xapian-core/net/progclient.h

   1 /** @file
   2  *  @brief Implementation of RemoteDatabase using a spawned server.
   3  */
   4 /* Copyright (C) 2007,2010,2011,2014,2019 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of the
   9  * License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #ifndef XAPIAN_INCLUDED_PROGCLIENT_H
  22 #define XAPIAN_INCLUDED_PROGCLIENT_H
  23
  24 #include <sys/types.h>
  25
  26 #include "backends/remote/remote-database.h"
  27
  28 /** Implementation of RemoteDatabase using a spawned server.
  29  *
  30  *  ProgClient spawns a child process to connect to the server - for example,
  31  *  an ssh command to run the server on a remote host.  Communication with the
  32  *  child process is via a pipe.
  33  */
  34 class ProgClient : public RemoteDatabase {
  35     /// Don't allow assignment.
  36     void operator=(const ProgClient &);
  37
  38     /// Don't allow copying.
  39     ProgClient(const ProgClient &);
  40
  41 #ifndef __WIN32__
  42     /// Process id of the child process.
  43     pid_t child;
  44 #else
  45     /// HANDLE of the child process.
  46     HANDLE child;
  47 #endif
  48
  49     /** Start the child process.
  50      *
  51      *  @param progname The program used to create the connection.
  52      *  @param args     Any arguments to the program.
  53      *  @param child    Reference to store the child process pid/HANDLE in.
  54      *
  55      *  @return file descriptor for reading from/writing to the child process.
  56      *
  57      *  Note: this method is called early on during class construction before
  58      *  any member variables or even the base class have been initialised.
  59      *  To help avoid accidentally trying to use member variables, this method
  60      *  has been deliberately made "static".
  61      */
  62     static int run_program(const std::string &progname,
  63                            const std::string &args,
  64 #ifndef __WIN32__
  65                            pid_t& child
  66 #else
  67                            HANDLE& child
  68 #endif
  69                            );
  70
  71     /** Generate context string for Xapian::Error exception objects.
  72      *
  73      *  @param progname The program used to create the connection.
  74      *  @param args     Any arguments to the program.
  75      *
  76      *  Note: this method is used from constructors so has been made static to
  77      *  avoid problems with trying to use uninitialised member variables.  In
  78      *  particular, it can't be made a virtual method of the base class.
  79      */
  80     static std::string get_progcontext(const std::string &progname,
  81                                        const std::string &args);
  82
  83   public:
  84     /** Constructor.
  85      *
  86      *  @param progname The program used to create the connection.
  87      *  @param args     Any arguments to the program.
  88      *  @param timeout  Timeout for communication (in seconds).
  89      *  @param writable Is this a WritableDatabase?
  90      *  @param flags    Xapian::DB_RETRY_LOCK or 0.
  91      */
  92     ProgClient(const std::string &progname,
  93                const std::string &arg,
  94                double msecs_timeout,
  95                bool writable,
  96                int flags);
  97
  98     /** Destructor. */
  99     ~ProgClient();
 100 };
 101
 102 #endif // XAPIAN_INCLUDED_PROGCLIENT_H