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/**
* @file llhttpretrypolicy.h
* @brief Header for a retry policy class intended for use with http responders.
*
* $LicenseInfo:firstyear=2013&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2013, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#include "llviewerprecompiledheaders.h"
#include "llhttpretrypolicy.h"
namespace
{
// Moved from httpconstants.h... only used in this file.
bool isHttpServerErrorStatus(S32 status)
{
// Status 499 is sometimes used for re-interpreted status 2xx errors.
// Allow retry of these, since we don't have enough information in this
// context to know if this will always fail.
if (HTTP_INTERNAL_ERROR == status) return true;
// Check for status 5xx.
return((500 <= status) && (status < 600));
}
}
LLAdaptiveRetryPolicy::LLAdaptiveRetryPolicy(F32 min_delay, F32 max_delay, F32 backoff_factor, U32 max_retries, bool retry_on_4xx):
mMinDelay(min_delay),
mMaxDelay(max_delay),
mBackoffFactor(backoff_factor),
mMaxRetries(max_retries),
mRetryOn4xx(retry_on_4xx)
{
init();
}
void LLAdaptiveRetryPolicy::init()
{
mDelay = mMinDelay;
mRetryCount = 0;
mShouldRetry = true;
}
void LLAdaptiveRetryPolicy::reset()
{
init();
}
bool LLAdaptiveRetryPolicy::getRetryAfter(const LLSD& headers, F32& retry_header_time)
{
return (headers.has(HTTP_IN_HEADER_RETRY_AFTER)
&& getSecondsUntilRetryAfter(headers[HTTP_IN_HEADER_RETRY_AFTER].asStringRef(), retry_header_time));
}
bool LLAdaptiveRetryPolicy::getRetryAfter(const LLCore::HttpHeaders::ptr_t &headers, F32& retry_header_time)
{
if (headers)
{
const std::string *retry_value = headers->find(HTTP_IN_HEADER_RETRY_AFTER.c_str());
if (retry_value &&
getSecondsUntilRetryAfter(*retry_value, retry_header_time))
{
return true;
}
}
return false;
}
void LLAdaptiveRetryPolicy::onSuccess()
{
init();
}
void LLAdaptiveRetryPolicy::onFailure(S32 status, const LLSD& headers)
{
F32 retry_header_time;
bool has_retry_header_time = getRetryAfter(headers,retry_header_time);
onFailureCommon(status, has_retry_header_time, retry_header_time);
}
void LLAdaptiveRetryPolicy::onFailure(const LLCore::HttpResponse *response)
{
F32 retry_header_time;
const LLCore::HttpHeaders::ptr_t headers = response->getHeaders();
bool has_retry_header_time = getRetryAfter(headers,retry_header_time);
onFailureCommon(response->getStatus().getType(), has_retry_header_time, retry_header_time);
}
void LLAdaptiveRetryPolicy::onFailureCommon(S32 status, bool has_retry_header_time, F32 retry_header_time)
{
if (!mShouldRetry)
{
LL_INFOS() << "keep on failing" << LL_ENDL;
return;
}
if (mRetryCount > 0)
{
mDelay = llclamp(mDelay*mBackoffFactor,mMinDelay,mMaxDelay);
}
// Honor server Retry-After header.
// Status 503 may ask us to wait for a certain amount of time before retrying.
F32 wait_time = mDelay;
if (has_retry_header_time)
{
wait_time = retry_header_time;
}
if (mRetryCount>=mMaxRetries)
{
LL_INFOS() << "Too many retries " << mRetryCount << ", will not retry" << LL_ENDL;
mShouldRetry = false;
}
if (!mRetryOn4xx && !isHttpServerErrorStatus(status))
{
LL_INFOS() << "Non-server error " << status << ", will not retry" << LL_ENDL;
mShouldRetry = false;
}
if (mShouldRetry)
{
LL_INFOS() << "Retry count " << mRetryCount << " should retry after " << wait_time << LL_ENDL;
mRetryTimer.reset();
mRetryTimer.setTimerExpirySec(wait_time);
}
mRetryCount++;
}
bool LLAdaptiveRetryPolicy::shouldRetry(F32& seconds_to_wait) const
{
if (mRetryCount == 0)
{
// Called shouldRetry before any failure.
seconds_to_wait = F32_MAX;
return false;
}
seconds_to_wait = mShouldRetry ? (F32) mRetryTimer.getRemainingTimeF32() : F32_MAX;
return mShouldRetry;
}
// Moved from httpconstants. Only used by this file.
// Parses 'Retry-After' header contents and returns seconds until retry should occur.
/*static*/
bool LLAdaptiveRetryPolicy::getSecondsUntilRetryAfter(const std::string& retry_after, F32& seconds_to_wait)
{
// *TODO: This needs testing! Not in use yet.
// Examples of Retry-After headers:
// Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
// Retry-After: 120
// Check for number of seconds version, first:
char* end = 0;
// Parse as double
double seconds = std::strtod(retry_after.c_str(), &end);
if (end != 0 && *end == 0)
{
// Successful parse
seconds_to_wait = (F32)seconds;
return true;
}
// Parse rfc1123 date.
time_t date = curl_getdate(retry_after.c_str(), NULL);
if (-1 == date) return false;
seconds_to_wait = (F64)date - LLTimer::getTotalSeconds();
return true;
}
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