src/support/FileMonitor.C

   1 /*
   2  * \file FileMonitor.C
   3  * Copyright 2002 the LyX Team
   4  * Read the file COPYING
   5  *
   6  * \author Angus Leeming <leeming@lyx.org>
   7  */
   8
   9 #include <config.h>
  10
  11 #ifdef __GNUG__
  12 #pragma implementation
  13 #endif
  14
  15 #include "FileMonitor.h"
  16
  17 #include "frontends/Timeout.h"
  18
  19 #include "support/FileInfo.h"
  20 #include "support/lyxlib.h"
  21
  22 #include <boost/bind.hpp>
  23 #include <boost/signals/trackable.hpp>
  24
  25 struct FileMonitor::Impl : public boost::signals::trackable {
  26
  27         ///
  28         Impl(string const & file_with_path, int interval);
  29
  30         ///
  31         void monitorFile();
  32
  33         ///
  34         string filename_;
  35
  36         ///
  37         Timeout timer_;
  38
  39         /// This signal is emitted if the file is modified (has a new checksum).
  40         boost::signal0<void> fileChanged_;
  41
  42         /** We use these to ascertain whether a file (once loaded successfully)
  43          *  has changed.
  44          */
  45         time_t timestamp_;
  46         ///
  47         unsigned long checksum_;
  48 };
  49
  50
  51 FileMonitor::FileMonitor(string const & file_with_path, int interval)
  52         : pimpl_(new Impl(file_with_path, interval))
  53 {}
  54
  55
  56 FileMonitor::~FileMonitor()
  57 {}
  58
  59
  60 void FileMonitor::reset(string const & file_with_path) const
  61 {
  62         if (pimpl_->filename_ == file_with_path)
  63                 return;
  64
  65         bool const monitor = pimpl_->timer_.running();
  66         if (monitor)
  67                 stop();
  68
  69         pimpl_->filename_ = file_with_path;
  70
  71         if (monitor)
  72                 start();
  73 }
  74
  75
  76 string const & FileMonitor::filename() const
  77 {
  78         return pimpl_->filename_;
  79 }
  80
  81
  82 void FileMonitor::start() const
  83 {
  84         if (monitoring())
  85                 return;
  86
  87         FileInfo finfo(pimpl_->filename_);
  88         if (!finfo.isOK())
  89                 return;
  90
  91         pimpl_->timestamp_ = finfo.getModificationTime();
  92         pimpl_->checksum_ = lyx::sum(pimpl_->filename_);
  93
  94         if (pimpl_->timestamp_ && pimpl_->checksum_) {
  95                 pimpl_->timer_.start();
  96         } else {
  97                 pimpl_->timestamp_ = 0;
  98                 pimpl_->checksum_ = 0;
  99         }
 100 }
 101
 102
 103 void FileMonitor::stop() const
 104 {
 105         pimpl_->timestamp_ = 0;
 106         pimpl_->checksum_ = 0;
 107         pimpl_->timer_.stop();
 108 }
 109
 110
 111 bool FileMonitor::monitoring() const
 112 {
 113         return pimpl_->timer_.running();
 114 }
 115
 116
 117 unsigned long FileMonitor::checksum() const
 118 {
 119         // If we aren't actively monitoring the file, then recompute the
 120         // checksum explicitly.
 121         if (!pimpl_->timer_.running() && !pimpl_->filename_.empty())
 122                 return lyx::sum(pimpl_->filename_);
 123
 124         return pimpl_->checksum_;
 125 }
 126
 127
 128 boost::signals::connection FileMonitor::connect(slot_type const & slot) const
 129 {
 130         return pimpl_->fileChanged_.connect(slot);
 131 }
 132
 133
 134 //------------------------------
 135 // Implementation details follow
 136 //------------------------------
 137
 138
 139 FileMonitor::Impl::Impl(string const & file_with_path, int interval)
 140         : filename_(file_with_path),
 141           timer_(interval, Timeout::ONETIME),
 142           timestamp_(0),
 143           checksum_(0)
 144 {
 145         timer_.timeout.connect(boost::bind(&Impl::monitorFile, this));
 146 }
 147
 148
 149 void FileMonitor::Impl::monitorFile()
 150 {
 151         bool changed = false;
 152
 153         FileInfo finfo(filename_);
 154         if (!finfo.isOK()) {
 155                 changed = timestamp_ || checksum_;
 156                 timestamp_ = 0;
 157                 checksum_ = 0;
 158
 159         } else {
 160                 time_t const new_timestamp = finfo.getModificationTime();
 161
 162                 if (new_timestamp != timestamp_) {
 163                         timestamp_ = new_timestamp;
 164
 165                         unsigned long const new_checksum = lyx::sum(filename_);
 166                         if (new_checksum != checksum_) {
 167                                 checksum_ = new_checksum;
 168                                 changed = true;
 169                         }
 170                 }
 171         }
 172
 173         timer_.start();
 174         if (changed)
 175                 fileChanged_();
 176 }