FsDiscoverer.cpp 14.5 KB
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/*****************************************************************************
 * Media Library
 *****************************************************************************
 * Copyright (C) 2015 Hugo Beauzée-Luyssen, Videolabs
 *
 * Authors: Hugo Beauzée-Luyssen<hugo@beauzee.fr>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

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#if HAVE_CONFIG_H
# include "config.h"
#endif

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#include "FsDiscoverer.h"

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#include <algorithm>
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#include <queue>
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#include <utility>
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#include "factory/FileSystemFactory.h"
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#include "filesystem/IDevice.h"
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#include "Media.h"
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#include "File.h"
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#include "Device.h"
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#include "Folder.h"
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#include "logging/Logger.h"
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#include "MediaLibrary.h"
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#include "utils/Filename.h"
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namespace
{

class DeviceRemovedException : public std::runtime_error
{
public:
    DeviceRemovedException() noexcept
        : std::runtime_error( "A device was removed during the discovery" )
    {
    }
};

}

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namespace medialibrary
{

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FsDiscoverer::FsDiscoverer( std::shared_ptr<factory::IFileSystem> fsFactory, MediaLibrary* ml, IMediaLibraryCb* cb )
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    : m_ml( ml )
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    , m_fsFactory( std::move( fsFactory ))
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    , m_cb( cb )
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{
}

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bool FsDiscoverer::discover( const std::string &entryPoint )
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{
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    LOG_INFO( "Adding to discovery list: ", entryPoint );
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    if ( m_fsFactory->isMrlSupported( entryPoint ) == false )
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        return false;
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    std::shared_ptr<fs::IDirectory> fsDir = m_fsFactory->createDirectory( entryPoint );
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    auto f = Folder::fromMrl( m_ml, entryPoint );
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    // If the folder exists, we assume it will be handled by reload()
    if ( f != nullptr )
        return true;
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    try
    {
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        if ( hasDotNoMediaFile( *fsDir ) )
            return true;
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        return addFolder( std::move( fsDir ), nullptr );
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    }
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    catch ( std::system_error& ex )
    {
        LOG_WARN( entryPoint, " discovery aborted because of a filesystem error: ", ex.what() );
    }
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    catch ( sqlite::errors::ConstraintViolation& ex )
    {
        LOG_WARN( entryPoint, " discovery aborted (assuming blacklisted folder): ", ex.what() );
    }
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    catch ( DeviceRemovedException& )
    {
        // Simply ignore, the device has already been marked as removed and the DB updated accordingly
        LOG_INFO( "Discovery of ", fsDir->mrl(), " was stopped after the device was removed" );
    }
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    return true;
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}

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void FsDiscoverer::reloadFolder( std::shared_ptr<Folder> f )
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{
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    auto mrl = f->mrl();
    auto folder = m_fsFactory->createDirectory( mrl );
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    assert( folder->device() != nullptr );
    if ( folder->device() == nullptr )
        return;
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    try
    {
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        checkFolder( std::move( folder ), std::move( f ), false );
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    }
    catch ( DeviceRemovedException& )
    {
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        LOG_INFO( "Reloading of ", mrl, " was stopped after the device was removed" );
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    }
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}

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bool FsDiscoverer::reload()
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{
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    LOG_INFO( "Reloading all folders" );
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    auto rootFolders = Folder::fetchRootFolders( m_ml );
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    for ( const auto& f : rootFolders )
        reloadFolder( f );
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    return true;
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}

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bool FsDiscoverer::reload( const std::string& entryPoint )
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{
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    if ( m_fsFactory->isMrlSupported( entryPoint ) == false )
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        return false;
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    LOG_INFO( "Reloading folder ", entryPoint );
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    auto folder = Folder::fromMrl( m_ml, entryPoint );
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    if ( folder == nullptr )
    {
        LOG_ERROR( "Can't reload ", entryPoint, ": folder wasn't found in database" );
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        return false;
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    }
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    reloadFolder( std::move( folder ) );
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    return true;
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}

