comphelper: fix MSVC hang in ThreadPool::shutdown()

Commit aa68c99d added some code using
std::condition_variable to comphelper.

Built with MSVC 2017, this causes many cppunittester.exe processes to
deadlock in ThreadPool::shutdown():

    maTasksChanged.notify_all();

This ultimately calls NtReleaseKeyedEvent(), which never returns.

The reason appears to be a bug in Windows 7, for which a "hotfix"[1] is
avaiable here, but it's apparently not distributed via Windows Update
so we likely can't rely on users or even developers having this installed.

However, the documentation of DllMain[2] and ExitProcess[3] indicates
that during shutdown, by the time global destructors are invoked
all threads other than the one that called ExitProcess have already
been terminated.

Returning from main() implicitly calls ExitProcess [4].

As it turns out the problem only happens for some CppUnitTests because
soffice.bin will call ThreadPool::shutdown() from Desktop::doShutdown()
while it is still safe.

[1] http://support.microsoft.com/kb/2582203
[2] https://msdn.microsoft.com/en-US/library/windows/desktop/ms682583(v=vs.85).aspx
[3] https://msdn.microsoft.com/en-us/library/windows/desktop/ms682658(v=vs.85).aspx
[4] https://blogs.msdn.microsoft.com/oldnewthing/20100827-00/?p=13023

Change-Id: I6137461ca7efe9a5fbe4f8f8478fb96de3570469
Reviewed-on: https://gerrit.libreoffice.org/35066Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

comphelper/source/misc/threadpool.cxx

@@ -89,7 +89,12 @@ ThreadPool::ThreadPool( sal_Int32 nWorkers ) :
 
 ThreadPool::~ThreadPool()
 {
-    shutdown();
+    // note: calling shutdown from global variable dtor blocks forever on Win7
+    // note2: there isn't enough MSVCRT left on exit to call assert() properly
+    // so these asserts just print something to stderr but exit status is
+    // still 0, but hopefully they will be more helpful on non-WNT platforms
+    assert(mbTerminate);
+    assert(maTasks.empty());
 }
 
 struct ThreadPoolStatic : public rtl::StaticWithInit< std::shared_ptr< ThreadPool >,
@@ -127,6 +132,7 @@ sal_Int32 ThreadPool::getPreferredConcurrency()
     return ThreadCount;
 }
 
+// FIXME: what does "this" refer to in the following?
 // FIXME: there should be no need for this as/when our baseline
 // is >VS2015 and drop WinXP; the sorry details are here:
 // https://connect.microsoft.com/VisualStudio/feedback/details/1282596

package/qa/cppunit/test_package.cxx

@@ -119,8 +119,16 @@ namespace
         uno::Reference<container::XNameAccess> xNA(xZip, uno::UNO_QUERY);
         CPPUNIT_ASSERT(xNA.is());
 
+        struct TestThreadPool
         {
-            comphelper::ThreadPool aPool(4);
+            comphelper::ThreadPool aPool;
+            TestThreadPool(sal_Int32 const i) : aPool(i) {}
+            ~TestThreadPool() { aPool.shutdown(); }
+        };
+
+        {
+            TestThreadPool aPool(4);
+            comphelper::ThreadPool & rPool(aPool.aPool);
             std::shared_ptr<comphelper::ThreadTaskTag> pTag = comphelper::ThreadPool::createThreadTaskTag();
 
             std::vector<std::vector<char>> aTestBuffers(26);
@@ -135,10 +143,10 @@ namespace
                 xNA->getByName(aName) >>= xStrm;
 
                 CPPUNIT_ASSERT(xStrm.is());
-                aPool.pushTask(new Worker(pTag, xStrm, *itBuf));
+                rPool.pushTask(new Worker(pTag, xStrm, *itBuf));
             }
 
-            aPool.waitUntilDone(pTag);
+            rPool.waitUntilDone(pTag);
 
             // Verify the streams.
             CPPUNIT_ASSERT_EQUAL(size_t(26), aTestBuffers.size());

pyuno/source/module/pyuno_module.cxx

@@ -318,7 +318,7 @@ static PyObject* getComponentContext(
 }
 
 static PyObject* initTestEnvironment(
-    SAL_UNUSED_PARAMETER PyObject*, SAL_UNUSED_PARAMETER PyObject*)
+    SAL_UNUSED_PARAMETER PyObject*, SAL_UNUSED_PARAMETER PyObject* args)
 {
     // this tries to bootstrap enough of the soffice from python to run
     // unit tests, which is only possible indirectly because pyuno is URE
@@ -349,10 +349,21 @@ static PyObject* initTestEnvironment(
         mod.load(OStringToOUString(libname, osl_getThreadTextEncoding()),
                                 SAL_LOADMODULE_LAZY | SAL_LOADMODULE_GLOBAL);
         if (!mod.is()) { abort(); }
-        oslGenericFunction const pFunc(
-                mod.getFunctionSymbol("test_init"));
-        if (!pFunc) { abort(); }
-        reinterpret_cast<void (SAL_CALL *)(XMultiServiceFactory*)>(pFunc)(xMSF.get());
+        assert(PyTuple_Check(args));
+        if (PyTuple_Size(args) == 0)
+        {
+            oslGenericFunction const pFunc(
+                    mod.getFunctionSymbol("test_init"));
+            if (!pFunc) { abort(); }
+            reinterpret_cast<void (SAL_CALL *)(XMultiServiceFactory*)>(pFunc)(xMSF.get());
+        }
+        else
+        {
+            oslGenericFunction const pFunc(
+                    mod.getFunctionSymbol("test_fini"));
+            if (!pFunc) { abort(); }
+            reinterpret_cast<void (SAL_CALL *)()>(pFunc)();
+        }
     }
     catch (const css::uno::Exception &)
     {

test/source/bootstrapfixture.cxx

@@ -16,6 +16,7 @@
 #include <rtl/bootstrap.hxx>
 #include <cppuhelper/bootstrap.hxx>
 #include <comphelper/processfactory.hxx>
+#include <comphelper/threadpool.hxx>
 
 #include <com/sun/star/lang/Locale.hpp>
 #include <com/sun/star/lang/XComponent.hpp>
@@ -97,6 +98,12 @@ SAL_DLLPUBLIC_EXPORT void test_init(lang::XMultiServiceFactory *pFactory)
     catch (...) { abort(); }
 }
 
+// this is called from pyuno
+SAL_DLLPUBLIC_EXPORT void test_fini()
+{
+    ::comphelper::ThreadPool::getSharedOptimalPool().shutdown();
+}
+
 } // extern "C"
 
 void test::BootstrapFixture::setUp()

test/source/vclbootstrapprotector.cxx

@@ -14,6 +14,7 @@
 #include <sal/types.h>
 #include <test/setupvcl.hxx>
 #include <vcl/svapp.hxx>
+#include <comphelper/threadpool.hxx>
 
 #include <isheadless.hxx>
 
@@ -28,6 +29,8 @@ public:
 private:
     virtual ~Protector() override {
         DeInitVCL();
+        // for the 6 tests that use it
+        comphelper::ThreadPool::getSharedOptimalPool().shutdown();
     }
 
     virtual bool protect(

unotest/source/python/org/libreoffice/unotest.py

@@ -182,6 +182,9 @@ class UnoInProcess:
         global havePonies
         if not(havePonies):
             pyuno.private_initTestEnvironment()
+            # note: this will be called early enough, from Py_Finalize
+            import atexit
+            atexit.register(pyuno.private_initTestEnvironment, False)
             havePonies = True
     def openEmptyWriterDoc(self):
         assert(self.xContext)