tdf#100412: Cope with recursive gdk_threads_enter/_leave

07157e644fa9666850767ff6bd54c1511167a0a2 "Keep track of ThreadsEnter/Leave
acquire counts per thread" was done under the assumption that these calls never
happen recursively, but tdf#100412 makes it look like such calls do happen, so
that in a pattern

gdk_threads_enter
gdk_threads_enter
gdk_threads_leave
gdk_threads_leave

the second gdk_threads_leave could find yieldCount non-zero.

Change-Id: If9837764d22473f21cf5b10d769929f3c86a0ba7

2 files changed, 15 insertions, 7 deletions

diff --git a/vcl/inc/unx/gtk/gtkinst.hxx b/vcl/inc/unx/gtk/gtkinst.hxx
index 86002fa7bf25..6212d5dcccba 100644
--- a/vcl/inc/unx/gtk/gtkinst.hxx
+++ b/vcl/inc/unx/gtk/gtkinst.hxx
@@ -20,6 +20,10 @@
 #ifndef INCLUDED_VCL_INC_UNX_GTK_GTKINST_HXX
 #define INCLUDED_VCL_INC_UNX_GTK_GTKINST_HXX
 
+#include <sal/config.h>
+
+#include <stack>
+
 #include <unx/salinst.h>
 #include <unx/gensys.h>
 #include <headless/svpinst.hxx>
@@ -42,7 +46,7 @@ class GtkPrintWrapper;
 class GenPspGraphics;
 class GtkYieldMutex : public SalYieldMutex
 {
-    thread_local static sal_uIntPtr yieldCount;
+    thread_local static std::stack<sal_uIntPtr> yieldCounts;
 
 public:
          GtkYieldMutex() {}
diff --git a/vcl/unx/gtk/gtkinst.cxx b/vcl/unx/gtk/gtkinst.cxx
index 04d78222f90b..22cdca8f1938 100644
--- a/vcl/unx/gtk/gtkinst.cxx
+++ b/vcl/unx/gtk/gtkinst.cxx
@@ -296,22 +296,26 @@ SalPrinter* GtkInstance::CreatePrinter( SalInfoPrinter* pInfoPrinter )
  * for each pair, so we can accurately restore
  * it later.
  */
-thread_local sal_uIntPtr GtkYieldMutex::yieldCount;
+thread_local std::stack<sal_uIntPtr> GtkYieldMutex::yieldCounts;
 
 void GtkYieldMutex::ThreadsEnter()
 {
     acquire();
-    for (; yieldCount != 0; --yieldCount) {
-        acquire();
+    if (!yieldCounts.empty()) {
+        auto n = yieldCounts.top();
+        yieldCounts.pop();
+        for (; n != 0; --n) {
+            acquire();
+        }
     }
 }
 
 void GtkYieldMutex::ThreadsLeave()
 {
     assert(mnCount != 0);
-    assert(yieldCount == 0);
-    yieldCount = mnCount - 1;
-    for (sal_uIntPtr i = 0; i != yieldCount + 1; ++i) {
+    auto n = mnCount - 1;
+    yieldCounts.push(n);
+    for (sal_uIntPtr i = 0; i != n + 1; ++i) {
         release();
     }
 }