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void FsDiscoverer::checkFolder( std::shared_ptr<fs::IDirectory> currentFolderFs,
                                std::shared_ptr<Folder> currentFolder,
                                bool newFolder ) const
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{
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    try
    {
        // We already know of this folder, though it may now contain a .nomedia file.
        // In this case, simply delete the folder.
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        if ( hasDotNoMediaFile( *currentFolderFs ) )
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        {
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            if ( newFolder == false )
            {
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                LOG_INFO( "Deleting folder ", currentFolderFs->mrl(), " due to a .nomedia file" );
                m_ml->deleteFolder( *currentFolder );
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            }
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            else
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                LOG_INFO( "Ignoring folder ", currentFolderFs->mrl(), " due to a .nomedia file" );
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            return;
        }
    }
    // Only check once for a system_error. They are bound to happen when we list the files/folders
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    // within, and hasDotMediaFile is the first place when this is done
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    catch ( std::system_error& ex )
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    {
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        LOG_WARN( "Failed to browse ", currentFolderFs->mrl(), ": ", ex.what() );
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        // Even when we're discovering a new folder, we want to rule out device removal as the cause of
        // an IO error. If this is the cause, simply abort the discovery. All the folder we have
        // discovered so far will be marked as non-present through sqlite hooks, and we'll resume the
        // discovery when the device gets plugged back in
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        auto device = currentFolderFs->device();
        // The device might not be present at all, and therefor we might miss a
        // representation for it.
        if ( device == nullptr || device->isRemovable() )
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        {
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            // If the device is removable/missing, check if it was indeed removed.
            LOG_INFO( "The device containing ", currentFolderFs->mrl(), " is ",
                      device != nullptr ? "removable" : "not found",
                      ". Refreshing device cache..." );

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            m_ml->refreshDevices( *m_fsFactory );
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            // If the device was missing, refresh our list of devices in case
            // the device was plugged back and/or we missed a notification for it
            if ( device == nullptr )
                device = currentFolderFs->device();
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            // The device presence flag will be changed in place, so simply retest it
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            if ( device == nullptr || device->isPresent() == false )
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                throw DeviceRemovedException();
            LOG_INFO( "Device was not removed" );
        }
        // However if the device isn't removable, we want to:
        // - ignore it when we're discovering a new folder.
        // - delete it when it was discovered in the past. This is likely to be due to a permission change
        //   as we would not check the folder if it wasn't present during the parent folder browsing
        //   but it might also be that we're checking an entry point.
        //   The error won't arise earlier, as we only perform IO when reading the folder from this function.
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        if ( newFolder == false )
        {
            // If we ever came across this folder, its content is now unaccessible: let's remove it.
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            m_ml->deleteFolder( *currentFolder );
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        }
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        return;
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    }
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    m_cb->onDiscoveryProgress( currentFolderFs->mrl() );
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    // Load the folders we already know of:
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    LOG_INFO( "Checking for modifications in ", currentFolderFs->mrl() );
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    // Don't try to fetch any potential sub folders if the folder was freshly added
    std::vector<std::shared_ptr<Folder>> subFoldersInDB;
    if ( newFolder == false )
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        subFoldersInDB = currentFolder->folders();
    for ( const auto& subFolder : currentFolderFs->dirs() )
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    {
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        if ( subFolder->device() == nullptr )
            continue;
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        auto it = std::find_if( begin( subFoldersInDB ), end( subFoldersInDB ), [&subFolder](const std::shared_ptr<Folder>& f) {
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            return f->mrl() == subFolder->mrl();
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        });
        // We don't know this folder, it's a new one
        if ( it == end( subFoldersInDB ) )
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        {
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            if ( hasDotNoMediaFile( *subFolder ) )
            {
                LOG_INFO( "Ignoring folder with a .nomedia file" );
                continue;
            }
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            LOG_INFO( "New folder detected: ", subFolder->mrl() );
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            try
            {
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                addFolder( subFolder, currentFolder.get() );
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                continue;
            }
            catch ( sqlite::errors::ConstraintViolation& ex )
            {
                // Best attempt to detect a foreign key violation, indicating the parent folders have been
                // deleted due to blacklisting
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                if ( strstr( ex.what(), "foreign key" ) != nullptr )
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                {
                    LOG_WARN( "Creation of a folder failed because the parent is non existing: ", ex.what(),
                              ". Assuming it was deleted due to blacklisting" );
                    return;
                }
                LOG_WARN( "Creation of a duplicated folder failed: ", ex.what(), ". Assuming it was blacklisted" );
                continue;
            }
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        }
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        auto folderInDb = *it;
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        // In any case, check for modifications, as a change related to a mountpoint might
        // not update the folder modification date.
        // Also, relying on the modification date probably isn't portable
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        checkFolder( subFolder, folderInDb, false );
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        subFoldersInDB.erase( it );
    }
    // Now all folders we had in DB but haven't seen from the FS must have been deleted.
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    for ( const auto& f : subFoldersInDB )
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    {
