src/support/FileMonitor.C

   1 /**
   2  * \file FileMonitor.C
   3  * This file is part of LyX, the document processor.
   4  * Licence details can be found in the file COPYING.
   5  *
   6  * \author Angus Leeming
   7  *
   8  * Full author contact details are available in file CREDITS
   9  */
  10
  11 #include <config.h>
  12
  13 #ifdef __GNUG__
  14 #pragma implementation
  15 #endif
  16
  17 #include "FileMonitor.h"
  18
  19 #include "frontends/Timeout.h"
  20
  21 #include "support/FileInfo.h"
  22 #include "support/lyxlib.h"
  23
  24 #include <boost/bind.hpp>
  25 #include <boost/signals/trackable.hpp>
  26
  27 struct FileMonitor::Impl : public boost::signals::trackable {
  28
  29         ///
  30         Impl(string const & file_with_path, int interval);
  31
  32         ///
  33         void monitorFile();
  34
  35         ///
  36         string filename_;
  37
  38         ///
  39         Timeout timer_;
  40
  41         /// This signal is emitted if the file is modified (has a new checksum).
  42         boost::signal0<void> fileChanged_;
  43
  44         /** We use these to ascertain whether a file (once loaded successfully)
  45          *  has changed.
  46          */
  47         time_t timestamp_;
  48         ///
  49         unsigned long checksum_;
  50 };
  51
  52
  53 FileMonitor::FileMonitor(string const & file_with_path, int interval)
  54         : pimpl_(new Impl(file_with_path, interval))
  55 {}
  56
  57
  58 FileMonitor::~FileMonitor()
  59 {}
  60
  61
  62 void FileMonitor::reset(string const & file_with_path) const
  63 {
  64         if (pimpl_->filename_ == file_with_path)
  65                 return;
  66
  67         bool const monitor = pimpl_->timer_.running();
  68         if (monitor)
  69                 stop();
  70
  71         pimpl_->filename_ = file_with_path;
  72
  73         if (monitor)
  74                 start();
  75 }
  76
  77
  78 string const & FileMonitor::filename() const
  79 {
  80         return pimpl_->filename_;
  81 }
  82
  83
  84 void FileMonitor::start() const
  85 {
  86         if (monitoring())
  87                 return;
  88
  89         FileInfo finfo(pimpl_->filename_);
  90         if (!finfo.isOK())
  91                 return;
  92
  93         pimpl_->timestamp_ = finfo.getModificationTime();
  94         pimpl_->checksum_ = lyx::sum(pimpl_->filename_);
  95
  96         if (pimpl_->timestamp_ && pimpl_->checksum_) {
  97                 pimpl_->timer_.start();
  98         } else {
  99                 pimpl_->timestamp_ = 0;
 100                 pimpl_->checksum_ = 0;
 101         }
 102 }
 103
 104
 105 void FileMonitor::stop() const
 106 {
 107         pimpl_->timestamp_ = 0;
 108         pimpl_->checksum_ = 0;
 109         pimpl_->timer_.stop();
 110 }
 111
 112
 113 bool FileMonitor::monitoring() const
 114 {
 115         return pimpl_->timer_.running();
 116 }
 117
 118
 119 unsigned long FileMonitor::checksum() const
 120 {
 121         // If we aren't actively monitoring the file, then recompute the
 122         // checksum explicitly.
 123         if (!pimpl_->timer_.running() && !pimpl_->filename_.empty())
 124                 return lyx::sum(pimpl_->filename_);
 125
 126         return pimpl_->checksum_;
 127 }
 128
 129
 130 boost::signals::connection FileMonitor::connect(slot_type const & slot) const
 131 {
 132         return pimpl_->fileChanged_.connect(slot);
 133 }
 134
 135
 136 //------------------------------
 137 // Implementation details follow
 138 //------------------------------
 139
 140
 141 FileMonitor::Impl::Impl(string const & file_with_path, int interval)
 142         : filename_(file_with_path),
 143           timer_(interval, Timeout::ONETIME),
 144           timestamp_(0),
 145           checksum_(0)
 146 {
 147         timer_.timeout.connect(boost::bind(&Impl::monitorFile, this));
 148 }
 149
 150
 151 void FileMonitor::Impl::monitorFile()
 152 {
 153         bool changed = false;
 154
 155         FileInfo finfo(filename_);
 156         if (!finfo.isOK()) {
 157                 changed = timestamp_ || checksum_;
 158                 timestamp_ = 0;
 159                 checksum_ = 0;
 160
 161         } else {
 162                 time_t const new_timestamp = finfo.getModificationTime();
 163
 164                 if (new_timestamp != timestamp_) {
 165                         timestamp_ = new_timestamp;
 166
 167                         unsigned long const new_checksum = lyx::sum(filename_);
 168                         if (new_checksum != checksum_) {
 169                                 checksum_ = new_checksum;
 170                                 changed = true;
 171                         }
 172                 }
 173         }
 174
 175         timer_.start();
 176         if (changed)
 177                 fileChanged_();
 178 }