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  * \author Guillaume Munch
   8  *
   9  * Full author contact details are available in file CREDITS.
  10  */
  11
  12 #include <config.h>
  13
  14 #include "support/FileMonitor.h"
  15
  16 #include "support/debug.h"
  17 #include "support/FileName.h"
  18 #include "support/qstring_helpers.h"
  19 #include "support/unique_ptr.h"
  20
  21 #include <QFile>
  22 #include <QStringList>
  23 #include <QTimer>
  24
  25 #include <algorithm>
  26
  27 using namespace std;
  28
  29 namespace lyx {
  30 namespace support {
  31
  32
  33 FileSystemWatcher & FileSystemWatcher::instance()
  34 {
  35         // This is thread-safe because QFileSystemWatcher is thread-safe.
  36         static FileSystemWatcher f;
  37         return f;
  38 }
  39
  40
  41 FileSystemWatcher::FileSystemWatcher()
  42         : qwatcher_(make_unique<QFileSystemWatcher>())
  43 {}
  44
  45
  46 shared_ptr<FileMonitorGuard>
  47 FileSystemWatcher::getGuard(FileName const & filename)
  48 {
  49         string const absfilename = filename.absFileName();
  50         weak_ptr<FileMonitorGuard> & wptr = store_[absfilename];
  51         if (shared_ptr<FileMonitorGuard> mon = wptr.lock())
  52                 return mon;
  53         auto mon = make_shared<FileMonitorGuard>(absfilename, qwatcher_.get());
  54         wptr = mon;
  55         return mon;
  56 }
  57
  58
  59 //static
  60 FileMonitorPtr FileSystemWatcher::monitor(FileName const & filename)
  61 {
  62         return make_unique<FileMonitor>(instance().getGuard(filename));
  63 }
  64
  65
  66 //static
  67 ActiveFileMonitorPtr FileSystemWatcher::activeMonitor(FileName const & filename,
  68                                                       int interval)
  69 {
  70         return make_unique<ActiveFileMonitor>(instance().getGuard(filename),
  71                                               filename, interval);
  72 }
  73
  74
  75 //static
  76 void FileSystemWatcher::debug()
  77 {
  78         FileSystemWatcher & f = instance();
  79         QStringList q_files = f.qwatcher_->files();
  80         for (pair<string, weak_ptr<FileMonitorGuard>> pair : f.store_) {
  81                 string const & name = pair.first;
  82                 if (!pair.second.expired()) {
  83                         if (!q_files.contains(toqstr(name)))
  84                                 LYXERR0("Monitored but not QFileSystemWatched (bad): " << name);
  85                         else {
  86                                 //LYXERR0("Monitored and QFileSystemWatched (good): " << name);
  87                         }
  88                 }
  89         }
  90         for (QString const & qname : q_files) {
  91                 string const name = fromqstr(qname);
  92                 weak_ptr<FileMonitorGuard> & wptr = f.store_[name];
  93                 if (wptr.expired())
  94                         LYXERR0("QFileSystemWatched but not monitored (bad): " << name);
  95         }
  96 }
  97
  98
  99 FileMonitorGuard::FileMonitorGuard(string const & filename,
 100                                    QFileSystemWatcher * qwatcher)
 101         : filename_(filename), qwatcher_(qwatcher), exists_(true)
 102 {
 103         if (filename.empty())
 104                 return;
 105         QObject::connect(qwatcher, SIGNAL(fileChanged(QString const &)),
 106                          this, SLOT(notifyChange(QString const &)));
 107         if (qwatcher_->files().contains(toqstr(filename)))
 108                 LYXERR0("This file is already being QFileSystemWatched: " << filename
 109                         << ". This should not happen.");
 110         refresh();
 111 }
 112
 113
 114 FileMonitorGuard::~FileMonitorGuard()
 115 {
 116         if (!filename_.empty())
 117                 qwatcher_->removePath(toqstr(filename_));
 118 }
 119
 120
 121 void FileMonitorGuard::refresh(bool const emit)
 122 {
 123         if (filename_.empty())
 124                 return;
 125         QString const qfilename = toqstr(filename_);
 126         if (!qwatcher_->files().contains(qfilename)) {
 127                 bool const existed = exists_;
 128                 exists_ = QFile(qfilename).exists();
 129 #if (QT_VERSION >= 0x050000)
 130                 if (exists_ && !qwatcher_->addPath(qfilename))
 131 #else
 132                 auto add_path = [&]() {
 133                         qwatcher_->addPath(qfilename);
 134                         return qwatcher_->files().contains(qfilename);
 135                 };
 136                 if (exists_ && !add_path())
 137 #endif
 138                 {
 139                         LYXERR(Debug::FILES,
 140                                "Could not add path to QFileSystemWatcher: " << filename_);
 141                         QTimer::singleShot(5000, this, SLOT(refresh()));
 142                 } else {
 143                         if (!exists_)
 144                                 // The standard way to overwrite a file is to delete it and
 145                                 // create a new file with the same name. Therefore if the file
 146                                 // has just been deleted, it is smart to check not too long
 147                                 // after whether it has been recreated.
