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