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 "support/FileMonitor.h"
  14 #include "support/FileInfo.h"
  15 #include "support/lyxlib.h"
  16
  17 // FIXME Interface violation
  18 #include "frontends/Timeout.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 class FileMonitor::Impl : public boost::signals::trackable {
  31 public:
  32
  33         ///
  34         Impl(string const & file_with_path, int interval);
  35
  36         ///
  37         void monitorFile();
  38
  39         ///
  40         string filename_;
  41
  42         ///
  43         Timeout timer_;
  44
  45         /// This signal is emitted if the file is modified (has a new checksum).
  46         FileMonitor::FileChangedSig fileChanged_;
  47
  48         /** We use these to ascertain whether a file (once loaded successfully)
  49          *  has changed.
  50          */
  51         time_t timestamp_;
  52         ///
  53         unsigned long checksum_;
  54 };
  55
  56
  57 FileMonitor::FileMonitor(string const & file_with_path, int interval)
  58         : pimpl_(new Impl(file_with_path, interval))
  59 {}
  60
  61
  62 FileMonitor::~FileMonitor()
  63 {}
  64
  65
  66 void FileMonitor::reset(string const & file_with_path) const
  67 {
  68         if (pimpl_->filename_ == file_with_path)
  69                 return;
  70
  71         bool const monitor = pimpl_->timer_.running();
  72         if (monitor)
  73                 stop();
  74
  75         pimpl_->filename_ = file_with_path;
  76
  77         if (monitor)
  78                 start();
  79 }
  80
  81
  82 string const & FileMonitor::filename() const
  83 {
  84         return pimpl_->filename_;
  85 }
  86
  87
  88 void FileMonitor::start() const
  89 {
  90         if (monitoring())
  91                 return;
  92
  93         FileInfo finfo(pimpl_->filename_);
  94         if (!finfo.isOK())
  95                 return;
  96
  97         pimpl_->timestamp_ = finfo.getModificationTime();
  98         pimpl_->checksum_ = sum(pimpl_->filename_);
  99
 100         if (pimpl_->timestamp_ && pimpl_->checksum_) {
 101                 pimpl_->timer_.start();
 102         } else {
 103                 pimpl_->timestamp_ = 0;
 104                 pimpl_->checksum_ = 0;
 105         }
 106 }
 107
 108
 109 void FileMonitor::stop() const
 110 {
 111         pimpl_->timestamp_ = 0;
 112         pimpl_->checksum_ = 0;
 113         pimpl_->timer_.stop();
 114 }
 115
 116
 117 bool FileMonitor::monitoring() const
 118 {
 119         return pimpl_->timer_.running();
 120 }
 121
 122
 123 unsigned long FileMonitor::checksum() const
 124 {
 125         // If we aren't actively monitoring the file, then recompute the
 126         // checksum explicitly.
 127         if (!pimpl_->timer_.running() && !pimpl_->filename_.empty())
 128                 return sum(pimpl_->filename_);
 129
 130         return pimpl_->checksum_;
 131 }
 132
 133
 134 boost::signals::connection FileMonitor::connect(slot_type const & slot) const
 135 {
 136         return pimpl_->fileChanged_.connect(slot);
 137 }
 138
 139
 140 //------------------------------
 141 // Implementation details follow
 142 //------------------------------
 143
 144
 145 FileMonitor::Impl::Impl(string const & file_with_path, int interval)
 146         : filename_(file_with_path),
 147           timer_(interval, Timeout::ONETIME),
 148           timestamp_(0),
 149           checksum_(0)
 150 {
 151         timer_.timeout.connect(boost::bind(&Impl::monitorFile, this));
 152 }
 153
 154
 155 void FileMonitor::Impl::monitorFile()
 156 {
 157         bool changed = false;
 158
 159         FileInfo finfo(filename_);
 160         if (!finfo.isOK()) {
 161                 changed = timestamp_ || checksum_;
 162                 timestamp_ = 0;
 163                 checksum_ = 0;
 164
 165         } else {
 166                 time_t const new_timestamp = finfo.getModificationTime();
 167
 168                 if (new_timestamp != timestamp_) {
 169                         timestamp_ = new_timestamp;
 170
 171                         unsigned long const new_checksum = sum(filename_);
 172                         if (new_checksum != checksum_) {
 173                                 checksum_ = new_checksum;
 174                                 changed = true;
 175                         }
 176                 }
 177         }
 178
 179         timer_.start();
 180         if (changed)
 181                 fileChanged_();
 182 }
 183
 184 } // namespace support
 185 } // namespace lyx