Per-capability nursery weak pointer lists, fixes #9075

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

3 files changed, 39 insertions, 0 deletions

diff --git a/rts/sm/GC.c b/rts/sm/GC.c
index d22a31eccb..61432eabde 100644
--- a/rts/sm/GC.c
+++ b/rts/sm/GC.c
@@ -286,6 +286,9 @@ GarbageCollect (nat collect_gen,
   memInventory(DEBUG_gc);
 #endif
 
+  // do this *before* we start scavenging
+  collectFreshWeakPtrs();
+
   // check sanity *before* GC
   IF_DEBUG(sanity, checkSanity(rtsFalse /* before GC */, major_gc));
 
diff --git a/rts/sm/MarkWeak.c b/rts/sm/MarkWeak.c
index af953cd881..0324f3b4b9 100644
--- a/rts/sm/MarkWeak.c
+++ b/rts/sm/MarkWeak.c
@@ -25,6 +25,8 @@
 #include "Storage.h"
 #include "Threads.h"
 
+#include "sm/Sanity.h"
+
 /* -----------------------------------------------------------------------------
    Weak Pointers
 
@@ -341,6 +343,39 @@ static void tidyThreadList (generation *gen)
     }
 }
 
+#ifdef DEBUG
+static void checkWeakPtrSanity(StgWeak *hd, StgWeak *tl)
+{
+    StgWeak *w, *prev;
+    for (w = hd; w != NULL; prev = w, w = w->link) {
+        ASSERT(INFO_PTR_TO_STRUCT(UNTAG_CLOSURE((StgClosure*)w)->header.info)->type == WEAK);
+        checkClosure((StgClosure*)w);
+    }
+    if (tl != NULL) {
+        ASSERT(prev == tl);
+    }
+}
+#endif
+
+void collectFreshWeakPtrs()
+{
+    nat i;
+    generation *gen = &generations[0];
+    // move recently allocated weak_ptr_list to the old list as well
+    for (i = 0; i < n_capabilities; i++) {
+        Capability *cap = capabilities[i];
+        if (cap->weak_ptr_list_tl != NULL) {
+            IF_DEBUG(sanity, checkWeakPtrSanity(cap->weak_ptr_list_hd, cap->weak_ptr_list_tl));
+            cap->weak_ptr_list_tl->link = gen->weak_ptr_list;
+            gen->weak_ptr_list = cap->weak_ptr_list_hd;
+            cap->weak_ptr_list_tl = NULL;
+            cap->weak_ptr_list_hd = NULL;
+        } else {
+            ASSERT(cap->weak_ptr_list_hd == NULL);
+        }
+    }
+}
+
 /* -----------------------------------------------------------------------------
    Evacuate every weak pointer object on the weak_ptr_list, and update
    the link fields.
diff --git a/rts/sm/MarkWeak.h b/rts/sm/MarkWeak.h
index f9bacfa0da..bd0231d74c 100644
--- a/rts/sm/MarkWeak.h
+++ b/rts/sm/MarkWeak.h
@@ -20,6 +20,7 @@ extern StgWeak *old_weak_ptr_list;
 extern StgTSO *resurrected_threads;
 extern StgTSO *exception_threads;
 
+void    collectFreshWeakPtrs   ( void );
 void    initWeakForGC          ( void );
 rtsBool traverseWeakPtrList    ( void );
 void    markWeakPtrList        ( void );