Fix #1185 (RTS part, also needs corresponding change to libraries/base)

[ghc-hetmet.git] / rts / Linker.c

diff --git a/rts/Linker.c b/rts/Linker.c
index a2b69f9..1d955a3 100644 (file)
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -957,6 +957,37 @@ typedef struct _RtsSymbolVal {
 #define RTS_LIBGCC_SYMBOLS
 #endif
 
+/* NOTE [io-manager-ghci]
+
+   When GHCi loads the base package, it gets another copy of the CAFs
+   in GHC.Conc that record the IO manager's ThreadId, and the blocking
+   queues, so we get another IO manager.  This is bad enough, but what
+   is worse is that GHCi by default reverts all CAFs on every :load,
+   so we'll get *another* IO manager thread (and an associated pipe)
+   every time the user does :load.  Miraculously, this actually
+   manages to just about work in GHC 6.10 and earlier, but broke when
+   I tried to fix #1185 (restarting the IO manager after a fork()).
+
+   To work around it and ensure that we only have a single IO manager,
+   we map the CAFs in the dynamically-loaded GHC.Conc to the
+   statically-linked GHC.Conc.  This is an ugly hack, but it's the
+   least ugly hack that I could think of (SDM 3/11/2009)
+*/
+
+#define RTS_GHC_CONC_SYMBOLS \
+      SymI_NeedsProto(base_GHCziConc_pendingDelays_closure) \
+      SymI_NeedsProto(base_GHCziConc_pendingEvents_closure) \
+      SymI_NeedsProto(base_GHCziConc_ioManagerThread_closure)
+
+#ifdef mingw32_HOST_OS
+#define RTS_GHC_CONC_OS_SYMBOLS /* empty */
+#else
+#define RTS_GHC_CONC_OS_SYMBOLS \
+      SymI_NeedsProto(base_GHCziConc_prodding_closure) \
+      SymI_NeedsProto(base_GHCziConc_sync_closure) \
+      SymI_NeedsProto(base_GHCziConc_stick_closure)
+#endif
+
 #if defined(darwin_HOST_OS) && defined(powerpc_HOST_ARCH)
       // Symbols that don't have a leading underscore
       // on Mac OS X. They have to receive special treatment,
@@ -985,6 +1016,8 @@ RTS_CYGWIN_ONLY_SYMBOLS
 RTS_DARWIN_ONLY_SYMBOLS
 RTS_LIBGCC_SYMBOLS
 RTS_LIBFFI_SYMBOLS
+RTS_GHC_CONC_SYMBOLS
+RTS_GHC_CONC_OS_SYMBOLS
 #undef SymI_NeedsProto
 #undef SymI_HasProto
 #undef SymI_HasProto_redirect
@@ -1020,6 +1053,8 @@ static RtsSymbolVal rtsSyms[] = {
       RTS_DARWIN_ONLY_SYMBOLS
       RTS_LIBGCC_SYMBOLS
       RTS_LIBFFI_SYMBOLS
+      RTS_GHC_CONC_SYMBOLS
+      RTS_GHC_CONC_OS_SYMBOLS
 #if defined(darwin_HOST_OS) && defined(i386_HOST_ARCH)
       // dyld stub code contains references to this,
       // but it should never be called because we treat
@@ -1041,12 +1076,18 @@ static void ghciInsertStrHashTable ( char* obj_name,
                                      void *data
                                   )
 {
-   if (lookupHashTable(table, (StgWord)key) == NULL)
-   {
+#define GHC_CONC "base_GHCziConc"
+
+    if (lookupHashTable(table, (StgWord)key) == NULL)
+    {
       insertStrHashTable(table, (StgWord)key, data);
       return;
-   }
-   debugBelch(
+    }
+    if (strncmp(key, GHC_CONC, strlen(GHC_CONC)) == 0) {
+        /* see NOTE [io-manager-ghci] */
+        return;
+    }
+    debugBelch(
       "\n\n"
       "GHCi runtime linker: fatal error: I found a duplicate definition for symbol\n"
       "   %s\n"
@@ -1061,8 +1102,8 @@ static void ghciInsertStrHashTable ( char* obj_name,
       "\n",
       (char*)key,
       obj_name
-   );
-   exit(1);
+    );
+    exit(1);
 }
 /* -----------------------------------------------------------------------------
  * initialize the object linker