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 #include "support/FileName.h"
  15 #include "support/lyxlib.h"
  16 #include "support/Timeout.h"
  17
  18 #include <boost/bind.hpp>
  19 #include <boost/signals/trackable.hpp>
  20
  21
  22 using std::string;
  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
  62
  63 void FileMonitor::reset(FileName const & file_with_path) const
  64 {
  65         if (pimpl_->filename_ == file_with_path)
  66                 return;
  67
  68         bool const monitor = pimpl_->timer_.running();
  69         if (monitor)
  70                 stop();
  71
  72         pimpl_->filename_ = file_with_path;
  73
  74         if (monitor)
  75                 start();
  76 }
  77
  78
  79 FileName const & FileMonitor::filename() const
  80 {
  81         return pimpl_->filename_;
  82 }
  83
  84
  85 void FileMonitor::start() const
  86 {
  87         if (monitoring())
  88                 return;
  89
  90         if (!pimpl_->filename_.exists())
  91                 return;
  92
  93         pimpl_->timestamp_ = pimpl_->filename_.lastModified();
  94         pimpl_->checksum_ = sum(pimpl_->filename_);
  95
  96         if (pimpl_->timestamp_ && pimpl_->checksum_) {
  97                 pimpl_->timer_.start();
  98         } else {
  99                 pimpl_->timestamp_ = 0;
 100                 pimpl_->checksum_ = 0;
 101         }
 102 }
 103
 104
 105 void FileMonitor::stop() const
 106 {
 107         pimpl_->timestamp_ = 0;
 108         pimpl_->checksum_ = 0;
 109         pimpl_->timer_.stop();
 110 }
 111
 112
 113 bool FileMonitor::monitoring() const
 114 {
 115         return pimpl_->timer_.running();
 116 }
 117
 118
 119 unsigned long FileMonitor::checksum() const
 120 {
 121         // If we aren't actively monitoring the file, then recompute the
 122         // checksum explicitly.
 123         if (!pimpl_->timer_.running() && !pimpl_->filename_.empty())
 124                 return sum(pimpl_->filename_);
 125
 126         return pimpl_->checksum_;
 127 }
 128
 129
 130 boost::signals::connection FileMonitor::connect(slot_type const & slot) const
 131 {
 132         return pimpl_->fileChanged_.connect(slot);
 133 }
 134
 135
 136 //------------------------------
 137 // Implementation details follow
 138 //------------------------------
 139
 140
 141 FileMonitor::Impl::Impl(FileName const & file_with_path, int interval)
 142         : filename_(file_with_path),
 143           timer_(interval, Timeout::ONETIME),
 144           timestamp_(0),
 145           checksum_(0)
 146 {
 147         timer_.timeout.connect(boost::bind(&Impl::monitorFile, this));
 148 }
 149
 150
 151 void FileMonitor::Impl::monitorFile()
 152 {
 153         bool changed = false;
 154
 155         if (!filename_.exists()) {
 156                 changed = timestamp_ || checksum_;
 157                 timestamp_ = 0;
 158                 checksum_ = 0;
 159
 160         } else {
 161                 time_t const new_timestamp = filename_.lastModified();
 162
 163                 if (new_timestamp != timestamp_) {
 164                         timestamp_ = new_timestamp;
 165
 166                         unsigned long const new_checksum = sum(filename_);
 167                         if (new_checksum != checksum_) {
 168                                 checksum_ = new_checksum;
 169                                 changed = true;
 170                         }
 171                 }
 172         }
 173
 174         timer_.start();
 175         if (changed)
 176                 fileChanged_();
 177 }
 178
 179 } // namespace support
 180 } // namespace lyx