AUP3: Provides relief from slow shutdown

This is a hack to fix the long delay at Audacity shutdown
after editing large files and tossing the results (not
saving).

src/ProjectFileIO.cpp

@@ -87,13 +87,12 @@ static const char *ProjectFileSchema =
    ");"
    ""
    // CREATE SQL sampleblocks
-   // 'samples' are fixed size blocks of float32 numbers.
+   // 'samples' are fixed size blocks of int16, int32 or float32 numbers.
    // The blocks may be partially empty.
    // The quantity of valid data in the blocks is
    // provided in the project XML.
    // 
-   // sampleformat was once used to specify whether floats 
-   // or ints for the data, but is no longer used.
+   // sampleformat specifies the format of the samples stored.
    //
    // blockID is a 64 bit number.
    //
@@ -198,6 +197,8 @@ ProjectFileIO::ProjectFileIO(AudacityProject &)
    mModified = false;
    mTemporary = true;
 
+   mBypass = false;
+
    UpdatePrefs();
 }
 
@@ -1289,3 +1290,14 @@ void ProjectFileIO::SetDBError(const TranslatableString & msg)
       mLibraryError = Verbatim(sqlite3_errmsg(mDB));
    }
 }
+
+void ProjectFileIO::Bypass(bool bypass)
+{
+   mBypass = bypass;
+}
+
+bool ProjectFileIO::ShouldBypass()
+{
+   return mBypass;
+}
+

src/ProjectFileIO.h

@@ -19,6 +19,7 @@ Paul Licameli split from AudacityProject.h
 struct sqlite3;
 
 class AudacityProject;
+class AutoCommitTransaction;
 class AutoSaveFile;
 class SqliteSampleBlock;
 class WaveTrack;
@@ -46,8 +47,6 @@ public:
    ProjectFileIO &operator=( const ProjectFileIO & ) PROHIBITED;
    ~ProjectFileIO();
 
-   bool WarnOfLegacyFile( );
-   
    // It seems odd to put this method in this class, but the results do depend
    // on what is discovered while opening the file, such as whether it is a
    // recovery file
@@ -79,6 +78,21 @@ public:
    const TranslatableString &GetLastError() const;
    const TranslatableString &GetLibraryError() const;
 
+   // Provides a means to bypass "DELETE"s at shutdown if the database
+   // is just going to be deleted anyway.  This prevents a noticable
+   // delay caused by SampleBlocks being deleted when the Sequences that
+   // own them are deleted.
+   //
+   // This is definitely hackage territory.  While this ability would
+   // still be needed, I think handling it in a DB abstraction might be
+   // a tad bit cleaner.
+   //
+   // For it's usage, see:
+   //    SqliteSampleBlock::~SqliteSampleBlock()
+   //    ProjectManager::OnCloseWindow()
+   void Bypass(bool bypass);
+   bool ShouldBypass();
+
 private:
    // XMLTagHandler callback methods
    bool HandleXMLTag(const wxChar *tag, const wxChar **attrs) override;
@@ -128,6 +142,9 @@ private:
    // Is this project still a temporary/unsaved project
    bool mTemporary;
 
+   // Bypass transactions if database will be deleted after close
+   bool mBypass;
+
    sqlite3 *mDB;
    FilePath mDBPath;
    TranslatableString mLastError;

src/ProjectManager.cpp

@@ -672,6 +672,9 @@ void ProjectManager::OnCloseWindow(wxCloseEvent & event)
       }
    }
 
+   // See ProjectFileIO::Bypass() for a description
+   projectFileIO.Bypass(true);
+
 #ifdef __WXMAC__
    // Fix bug apparently introduced into 2.1.2 because of wxWidgets 3:
    // closing a project that was made full-screen (as by clicking the green dot

src/SqliteSampleBlock.cpp

@@ -283,7 +283,8 @@ SqliteSampleBlock::SqliteSampleBlock(AudacityProject *project)
 
 SqliteSampleBlock::~SqliteSampleBlock()
 {
-   if (mRefCnt == 0)
+   // See ProjectFileIO::Bypass() for a description of mIO.mBypass
+   if (mRefCnt == 0 && !mIO.ShouldBypass())
    {
       Delete();
    }