Preliminaries for fixing Bug2550 residuals

src/ProjectFileIO.cpp

@@ -44,6 +44,7 @@ Paul Licameli split from AudacityProject.cpp
 
 wxDEFINE_EVENT(EVT_PROJECT_TITLE_CHANGE, wxCommandEvent);
 wxDEFINE_EVENT( EVT_CHECKPOINT_FAILURE, wxCommandEvent);
+wxDEFINE_EVENT( EVT_RECONNECTION_FAILURE, wxCommandEvent);
 
 static const int ProjectFileID = ('A' << 24 | 'U' << 16 | 'D' << 8 | 'Y');
 static const int ProjectFileVersion = 1;
@@ -263,6 +264,12 @@ ProjectFileIO::~ProjectFileIO()
 {
 }
 
+bool ProjectFileIO::HasConnection() const
+{
+   auto &connectionPtr = ConnectionPtr::Get( mProject );
+   return connectionPtr.mpConnection != nullptr;
+}
+
 DBConnection &ProjectFileIO::GetConnection()
 {
    auto &curConn = CurrConn();
@@ -331,6 +338,7 @@ bool ProjectFileIO::OpenConnection(FilePath fileName /* = {}  */)
    if (!CheckVersion())
    {
       CloseConnection();
+      curConn.reset();
       return false;
    }
 
@@ -344,7 +352,8 @@ bool ProjectFileIO::OpenConnection(FilePath fileName /* = {}  */)
 bool ProjectFileIO::CloseConnection()
 {
    auto &curConn = CurrConn();
-   wxASSERT(curConn);
+   if (!curConn)
+      return false;
 
    if (!curConn->Close())
    {
@@ -689,6 +698,10 @@ bool ProjectFileIO::CopyTo(const FilePath &destpath,
    bool prune /* = false */,
    const std::vector<const TrackList *> &tracks /* = {} */)
 {
+   auto pConn = CurrConn().get();
+   if (!pConn)
+      return false;
+
    // Get access to the active tracklist
    auto pProject = &mProject;
 
@@ -763,7 +776,7 @@ bool ProjectFileIO::CopyTo(const FilePath &destpath,
    //
    // NOTE:  Between the above attach and setting the mode here, a normal DELETE
    //        mode journal will be used and will briefly appear in the filesystem.
-   CurrConn()->FastMode("outbound");
+   pConn->FastMode("outbound");
 
    // Install our schema into the new database
    if (!InstallSchema(db, "outbound"))
@@ -2039,20 +2052,38 @@ bool ProjectFileIO::SaveProject(
       FilePath savedName = mFileName;
       if (CloseConnection())
       {
-         if (MoveProject(savedName, fileName))
+         bool reopened = false;
+         bool moved = false;
+         if (true == (moved = MoveProject(savedName, fileName)))
          {
-            if (!OpenConnection(fileName))
-            {
+            if (OpenConnection(fileName))
+               reopened = true;
+            else {
                MoveProject(fileName, savedName);
-               OpenConnection(savedName);
+               reopened = OpenConnection(savedName);
             }
          }
          else {
             // Rename can fail -- if it's to a different device, requiring
             // real copy of contents, which might exhaust space
-            OpenConnection(savedName);
-            return false;
+            reopened = OpenConnection(savedName);
          }
+
+         if (!reopened)
+            wxTheApp->CallAfter([this]{
+               ShowErrorDialog(nullptr,
+                  XO("Warning"),
+                  XO(
+"The project's database failed to reopen, "
+"possibly because of limited space on the storage device."),
+                  "Error:_Disk_full_or_not_writable"
+               );
+               wxCommandEvent evt{ EVT_RECONNECTION_FAILURE };
+               mProject.ProcessEvent(evt);
+            });
+
+         if (!moved)
+            return false;
       }
    }
 
@@ -2179,11 +2210,9 @@ bool ProjectFileIO::OpenProject()
 bool ProjectFileIO::CloseProject()
 {
    auto &currConn = CurrConn();
-   wxASSERT(currConn);
-
-   // Protect...
    if (!currConn)
    {
+      wxLogDebug("Closing project with no database connection");
       return true;
    }
 