 148                             QTimer::singleShot(existed ? 100 : 2000, this, SLOT(refresh()));
 149                         if (existed != exists_ && emit)
 150                                 Q_EMIT fileChanged(exists_);
 151                 }
 152         }
 153 }
 154
 155
 156 void FileMonitorGuard::notifyChange(QString const & path)
 157 {
 158         if (path == toqstr(filename_)) {
 159                 // If the file has been modified by delete-move, we are notified of the
 160                 // deletion but we no longer track the file. See
 161                 // <https://bugreports.qt.io/browse/QTBUG-46483> (not a bug).
 162                 // Therefore we must refresh.
 163                 refresh(false);
 164                 Q_EMIT fileChanged(exists_);
 165         }
 166 }
 167
 168
 169 FileMonitor::FileMonitor(std::shared_ptr<FileMonitorGuard> monitor)
 170         : monitor_(monitor)
 171 {
 172         connectToFileMonitorGuard();
 173         refresh();
 174 }
 175
 176
 177 void FileMonitor::connectToFileMonitorGuard()
 178 {
 179         // Connections need to be asynchronous because the receiver can own this
 180         // object and therefore is allowed to delete it.
 181         // Qt signal:
 182         QObject::connect(monitor_.get(), SIGNAL(fileChanged(bool)),
 183                          this, SIGNAL(fileChanged(bool)),
 184                          Qt::QueuedConnection);
 185         // Boost signal:
 186         QObject::connect(this, SIGNAL(fileChanged(bool)),
 187                          this, SLOT(changed(bool)));
 188 }
 189
 190
 191 signals2::connection FileMonitor::connect(slot const & slot)
 192 {
 193         return fileChanged_.connect(slot);
 194 }
 195
 196
 197 void FileMonitor::changed(bool const exists)
 198 {
 199         // emit boost signal
 200         fileChanged_(exists);
 201 }
 202
 203
 204 ActiveFileMonitor::ActiveFileMonitor(std::shared_ptr<FileMonitorGuard> monitor,
 205                                      FileName const & filename, int interval)
 206         : FileMonitor(monitor), filename_(filename), interval_(interval),
 207           timestamp_(0), checksum_(0), cooldown_(true)
 208 {
 209         QObject::connect(this, SIGNAL(fileChanged(bool)), this, SLOT(setCooldown()));
 210         QTimer::singleShot(interval_, this, SLOT(clearCooldown()));
 211         filename_.refresh();
 212         if (!filename_.exists())
 213                 return;
 214         timestamp_ = filename_.lastModified();
 215         checksum_ = filename_.checksum();
 216 }
 217
 218
 219 void ActiveFileMonitor::checkModified()
 220 {
 221         if (cooldown_)
 222                 return;
 223
 224         cooldown_ = true;
 225         bool changed = false;
 226         filename_.refresh();
 227         bool exists = filename_.exists();
 228         if (!exists) {
 229                 changed = timestamp_ || checksum_;
 230                 timestamp_ = 0;
 231                 checksum_ = 0;
 232         } else {
 233                 time_t const new_timestamp = filename_.lastModified();
 234
 235                 if (new_timestamp != timestamp_) {
 236                         timestamp_ = new_timestamp;
 237
 238                         unsigned long const new_checksum = filename_.checksum();
 239                         if (new_checksum != checksum_) {
 240                                 checksum_ = new_checksum;
 241                                 changed = true;
 242                         }
 243                 }
 244         }
 245         if (changed)
 246                 Q_EMIT FileMonitor::fileChanged(exists);
 247         QTimer::singleShot(interval_, this, SLOT(clearCooldown()));
 248 }
 249
 250
 251 void ActiveFileMonitor::checkModifiedAsync()
 252 {
 253         if (!cooldown_)
 254                 QTimer::singleShot(0, this, SLOT(checkModified()));
 255 }
 256
 257
 258
 259 } // namespace support
 260 } // namespace lyx
 261
 262 #include "moc_FileMonitor.cpp"