src/support/FileMonitor.cpp

   1 /**
   2  * \file FileMonitor.cpp
   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
  15 #include "support/FileName.h"
  16 #include "support/Timeout.h"
  17
  18 #include "support/bind.h"
  19 #include <boost/signals2/trackable.hpp>
  20
  21 using namespace std;
  22
  23 namespace lyx {
  24 namespace support {
  25
  26 class FileMonitor::Impl : public boost::signals2::trackable {
  27 public:
  28
  29         ///
  30         Impl(FileName const & file_with_path, int interval);
  31
  32         ///
  33         void monitorFile();
  34
  35         ///
  36         FileName filename_;
  37
  38         ///
  39         Timeout timer_;
  40
  41         /// This signal is emitted if the file is modified (has a new checksum).
  42         FileMonitor::FileChangedSig fileChanged_;
  43
  44         /** We use these to ascertain whether a file (once loaded successfully)
  45          *  has changed.
  46          */
  47         time_t timestamp_;
  48         ///
  49         unsigned long checksum_;
  50 };
  51
  52
  53 FileMonitor::FileMonitor(FileName const & file_with_path, int interval)
  54         : pimpl_(new Impl(file_with_path, interval))
  55 {}
  56
  57
  58 FileMonitor::~FileMonitor()
  59 {
  60         delete pimpl_;
  61 }
  62
  63
  64 void FileMonitor::reset(FileName const & file_with_path) const
  65 {
  66         if (pimpl_->filename_ == file_with_path)
  67                 return;
  68
  69         bool const monitor = pimpl_->timer_.running();
  70         if (monitor)
  71                 stop();
  72
  73         pimpl_->filename_ = file_with_path;
  74
  75         if (monitor)
  76                 start();
  77 }
  78
  79
  80 FileName const & FileMonitor::filename() const
  81 {
  82         return pimpl_->filename_;
  83 }
  84
  85
  86 void FileMonitor::start() const
  87 {
  88         if (monitoring())
  89                 return;
  90
  91         if (!pimpl_->filename_.exists())
  92                 return;
  93
  94         pimpl_->timestamp_ = pimpl_->filename_.lastModified();
  95         pimpl_->checksum_ = pimpl_->filename_.checksum();
  96
  97         if (pimpl_->timestamp_ && pimpl_->checksum_) {
  98                 pimpl_->timer_.start();
  99         } else {
 100                 pimpl_->timestamp_ = 0;
 101                 pimpl_->checksum_ = 0;
 102         }
 103 }
 104
 105
 106 void FileMonitor::stop() const
 107 {
 108         pimpl_->timestamp_ = 0;
 109         pimpl_->checksum_ = 0;
 110         pimpl_->timer_.stop();
 111 }
 112
 113
 114 bool FileMonitor::monitoring() const
 115 {
 116         return pimpl_->timer_.running();
 117 }
 118
 119
 120 unsigned long FileMonitor::checksum() const
 121 {
 122         // If we aren't actively monitoring the file, then recompute the
 123         // checksum explicitly.
 124         if (!pimpl_->timer_.running() && !pimpl_->filename_.empty())
 125                 return pimpl_->filename_.checksum();
 126
 127         return pimpl_->checksum_;
 128 }
 129
 130
 131 boost::signals2::connection FileMonitor::connect(slot_type const & slot) const
 132 {
 133         return pimpl_->fileChanged_.connect(slot);
 134 }
 135
 136
 137 //------------------------------
 138 // Implementation details follow
 139 //------------------------------
 140
 141
 142 FileMonitor::Impl::Impl(FileName const & file_with_path, int interval)
 143         : filename_(file_with_path),
 144           timer_(interval, Timeout::ONETIME),
 145           timestamp_(0),
 146           checksum_(0)
 147 {
 148         timer_.timeout.connect(bind(&Impl::monitorFile, this));
 149 }
 150
 151
 152 void FileMonitor::Impl::monitorFile()
 153 {
 154         bool changed = false;
 155
 156         if (!filename_.exists()) {
 157                 changed = timestamp_ || checksum_;
 158                 timestamp_ = 0;
 159                 checksum_ = 0;
 160
 161         } else {
 162                 time_t const new_timestamp = filename_.lastModified();
 163
 164                 if (new_timestamp != timestamp_) {
 165                         timestamp_ = new_timestamp;
 166
 167                         unsigned long const new_checksum = filename_.checksum();
 168                         if (new_checksum != checksum_) {
 169                                 checksum_ = new_checksum;
 170                                 changed = true;
 171                         }
 172                 }
 173         }
 174
 175         timer_.start();
 176         if (changed)
 177                 fileChanged_();
 178 }
 179
 180 } // namespace support
 181 } // namespace lyx