From 186679b3a699092fbb64b38b12b2399517235427 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Tue, 2 Aug 2016 22:07:20 -0400
Subject: [PATCH] RAII for locking the all-projects mutex

---
 src/AudacityApp.cpp        |  3 ---
 src/Project.cpp            | 35 +++++++++--------------------------
 src/Project.h              | 10 ++++------
 src/ondemand/ODManager.cpp |  3 +--
 src/ondemand/ODTask.cpp    |  6 ++----
 5 files changed, 16 insertions(+), 41 deletions(-)

diff --git a/src/AudacityApp.cpp b/src/AudacityApp.cpp
index ac839a250..ff2d2d8c8 100644
--- a/src/AudacityApp.cpp
+++ b/src/AudacityApp.cpp
@@ -316,9 +316,6 @@ void QuitAudacity(bool bForce)
    //temporarilly commented out till it is added to all projects
    //delete Profiler::Instance();
 
-   //DELETE the static lock for audacity projects
-   AudacityProject::DeleteAllProjectsDeleteLock();
-
    //remove our logger
    std::unique_ptr<wxLog>{ wxLog::SetActiveTarget(NULL) }; // DELETE
 
diff --git a/src/Project.cpp b/src/Project.cpp
index 23185edc4..f5ee51616 100644
--- a/src/Project.cpp
+++ b/src/Project.cpp
@@ -173,7 +173,11 @@ std::unique_ptr<TrackList> AudacityProject::msClipboard{ safenew TrackList() };
 double AudacityProject::msClipT0 = 0.0;
 double AudacityProject::msClipT1 = 0.0;
 AudacityProject *AudacityProject::msClipProject = NULL;
-ODLock   *AudacityProject::msAllProjectDeleteMutex = new ODLock();
+ODLock &AudacityProject::AllProjectDeleteMutex()
+{
+   static ODLock theMutex;
+   return theMutex;
+};
 
 #if defined(__WXMAC__)
 const int sbarSpaceWidth = 15;
@@ -2054,18 +2058,6 @@ void AudacityProject::OnTrackListUpdated(wxCommandEvent & event)
    event.Skip();
 }
 
-///Prevents deletion of projects from outside threads.
-void AudacityProject::AllProjectsDeleteLock()
-{
-   msAllProjectDeleteMutex->Lock();
-}
-
-///Reallows deletion of projects from outside threads.
-void AudacityProject::AllProjectsDeleteUnlock()
-{
-   msAllProjectDeleteMutex->Unlock();
-}
-
 ///Handles the redrawing necessary for tasks as they partially update in the background.
 void AudacityProject::OnODTaskUpdate(wxCommandEvent & WXUNUSED(event))
 {
@@ -2454,9 +2446,10 @@ void AudacityProject::OnCloseWindow(wxCloseEvent & event)
    //     have been deleted before this.
    mDirManager->Deref();
 
-   AllProjectsDeleteLock();
-   gAudacityProjects.Remove(this);
-   AllProjectsDeleteUnlock();
+   {
+      ODLocker locker{ &AudacityProject::AllProjectDeleteMutex() };
+      gAudacityProjects.Remove(this);
+   }
 
    if (gActiveProject == this) {
       // Find a NEW active project
@@ -4283,16 +4276,6 @@ void AudacityProject::DeleteClipboard()
    msClipboard.reset();
 }
 
-//static
-void AudacityProject::DeleteAllProjectsDeleteLock()
-{
-   if(msAllProjectDeleteMutex)
-   {
-      delete msAllProjectDeleteMutex;
-      msAllProjectDeleteMutex=NULL;
-   }
-}
-
 void AudacityProject::ClearClipboard()
 {
    msClipT0 = 0.0;
diff --git a/src/Project.h b/src/Project.h
index 94ef2b4c9..4d430f694 100644
--- a/src/Project.h
+++ b/src/Project.h
@@ -339,7 +339,6 @@ class AUDACITY_DLL_API AudacityProject final : public wxFrame,
    // Other commands
    static TrackList *GetClipboardTracks();
    static void DeleteClipboard();
-   static void DeleteAllProjectsDeleteLock();
 
