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
  24 using std::string;
  25
  26
  27 namespace lyx {
  28 namespace support {
  29
  30 struct FileMonitor::Impl : public boost::signals::trackable {
  31
  32         ///
  33         Impl(string const & file_with_path, int interval);
  34
  35         ///
  36         void monitorFile();
  37
  38         ///
  39         string filename_;
  40
  41         ///
  42         Timeout timer_;
  43
  44         /// This signal is emitted if the file is modified (has a new checksum).
  45         FileMonitor::FileChangedSig fileChanged_;
  46
  47         /** We use these to ascertain whether a file (once loaded successfully)
  48          *  has changed.
  49          */
  50         time_t timestamp_;
  51         ///
  52         unsigned long checksum_;
  53 };
  54
  55
  56 FileMonitor::FileMonitor(string const & file_with_path, int interval)
  57         : pimpl_(new Impl(file_with_path, interval))
  58 {}
  59
  60
  61 FileMonitor::~FileMonitor()
  62 {}
  63
  64
  65 void FileMonitor::reset(string const & file_with_path) const
  66 {
  67         if (pimpl_->filename_ == file_with_path)
  68                 return;
  69
  70         bool const monitor = pimpl_->timer_.running();
  71         if (monitor)
  72                 stop();
  73
  74         pimpl_->filename_ = file_with_path;
  75
  76         if (monitor)
  77                 start();
  78 }
  79
  80
  81 string const & FileMonitor::filename() const
  82 {
  83         return pimpl_->filename_;
  84 }
  85
  86
  87 void FileMonitor::start() const
  88 {
  89         if (monitoring())
  90                 return;
  91
  92         FileInfo finfo(pimpl_->filename_);
  93         if (!finfo.isOK())
  94                 return;
  95
  96         pimpl_->timestamp_ = finfo.getModificationTime();
  97         pimpl_->checksum_ = sum(pimpl_->filename_);
  98
  99         if (pimpl_->timestamp_ && pimpl_->checksum_) {
 100                 pimpl_->timer_.start();
 101         } else {
 102                 pimpl_->timestamp_ = 0;
 103                 pimpl_->checksum_ = 0;
 104         }
 105 }
 106
 107
 108 void FileMonitor::stop() const
 109 {
 110         pimpl_->timestamp_ = 0;
 111         pimpl_->checksum_ = 0;
 112         pimpl_->timer_.stop();
 113 }
 114
 115
 116 bool FileMonitor::monitoring() const
 117 {
 118         return pimpl_->timer_.running();
 119 }
 120
 121
 122 unsigned long FileMonitor::checksum() const
 123 {
 124         // If we aren't actively monitoring the file, then recompute the
 125         // checksum explicitly.
 126         if (!pimpl_->timer_.running() && !pimpl_->filename_.empty())
 127                 return sum(pimpl_->filename_);
 128
 129         return pimpl_->checksum_;
 130 }
 131
 132
 133 boost::signals::connection FileMonitor::connect(slot_type const & slot) const
 134 {
 135         return pimpl_->fileChanged_.connect(slot);
 136 }
 137
 138
 139 //------------------------------
 140 // Implementation details follow
 141 //------------------------------
 142
 143
 144 FileMonitor::Impl::Impl(string const & file_with_path, int interval)
 145         : filename_(file_with_path),
 146           timer_(interval, Timeout::ONETIME),
 147           timestamp_(0),
 148           checksum_(0)
 149 {
 150         timer_.timeout.connect(boost::bind(&Impl::monitorFile, this));
 151 }
 152
 153
 154 void FileMonitor::Impl::monitorFile()
 155 {
 156         bool changed = false;
 157
 158         FileInfo finfo(filename_);
 159         if (!finfo.isOK()) {
 160                 changed = timestamp_ || checksum_;
 161                 timestamp_ = 0;
 162                 checksum_ = 0;
 163
 164         } else {
 165                 time_t const new_timestamp = finfo.getModificationTime();
 166
 167                 if (new_timestamp != timestamp_) {
 168                         timestamp_ = new_timestamp;
 169
 170                         unsigned long const new_checksum = sum(filename_);
 171                         if (new_checksum != checksum_) {
 172                                 checksum_ = new_checksum;
 173                                 changed = true;
 174                         }
 175                 }
 176         }
 177
 178         timer_.start();
 179         if (changed)
 180                 fileChanged_();
 181 }
 182
 183 } // namespace support
 184 } // namespace lyx