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/**
* @file _httplibcurl.h
* @brief Declarations for internal class providing libcurl transport.
*
* $LicenseInfo:firstyear=2012&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2012-2014, 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_LIBCURL_H_
#define _LLCORE_HTTP_LIBCURL_H_
#include "linden_common.h" // Modifies curl/curl.h interfaces
#include <curl/curl.h>
#include <curl/multi.h>
#include <set>
#include "httprequest.h"
#include "_httpservice.h"
#include "_httpinternal.h"
namespace LLCore
{
class HttpPolicy;
class HttpOpRequest;
class HttpHeaders;
/// Implements libcurl-based transport 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 HttpLibcurl
{
public:
HttpLibcurl(HttpService * service);
virtual ~HttpLibcurl();
private:
HttpLibcurl(const HttpLibcurl &); // Not defined
void operator=(const HttpLibcurl &); // Not defined
public:
typedef std::shared_ptr<HttpOpRequest> opReqPtr_t;
/// Give cycles to libcurl to run active requests. Completed
/// operations (successful or failed) will be retried or handed
/// over to the reply queue as final responses.
///
/// @return Indication of how long this method is
/// willing to wait for next service call.
///
/// Threading: called by worker thread.
HttpService::ELoopSpeed processTransport();
/// Add request to the active list. Caller is expected to have
/// provided us with a reference count on the op to hold the
/// request. (No additional references will be added.)
///
/// Threading: called by worker thread.
void addOp(const opReqPtr_t & op);
/// One-time call to set the number of policy classes to be
/// serviced and to create the resources for each. Value
/// must agree with HttpPolicy::setPolicies() call.
///
/// Threading: called by init thread.
void start(int policy_count);
/// Synchronously stop libcurl operations. All active requests
/// are canceled and removed from libcurl's handling. Easy
/// handles are detached from their multi handles and released.
/// Multi handles are also released. Canceled requests are
/// completed with canceled status and made available on their
/// respective reply queues.
///
/// Can be restarted with a start() call.
///
/// Threading: called by worker thread.
void shutdown();
/// Return global and per-class counts of active requests.
///
/// Threading: called by worker thread.
int getActiveCount() const;
int getActiveCountInClass(unsigned int policy_class) const;
/// Attempt to cancel a request identified by handle.
///
/// Interface shadows HttpService's method.
///
/// @return True if handle was found and operation canceled.
///
/// Threading: called by worker thread.
bool cancel(HttpHandle handle);
/// Informs transport that a particular policy class has had
/// options changed and so should effect any transport state
/// change necessary to effect those changes. Used mainly for
/// initialization and dynamic option setting.
///
/// Threading: called by worker thread.
void policyUpdated(unsigned int policy_class);
/// Allocate a curl handle for caller. May be freed using
/// either the freeHandle() method or calling curl_easy_cleanup()
/// directly.
///
/// @return Libcurl handle (CURL *) or NULL on allocation
/// problem. Handle will be in curl_easy_reset()
/// condition.
///
/// Threading: callable by worker thread.
///
/// Deprecation: Expect this to go away after _httpoprequest is
/// refactored bringing code into this class.
CURL * getHandle()
{
return mHandleCache.getHandle();
}
protected:
/// Invoked when libcurl has indicated a request has been processed
/// to completion and we need to move the request to a new state.
bool completeRequest(CURLM * multi_handle, CURL * handle, CURLcode status);
/// Invoked to cancel an active request, mainly during shutdown
/// and destroy.
void cancelRequest(const opReqPtr_t &op);
protected:
typedef std::set<opReqPtr_t> active_set_t;
/// Simple request handle cache for libcurl.
///
/// Handle creation is somewhat slow and chunky in libcurl and there's
/// a pretty good speedup to be had from handle re-use. So, a simple
/// vector is kept of 'freed' handles to be reused as needed. When
/// that is empty, the first freed handle is kept as a template for
/// handle duplication. This is still faster than creation from nothing.
/// And when that fails, we init fresh from curl_easy_init().
///
/// Handles allocated with getHandle() may be freed with either
/// freeHandle() or curl_easy_cleanup(). Choice may be dictated
/// by thread constraints.
///
/// Threading: Single-threaded. May only be used by a single thread,
/// typically the worker thread. If freeing requests' handles in an
/// unknown threading context, use curl_easy_cleanup() for safety.
class HandleCache
{
public:
HandleCache();
~HandleCache();
private:
HandleCache(const HandleCache &); // Not defined
void operator=(const HandleCache &); // Not defined
public:
/// Allocate a curl handle for caller. May be freed using
/// either the freeHandle() method or calling curl_easy_cleanup()
/// directly.
///
/// @return Libcurl handle (CURL *) or NULL on allocation
/// problem.
///
/// Threading: Single-thread (worker) only.
CURL * getHandle();
/// Free a libcurl handle acquired by whatever means. Thread
/// safety is left to the caller.
///
/// Threading: Single-thread (worker) only.
void freeHandle(CURL * handle);
protected:
typedef std::vector<CURL *> handle_cache_t;
protected:
CURL * mHandleTemplate; // Template for duplicating new handles
handle_cache_t mCache; // Cache of old handles
}; // end class HandleCache
protected:
HttpService * mService; // Simple reference, not owner
HandleCache mHandleCache; // Handle allocator, owner
active_set_t mActiveOps;
unsigned int mPolicyCount;
CURLM ** mMultiHandles; // One handle per policy class
int * mActiveHandles; // Active count per policy class
bool * mDirtyPolicy; // Dirty policy update waiting for stall (per pc)
}; // end class HttpLibcurl
} // end namespace LLCore
#endif // _LLCORE_HTTP_LIBCURL_H_
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