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/**
* @file _httppolicy.h
* @brief Declarations for internal class enforcing policy decisions.
*
* $LicenseInfo:firstyear=2012&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2012-2013, 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 _LLCORE_HTTP_POLICY_H_
#define _LLCORE_HTTP_POLICY_H_
#include "httprequest.h"
#include "_httpservice.h"
#include "_httpreadyqueue.h"
#include "_httpretryqueue.h"
#include "_httppolicyglobal.h"
#include "_httppolicyclass.h"
#include "_httpinternal.h"
namespace LLCore
{
class HttpReadyQueue;
class HttpOpRequest;
/// Implements class-based queuing policies for an HttpService instance.
///
/// Threading: Single-threaded. Other than for construction/destruction,
/// all methods are expected to be invoked in a single thread, typically
/// a worker thread of some sort.
class HttpPolicy
{
public:
HttpPolicy(HttpService *);
virtual ~HttpPolicy();
private:
HttpPolicy(const HttpPolicy &); // Not defined
void operator=(const HttpPolicy &); // Not defined
public:
typedef boost::shared_ptr<HttpOpRequest> opReqPtr_t;
/// Threading: called by init thread.
HttpRequest::policy_t createPolicyClass();
/// Cancel all ready and retry requests sending them to
/// their notification queues. Release state resources
/// making further request handling impossible.
///
/// Threading: called by worker thread
void shutdown();
/// Deliver policy definitions and enable handling of
/// requests. One-time call invoked before starting
/// the worker thread.
///
/// Threading: called by init thread
void start();
/// Give the policy layer some cycles to scan the ready
/// queue promoting higher-priority requests to active
/// as permited.
///
/// @return Indication of how soon this method
/// should be called again.
///
/// Threading: called by worker thread
HttpService::ELoopSpeed processReadyQueue();
/// Add request to a ready queue. Caller is expected to have
/// provided us with a reference count to hold the request. (No
/// additional references will be added.)
///
/// OpRequest is owned by the request queue after this call
/// and should not be modified by anyone until retrieved
/// from queue.
///
/// Threading: called by worker thread
void addOp(const opReqPtr_t &);
/// Similar to addOp, used when a caller wants to retry a
/// request that has failed. It's placed on a special retry
/// queue but ordered by retry time not priority. Otherwise,
/// handling is the same and retried operations are considered
/// before new ones but that doesn't guarantee completion
/// order.
///
/// Threading: called by worker thread
void retryOp(const opReqPtr_t &);
/// Attempt to change the priority of an earlier request.
/// Request that Shadows HttpService's method
///
/// Threading: called by worker thread
bool changePriority(HttpHandle handle, HttpRequest::priority_t priority);
/// Attempt to cancel a previous request.
/// Shadows HttpService's method as well
///
/// Threading: called by worker thread
bool cancel(HttpHandle handle);
/// When transport is finished with an op and takes it off the
/// active queue, it is delivered here for dispatch. Policy
/// may send it back to the ready/retry queues if it needs another
/// go or we may finalize it and send it on to the reply queue.
///
/// @return Returns true of the request is still active
/// or ready after staging, false if has been
/// sent on to the reply queue.
///
/// Threading: called by worker thread
bool stageAfterCompletion(const opReqPtr_t &op);
/// Get a reference to global policy options. Caller is expected
/// to do context checks like no setting once running. These
/// are done, for example, in @see HttpService interfaces.
///
/// Threading: called by any thread *but* the object may
/// only be modified by the worker thread once running.
HttpPolicyGlobal & getGlobalOptions()
{
return mGlobalOptions;
}
/// Get a reference to class policy options. Caller is expected
/// to do context checks like no setting once running. These
/// are done, for example, in @see HttpService interfaces.
///
/// Threading: called by any thread *but* the object may
/// only be modified by the worker thread once running and
/// read accesses by other threads are exposed to races at
/// that point.
HttpPolicyClass & getClassOptions(HttpRequest::policy_t pclass);
/// Get ready counts for a particular policy class
///
/// Threading: called by worker thread
int getReadyCount(HttpRequest::policy_t policy_class) const;
/// Stall (or unstall) a policy class preventing requests from
/// transitioning to an active state. Used to allow an HTTP
/// request policy to empty prior to changing settings or state
/// that isn't tolerant of changes when work is outstanding.
///
/// Threading: called by worker thread
bool stallPolicy(HttpRequest::policy_t policy_class, bool stall);
protected:
struct ClassState;
typedef std::vector<ClassState *> class_list_t;
HttpPolicyGlobal mGlobalOptions;
class_list_t mClasses;
HttpService * mService; // Naked pointer, not refcounted, not owner
}; // end class HttpPolicy
} // end namespace LLCore
#endif // _LLCORE_HTTP_POLICY_H_
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