    // checkActive is a temporary hack that should be removed as soon as we
    // get multiple effect preview working
@@ -514,10 +513,6 @@ public:
    bool TryToMakeActionAllowed
       ( CommandFlag & flags, CommandFlag flagsRqd, CommandFlag mask );
 
-   ///Prevents DELETE from external thread - for e.g. use of GetActiveProject
-   static void AllProjectsDeleteLock();
-   static void AllProjectsDeleteUnlock();
-
    void PushState(const wxString &desc, const wxString &shortDesc); // use UndoPush::AUTOSAVE
    void PushState(const wxString &desc, const wxString &shortDesc, UndoPush flags);
    void RollbackState();
@@ -577,9 +572,12 @@ public:
    static double msClipT0;
    static double msClipT1;
 
+public:
+   ///Prevents DELETE from external thread - for e.g. use of GetActiveProject
    //shared by all projects
-   static ODLock *msAllProjectDeleteMutex;
+   static ODLock &AllProjectDeleteMutex();
 
+private:
    // History/Undo manager
    std::unique_ptr<UndoManager> mUndoManager;
    bool mDirty{ false };
diff --git a/src/ondemand/ODManager.cpp b/src/ondemand/ODManager.cpp
index 2c9c00fd2..92c4bfedd 100644
--- a/src/ondemand/ODManager.cpp
+++ b/src/ondemand/ODManager.cpp
@@ -295,11 +295,10 @@ void ODManager::Start()
       {
          mNeedsDraw=0;
          wxCommandEvent event( EVT_ODTASK_UPDATE );
-         AudacityProject::AllProjectsDeleteLock();
+         ODLocker locker{ &AudacityProject::AllProjectDeleteMutex() };
          AudacityProject* proj = GetActiveProject();
          if(proj)
             proj->GetEventHandler()->AddPendingEvent(event);
-         AudacityProject::AllProjectsDeleteUnlock();
       }
       mTerminateMutex.Lock();
    }
diff --git a/src/ondemand/ODTask.cpp b/src/ondemand/ODTask.cpp
index 19186453c..93b5e5f84 100644
--- a/src/ondemand/ODTask.cpp
+++ b/src/ondemand/ODTask.cpp
@@ -128,7 +128,7 @@ void ODTask::DoSome(float amountWork)
       ODManager::Instance()->AddTask(this);
 
       //we did a bit of progress - we should allow a resave.
-      AudacityProject::AllProjectsDeleteLock();
+      ODLocker locker{ &AudacityProject::AllProjectDeleteMutex() };
       for(unsigned i=0; i<gAudacityProjects.GetCount(); i++)
       {
          if(IsTaskAssociatedWithProject(gAudacityProjects[i]))
@@ -138,7 +138,6 @@ void ODTask::DoSome(float amountWork)
             break;
          }
       }
-      AudacityProject::AllProjectsDeleteUnlock();
 
 
 //      printf("%s %i is %f done\n", GetTaskName(),GetTaskNumber(),PercentComplete());
@@ -152,8 +151,8 @@ void ODTask::DoSome(float amountWork)
       //END_TASK_PROFILING("On Demand open an 80 mb wav stereo file");
 
       wxCommandEvent event( EVT_ODTASK_COMPLETE );
-      AudacityProject::AllProjectsDeleteLock();
 
+      ODLocker locker{ &AudacityProject::AllProjectDeleteMutex() };
       for(unsigned i=0; i<gAudacityProjects.GetCount(); i++)
       {
          if(IsTaskAssociatedWithProject(gAudacityProjects[i]))
@@ -165,7 +164,6 @@ void ODTask::DoSome(float amountWork)
             break;
          }
       }
-      AudacityProject::AllProjectsDeleteUnlock();
 
 //      printf("%s %i complete\n", GetTaskName(),GetTaskNumber());
    }