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 Guillaume Munch
   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/debug.h"
  16 #include "support/FileName.h"
  17 #include "support/qstring_helpers.h"
  18 #include "support/unique_ptr.h"
  19
  20 #include <QFile>
  21 #include <QStringList>
  22 #include <QTimer>
  23
  24 #include <algorithm>
  25
  26 using namespace std;
  27
  28 namespace lyx {
  29 namespace support {
  30
  31
  32 FileSystemWatcher & FileSystemWatcher::instance()
  33 {
  34         // This is thread-safe because QFileSystemWatcher is thread-safe.
  35         static FileSystemWatcher f;
  36         return f;
  37 }
  38
  39
  40 FileSystemWatcher::FileSystemWatcher()
  41         : qwatcher_(make_unique<QFileSystemWatcher>())
  42 {}
  43
  44
  45 //static
  46 FileMonitorPtr FileSystemWatcher::monitor(FileName const & file_with_path)
  47 {
  48         FileSystemWatcher & f = instance();
  49         string const filename = file_with_path.absFileName();
  50         weak_ptr<FileMonitorGuard> & wptr = f.store_[filename];
  51         if (shared_ptr<FileMonitorGuard> mon = wptr.lock())
  52                 return make_unique<FileMonitor>(mon);
  53         auto mon = make_shared<FileMonitorGuard>(filename, f.qwatcher_.get());
  54         wptr = mon;
  55         return make_unique<FileMonitor>(mon);
  56 }
  57
  58
  59 //static
  60 void FileSystemWatcher::debug()
  61 {
  62         FileSystemWatcher & f = instance();
  63         QStringList q_files = f.qwatcher_->files();
  64         for (pair<string, weak_ptr<FileMonitorGuard>> pair : f.store_) {
  65                 string const & name = pair.first;
  66                 if (!pair.second.expired()) {
  67                         if (!q_files.contains(toqstr(name)))
  68                                 LYXERR0("Monitored but not QFileSystemWatched (bad): " << name);
  69                         else {
  70                                 //LYXERR0("Monitored and QFileSystemWatched (good): " << name);
  71                         }
  72                 }
  73         }
  74         for (QString const & qname : q_files) {
  75                 string const name = fromqstr(qname);
  76                 weak_ptr<FileMonitorGuard> & wptr = f.store_[name];
  77                 if (wptr.expired())
  78                         LYXERR0("QFileSystemWatched but not monitored (bad): " << name);
  79         }
  80 }
  81
  82
  83 FileMonitorGuard::FileMonitorGuard(string const & filename,
  84                                    QFileSystemWatcher * qwatcher)
  85         : filename_(filename), qwatcher_(qwatcher), exists_(true)
  86 {
  87         QObject::connect(qwatcher, SIGNAL(fileChanged(QString const &)),
  88                          this, SLOT(notifyChange(QString const &)));
  89         if (qwatcher_->files().contains(toqstr(filename)))
  90                 LYXERR0("This file is already being QFileSystemWatched: " << filename
  91                         << ". This should not happen.");
  92         refresh();
  93 }
  94
  95
  96 FileMonitorGuard::~FileMonitorGuard()
  97 {
  98         qwatcher_->removePath(toqstr(filename_));
  99 }
 100
 101
 102 void FileMonitorGuard::refresh()
 103 {
 104         QString const qfilename = toqstr(filename_);
 105         if(!qwatcher_->files().contains(qfilename)) {
 106                 bool exists = QFile(qfilename).exists();
 107 #if (QT_VERSION >= 0x050000)
 108                 if (!exists || !qwatcher_->addPath(qfilename)) {
 109 #else
 110                 auto add_path = [&]() {
 111                         qwatcher_->addPath(qfilename);
 112                         return qwatcher_->files().contains(qfilename);
 113                 };
 114                 if (!exists || !add_path()) {
 115 #endif
 116                         if (exists)
 117                                 LYXERR(Debug::FILES,
 118                                        "Could not add path to QFileSystemWatcher: "
 119                                        << filename_);
 120                         QTimer::singleShot(2000, this, SLOT(refresh()));
 121                 } else if (exists && !exists_)
 122                         Q_EMIT fileChanged();
 123                 setExists(exists);
 124         }
 125 }
 126
 127
 128 void FileMonitorGuard::notifyChange(QString const & path)
 129 {
 130         if (path == toqstr(filename_)) {
 131                 Q_EMIT fileChanged();
 132                 // If the file has been modified by delete-move, we are notified of the
 133                 // deletion but we no longer track the file. See
 134                 // <https://bugreports.qt.io/browse/QTBUG-46483> (not a bug).
 135                 refresh();
 136         }
 137 }
 138
 139
 140 FileMonitor::FileMonitor(std::shared_ptr<FileMonitorGuard> monitor)
 141         : monitor_(monitor)
 142 {
 143         QObject::connect(monitor_.get(), SIGNAL(fileChanged()),
 144                          this, SLOT(changed()));
 145         refresh();
 146 }
 147
 148
 149 void FileMonitor::reconnectToFileMonitorGuard()
 150 {
 151         monitor_->setExists(true);
 152         QObject::connect(monitor_.get(), SIGNAL(fileChanged()),
 153                          this, SLOT(changed()));
 154 }
 155
 156
 157 boost::signals2::connection
 158 FileMonitor::connect(sig::slot_type const & slot)
 159 {
 160         return fileChanged_.connect(slot);
 161 }
 162
 163
 164 void FileMonitor::disconnect()
 165 {
 166         fileChanged_.disconnect_all_slots();
 167         QObject::disconnect(this, SIGNAL(fileChanged()));
 168 }
 169
 170
 171 void FileMonitor::changed()
 172 {
 173         // emit boost signal
 174         fileChanged_();
 175         Q_EMIT fileChanged();
 176 }
 177
 178
 179 FileMonitorBlocker FileMonitor::block(int delay)
 180 {
 181         FileMonitorBlocker blocker = blocker_.lock();
 182         if (!blocker)
 183                 blocker_ = blocker = make_shared<FileMonitorBlockerGuard>(this);
 184         blocker->setDelay(delay);
 185         return blocker;
 186 }
 187
 188
 189 FileMonitorBlockerGuard::FileMonitorBlockerGuard(FileMonitor * monitor)
 190         : monitor_(monitor), delay_(0)
 191 {
 192         QObject::disconnect(monitor->monitor_.get(), SIGNAL(fileChanged()),
 193                             monitor, SLOT(changed()));
 194 }
 195
 196
 197 void FileMonitorBlockerGuard::setDelay(int delay)
 198 {
 199         delay_ = max(delay_, delay);
 200 }
 201
 202
 203 FileMonitorBlockerGuard::~FileMonitorBlockerGuard()
 204 {
 205         if (!monitor_)
 206                 return;
 207         // Even if delay_ is 0, the QTimer is necessary. Indeed, the notifications
 208         // from QFileSystemWatcher that we meant to ignore are not going to be
 209         // treated immediately, so we must yield to give us the opportunity to
 210         // ignore them.
 211         QTimer::singleShot(delay_, monitor_, SLOT(reconnectToFileMonitorGuard()));
 212 }
 213
 214 } // namespace support
 215 } // namespace lyx
 216
 217 #include "moc_FileMonitor.cpp"