00001 #ifndef __POSIX_CALLBACK_HH__ 00002 #define __POSIX_CALLBACK_HH__ 00003 /******************************************************************************/ 00004 /* */ 00005 /* X r d P o s i x C a l l B a c k . h h */ 00006 /* */ 00007 /* (c) 2010 by the Board of Trustees of the Leland Stanford, Jr., University */ 00008 /* All Rights Reserved */ 00009 /* Produced by Andrew Hanushevsky for Stanford University under contract */ 00010 /* DE-AC02-76-SFO0515 with the Department of Energy */ 00011 /* */ 00012 /* This file is part of the XRootD software suite. */ 00013 /* */ 00014 /* XRootD is free software: you can redistribute it and/or modify it under */ 00015 /* the terms of the GNU Lesser General Public License as published by the */ 00016 /* Free Software Foundation, either version 3 of the License, or (at your */ 00017 /* option) any later version. */ 00018 /* */ 00019 /* XRootD is distributed in the hope that it will be useful, but WITHOUT */ 00020 /* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or */ 00021 /* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public */ 00022 /* License for more details. */ 00023 /* */ 00024 /* You should have received a copy of the GNU Lesser General Public License */ 00025 /* along with XRootD in a file called COPYING.LESSER (LGPL license) and file */ 00026 /* COPYING (GPL license). If not, see <http://www.gnu.org/licenses/>. */ 00027 /* */ 00028 /* The copyright holder's institutional names and contributor's names may not */ 00029 /* be used to endorse or promote products derived from this software without */ 00030 /* specific prior written permission of the institution or contributor. */ 00031 /******************************************************************************/ 00032 00033 // This abstract class defines the callback interface for file open() calls. 00034 // It is passed when using the XrdPosixXrootd::Open() call. When passed, the 00035 // open request will be done in the background. When a callback object is 00036 // supplied, Open() will *always* return -1. However, if started successfully, 00037 // Open() will return -1 with errno set to EINPROGRESS. Otherwise, errno will 00038 // contain the reason the Open() request immediately failed. Upon completion, 00039 // the callback's Compete() method is invoked. The Result parameter will either 00040 // be a non-negative file descriptor or -errno indicating that the Open() 00041 // failed. Note that the caller is responsible for deleting the callback object 00042 // after it has been invoked. Note that callbacks will be executed in a 00043 // separate thread unless open() is called with O_SYNC or maxThreads is zero. 00044 // WARNING: If O_SYNC or maxThreads is zero, then the callback must *not* 00045 // issue any filesystem calls using the supplied file descriptor. 00046 // Ignoring this will produce undetermined results including possible 00047 // deadlock. Synchrnous callbacks are only meant to support private 00048 // thread management. 00049 00050 class XrdPosixCallBack 00051 { 00052 public: 00053 00054 virtual void Complete(int Result) = 0; 00055 00056 XrdPosixCallBack() {} 00057 virtual ~XrdPosixCallBack() {} 00058 }; 00059 #endif