@@ -2270,14 +2299,16 @@ void ProjectFileIO::SetError(
    const TranslatableString &msg, const TranslatableString &libraryError )
 {
    auto &currConn = CurrConn();
-   currConn->SetError(msg, libraryError);
+   if (currConn)
+      currConn->SetError(msg, libraryError);
 }
 
 void ProjectFileIO::SetDBError(
    const TranslatableString &msg, const TranslatableString &libraryError)
 {
    auto &currConn = CurrConn();
-   currConn->SetDBError(msg, libraryError);
+   if (currConn)
+      currConn->SetDBError(msg, libraryError);
 }
 
 void ProjectFileIO::SetBypass()
@@ -2316,7 +2347,10 @@ void ProjectFileIO::SetBypass()
 
 int64_t ProjectFileIO::GetBlockUsage(SampleBlockID blockid)
 {
-   return GetDiskUsage(CurrConn().get(), blockid);
+   auto pConn = CurrConn().get();
+   if (!pConn)
+      return 0;
+   return GetDiskUsage(*pConn, blockid);
 }
 
 int64_t ProjectFileIO::GetCurrentUsage(
@@ -2337,7 +2371,10 @@ int64_t ProjectFileIO::GetCurrentUsage(
 
 int64_t ProjectFileIO::GetTotalUsage()
 {
-   return GetDiskUsage(CurrConn().get(), 0);
+   auto pConn = CurrConn().get();
+   if (!pConn)
+      return 0;
+   return GetDiskUsage(*pConn, 0);
 }
 
 //
@@ -2346,7 +2383,7 @@ int64_t ProjectFileIO::GetTotalUsage()
 // pages available from the "sqlite_dbpage" virtual table to traverse the SQLite
 // table b-tree described here:  https://www.sqlite.org/fileformat.html
 //
-int64_t ProjectFileIO::GetDiskUsage(DBConnection *conn, SampleBlockID blockid /* = 0 */)
+int64_t ProjectFileIO::GetDiskUsage(DBConnection &conn, SampleBlockID blockid /* = 0 */)
 {
    // Information we need to track our travels through the b-tree
    typedef struct
@@ -2365,7 +2402,7 @@ int64_t ProjectFileIO::GetDiskUsage(DBConnection *conn, SampleBlockID blockid /*
 
    // Get the rootpage for the sampleblocks table.
    sqlite3_stmt *stmt =
-      conn->Prepare(DBConnection::GetRootPage,
+      conn.Prepare(DBConnection::GetRootPage,
                     "SELECT rootpage FROM sqlite_master WHERE tbl_name = 'sampleblocks';");
    if (stmt == nullptr || sqlite3_step(stmt) != SQLITE_ROW)
    {
@@ -2380,7 +2417,7 @@ int64_t ProjectFileIO::GetDiskUsage(DBConnection *conn, SampleBlockID blockid /*
    sqlite3_reset(stmt);
 
    // Prepare/retrieve statement to read raw database page
-   stmt = conn->Prepare(DBConnection::GetDBPage,
+   stmt = conn.Prepare(DBConnection::GetDBPage,
       "SELECT data FROM sqlite_dbpage WHERE pgno = ?1;");
    if (stmt == nullptr)
    {

src/ProjectFileIO.h

@@ -45,6 +45,11 @@ using BlockIDs = std::unordered_set<SampleBlockID>;
 wxDECLARE_EXPORTED_EVENT( AUDACITY_DLL_API,
                           EVT_CHECKPOINT_FAILURE, wxCommandEvent );
 
+// An event processed by the project in the main thread after failure to
+// reconnect to the database, after temporary close and attempted file movement
+wxDECLARE_EXPORTED_EVENT( AUDACITY_DLL_API,
+                          EVT_RECONNECTION_FAILURE, wxCommandEvent );
+
 ///\brief Object associated with a project that manages reading and writing
 /// of Audacity project file formats, and autosave
 class ProjectFileIO final
@@ -108,7 +113,7 @@ public:
 
