4 files changed, 49 insertions, 4 deletions

diff --git a/includes/rts/storage/ClosureMacros.h b/includes/rts/storage/ClosureMacros.h
index a115f6f38f..098c65db15 100644
--- a/includes/rts/storage/ClosureMacros.h
+++ b/includes/rts/storage/ClosureMacros.h
@@ -129,6 +129,12 @@
    SET_HDR(c,info,costCentreStack);			\
    (c)->words = n_words;
 
+// Use when changing a closure from one kind to another
+#define OVERWRITE_INFO(c, new_info)                             \
+   LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC((StgClosure *)(c));       \
+   SET_INFO((c), (new_info));                                  \
+   LDV_RECORD_CREATE(c);
+
 /* -----------------------------------------------------------------------------
    How to get hold of the static link field for a static closure.
    -------------------------------------------------------------------------- */
@@ -249,7 +255,7 @@ INLINE_HEADER StgOffset THUNK_SELECTOR_sizeW ( void )
 { return sizeofW(StgSelector); }
 
 INLINE_HEADER StgOffset BLACKHOLE_sizeW ( void )
-{ return sizeofW(StgHeader)+MIN_PAYLOAD_SIZE; }
+{ return sizeofW(StgInd); } // a BLACKHOLE is a kind of indirection
 
 /* --------------------------------------------------------------------------
    Sizes of closures
diff --git a/includes/rts/storage/ClosureTypes.h b/includes/rts/storage/ClosureTypes.h
index 6a76772d61..518d39bb11 100644
--- a/includes/rts/storage/ClosureTypes.h
+++ b/includes/rts/storage/ClosureTypes.h
@@ -62,7 +62,7 @@
 #define UPDATE_FRAME	        38
 #define CATCH_FRAME	        39
 #define STOP_FRAME	        40
-#define CAF_BLACKHOLE		41
+#define BLOCKING_QUEUE		41
 #define BLACKHOLE	        42
 #define MVAR_CLEAN	        43
 #define MVAR_DIRTY	        44
diff --git a/includes/rts/storage/Closures.h b/includes/rts/storage/Closures.h
index d7498e2882..802746868c 100644
--- a/includes/rts/storage/Closures.h
+++ b/includes/rts/storage/Closures.h
@@ -127,6 +127,14 @@ typedef struct {
     StgInfoTable *saved_info;
 } StgIndStatic;
 
+typedef struct StgBlockingQueue_ {
+    StgHeader   header;
+    struct StgBlockingQueue_ *link; // here so it looks like an IND
+    StgClosure *bh;  // the BLACKHOLE
+    StgTSO     *owner;
+    struct MessageBlackHole_ *queue;
+} StgBlockingQueue;
+
 typedef struct {
     StgHeader  header;
     StgWord    words;
@@ -433,10 +441,17 @@ typedef struct MessageWakeup_ {
 
 typedef struct MessageThrowTo_ {
     StgHeader   header;
-    Message    *link;
+    struct MessageThrowTo_ *link;
     StgTSO     *source;
     StgTSO     *target;
     StgClosure *exception;
 } MessageThrowTo;
 
+typedef struct MessageBlackHole_ {
+    StgHeader   header;
+    struct MessageBlackHole_ *link;
+    StgTSO     *tso;
+    StgClosure *bh;
+} MessageBlackHole;
+
 #endif /* RTS_STORAGE_CLOSURES_H */
diff --git a/includes/rts/storage/TSO.h b/includes/rts/storage/TSO.h
index e2015f28ac..e07be88ac5 100644
--- a/includes/rts/storage/TSO.h
+++ b/includes/rts/storage/TSO.h
@@ -46,6 +46,7 @@ typedef struct {
 /* Reason for thread being blocked. See comment above struct StgTso_. */
 typedef union {
   StgClosure *closure;
+  struct MessageBlackHole_ *bh;
   struct MessageThrowTo_ *throwto;
   struct MessageWakeup_  *wakeup;
   StgInt fd;	/* StgInt instead of int, so that it's the same size as the ptrs */
@@ -78,12 +79,17 @@ typedef struct StgTSO_ {
     */
     struct StgTSO_*         _link;
     /*
+      Currently used for linking TSOs on:
+      * cap->run_queue_{hd,tl}
+      * MVAR queue
+      * (non-THREADED_RTS); the blocked_queue
+      * and pointing to the relocated version of a ThreadRelocated
+
        NOTE!!!  do not modify _link directly, it is subject to
        a write barrier for generational GC.  Instead use the
        setTSOLink() function.  Exceptions to this rule are:
 
        * setting the link field to END_TSO_QUEUE
-       * putting a TSO on the blackhole_queue
        * setting the link field of the currently running TSO, as it
          will already be dirty.
     */
@@ -127,6 +133,12 @@ typedef struct StgTSO_ {
     */
     struct MessageThrowTo_ * blocked_exceptions;
 
+    /*
+      A list of StgBlockingQueue objects, representing threads blocked
+      on thunks that are under evaluation by this thread.
+    */
+    struct StgBlockingQueue_ *bq;
+
 #ifdef TICKY_TICKY
     /* TICKY-specific stuff would go here. */
 #endif
@@ -152,6 +164,18 @@ typedef struct StgTSO_ {
 void dirty_TSO  (Capability *cap, StgTSO *tso);
 void setTSOLink (Capability *cap, StgTSO *tso, StgTSO *target);
 
+// Apply to a TSO before looking at it if you are not sure whether it
+// might be ThreadRelocated or not (basically, that's most of the time
+// unless the TSO is the current TSO).
+//
+INLINE_HEADER StgTSO * deRefTSO(StgTSO *tso)
+{
+    while (tso->what_next == ThreadRelocated) {
+	tso = tso->_link;
+    }
+    return tso;
+}
+
 /* -----------------------------------------------------------------------------
    Invariants: