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
  17 // FIXME Interface violation
  18 #include "frontends/Timeout.h"
  19
  20 #include <boost/bind.hpp>
  21 #include <boost/filesystem/operations.hpp>
  22 #include <boost/signals/trackable.hpp>
  23
  24
  25 using std::string;
  26
  27 namespace fs = boost::filesystem;
  28
  29 namespace lyx {
  30 namespace support {
  31
  32 class FileMonitor::Impl : public boost::signals::trackable {
  33 public:
  34
  35         ///
  36         Impl(FileName const & file_with_path, int interval);
  37
  38         ///
  39         void monitorFile();
  40
  41         ///
  42         FileName filename_;
  43
  44         ///
  45         Timeout timer_;
  46
  47         /// This signal is emitted if the file is modified (has a new checksum).
  48         FileMonitor::FileChangedSig fileChanged_;
  49
  50         /** We use these to ascertain whether a file (once loaded successfully)
  51          *  has changed.
  52          */
  53         time_t timestamp_;
  54         ///
  55         unsigned long checksum_;
  56 };
  57
  58
  59 FileMonitor::FileMonitor(FileName const & file_with_path, int interval)
  60         : pimpl_(new Impl(file_with_path, interval))
  61 {}
  62
  63
  64 FileMonitor::~FileMonitor()
  65 {}
  66
  67
  68 void FileMonitor::reset(FileName const & file_with_path) const
  69 {
  70         if (pimpl_->filename_ == file_with_path)
  71                 return;
  72
  73         bool const monitor = pimpl_->timer_.running();
  74         if (monitor)
  75                 stop();
  76
  77         pimpl_->filename_ = file_with_path;
  78
  79         if (monitor)
  80                 start();
  81 }
  82
  83
  84 FileName const & FileMonitor::filename() const
  85 {
  86         return pimpl_->filename_;
  87 }
  88
  89
  90 void FileMonitor::start() const
  91 {
  92         if (monitoring())
  93                 return;
  94
  95         if (!fs::exists(pimpl_->filename_.toFilesystemEncoding()))
  96                 return;
  97
  98         pimpl_->timestamp_ = fs::last_write_time(pimpl_->filename_.toFilesystemEncoding());
  99         pimpl_->checksum_ = sum(pimpl_->filename_);
 100
 101         if (pimpl_->timestamp_ && pimpl_->checksum_) {
 102                 pimpl_->timer_.start();
 103         } else {
 104                 pimpl_->timestamp_ = 0;
 105                 pimpl_->checksum_ = 0;
 106         }
 107 }
 108
 109
 110 void FileMonitor::stop() const
 111 {
 112         pimpl_->timestamp_ = 0;
 113         pimpl_->checksum_ = 0;
 114         pimpl_->timer_.stop();
 115 }
 116
 117
 118 bool FileMonitor::monitoring() const
 119 {
 120         return pimpl_->timer_.running();
 121 }
 122
 123
 124 unsigned long FileMonitor::checksum() const
 125 {
 126         // If we aren't actively monitoring the file, then recompute the
 127         // checksum explicitly.
 128         if (!pimpl_->timer_.running() && !pimpl_->filename_.empty())
 129                 return sum(pimpl_->filename_);
 130
 131         return pimpl_->checksum_;
 132 }
 133
 134
 135 boost::signals::connection FileMonitor::connect(slot_type const & slot) const
 136 {
 137         return pimpl_->fileChanged_.connect(slot);
 138 }
 139
 140
 141 //------------------------------
 142 // Implementation details follow
 143 //------------------------------
 144
 145
 146 FileMonitor::Impl::Impl(FileName const & file_with_path, int interval)
 147         : filename_(file_with_path),
 148           timer_(interval, Timeout::ONETIME),
 149           timestamp_(0),
 150           checksum_(0)
 151 {
 152         timer_.timeout.connect(boost::bind(&Impl::monitorFile, this));
 153 }
 154
 155
 156 void FileMonitor::Impl::monitorFile()
 157 {
 158         bool changed = false;
 159
 160         if (!fs::exists(filename_.toFilesystemEncoding())) {
 161                 changed = timestamp_ || checksum_;
 162                 timestamp_ = 0;
 163                 checksum_ = 0;
 164
 165         } else {
 166                 time_t const new_timestamp = fs::last_write_time(filename_.toFilesystemEncoding());
 167
 168                 if (new_timestamp != timestamp_) {
 169                         timestamp_ = new_timestamp;
 170
 171                         unsigned long const new_checksum = sum(filename_);
 172                         if (new_checksum != checksum_) {
 173                                 checksum_ = new_checksum;
 174                                 changed = true;
 175                         }
 176                 }
 177         }
 178
 179         timer_.start();
 180         if (changed)
 181                 fileChanged_();
 182 }
 183
 184 } // namespace support
 185 } // namespace lyx