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()
 122 {
 123         if (filename_.empty())
 124                 return;
 125         QString const qfilename = toqstr(filename_);
 126         if(!qwatcher_->files().contains(qfilename)) {
 127                 bool exists = QFile(qfilename).exists();
 128 #if (QT_VERSION >= 0x050000)
 129                 if (!exists || !qwatcher_->addPath(qfilename))
 130 #else
 131                 auto add_path = [&]() {
 132                         qwatcher_->addPath(qfilename);
 133                         return qwatcher_->files().contains(qfilename);
 134                 };
 135                 if (!exists || !add_path())
 136 #endif
 137                 {
 138                         if (exists)
 139                                 LYXERR(Debug::FILES,
 140                                        "Could not add path to QFileSystemWatcher: "
 141                                        << filename_);
 142                         QTimer::singleShot(2000, this, SLOT(refresh()));
 143                 } else if (exists && !exists_)
 144                         Q_EMIT fileChanged();
 145                 setExists(exists);
 146         }
 147 }
 148
 149
 150 void FileMonitorGuard::notifyChange(QString const & path)
 151 {
 152         if (path == toqstr(filename_)) {
 153                 Q_EMIT fileChanged();
 154                 // If the file has been modified by delete-move, we are notified of the
 155                 // deletion but we no longer track the file. See
 156                 // <https://bugreports.qt.io/browse/QTBUG-46483> (not a bug).
 157                 refresh();
 158         }
 159 }
 160
 161
 162 FileMonitor::FileMonitor(std::shared_ptr<FileMonitorGuard> monitor)
 163         : monitor_(monitor)
 164 {
 165         QObject::connect(monitor_.get(), SIGNAL(fileChanged()),
 166                          this, SLOT(changed()));
 167         refresh();
 168 }
 169
 170
 171 void FileMonitor::reconnectToFileMonitorGuard()
 172 {
 173         monitor_->setExists(true);
 174         QObject::connect(monitor_.get(), SIGNAL(fileChanged()),
 175                          this, SLOT(changed()));
 176 }
 177
 178
 179 boost::signals2::connection
 180 FileMonitor::connect(sig::slot_type const & slot)
 181 {
 182         return fileChanged_.connect(slot);
 183 }
 184
 185
 186 void FileMonitor::disconnect()
 187 {
 188         fileChanged_.disconnect_all_slots();
 189         QObject::disconnect(this, SIGNAL(fileChanged()));
 190 }
 191
 192
 193 void FileMonitor::changed()
 194 {
 195         // emit boost signal
 196         fileChanged_();
 197         Q_EMIT fileChanged();
 198 }
 199
 200
 201 FileMonitorBlocker FileMonitor::block(int delay)
 202 {
 203         FileMonitorBlocker blocker = blocker_.lock();
 204         if (!blocker)
 205                 blocker_ = blocker = make_shared<FileMonitorBlockerGuard>(this);
 206         blocker->setDelay(delay);
 207         return blocker;
 208 }
 209
 210
 211 FileMonitorBlockerGuard::FileMonitorBlockerGuard(FileMonitor * monitor)
 212         : monitor_(monitor), delay_(0)
 213 {
 214         QObject::disconnect(monitor->monitor_.get(), SIGNAL(fileChanged()),
 215                             monitor, SLOT(changed()));
 216 }
 217
 218
 219 void FileMonitorBlockerGuard::setDelay(int delay)
 220 {
 221         delay_ = max(delay_, delay);
 222 }
 223
 224
 225 FileMonitorBlockerGuard::~FileMonitorBlockerGuard()
 226 {
 227         if (!monitor_)
 228                 return;
 229         // Even if delay_ is 0, the QTimer is necessary. Indeed, the notifications
 230         // from QFileSystemWatcher that we meant to ignore are not going to be
 231         // treated immediately, so we must yield to give us the opportunity to
 232         // ignore them.
 233         QTimer::singleShot(delay_, monitor_, SLOT(reconnectToFileMonitorGuard()));
 234 }
 235
 236
 237 ActiveFileMonitor::ActiveFileMonitor(std::shared_ptr<FileMonitorGuard> monitor,
 238                                      FileName const & filename, int interval)
 239         : FileMonitor(monitor), filename_(filename), interval_(interval),
 240           timestamp_(0), checksum_(0), cooldown_(true)
 241 {
 242         QObject::connect(this, SIGNAL(fileChanged()), this, SLOT(setCooldown()));
 243         QTimer::singleShot(interval_, this, SLOT(clearCooldown()));
 244         if (!filename_.exists())
 245                 return;
 246         timestamp_ = filename_.lastModified();
 247         checksum_ = filename_.checksum();
 248 }
 249
 250
 251 void ActiveFileMonitor::checkModified()
 252 {
 253         if (cooldown_)
 254                 return;
 255
 256         cooldown_ = true;
 257         bool changed = false;
 258         if (!filename_.exists()) {
 259                 changed = timestamp_ || checksum_;
 260                 timestamp_ = 0;
 261                 checksum_ = 0;
 262         } else {
 263                 time_t const new_timestamp = filename_.lastModified();
 264
 265                 if (new_timestamp != timestamp_) {
 266                         timestamp_ = new_timestamp;
 267
 268                         unsigned long const new_checksum = filename_.checksum();
 269                         if (new_checksum != checksum_) {
 270                                 checksum_ = new_checksum;
 271                                 changed = true;
 272                         }
 273                 }
 274         }
 275         if (changed)
 276                 FileMonitor::changed();
 277         QTimer::singleShot(interval_, this, SLOT(clearCooldown()));
 278 }
 279
 280
 281 void ActiveFileMonitor::checkModifiedAsync()
 282 {
 283         if (!cooldown_)
 284                 QTimer::singleShot(0, this, SLOT(checkModified()));
 285 }
 286
 287
 288
 289 } // namespace support
 290 } // namespace lyx
 291
 292 #include "moc_FileMonitor.cpp"