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 <QTimer>
  22
  23 #include <algorithm>
  24
  25 using namespace std;
  26
  27 namespace lyx {
  28 namespace support {
  29
  30
  31 FileSystemWatcher & FileSystemWatcher::instance()
  32 {
  33         // This thread-safe because QFileSystemWatcher is thread-safe.
  34         static FileSystemWatcher f;
  35         return f;
  36 }
  37
  38
  39 FileSystemWatcher::FileSystemWatcher()
  40         : qwatcher_(make_unique<QFileSystemWatcher>())
  41 {}
  42
  43
  44 //static
  45 FileMonitorPtr FileSystemWatcher::monitor(FileName const & file_with_path)
  46 {
  47         FileSystemWatcher & f = instance();
  48         string const filename = file_with_path.absFileName();
  49         weak_ptr<FileMonitorGuard> & wptr = f.store_[filename];
  50         if (shared_ptr<FileMonitorGuard> mon = wptr.lock())
  51                 return make_unique<FileMonitor>(mon);
  52         auto mon = make_shared<FileMonitorGuard>(filename, f.qwatcher_.get());
  53         wptr = mon;
  54         return make_unique<FileMonitor>(mon);
  55 }
  56
  57
  58 //static
  59 void FileSystemWatcher::debug()
  60 {
  61         FileSystemWatcher & f = instance();
  62         QStringList q_files = f.qwatcher_->files();
  63         for (pair<string, weak_ptr<FileMonitorGuard>> pair : f.store_) {
  64                 string const & name = pair.first;
  65                 if (!pair.second.expired()) {
  66                         if (!q_files.contains(toqstr(name)))
  67                                 LYXERR0("Monitored but not QFileSystemWatched (bad): " << name);
  68                         else {
  69                                 //LYXERR0("Monitored and QFileSystemWatched (good): " << name);
  70                         }
  71                 }
  72         }
  73         for (QString const & qname : q_files) {
  74                 string const name = fromqstr(qname);
  75                 weak_ptr<FileMonitorGuard> & wptr = f.store_[name];
  76                 if (wptr.expired())
  77                         LYXERR0("QFileSystemWatched but not monitored (bad): " << name);
  78         }
  79 }
  80
  81
  82 FileMonitorGuard::FileMonitorGuard(string const & filename,
  83                                    QFileSystemWatcher * qwatcher)
  84         : filename_(filename), qwatcher_(qwatcher)
  85 {
  86         QObject::connect(qwatcher, SIGNAL(fileChanged(QString const &)),
  87                          this, SLOT(notifyChange(QString const &)));
  88         if (qwatcher_->files().contains(toqstr(filename)))
  89                 LYXERR0("This file is already being QFileSystemWatched: " << filename
  90                         << ". This should not happen.");
  91         refresh();
  92 }
  93
  94
  95 FileMonitorGuard::~FileMonitorGuard()
  96 {
  97         qwatcher_->removePath(toqstr(filename_));
  98 }
  99
 100
 101 void FileMonitorGuard::refresh(bool new_file)
 102 {
 103         QString const qfilename = toqstr(filename_);
 104         if(!qwatcher_->files().contains(qfilename)) {
 105                 bool exists = QFile(qfilename).exists();
 106                 if (!exists || !qwatcher_->addPath(qfilename)) {
 107                         if (exists)
 108                                 LYXERR(Debug::FILES,
 109                                        "Could not add path to QFileSystemWatcher: "
 110                                        << filename_);
 111                         QTimer::singleShot(1000, this, [=](){
 112                                         refresh(new_file || !exists);
 113                                 });
 114                 } else if (exists && new_file)
 115                         Q_EMIT fileChanged();
 116         }
 117 }
 118
 119
 120 void FileMonitorGuard::notifyChange(QString const & path)
 121 {
 122         if (path == toqstr(filename_)) {
 123                 Q_EMIT fileChanged();
 124                 // If the file has been modified by delete-move, we are notified of the
 125                 // deletion but we no longer track the file. See
 126                 // <https://bugreports.qt.io/browse/QTBUG-46483> (not a bug).
 127                 refresh();
 128         }
 129 }
 130
 131
 132 FileMonitor::FileMonitor(std::shared_ptr<FileMonitorGuard> monitor)
 133         : monitor_(monitor)
 134 {
 135         connectToFileMonitorGuard();
 136         refresh();
 137 }
 138
 139
 140 void FileMonitor::connectToFileMonitorGuard()
 141 {
 142         QObject::connect(monitor_.get(), SIGNAL(fileChanged()),
 143                          this, SLOT(changed()));
 144 }
 145
 146
 147 boost::signals2::connection
 148 FileMonitor::connect(sig::slot_type const & slot)
 149 {
 150         return fileChanged_.connect(slot);
 151 }
 152
 153
 154 void FileMonitor::disconnect()
 155 {
 156         fileChanged_.disconnect_all_slots();
 157         QObject::disconnect(this, SIGNAL(fileChanged()));
 158 }
 159
 160
 161 void FileMonitor::changed()
 162 {
 163         // emit boost signal
 164         fileChanged_();
 165         Q_EMIT fileChanged();
 166 }
 167
 168
 169 FileMonitorBlocker FileMonitor::block(int delay)
 170 {
 171         FileMonitorBlocker blocker = blocker_.lock();
 172         if (!blocker)
 173                 blocker_ = blocker = make_shared<FileMonitorBlockerGuard>(this);
 174         blocker->setDelay(delay);
 175         return blocker;
 176 }
 177
 178
 179 FileMonitorBlockerGuard::FileMonitorBlockerGuard(FileMonitor * parent)
 180         : QObject(parent), parent_(parent), delay_(0)
 181 {
 182         QObject::disconnect(parent_->monitor_.get(), SIGNAL(fileChanged()),
 183                             parent_, SLOT(changed()));
 184 }
 185
 186
 187 void FileMonitorBlockerGuard::setDelay(int delay)
 188 {
 189         delay_ = max(delay_, delay);
 190 }
 191
 192
 193 FileMonitorBlockerGuard::~FileMonitorBlockerGuard()
 194 {
 195         // closures can only copy local copies
 196         FileMonitor * parent = parent_;
 197         // parent is also our QObject::parent() so we are deleted before parent.
 198         // Even if delay_ is 0, the QTimer is necessary. Indeed, the notifications
 199         // from QFileSystemWatcher that we meant to ignore are not going to be
 200         // treated immediately, so we must yield to give us the opportunity to
 201         // ignore them.
 202         QTimer::singleShot(delay_, parent, [parent]() {
 203                         parent->connectToFileMonitorGuard();
 204                 });
 205 }
 206
 207 } // namespace support
 208 } // namespace lyx
 209
 210 #include "moc_FileMonitor.cpp"