    // Return the bytes used for the given block using the connection to a
    // specific database. This is the workhorse for the above 3 methods.
-   static int64_t GetDiskUsage(DBConnection *conn, SampleBlockID blockid);
+   static int64_t GetDiskUsage(DBConnection &conn, SampleBlockID blockid);
 
    const TranslatableString &GetLastError();
    const TranslatableString &GetLibraryError();
@@ -179,6 +184,10 @@ public:
    // 0 for success or non-zero to stop the query
    using ExecCB = std::function<int(int cols, char **vals, char **names)>;
 
+   //! Return true if a connetion is now open
+   bool HasConnection() const;
+
+   //! Return a reference to a connection, creating it as needed on demand; throw on failure
    DBConnection &GetConnection();
 
 private:

src/ProjectFileManager.cpp

@@ -302,15 +302,17 @@ bool ProjectFileManager::DoSave(const FilePath & fileName, const bool fromSaveAs
    bool success = projectFileIO.SaveProject(fileName, mLastSavedTracks.get());
    if (!success)
    {
-      ShowErrorDialog(
-         &window,
-         XO("Error Saving Project"),
-         XO("Could not save project. Perhaps %s \n"
-            "is not writable or the disk is full.\n"
-            "For tips on freeing up space, click the help button.")
-            .Format(fileName),
-         "Error:_Disk_full_or_not_writable"
-         );
+      // Show this error only if we didn't fail reconnection in SaveProject
+      if (projectFileIO.HasConnection())
+         ShowErrorDialog(
+            &window,
+            XO("Error Saving Project"),
+            XO("Could not save project. Perhaps %s \n"
+               "is not writable or the disk is full.\n"
+               "For tips on freeing up space, click the help button.")
+               .Format(fileName),
+            "Error:_Disk_full_or_not_writable"
+            );
       return false;
    }
 

src/ProjectManager.cpp

@@ -82,6 +82,8 @@ ProjectManager::ProjectManager( AudacityProject &project )
    window.Bind( wxEVT_CLOSE_WINDOW, &ProjectManager::OnCloseWindow, this );
    mProject.Bind(EVT_PROJECT_STATUS_UPDATE,
       &ProjectManager::OnStatusChange, this);
+   project.Bind( EVT_RECONNECTION_FAILURE,
+      &ProjectManager::OnReconnectionFailure, this );
 }
 
 ProjectManager::~ProjectManager() = default;
@@ -589,6 +591,14 @@ AudacityProject *ProjectManager::New()
    return p;
 }
 
+void ProjectManager::OnReconnectionFailure(wxCommandEvent & event)
+{
+   event.Skip();
+   wxTheApp->CallAfter([this]{
+      ProjectWindow::Get(mProject).Close(true);
+   });
+}
+
 void ProjectManager::OnCloseWindow(wxCloseEvent & event)
 {
    auto &project = mProject;

src/ProjectManager.h

@@ -65,6 +65,7 @@ public:
    void SetSkipSavePrompt(bool bSkip) { sbSkipPromptingForSave = bSkip; };
 
 private:
+   void OnReconnectionFailure(wxCommandEvent & event);
    void OnCloseWindow(wxCloseEvent & event);
    void OnTimer(wxTimerEvent & event);
    void OnOpenAudioFile(wxCommandEvent & event);

src/SqliteSampleBlock.cpp

@@ -88,6 +88,7 @@ private:
 
 private:
    //! This must never be called for silent blocks
+   /*! @post return value is not null */
    DBConnection *Conn() const;
    sqlite3 *DB() const
    {
@@ -527,7 +528,7 @@ size_t SqliteSampleBlock::GetSpaceUsage() const
    if (IsSilent())
       return 0;
    else
-      return ProjectFileIO::GetDiskUsage(Conn(), mBlockID);
+      return ProjectFileIO::GetDiskUsage(*Conn(), mBlockID);
 }
 
 size_t SqliteSampleBlock::GetBlob(void *dest,