Move VLC instance initialization into a separate class

src/CMakeLists.txt

@@ -84,6 +84,7 @@ list(APPEND SRC_LIST ${HEADERS_LIST}
     discoverer/DiscovererWorker.cpp
 
     utils/Filename.cpp
+    utils/VLCInstance.cpp
 
     database/SqliteConnection.cpp
     database/SqliteTransaction.cpp

src/MediaLibrary.cpp

@@ -449,24 +449,9 @@ void MediaLibrary::startParser()
 {
     m_parser.reset( new Parser( m_dbConnection.get(), this, m_callback ) );
 
-    const char* args[] = {
-        "-vv",
-    };
-    m_vlcInstance = VLC::Instance( sizeof(args) / sizeof(args[0]), args );
-    m_vlcInstance.logSet([this](int lvl, const libvlc_log_t*, std::string msg) {
-        if ( m_verbosity != LogLevel::Verbose )
-            return ;
-        if ( lvl == LIBVLC_ERROR )
-            Log::Error( msg );
-        else if ( lvl == LIBVLC_WARNING )
-            Log::Warning( msg );
-        else
-            Log::Info( msg );
-    });
-
-    auto vlcService = std::unique_ptr<VLCMetadataService>( new VLCMetadataService( m_vlcInstance ) );
+    auto vlcService = std::unique_ptr<VLCMetadataService>( new VLCMetadataService );
     auto metadataService = std::unique_ptr<MetadataParser>( new MetadataParser( m_dbConnection.get() ) );
-    auto thumbnailerService = std::unique_ptr<VLCThumbnailer>( new VLCThumbnailer( m_vlcInstance ) );
+    auto thumbnailerService = std::unique_ptr<VLCThumbnailer>( new VLCThumbnailer );
     m_parser->addService( std::move( vlcService ) );
     m_parser->addService( std::move( metadataService ) );
     m_parser->addService( std::move( thumbnailerService ) );

src/MediaLibrary.h

@@ -31,7 +31,6 @@ class SqliteConnection;
 #include "IMediaLibrary.h"
 #include "IDiscoverer.h"
 #include "logging/Logger.h"
-#include "vlcpp/vlc.hpp"
 #include "Settings.h"
 
 class Album;
@@ -132,10 +131,6 @@ class MediaLibrary : public IMediaLibrary
         std::string m_thumbnailPath;
         IMediaLibraryCb* m_callback;
 
-        // This probably qualifies as a work around, but we need to keep the VLC::Instance
-        // alive to be able to use the logging wrapper lambda
-        VLC::Instance m_vlcInstance;
-
         // Keep the parser as last field.
         // The parser holds a (raw) pointer to the media library. When MediaLibrary's destructor gets called
         // it might still finish a few operations before exiting the parser thread. Those operations are

src/logging/Logger.h

@@ -99,6 +99,11 @@ public:
         s_logLevel.store( level, std::memory_order_relaxed );
     }
 
+    static LogLevel logLevel()
+    {
+        return s_logLevel.load( std::memory_order_relaxed );
+    }
+
     template <typename... Args>
     static void Error( Args... args )
     {

src/metadata_services/vlc/VLCMetadataService.cpp

@@ -24,9 +24,10 @@
 
 #include "VLCMetadataService.h"
 #include "Media.h"
+#include "utils/VLCInstance.h"
 
-VLCMetadataService::VLCMetadataService( const VLC::Instance& vlc )
-    : m_instance( vlc )
+VLCMetadataService::VLCMetadataService()
+    : m_instance( VLCInstance::get() )
 {
 }
 

src/metadata_services/vlc/VLCMetadataService.h

@@ -33,7 +33,7 @@
 class VLCMetadataService : public ParserService
 {
     public:
-        explicit VLCMetadataService(const VLC::Instance& vlc);
+        explicit VLCMetadataService();
 
 private:
         virtual parser::Task::Status run( parser::Task& task ) override;

src/metadata_services/vlc/VLCThumbnailer.cpp

@@ -41,9 +41,10 @@
 #include "File.h"
 #include "logging/Logger.h"
 #include "MediaLibrary.h"
+#include "utils/VLCInstance.h"
 
-VLCThumbnailer::VLCThumbnailer( const VLC::Instance &vlc )
-    : m_instance( vlc )
+VLCThumbnailer::VLCThumbnailer()
+    : m_instance( VLCInstance::get() )
     , m_ml( nullptr )
 #ifdef WITH_EVAS
     , m_canvas( nullptr, &evas_free )

src/metadata_services/vlc/VLCThumbnailer.h

@@ -45,7 +45,7 @@
 class VLCThumbnailer : public ParserService
 {
 public:
-    explicit VLCThumbnailer( const VLC::Instance& vlc );
+    explicit VLCThumbnailer();
     virtual ~VLCThumbnailer();
     virtual parser::Task::Status run( parser::Task& task ) override;
     virtual bool initialize() override;

src/utils/VLCInstance.cpp

+/*****************************************************************************
+ * 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.
+ *****************************************************************************/
+
+#include "VLCInstance.h"
+#include "logging/Logger.h"
+#include "vlcpp/vlc.hpp"
+
+namespace
+{
+// Define this in the .cpp file to avoid including libvlcpp from the header.
+struct Init
+{
+    Init()
+    {
+        const char* args[] = {
+            "-vv",
+        };
+        instance = VLC::Instance( sizeof(args) / sizeof(args[0]), args );
+        instance.logSet([this](int lvl, const libvlc_log_t*, std::string msg) {
+            if ( Log::logLevel() != LogLevel::Verbose )
+                return;
+            if ( lvl == LIBVLC_ERROR )
+                Log::Error( msg );
+            else if ( lvl == LIBVLC_WARNING )
+                Log::Warning( msg );
+            else
+                Log::Info( msg );
+        });
+    }
+
+    VLC::Instance instance;
+};
+}
+
+VLC::Instance& VLCInstance::get()
+{
+    // Instanciate the wrapper only once, and run initialization in its constructor.
+    static Init wrapper;
+    return wrapper.instance;
+}

src/utils/VLCInstance.h

+/*****************************************************************************
+ * 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.
+ *****************************************************************************/
+
+#pragma once
+
+namespace VLC
+{
+class Instance;
+}
+
+class VLCInstance
+{
+public:
+    static VLC::Instance& get();
+};