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