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authorprep <prep@lindenlab.com>2012-11-28 16:36:34 -0500
committerprep <prep@lindenlab.com>2012-11-28 16:36:34 -0500
commite0432f98ee515f9777604aa784d28b63d2abfe40 (patch)
tree398fcae43d9904bde2112a7085c7ef7c1a926100 /indra/llcorehttp/_httpoperation.h
parentbf87920fc91e2ca2b8d9f6f2656ad632c3005164 (diff)
parentf5a47417fde70f78b99744386c6da0bcf78e60d5 (diff)
SH-3563. Pull and merge from viewer-development. Modest code changes to fix alignment issue in llAppearance.
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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_
+