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        LOG_INFO( "Folder ", f->mrl(), " not found in FS, deleting it" );
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        m_ml->deleteFolder( *f );
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    }
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    checkFiles( currentFolderFs, currentFolder );
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    LOG_INFO( "Done checking subfolders in ", currentFolderFs->mrl() );
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}
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void FsDiscoverer::checkFiles( std::shared_ptr<fs::IDirectory> parentFolderFs,
                               std::shared_ptr<Folder> parentFolder ) const
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{
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    LOG_INFO( "Checking file in ", parentFolderFs->mrl() );
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    static const std::string req = "SELECT * FROM " + policy::FileTable::Name
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            + " WHERE folder_id = ?";
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    auto files = File::fetchAll<File>( m_ml, req, parentFolder->id() );
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    std::vector<std::shared_ptr<fs::IFile>> filesToAdd;
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    std::vector<std::shared_ptr<File>> filesToRemove;
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    for ( const auto& fileFs: parentFolderFs->files() )
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    {
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        auto it = std::find_if( begin( files ), end( files ), [fileFs](const std::shared_ptr<File>& f) {
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            return f->mrl() == fileFs->mrl();
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        });
        if ( it == end( files ) )
        {
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            if ( MediaLibrary::isExtensionSupported( fileFs->extension().c_str() ) == true )
                filesToAdd.push_back( fileFs );
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            continue;
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        }
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        if ( fileFs->lastModificationDate() == (*it)->lastModificationDate() )
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        {
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            // Unchanged file
            files.erase( it );
            continue;
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        }
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        auto& file = (*it);
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        LOG_INFO( "Forcing file refresh ", fileFs->mrl() );
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        // Pre-cache the file's media, since we need it to remove. However, better doing it
        // out of a write context, since that way, other threads can also read the database.
        file->media();
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        filesToRemove.push_back( std::move( file ) );
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        filesToAdd.push_back( fileFs );
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        files.erase( it );
    }
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    using FilesT = decltype( files );
    using FilesToRemoveT = decltype( filesToRemove );
    using FilesToAddT = decltype( filesToAdd );
    sqlite::Tools::withRetries( 3, [this, &parentFolder, &parentFolderFs]
                            ( FilesT files, FilesToAddT filesToAdd, FilesToRemoveT filesToRemove ) {
        auto t = m_ml->getConn()->newTransaction();
        for ( auto file : files )
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        {
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            LOG_INFO( "File ", file->mrl(), " not found on filesystem, deleting it" );
            auto media = file->media();
            if ( media != nullptr && media->isDeleted() == false )
                media->removeFile( *file );
            else if ( file->isDeleted() == false )
            {
                // This is unexpected, as the file should have been deleted when the media was
                // removed.
                LOG_WARN( "Deleting a file without an associated media." );
                file->destroy();
            }
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        }
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        for ( auto& f : filesToRemove )
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        {
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            auto media = f->media();
            if ( media != nullptr )
                media->removeFile( *f );
            else
            {
                // If there is no media associated with this file, the file had to be removed through
                // a trigger
                assert( f->isDeleted() );
            }
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        }
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        // Insert all files at once to avoid SQL write contention
        for ( auto& p : filesToAdd )
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            m_ml->addFile( p, parentFolder, parentFolderFs );
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        t->commit();
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        LOG_INFO( "Done checking files in ", parentFolderFs->mrl() );
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    }, std::move( files ), std::move( filesToAdd ), std::move( filesToRemove ) );
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}
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bool FsDiscoverer::hasDotNoMediaFile( const fs::IDirectory& directory )
{
    const auto& files = directory.files();
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    return std::find_if( begin( files ), end( files ), []( const std::shared_ptr<fs::IFile>& file ){
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        return strcasecmp( file->name().c_str(), ".nomedia" ) == 0;
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    }) != end( files );
}

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bool FsDiscoverer::addFolder( std::shared_ptr<fs::IDirectory> folder,
                              Folder* parentFolder ) const
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{
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    auto deviceFs = folder->device();
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    // We are creating a folder, there has to be a device containing it.
    assert( deviceFs != nullptr );
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    // But gracefully handle failure in release mode
    if( deviceFs == nullptr )
        return false;
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    auto device = Device::fromUuid( m_ml, deviceFs->uuid() );
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    if ( device == nullptr )
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    {
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        LOG_INFO( "Creating new device in DB ", deviceFs->uuid() );
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        device = Device::create( m_ml, deviceFs->uuid(),
                                 utils::file::scheme( folder->mrl() ),
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                                 deviceFs->isRemovable() );
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        if ( device == nullptr )
            return false;
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    }

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    auto f = Folder::create( m_ml, folder->mrl(),
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                             parentFolder != nullptr ? parentFolder->id() : 0,
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                             *device, *deviceFs );
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    if ( f == nullptr )
        return false;
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    checkFolder( std::move( folder ), std::move( f ), true );
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    return true;
}
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}