[PATCH v4 3/5] msvcr100: Cache one Context instance.

[Torge Matthies]

From: Torge Matthies

Keep the one with the lowest id, which seems to be the behavior on native.

Signed-off-by: Torge Matthies 
---
 dlls/msvcrt/concurrency.c | 68 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 63 insertions(+), 5 deletions(-)

diff --git a/dlls/msvcrt/concurrency.c b/dlls/msvcrt/concurrency.c
index d0c9924c631..3ca8d748cad 100644
--- a/dlls/msvcrt/concurrency.c
+++ b/dlls/msvcrt/concurrency.c
@@ -97,6 +97,7 @@ typedef struct {
 } ExternalContextBase;
 extern const vtable_ptr ExternalContextBase_vtable;
 static void ExternalContextBase_ctor(ExternalContextBase*);
+static void ExternalContextBase_dtor(ExternalContextBase*);

typedef struct Scheduler {
     const vtable_ptr *vtable;
@@ -359,6 +360,16 @@ enum ConcRT_EventType
     CONCRT_EVENT_DETACH
 };

+static CRITICAL_SECTION cached_context_cs;
+static CRITICAL_SECTION_DEBUG cached_context_cs_debug =
+{
+    0, 0, &cached_context_cs,
+    { &cached_context_cs_debug.ProcessLocksList, &cached_context_cs_debug.ProcessLocksList },
+      0, 0, { (DWORD_PTR)(__FILE__ ": cached_context_cs") }
+};
+static CRITICAL_SECTION cached_context_cs = { &cached_context_cs_debug, -1, 0, 0, 0, 0 };
+static ExternalContextBase* cached_context;
+
 static DWORD context_tls_index = TLS_OUT_OF_INDEXES;

static CRITICAL_SECTION default_scheduler_cs;
@@ -674,6 +685,55 @@ static BOOL WINAPI init_context_tls_index(INIT_ONCE *once, void *param, void **c
     return context_tls_index != TLS_OUT_OF_INDEXES;
 }

+static Context* allocate_context(void)
+{
+    ExternalContextBase *context = NULL;
+
+    EnterCriticalSection(&cached_context_cs);
+    if (cached_context)
+    {
+        context = cached_context;
+        cached_context = NULL;
+    }
+    LeaveCriticalSection(&cached_context_cs);
+    if (!context)
+    {
+        context = operator_new(sizeof(ExternalContextBase));
+        ExternalContextBase_ctor(context);
+    }
+    return &context->context;
+}
+
+static void free_context(Context* ctx)
+{
+    ExternalContextBase *context = (ExternalContextBase*)ctx;
+
+    if (context->context.vtable != &ExternalContextBase_vtable)
+    {
+        call_Context_dtor(ctx, 1);
+        return;
+    }
+
+    EnterCriticalSection(&cached_context_cs);
+    if (cached_context && context->id < cached_context->id)
+    {
+        ExternalContextBase_dtor(cached_context);
+        operator_delete(cached_context);
+        cached_context = NULL;
+    }
+    if (!cached_context)
+    {
+        cached_context = context;
+        context = NULL;
+    }
+    LeaveCriticalSection(&cached_context_cs);
+    if (context)
+    {
+        ExternalContextBase_dtor(context);
+        operator_delete(context);
+    }
+}
+
 static Context* get_current_context(void)
 {
     static INIT_ONCE init_once = INIT_ONCE_STATIC_INIT;
@@ -689,10 +749,8 @@ static Context* get_current_context(void)

ret = TlsGetValue(context_tls_index);
     if (!ret) {
-        ExternalContextBase *context = operator_new(sizeof(ExternalContextBase));
-        ExternalContextBase_ctor(context);
-        TlsSetValue(context_tls_index, context);
-        ret = &context->context;
+        ret = allocate_context();
+        TlsSetValue(context_tls_index, ret);
     }
     return ret;
 }
@@ -3122,7 +3180,7 @@ void msvcrt_free_scheduler_thread(void)
 {
     Context *context = try_get_current_context();
     if (!context) return;
-    call_Context_dtor(context, 1);
+    free_context(context);
 }

#endif /* _MSVCR_VER >= 100 */