Fix python 3.9 AL TransactionManager crash

plugin/al/lib/AL_USDMaya/AL/usdmaya/Global.cpp

@@ -15,6 +15,7 @@
 //
 #include "AL/usdmaya/Global.h"
 
+#include "AL/usd/transaction/TransactionManager.h"
 #include "AL/usdmaya/DebugCodes.h"
 #include "AL/usdmaya/StageCache.h"
 #include "AL/usdmaya/nodes/LayerManager.h"
@@ -201,6 +202,7 @@ AL::event::CallbackId Global::m_postSave;
 AL::event::CallbackId Global::m_preRead;
 AL::event::CallbackId Global::m_postRead;
 AL::event::CallbackId Global::m_fileNew;
+AL::event::CallbackId Global::m_mayaExit;
 AL::event::CallbackId Global::m_preExport;
 AL::event::CallbackId Global::m_postExport;
 
@@ -284,6 +286,14 @@ static void onFileNew(void*)
     // Puzzled.
     UsdUtilsStageCache::Get().Clear();
     StageCache::Clear();
+    AL::usd::transaction::TransactionManager::CloseAll();
+}
+
+//----------------------------------------------------------------------------------------------------------------------
+static void onMayaExit(void*)
+{
+    TF_DEBUG(ALUSDMAYA_EVENTS).Msg("onMayaExit\n");
+    onFileNew(nullptr);
 }
 
 //----------------------------------------------------------------------------------------------------------------------
@@ -441,6 +451,7 @@ void Global::onPluginLoad()
 
     auto& manager = AL::maya::event::MayaEventManager::instance();
     m_fileNew = manager.registerCallback(onFileNew, "AfterNew", "usdmaya_onFileNew", 0x1000);
+    m_mayaExit = manager.registerCallback(onMayaExit, "MayaExiting", "usdmaya_onMayaExit", 0x1000);
     m_preSave = manager.registerCallback(preFileSave, "BeforeSave", "usdmaya_preFileSave", 0x1000);
     m_postSave
         = manager.registerCallback(postFileSave, "AfterSave", "usdmaya_postFileSave", 0x1000);

plugin/al/lib/AL_USDMaya/AL/usdmaya/Global.h

@@ -54,6 +54,9 @@ class Global
     /// callback used to flush the USD caches after a file new
     static AL::event::CallbackId fileNew() { return m_fileNew; }
 
+    /// callback used to flush the USD caches on exit
+    static AL::event::CallbackId mayaExit() { return m_mayaExit; }
+
     static void openingFile(bool val);
 
 private:
@@ -64,7 +67,8 @@ class Global
     static AL::event::CallbackId m_postRead; ///< callback executed after opening a maya file -
                                              ///< needed to re-hook up the UsdPrims
     static AL::event::CallbackId
-        m_fileNew; ///< callback used to flush the USD caches after a file new
+                                 m_fileNew; ///< callback used to flush the USD caches after a file new
+    static AL::event::CallbackId m_mayaExit; ///< callback used to flush the USD caches on exit
     static AL::event::CallbackId
                                  m_preExport; ///< callback prior to exporting the scene (so we can store the session layer)
     static AL::event::CallbackId m_postExport; ///< callback after exporting

plugin/al/usdtransaction/AL/usd/transaction/TransactionManager.cpp

@@ -199,6 +199,9 @@ bool TransactionManager::Close(const UsdStageWeakPtr& stage, const SdfLayerHandl
     return false;
 }
 
+//----------------------------------------------------------------------------------------------------------------------
+void TransactionManager::CloseAll() { GetManagers().clear(); }
+
 //----------------------------------------------------------------------------------------------------------------------
 } // namespace transaction
 } // namespace usd

plugin/al/usdtransaction/AL/usd/transaction/TransactionManager.h

@@ -116,6 +116,11 @@ class TransactionManager
     AL_USD_TRANSACTION_PUBLIC
     static bool Close(const PXR_NS::UsdStageWeakPtr& stage, const PXR_NS::SdfLayerHandle& layer);
 
+    /// \brief  clears the transaction manager of all active transactions, effectively closing them
+    /// all. Intended to be used for File->New and on exit.
+    AL_USD_TRANSACTION_PUBLIC
+    static void CloseAll();
+
 private:
     typedef std::map<PXR_NS::UsdStageWeakPtr, TransactionManager> StageManagerMap;
     static StageManagerMap&                                       GetManagers();

plugin/al/usdtransaction/AL/usd/transaction/tests/testTransaction.py

@@ -18,6 +18,9 @@ def setUp(self):
         if sys.version_info[0] >= 3:
             self.assertItemsEqual = self.assertCountEqual
 
+    def tearDown(self):
+        transaction.TransactionManager.CloseAll()
+
     def _openNoticeHandler(self, notice, stage):
         self.assertEqual(stage, self._stage)
         self._opened += 1

plugin/al/usdtransaction/AL/usd/transaction/tests/testTransactionManager.py

@@ -33,6 +33,8 @@ def test_InProgress_Stage(self):
         self.assertFalse(TransactionManager.InProgress(stageA))
         self.assertFalse(TransactionManager.InProgress(stageB))
 
+        TransactionManager.CloseAll()
+
     ## Test that TransactionManager reports transactions for multiple layers as expected
     def test_InProgress_Layer(self):
         stage = Usd.Stage.CreateInMemory()
@@ -67,6 +69,8 @@ def test_InProgress_Layer(self):
         self.assertFalse(TransactionManager.InProgress(stage, layerA))
         self.assertFalse(TransactionManager.InProgress(stage, layerB))
 
+        TransactionManager.CloseAll()
+
 
 if __name__ == '__main__':
     unittest.main()

plugin/al/usdtransaction/AL/usd/transaction/wrapTransactionManager.cpp

@@ -44,6 +44,8 @@ static bool CloseStageLayer(const UsdStageWeakPtr& stage, const SdfLayerHandle&
     return This::Close(stage, layer);
 }
 
+static void CloseAllStage() { This::CloseAll(); }
+
 void wrapTransactionManager()
 {
     {
@@ -56,6 +58,9 @@ void wrapTransactionManager()
             .staticmethod("Open")
 
             .def("Close", CloseStageLayer, (arg("stage"), arg("layer")))
-            .staticmethod("Close");
+            .staticmethod("Close")
+
+            .def("CloseAll", CloseAllStage)
+            .staticmethod("CloseAll");
     }
 }