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XrdOuc
XrdOucCallBack.hh
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#ifndef __XRDOUCCALLBACK__HH_
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#define __XRDOUCCALLBACK__HH_
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/******************************************************************************/
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/* */
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/* X r d O u c C a l l B a c k . h h */
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/* */
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/* (c) 2011 by the Board of Trustees of the Leland Stanford, Jr., University */
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/* All Rights Reserved */
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/* Produced by Andrew Hanushevsky for Stanford University under contract */
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/* DE-AC02-76-SFO0515 with the Department of Energy */
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/* */
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/* This file is part of the XRootD software suite. */
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/* */
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/* XRootD is free software: you can redistribute it and/or modify it under */
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/* the terms of the GNU Lesser General Public License as published by the */
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/* Free Software Foundation, either version 3 of the License, or (at your */
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/* option) any later version. */
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/* */
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/* XRootD is distributed in the hope that it will be useful, but WITHOUT */
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/* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or */
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/* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public */
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/* License for more details. */
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/* */
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/* You should have received a copy of the GNU Lesser General Public License */
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/* along with XRootD in a file called COPYING.LESSER (LGPL license) and file */
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/* COPYING (GPL license). If not, see <http://www.gnu.org/licenses/>. */
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/* */
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/* The copyright holder's institutional names and contributor's names may not */
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/* be used to endorse or promote products derived from this software without */
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/* specific prior written permission of the institution or contributor. */
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/******************************************************************************/
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#include "
XrdOuc/XrdOucErrInfo.hh
"
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#include "
XrdSys/XrdSysPthread.hh
"
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/* The XrdOucCallBack object encapsulates the vagaries of handling callbacks
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in the xrootd framework; where callbacks are allowed. Once a callback is
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successfully established using Init() this object should not be deleted
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until Reply() of Cancel() is called. The destructor automatically calls
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Cancel() is a callback is outstanding. The object may be reused after
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Cancel() or Reply is called. See warnings on Init() and Cancel().
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This object is not MT-safe and must be used in a serial fashion.
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*/
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class
XrdOucCallBack
:
public
XrdOucEICB
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{
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public
:
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/* Allowed() tell you whether or not am XrdOucErrInfo object has been setup to
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allow callbacks. You should test this before assuming you can use
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the object to effect a callback.
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Returns: True - if a callback is allowed.
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False - otherwise.
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*/
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static
int
Allowed
(
XrdOucErrInfo
*eInfo) {
return
eInfo->
getErrCB
() != 0;}
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/* Cancel() cancels the callback. If no callback is oustanding, it does
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nothing. Otherwise, the associated endpoint is told to retry
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whatever operation caused the callback to be setup. Warning,
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calling Cancel() or deleting this object after calling Init()
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but not effecting a callback response will cause the calling
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thread to hang!
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*/
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void
Cancel
();
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/* Init() sets up a call back using the provided XrdOucErrInfo object.
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You must successfully call Init() before calling Reply()!
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Warning, once you cann Init() you *must* effect a callback
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response; otherwise, it is likely a subsequent thread using
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this object will hang!
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Returns: True - if a callback was set up.
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False - otherwise (i.e., object does not allow callbacks).
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*/
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int
Init
(
XrdOucErrInfo
*eInfo);
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/* Reply() sends the specified results to the endpoint associated with the
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callback esablished by Init(). The parameters are:
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retVal - The value you would have synchrnously returned.
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eValue - The numeric value that would have been returned in the
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original XrdOucErrInfo object.
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eText - The character string that would have been returned in the
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original XrdOucErrInfo object.
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Path - Optional path related to the reply. It is passed to the
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callback effector and is used for tracing & monitoring.
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Returns: True - if a callback was initiated.
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False - callback failed; likely Init() was not successfully called.
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*/
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int
Reply
(
int
retVal,
int
eValue,
const
char
*eText,
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const
char
*Path=0);
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XrdOucCallBack
() :
Next
(0),
cbSync
(0),
cbArg
(0),
cbObj
(0) {}
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~XrdOucCallBack
() {
if
(
cbObj
)
Cancel
();}
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// The following is a handy pointer to allow for linking these objects together
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//
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XrdOucCallBack
*
Next
;
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private
:
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void
Done
(
int
&Result,
XrdOucErrInfo
*eInfo,
const
char
*Path=0) {
cbSync
.
Post
();}
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int
Same
(
unsigned
long
long
arg1,
unsigned
long
long
arg2) {
return
0;}
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XrdSysSemaphore
cbSync
;
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unsigned
long
long
cbArg
;
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XrdOucEICB
*
cbObj
;
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char
UserID
[64];
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};
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#endif
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