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 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)
  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(bool new_file)
 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                         if (new_file || !exists)
 121                                 QTimer::singleShot(1000, this, SLOT(refreshTrue()));
 122                         else
 123                                 QTimer::singleShot(1000, this, SLOT(refreshFalse()));
 124                         // Better (qt>=5.4):
 125                         /*QTimer::singleShot(1000, this, [=](){
 126                                         refresh(new_file || !exists);
 127                                 });*/
 128                 } else if (exists && new_file)
 129                         Q_EMIT fileChanged();
 130         }
 131 }
 132
 133
 134 void FileMonitorGuard::notifyChange(QString const & path)
 135 {
 136         if (path == toqstr(filename_)) {
 137                 Q_EMIT fileChanged();
 138                 // If the file has been modified by delete-move, we are notified of the
 139                 // deletion but we no longer track the file. See
 140                 // <https://bugreports.qt.io/browse/QTBUG-46483> (not a bug).
 141                 refresh();
 142         }
 143 }
 144
 145
 146 FileMonitor::FileMonitor(std::shared_ptr<FileMonitorGuard> monitor)
 147         : monitor_(monitor)
 148 {
 149         connectToFileMonitorGuard();
 150         refresh();
 151 }
 152
 153
 154 void FileMonitor::connectToFileMonitorGuard()
 155 {
 156         QObject::connect(monitor_.get(), SIGNAL(fileChanged()),
 157                          this, SLOT(changed()));
 158 }
 159
 160
 161 boost::signals2::connection
 162 FileMonitor::connect(sig::slot_type const & slot)
 163 {
 164         return fileChanged_.connect(slot);
 165 }
 166
 167
 168 void FileMonitor::disconnect()
 169 {
 170         fileChanged_.disconnect_all_slots();
 171         QObject::disconnect(this, SIGNAL(fileChanged()));
 172 }
 173
 174
 175 void FileMonitor::changed()
 176 {
 177         // emit boost signal
 178         fileChanged_();
 179         Q_EMIT fileChanged();
 180 }
 181
 182
 183 FileMonitorBlocker FileMonitor::block(int delay)
 184 {
 185         FileMonitorBlocker blocker = blocker_.lock();
 186         if (!blocker)
 187                 blocker_ = blocker = make_shared<FileMonitorBlockerGuard>(this);
 188         blocker->setDelay(delay);
 189         return blocker;
 190 }
 191
 192
 193 FileMonitorBlockerGuard::FileMonitorBlockerGuard(FileMonitor * parent)
 194         : QObject(parent), parent_(parent), delay_(0)
 195 {
 196         QObject::disconnect(parent_->monitor_.get(), SIGNAL(fileChanged()),
 197                             parent_, SLOT(changed()));
 198 }
 199
 200
 201 void FileMonitorBlockerGuard::setDelay(int delay)
 202 {
 203         delay_ = max(delay_, delay);
 204 }
 205
 206
 207 FileMonitorBlockerGuard::~FileMonitorBlockerGuard()
 208 {
 209         // closures can only copy local copies
 210         FileMonitor * parent = parent_;
 211         // parent is also our QObject::parent() so we are deleted before parent.
 212         // Even if delay_ is 0, the QTimer is necessary. Indeed, the notifications
 213         // from QFileSystemWatcher that we meant to ignore are not going to be
 214         // treated immediately, so we must yield to give us the opportunity to
 215         // ignore them.
 216         QTimer::singleShot(delay_, parent, SLOT(connectToFileMonitorGuard()));
 217 }
 218
 219 } // namespace support
 220 } // namespace lyx
 221
 222 #include "moc_FileMonitor.cpp"