted URL
//• Obey robots.txt (freshness caveat)
//c. Check that not already in frontier
var paths = newPage.OutLinks.Where(x => b.RobotsAreObeyed(x) &&
b.Contains(x) == false);
//d. Add to frontier if passing tests
addPathToFrontierIfTestsPassed(b, paths);
}
//5. Delete or re-prioritize current URL from queue
}
private void addPathToFrontierIfTestsPassed(BackQueue b, IEnumerable <Uri> paths)
{
foreach (Uri path in paths)
{
String pathDomain = path.GetLeftPart(UriPartial.Authority);
if (pathDomain.Equals(b.Domain))
{
b.Enqueue(path);
}
else if (BackQueues.Any(x => x.Value.Domain.Equals(pathDomain)))
{
BackQueues.First(x => x.Value.Domain.Equals(pathDomain)).Value.Enqueue(path);
}
else
{
BackQueue newQueue = new BackQueue(pathDomain);
newQueue.Enqueue(path);
BackQueues.TryAdd(Interlocked.Increment(ref i), newQueue);
}
}
}
