Pull and merge from https://bitbucket.org/lindenlab/viewer-development.

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diff --git a/indra/llcorehttp/_httpoperation.h b/indra/llcorehttp/_httpoperation.h
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+/**
+ * @file _httpoperation.h
+ * @brief Internal declarations for HttpOperation and sub-classes
+ *
+ * $LicenseInfo:firstyear=2012&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2012, 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_OPERATION_H_
+#define	_LLCORE_HTTP_OPERATION_H_
+
+
+#include "httpcommon.h"
+#include "httprequest.h"
+#include "_refcounted.h"
+
+
+namespace LLCore
+{
+
+class HttpReplyQueue;
+class HttpHandler;
+class HttpService;
+
+/// HttpOperation is the base class for all request/reply
+/// pairs.
+///
+/// Operations are expected to be of two types:  immediate
+/// and queued.  Immediate requests go to the singleton
+/// request queue and when picked up by the worker thread
+/// are executed immediately and there results placed on
+/// the supplied reply queue.  Queued requests (namely for
+/// HTTP operations), go to the request queue, are picked
+/// up and moved to a ready queue where they're ordered by
+/// priority and managed by the policy component, are
+/// then activated issuing HTTP requests and moved to an
+/// active list managed by the transport (libcurl) component
+/// and eventually finalized when a response is available
+/// and status and data return via reply queue.
+///
+/// To manage these transitions, derived classes implement
+/// three methods:  stageFromRequest, stageFromReady and
+/// stageFromActive.  Immediate requests will only override
+/// stageFromRequest which will perform the operation and
+/// return the result by invoking addAsReply() to put the
+/// request on a reply queue.  Queued requests will involve
+/// all three stage methods.
+///
+/// Threading:  not thread-safe.  Base and derived classes
+/// provide no locking.  Instances move across threads
+/// via queue-like interfaces that are thread compatible
+/// and those interfaces establish the access rules.
+
+class HttpOperation : public LLCoreInt::RefCounted
+{
+public:
+	/// Threading:  called by a consumer/application thread.
+	HttpOperation();
+
+protected:
+	/// Threading:  called by any thread.
+	virtual ~HttpOperation();							// Use release()
+
+private:
+	HttpOperation(const HttpOperation &);				// Not defined
+	void operator=(const HttpOperation &);				// Not defined
+
+public:
+	/// Register a reply queue and a handler for completion notifications.
+	///
+	/// Invokers of operations that want to receive notification that an
+	/// operation has been completed do so by binding a reply queue and
+	/// a handler object to the request.
+	///
+	/// @param	reply_queue		Pointer to the reply queue where completion
+	///							notifications are to be queued (typically
+	///							by addAsReply()).  This will typically be
+	///							the reply queue referenced by the request
+	///							object.  This method will increment the
+	///							refcount on the queue holding the queue
+	///							until delivery is complete.  Using a reply_queue
+	///							even if the handler is NULL has some benefits
+	///							for memory deallocation by keeping it in the
+	///							originating thread.
+	///
+	/// @param	handler			Possibly NULL pointer to a non-refcounted
+	////						handler object to be invoked (onCompleted)
+	///							when the operation is finished.  Note that
+	///							the handler object is never dereferenced
+	///							by the worker thread.  This is passible data
+	///							until notification is performed.
+	///
+	/// Threading:  called by application thread.
+	///
+	void setReplyPath(HttpReplyQueue * reply_queue,
+					  HttpHandler * handler);
+
+	/// The three possible staging steps in an operation's lifecycle.
+	/// Asynchronous requests like HTTP operations move from the
+	/// request queue to the ready queue via stageFromRequest.  Then
+	/// from the ready queue to the active queue by stageFromReady.  And
+	/// when complete, to the reply queue via stageFromActive and the
+	/// addAsReply utility.
+	///
+	/// Immediate mode operations (everything else) move from the
+	/// request queue to the reply queue directly via stageFromRequest
+	/// and addAsReply with no existence on the ready or active queues.
