private static async Task <WebsiteDataModel> DownloadWebsiteAsync(string websiteURL)
{
WebsiteDataModel output = new WebsiteDataModel();
WebClient client = new WebClient();
output.WebsiteUrl = websiteURL;
output.WebsiteData = await client.DownloadStringTaskAsync(websiteURL);
return(output);
}
private static WebsiteDataModel DownloadWebsite(string websiteURL)
{
WebsiteDataModel output = new WebsiteDataModel();
WebClient client = new WebClient();
output.WebsiteUrl = websiteURL;
output.WebsiteData = client.DownloadString(websiteURL);
return(output);
}
public static List <WebsiteDataModel> RunDownloadSync()
{
List <string> websites = PrepData();
List <WebsiteDataModel> output = new List <WebsiteDataModel>();
foreach (string site in websites)
{
WebsiteDataModel results = DownloadWebsite(site);
output.Add(results);
}
return(output);
}
/*
* async methods need to have Task as a return type. It is not recommended to use void return type for asyn methods. You can use the void return type in
* asynchronous event handlers, which require a void return type. For methods other than event handlers that don't return a value, you should return a Task
* instead, because an async method that returns void can't be awaited.
*/
public static async Task <List <WebsiteDataModel> > RunDownloadAsync(IProgress <ProgressReportModel> progress, CancellationToken cancellationToken)
{
List <string> websites = PrepData();
List <WebsiteDataModel> output = new List <WebsiteDataModel>();
ProgressReportModel report = new ProgressReportModel();
foreach (string site in websites)
{
/*
* When you check the execution time of both Normal Execution & Async Execution they are nearly have the same execution time. The reason why the
* execute on the same time or the same speed is because of the await keyword below.
*
* Here, what it's doing is calling a first website say download that but wait for it. So, it blocks this particular method from getting to the next
* website and it blocks the execution for the next website. So let's solve this problem with the help of parallel execution.
*/
WebsiteDataModel results = await Task.Run(() => DownloadWebsite(site));
output.Add(results);
/*
* The logical place to add the CancellationToken is after we download our first website. The CancellationToken is activated if we say go ahead and
* cancel that Task we're going to throw and exception essentially and then exception is going to be the operation cancelled exception.
*
* That allows us couple of benefits:
* 1. It will stop right away and go back to the caller but it's also going to allow us to do any kind of clean-up on the caller end that we need to
* do before we continue. Say we have open connections or something like that we can go ahead and close them.
* 2. Another thing is we should do some cleanup in here if we need to before we actually throw this. IsCancellationRequested that can check to see
* if the cancellation has been requested. We check the value of IsCancellationRequested in the if condition and do cleanup and then
* ThrowIfCancellationRequested().
*/
cancellationToken.ThrowIfCancellationRequested();
report.SitesDownloaded = output;
report.PercentageComplete = (output.Count * 100) / websites.Count;
progress.Report(report);
}
return(output);
}
public async static Task <List <WebsiteDataModel> > RunDownloadParallelAsyncV2(IProgress <ProgressReportModel> progress)
{
List <string> websites = PrepData();
List <WebsiteDataModel> output = new List <WebsiteDataModel>();
ProgressReportModel report = new ProgressReportModel();
/*
* For Parallel.ForEach we are passing a List of string and then for each item we are going to do an Action. What site represents is each of the website.
* This is same essentially for RunDownloadSync except for the fact that ForEach it does each of these download in parallel to each other. Parallel.ForEach
* gets a list of things do each one in parallel the others.
*
* The difference between Parallel.ForEach and RunDownloadParallelAsync (where we created our own parallel execution). The difference is Parallel.ForEach
* do the task in Parallel in a synchronous way meaning it locks everything up until they're all done. So the longest download that's how long we have to
* wait for this to be done. It's a short amount of time then the code written in RunDownloadSync method, which actually downloads one at a time and the
* time is cumulative. There is benefit in using Parallel.ForEach but still it's synchronous.
*
* RunDownloadParallelAsyncV2 is actually better and faster than RunDownloadParallelAsync because it will return the smallest website name which is
* downloaded first and returns the largest website which is downloaded last. Unlike in RunDownloadParallelAsync website is downloaded in an order they
* were added to the list.
*/
await Task.Run(() =>
{
Parallel.ForEach <string>(websites, (site) =>
{
WebsiteDataModel results = DownloadWebsite(site);
output.Add(results);
report.SitesDownloaded = output;
report.PercentageComplete = (output.Count * 100) / websites.Count;
progress.Report(report);
});
});
return(output);
}
public static List <WebsiteDataModel> RunDownloadParallelSync()
{
List <string> websites = PrepData();
List <WebsiteDataModel> output = new List <WebsiteDataModel>();
/*
* For Parallel.ForEach we are passing a List of string and then for each item we are going to do an Action. What site represents is each of the website.
* This is same essentially for RunDownloadSync except for the fact that ForEach it does each of these download in parallel to each other. Parallel.ForEach
* gets a list of things do each one in parallel the others.
*
* The difference between Parallel.ForEach and RunDownloadParallelAsync (where we created our own parallel execution). The difference is Parallel.ForEach
* do the task in Parallel in a synchronous way meaning it locks everything up until they're all done. So the longest download that's how long we have to
* wait for this to be done. It's a short amount of time then the code written in RunDownloadSync method, which actually downloads one at a time and the
* time is cumulative. There is benefit in using Parallel.ForEach but still it's synchronous.
*/
Parallel.ForEach <string>(websites, (site) =>
{
WebsiteDataModel results = DownloadWebsite(site);
output.Add(results);
});
return(output);
}
