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