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/lyxlib.h"
  17 #include "support/Timeout.h"
  18
  19 #include <boost/bind.hpp>
  20 #include <boost/signals/trackable.hpp>
  21
  22
  23 using std::string;
  24
  25 namespace lyx {
  26 namespace support {
  27
  28 class FileMonitor::Impl : public boost::signals::trackable {
  29 public:
  30
  31         ///
  32         Impl(FileName const & file_with_path, int interval);
  33
  34         ///
  35         void monitorFile();
  36
  37         ///
  38         FileName filename_;
  39
  40         ///
  41         Timeout timer_;
  42
  43         /// This signal is emitted if the file is modified (has a new checksum).
  44         FileMonitor::FileChangedSig fileChanged_;
  45
  46         /** We use these to ascertain whether a file (once loaded successfully)
  47          *  has changed.
  48          */
  49         time_t timestamp_;
  50         ///
  51         unsigned long checksum_;
  52 };
  53
  54
  55 FileMonitor::FileMonitor(FileName const & file_with_path, int interval)
  56         : pimpl_(new Impl(file_with_path, interval))
  57 {}
  58
  59
  60 FileMonitor::~FileMonitor()
  61 {
  62         delete pimpl_;
  63 }
  64
  65
  66 void FileMonitor::reset(FileName 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 FileName 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         if (!pimpl_->filename_.exists())
  94                 return;
  95
  96         pimpl_->timestamp_ = pimpl_->filename_.lastModified();
  97         pimpl_->checksum_ = pimpl_->filename_.checksum();
  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 pimpl_->filename_.checksum();
 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(FileName 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         if (!filename_.exists()) {
 159                 changed = timestamp_ || checksum_;
 160                 timestamp_ = 0;
 161                 checksum_ = 0;
 162
 163         } else {
 164                 time_t const new_timestamp = filename_.lastModified();
 165
 166                 if (new_timestamp != timestamp_) {
 167                         timestamp_ = new_timestamp;
 168
 169                         unsigned long const new_checksum = filename_.checksum();
 170                         if (new_checksum != checksum_) {
 171                                 checksum_ = new_checksum;
 172                                 changed = true;
 173                         }
 174                 }
 175         }
 176
 177         timer_.start();
 178         if (changed)
 179                 fileChanged_();
 180 }
 181
 182 } // namespace support
 183 } // namespace lyx