+	///
+	/// These methods will take out a reference count on the request,
+	/// caller only needs to dispose of its reference when done with
+	/// the request. 
+	///
+	/// Threading:  called by worker thread.
+	///
+	virtual void stageFromRequest(HttpService *);
+	virtual void stageFromReady(HttpService *);
+	virtual void stageFromActive(HttpService *);
+
+	/// Delivers a notification to a handler object on completion.
+	///
+	/// Once a request is complete and it has been removed from its
+	/// reply queue, a handler notification may be delivered by a
+	/// call to HttpRequest::update().  This method does the necessary
+	/// dispatching.
+	///
+	/// Threading:  called by application thread.
+	///
+	virtual void visitNotifier(HttpRequest *);
+
+	/// Cancels the operation whether queued or active.
+	/// Final status of the request becomes canceled (an error) and
+	/// that will be delivered to caller via notification scheme.
+	///
+	/// Threading:  called by worker thread.
+	///
+	virtual HttpStatus cancel();
+	
+protected:
+	/// Delivers request to reply queue on completion.  After this
+	/// call, worker thread no longer accesses the object and it
+	/// is owned by the reply queue.
+	///
+	/// Threading:  called by worker thread.
+	///
+	void addAsReply();
+	
+protected:
+	HttpReplyQueue *			mReplyQueue;			// Have refcount
+	HttpHandler *				mUserHandler;			// Naked pointer
+
+public:
+	// Request Data
+	HttpRequest::policy_t		mReqPolicy;
+	HttpRequest::priority_t		mReqPriority;
+
+	// Reply Data
+	HttpStatus					mStatus;
+
+	// Tracing, debug and metrics
+	HttpTime					mMetricCreated;
+	int							mTracing;
+};  // end class HttpOperation
+
+
+/// HttpOpStop requests the servicing thread to shutdown
+/// operations, cease pulling requests from the request
+/// queue and release shared resources (particularly
+/// those shared via reference count).  The servicing
+/// thread will then exit.  The underlying thread object
+/// remains so that another thread can join on the
+/// servicing thread prior to final cleanup.  The
+/// request *does* generate a reply on the response
+/// queue, if requested.
+
+class HttpOpStop : public HttpOperation
+{
+public:
+	HttpOpStop();
+
+protected:
+	virtual ~HttpOpStop();
+
+private:
+	HttpOpStop(const HttpOpStop &);					// Not defined
+	void operator=(const HttpOpStop &);				// Not defined
+
+public:
+	virtual void stageFromRequest(HttpService *);
+
+};  // end class HttpOpStop
+
+
+/// HttpOpNull is a do-nothing operation used for testing via
+/// a basic loopback pattern.  It's executed immediately by
+/// the servicing thread which bounces a reply back to the
+/// caller without any further delay.
+
+class HttpOpNull : public HttpOperation
+{
+public:
+	HttpOpNull();
+
+protected:
+	virtual ~HttpOpNull();
+
+private:
+	HttpOpNull(const HttpOpNull &);					// Not defined
+	void operator=(const HttpOpNull &);				// Not defined
+
+public:
+	virtual void stageFromRequest(HttpService *);
+
+};  // end class HttpOpNull
+
+
+/// HttpOpSpin is a test-only request that puts the worker
+/// thread into a cpu spin.  Used for unit tests and cleanup
+/// evaluation.  You do not want to use this in production.
+class HttpOpSpin : public HttpOperation
+{
+public:
+	// 0 does a hard spin in the operation
+	// 1 does a soft spin continuously requeuing itself
+	HttpOpSpin(int mode);
+
+protected:
+	virtual ~HttpOpSpin();
+
+private:
+	HttpOpSpin(const HttpOpSpin &);					// Not defined
+	void operator=(const HttpOpSpin &);				// Not defined
+
+public:
+	virtual void stageFromRequest(HttpService *);
+
+protected:
+	int			mMode;
+};  // end class HttpOpSpin
+
+
+}   // end namespace LLCore
+
+#endif	// _LLCORE_HTTP_OPERATION_H_
+