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/**
* @file file llhttpretrypolicy.h
* @brief declarations for http retry policy class.
*
* $LicenseInfo:firstyear=2013&license=viewerlgpl$
* 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
* $/LicenseInfo$
*/
#ifndef LL_RETRYPOLICY_H
#define LL_RETRYPOLICY_H
#include "lltimer.h"
#include "llthread.h"
#include "llhttpconstants.h"
// For compatibility with new core http lib.
#include "httpresponse.h"
#include "httpheaders.h"
// This is intended for use with HTTP Clients/Responders, but is not
// specifically coupled with those classes.
class LLHTTPRetryPolicy: public LLThreadSafeRefCount
{
public:
LLHTTPRetryPolicy() {}
virtual ~LLHTTPRetryPolicy() {}
// Call after a sucess to reset retry state.
virtual void onSuccess() = 0;
// Call once after an HTTP failure to update state.
virtual void onFailure(S32 status, const LLSD& headers) = 0;
virtual void onFailure(const LLCore::HttpResponse *response) = 0;
virtual bool shouldRetry(F32& seconds_to_wait) const = 0;
virtual void reset() = 0;
};
// Very general policy with geometric back-off after failures,
// up to a maximum delay, and maximum number of retries.
class LLAdaptiveRetryPolicy: public LLHTTPRetryPolicy
{
public:
LLAdaptiveRetryPolicy(F32 min_delay, F32 max_delay, F32 backoff_factor, U32 max_retries, bool retry_on_4xx = false);
// virtual
void onSuccess();
void reset();
// virtual
void onFailure(S32 status, const LLSD& headers);
// virtual
void onFailure(const LLCore::HttpResponse *response);
// virtual
bool shouldRetry(F32& seconds_to_wait) const;
protected:
void init();
bool getRetryAfter(const LLSD& headers, F32& retry_header_time);
bool getRetryAfter(const LLCore::HttpHeaders *headers, F32& retry_header_time);
void onFailureCommon(S32 status, bool has_retry_header_time, F32 retry_header_time);
private:
const F32 mMinDelay; // delay never less than this value
const F32 mMaxDelay; // delay never exceeds this value
const F32 mBackoffFactor; // delay increases by this factor after each retry, up to mMaxDelay.
const U32 mMaxRetries; // maximum number of times shouldRetry will return true.
F32 mDelay; // current default delay.
U32 mRetryCount; // number of times shouldRetry has been called.
LLTimer mRetryTimer; // time until next retry.
bool mShouldRetry; // Becomes false after too many retries, or the wrong sort of status received, etc.
bool mRetryOn4xx; // Normally only retry on 5xx server errors.
};
#endif
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