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/lyxlib.h"
  15
  16 // FIXME Interface violation
  17 #include "frontends/Timeout.h"
  18
  19 #include <boost/bind.hpp>
  20 #include <boost/filesystem/operations.hpp>
  21 #include <boost/signals/trackable.hpp>
  22
  23
  24 using std::string;
  25
  26 namespace fs = boost::filesystem;
  27
  28 namespace lyx {
  29 namespace support {
  30
  31 class FileMonitor::Impl : public boost::signals::trackable {
  32 public:
  33
  34         ///
  35         Impl(string const & file_with_path, int interval);
  36
  37         ///
  38         void monitorFile();
  39
  40         ///
  41         string filename_;
  42
  43         ///
  44         Timeout timer_;
  45
  46         /// This signal is emitted if the file is modified (has a new checksum).
  47         FileMonitor::FileChangedSig fileChanged_;
  48
  49         /** We use these to ascertain whether a file (once loaded successfully)
  50          *  has changed.
  51          */
  52         time_t timestamp_;
  53         ///
  54         unsigned long checksum_;
  55 };
  56
  57
  58 FileMonitor::FileMonitor(string const & file_with_path, int interval)
  59         : pimpl_(new Impl(file_with_path, interval))
  60 {}
  61
  62
  63 FileMonitor::~FileMonitor()
  64 {}
  65
  66
  67 void FileMonitor::reset(string const & file_with_path) const
  68 {
  69         if (pimpl_->filename_ == file_with_path)
  70                 return;
  71
  72         bool const monitor = pimpl_->timer_.running();
  73         if (monitor)
  74                 stop();
  75
  76         pimpl_->filename_ = file_with_path;
  77
  78         if (monitor)
  79                 start();
  80 }
  81
  82
  83 string const & FileMonitor::filename() const
  84 {
  85         return pimpl_->filename_;
  86 }
  87
  88
  89 void FileMonitor::start() const
  90 {
  91         if (monitoring())
  92                 return;
  93
  94         if (!fs::exists(pimpl_->filename_))
  95                 return;
  96
  97         pimpl_->timestamp_ = fs::last_write_time(pimpl_->filename_);
  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         if (!fs::exists(filename_)) {
 160                 changed = timestamp_ || checksum_;
 161                 timestamp_ = 0;
 162                 checksum_ = 0;
 163
 164         } else {
 165                 time_t const new_timestamp = fs::last_write_time(filename_);
 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