GetXmlDocumentWithRetries
(
String sUrl,
HttpStatusCode [] aeHttpStatusCodesToFailImmediately,
RequestStatistics oRequestStatistics
)
{
Debug.Assert(!String.IsNullOrEmpty(sUrl));
Debug.Assert(oRequestStatistics != null);
AssertValid();
Stream oStream = null;
try
{
oStream =
HttpSocialNetworkUtil.GetHttpWebResponseStreamWithRetries(
sUrl, aeHttpStatusCodesToFailImmediately,
oRequestStatistics, UserAgent, HttpWebRequestTimeoutMs,
new ReportProgressHandler(this.ReportProgress),
new CheckCancellationPendingHandler(
this.CheckCancellationPending)
);
XmlDocument oXmlDocument = new XmlDocument();
oXmlDocument.Load(oStream);
return(oXmlDocument);
}
finally
{
if (oStream != null)
{
oStream.Close();
}
}
}
GetTwitterResponseAsString
(
String url,
RequestStatistics requestStatistics,
ReportProgressHandler reportProgressHandler,
CheckCancellationPendingHandler checkCancellationPendingHandler
)
{
Debug.Assert(!String.IsNullOrEmpty(url));
Debug.Assert(requestStatistics != null);
AssertValid();
Int32 iRateLimitPauses = 0;
Int32 iInvalidJsonRepeats = 0;
const Int32 MaximumInvalidJsonRepeats = 3;
while (true)
{
// Add the required authorization information to the URL.
//
// Note: Don't do this outside the while (true) loop. The
// authorization information includes a timestamp that will
// probably expire if the code within the catch block pauses.
oAuthTwitter oAuthTwitter = new oAuthTwitter(
m_UserAgent, m_TimeoutMs);
oAuthTwitter.Token = m_TwitterAccessToken;
oAuthTwitter.TokenSecret = m_TwitterAccessTokenSecret;
String sAuthorizedUrl, sAuthorizedPostData;
oAuthTwitter.ConstructAuthWebRequest(oAuthTwitter.Method.GET,
url, String.Empty, out sAuthorizedUrl,
out sAuthorizedPostData);
url = sAuthorizedUrl;
Stream oStream = null;
try
{
oStream =
HttpSocialNetworkUtil.GetHttpWebResponseStreamWithRetries(
url, HttpStatusCodesToFailImmediately,
requestStatistics, m_UserAgent, m_TimeoutMs,
reportProgressHandler, checkCancellationPendingHandler);
return(GetTwitterResponseAsString(oStream));
}
catch (InvalidJsonException oInvalidJsonException)
{
iInvalidJsonRepeats++;
if (iInvalidJsonRepeats > MaximumInvalidJsonRepeats)
{
throw oInvalidJsonException;
}
HttpSocialNetworkUtil.ReportProgress(reportProgressHandler,
"Received invalid JSON from Twitter. Trying again."
);
}
catch (WebException oWebException)
{
if (
!WebExceptionIsDueToRateLimit(oWebException)
||
iRateLimitPauses > 0
)
{
throw;
}
// Twitter rate limits have kicked in. Pause and try again.
iRateLimitPauses++;
Int32 iRateLimitPauseMs = GetRateLimitPauseMs(oWebException);
DateTime oWakeUpTime = DateTime.Now.AddMilliseconds(
iRateLimitPauseMs);
HttpSocialNetworkUtil.ReportProgress(reportProgressHandler,
"Reached Twitter rate limits. Pausing until {0}."
,
oWakeUpTime.ToLongTimeString()
);
// Don't pause in one large interval, which would prevent
// cancellation.
const Int32 SleepCycleDurationMs = 1000;
Int32 iSleepCycles = (Int32)Math.Ceiling(
(Double)iRateLimitPauseMs / SleepCycleDurationMs);
for (Int32 i = 0; i < iSleepCycles; i++)
{
if (checkCancellationPendingHandler != null)
{
checkCancellationPendingHandler();
}
System.Threading.Thread.Sleep(SleepCycleDurationMs);
}
}
finally
{
if (oStream != null)
{
oStream.Close();
}
}
}
}