OPeNDAP Hyrax Back End Server (BES)  Updated for version 3.8.3
BESPlugin.h
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1 // BESPlugin.h
2 
3 // This file is part of bes, A C++ back-end server implementation framework
4 // for the OPeNDAP Data Access Protocol.
5 
6 // Copyright (c) 2004-2009 University Corporation for Atmospheric Research
7 // Author: Patrick West <pwest@ucar.edu> and Jose Garcia <jgarcia@ucar.edu>
8 // and James Gallagher <jgallagher@gso.uri.edu>
9 //
10 // This library is free software; you can redistribute it and/or
11 // modify it under the terms of the GNU Lesser General Public
12 // License as published by the Free Software Foundation; either
13 // version 2.1 of the License, or (at your option) any later version.
14 //
15 // This library is distributed in the hope that it will be useful,
16 // but WITHOUT ANY WARRANTY; without even the implied warranty of
17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 // Lesser General Public License for more details.
19 //
20 // You should have received a copy of the GNU Lesser General Public
21 // License along with this library; if not, write to the Free Software
22 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 //
24 // You can contact University Corporation for Atmospheric Research at
25 // 3080 Center Green Drive, Boulder, CO 80301
26 
27 // (c) COPYRIGHT University Corporation for Atmospheric Research 2004-2005
28 // Please read the full copyright statement in the file COPYRIGHT_UCAR.
29 //
30 // Authors:
31 // pwest Patrick West <pwest@ucar.edu>
32 // jgarcia Jose Garcia <jgarcia@ucar.edu>
33 // jimg James Gallagher <jgallagher@gso.uri.edu>
34 
35 #ifndef T_BESPlugin_h
36 #define T_BESPlugin_h
37 
38 #include <dlfcn.h>
39 #include <string>
40 #include <iostream>
41 
42 #include "BESObj.h"
43 #include "BESInternalFatalError.h"
44 #include "BESInternalError.h"
45 #include "BESDebug.h"
46 
47 #undef UNPLUG_HANDLERS
48 
49 using std::string;
50 using std::cerr;
51 using std::endl;
52 
57 public:
58  NoSuchLibrary(const string &msg, const string &file, int line) :
59  BESInternalFatalError(msg, file, line)
60  {
61  }
62 };
63 
68 public:
69  NoSuchObject(const string &msg, const string &file, int line) :
70  BESInternalFatalError(msg, file, line)
71  {
72  }
73 };
74 
95 template<typename M>
96 class BESPlugin: public BESObj {
97 private:
98  string d_filename; // Library filename
99  void *d_lib; // Open library handle
100 
103  BESPlugin() throw (BESInternalError)
104  {
105  throw BESInternalError("Unimplemented method", __FILE__, __LINE__);
106  }
107 
112  BESPlugin(const BESPlugin &p) throw (BESInternalError)
113  {
114  throw BESInternalError("Unimplemented method.", __FILE__, __LINE__);
115  }
116 
120  BESPlugin &operator=(const BESPlugin &p) throw (BESInternalError)
121  {
122  throw BESInternalError("Unimplemented method.", __FILE__, __LINE__);
123  }
124 
125  void *get_lib() throw (NoSuchLibrary)
126  {
127  if (!d_lib) {
128  d_lib = dlopen(d_filename.c_str(), RTLD_NOW | RTLD_GLOBAL);
129  BESDEBUG( "bes", "BESPlugin: plug in handler:" << d_filename << ", " << d_lib << endl);
130  if (d_lib == NULL) {
131  throw NoSuchLibrary(string(dlerror()), __FILE__, __LINE__);
132  }
133  }
134 
135  return d_lib;
136  }
137 
138 public:
143  BESPlugin(const string &filename) :
144  d_filename(filename), d_lib(0)
145  {
146  }
147 
150  virtual ~BESPlugin()
151  {
152  BESDEBUG( "bes", "BESPlugin: unplugging handler:" << d_filename << ", " << d_lib << endl);
153 #ifdef UNPLUG_HANDLERS
154  if (d_lib) {
155  dlclose(d_lib);
156  d_lib = 0; // Added; paranoia. jhrg
157  }
158 #endif
159  }
160 
168  {
169  void *maker = dlsym(get_lib(), "maker");
170  if (!maker) {
171  throw NoSuchObject(string(dlerror()), __FILE__, __LINE__);
172  }
173 
174  typedef M *(*maker_func_ptr)();
175  maker_func_ptr my_maker = *reinterpret_cast<maker_func_ptr*>(&maker);
176  M *my_M = (my_maker)();
177 
178  return my_M;
179  }
180 
181  virtual void dump(ostream &strm) const
182  {
183  strm << "BESPlugin::dump - (" << (void *) this << ")" << endl;
184  strm << " plugin name: " << d_filename << endl;
185  strm << " library handle: " << (void *) d_lib << endl;
186  }
187 };
188 
189 #endif // T_BESPlugin_h