static void Main(string[] args)
{
// Creating Needed Instances
RequestsHandler httpClient = new RequestsHandler ();
AppStoreParser parser = new AppStoreParser ();
// Loading Configuration
LogSetup.InitializeLog ("Apple_Store_Urls_Worker.log", "info");
_logger = LogManager.GetCurrentClassLogger ();
// Loading Config
_logger.Info ("Loading Configurations from App.config");
LoadConfiguration ();
// Control Variable (Bool - Should the process use proxies? )
bool shouldUseProxies = false;
// Checking for the need to use proxies
if (args != null && args.Length == 1)
{
// Setting flag to true
shouldUseProxies = true;
// Loading proxies from .txt received as argument
String fPath = args[0];
// Sanity Check
if (!File.Exists (fPath))
{
_logger.Fatal ("Couldnt find proxies on path : " + fPath);
System.Environment.Exit (-100);
}
// Reading Proxies from File
string[] fLines = File.ReadAllLines (fPath, Encoding.GetEncoding ("UTF-8"));
try
{
// Actual Load of Proxies
ProxiesLoader.Load (fLines.ToList ());
}
catch (Exception ex)
{
_logger.Fatal (ex);
System.Environment.Exit (-101);
}
}
// AWS Queue Handler
_logger.Info ("Initializing Queues");
AzureSQSHelper charactersUrlQueue = new AzureSQSHelper (_characterUrlsQueueName, _maxMessagesPerDequeue, _azureQueueconn);
AzureSQSHelper numericUrlQueue = new AzureSQSHelper(_numericUrlsQueueName , _maxMessagesPerDequeue, _azureQueueconn);
// Setting Error Flag to No Error ( 0 )
System.Environment.ExitCode = 0;
// Initialiazing Control Variables
int fallbackWaitTime = 1;
_logger.Info ("Started Processing Character Urls");
do
{
try
{
// Dequeueing messages from the Queue
if (!charactersUrlQueue.DeQueueMessages())
{
Thread.Sleep (_hiccupTime); // Hiccup
continue;
}
// Checking for no message received, and false positives situations
if (!charactersUrlQueue.AnyMessageReceived())
{
// If no message was found, increases the wait time
int waitTime;
if (fallbackWaitTime <= 12)
{
// Exponential increase on the wait time, truncated after 12 retries
waitTime = Convert.ToInt32 (Math.Pow (2, fallbackWaitTime) * 1000);
}
else // Reseting Wait after 12 fallbacks
{
waitTime = 2000;
fallbackWaitTime = 0;
}
fallbackWaitTime++;
// Sleeping before next try
Console.WriteLine ("Fallback (seconds) => " + waitTime);
Thread.Sleep (waitTime);
continue;
}
// Reseting fallback time
fallbackWaitTime = 1;
// Iterating over dequeued Messages
foreach (var characterUrl in charactersUrlQueue.GetDequeuedMessages ())
{
// Console Feedback
_logger.Info ("Started Parsing Url : " + characterUrl.AsString);
try
{
// Retries Counter
int retries = 0;
string htmlResponse;
// Retrying if necessary
do
{
// Executing Http Request for the Category Url
htmlResponse = httpClient.Get (characterUrl.AsString, shouldUseProxies);
if (String.IsNullOrEmpty (htmlResponse))
{
_logger.Info ("Retrying Request for Character Page");
retries++;
// Small Hiccup
Thread.Sleep (_hiccupTime);
}
} while (String.IsNullOrWhiteSpace (htmlResponse) && retries <= _maxRetries);
// Checking if retries failed
if (String.IsNullOrWhiteSpace (htmlResponse))
{
// Deletes Message and moves on
charactersUrlQueue.DeleteMessage (characterUrl);
continue;
}
// Hashset of urls processed (to avoid duplicates)
HashSet<String> urlsQueued = new HashSet<String> ();
// Executing Request and Queueing Urls until there's no other Url to be queued
do
{
// Flag to check whether any url was added after the last iteration (avoids endless loop)
bool anyNewUrl = false;
// If the request worked, parses the Urls out of the page
foreach (string numericUrls in parser.ParseNumericUrls (htmlResponse).Select (t => HttpUtility.HtmlDecode (t)))
{
// Checking if this url was previously queued
if (!urlsQueued.Contains (numericUrls))
{
// Enqueueing Urls
numericUrlQueue.EnqueueMessage (HttpUtility.HtmlDecode (numericUrls));
// Adding url to the local hashset
urlsQueued.Add (numericUrls);
anyNewUrl = true;
}
}
// Checking for the need to perform another http request for the next page
if (parser.IsLastPage (htmlResponse) || !anyNewUrl)
{
break; // Breaks "While" Loop
}
// Feedback
_logger.Info ("Urls Queued For This Page : " + urlsQueued.Count, "\n\tProcessing Feedback");
// If it got to this point, it means that there are more pages to be processed
// Parsing URL of the "Last" page (the last that's visible)
string lastPageUrl = HttpUtility.HtmlDecode (parser.ParseLastPageUrl (htmlResponse));
// Executing Http Request for this Url (with retries)
retries = 0;
do
{
// HTTP Get for the Page
htmlResponse = httpClient.Get (lastPageUrl, shouldUseProxies);
if (String.IsNullOrEmpty (htmlResponse))
{
_logger.Error ("Retrying Request for Last Page");
retries++;
// Small Hiccup
Thread.Sleep (_hiccupTime);
}
} while (String.IsNullOrEmpty (htmlResponse) && retries <= _maxRetries);
} while (true);
}
catch (Exception ex)
{
_logger.Error (ex);
}
finally
{
charactersUrlQueue.DeleteMessage (characterUrl);
}
}
}
catch (Exception ex)
{
_logger.Error (ex);
}
} while (true);
}
