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

GHC.Conc.ensureIOManagerIsRunning now creates an IO manager thread if
one does not exist or has died/exited.

Unfortunately this exposed a problem caused by the fact that we have
two base packages, and hence two IO managers, in GHCi: see NOTE
[io-manager-ghci] in rts/Linker.c.  The workaround can go away if/when
we switch to a dynamically linked GHCi.

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

diff --git a/rts/Schedule.c b/rts/Schedule.c
index 539e006..998d846 100644 (file)
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -1683,6 +1683,10 @@ forkProcess(HsStablePtr *entry
         initTimer();
         startTimer();
 
+#if defined(THREADED_RTS)
+        cap = ioManagerStartCap(cap);
+#endif
+
        cap = rts_evalStableIO(cap, entry, NULL);  // run the action
        rts_checkSchedStatus("forkProcess",cap);
        

diff --git a/rts/package.conf.in b/rts/package.conf.in
index 087a7e9..131f1e3 100644 (file)
--- a/rts/package.conf.in
+++ b/rts/package.conf.in
@@ -99,6 +99,14 @@ ld-options:
         , "-u", "_base_GHCziConc_ensureIOManagerIsRunning_closure"
         , "-u", "_base_GHCziConc_runSparks_closure"
         , "-u", "_base_GHCziConc_runHandlers_closure"
+         , "-u", "_base_GHCziConc_pendingDelays_closure"
+         , "-u", "_base_GHCziConc_pendingEvents_closure"
+         , "-u", "_base_GHCziConc_ioManagerThread_closure"
+#if !defined(mingw32_HOST_OS)
+         , "-u", "_base_GHCziConc_prodding_closure"
+         , "-u", "_base_GHCziConc_sync_closure"
+         , "-u", "_base_GHCziConc_stick_closure"
+#endif
 #else
            "-u", "ghczmprim_GHCziTypes_Izh_static_info"
          , "-u", "ghczmprim_GHCziTypes_Czh_static_info"
@@ -137,6 +145,14 @@ ld-options:
         , "-u", "base_GHCziConc_ensureIOManagerIsRunning_closure"
         , "-u", "base_GHCziConc_runSparks_closure"
         , "-u", "base_GHCziConc_runHandlers_closure"
+         , "-u", "base_GHCziConc_pendingDelays_closure"
+         , "-u", "base_GHCziConc_pendingEvents_closure"
+         , "-u", "base_GHCziConc_ioManagerThread_closure"
+#if !defined(mingw32_HOST_OS)
+         , "-u", "base_GHCziConc_prodding_closure"
+         , "-u", "base_GHCziConc_sync_closure"
+         , "-u", "base_GHCziConc_stick_closure"
+#endif
 #endif
 
 /*  Pick up static libraries in preference over dynamic if in earlier search

diff --git a/rts/posix/Signals.c b/rts/posix/Signals.c
index 6600657..aa78774 100644 (file)
--- a/rts/posix/Signals.c
+++ b/rts/posix/Signals.c
@@ -124,6 +124,12 @@ ioManagerDie (void)
     }
 }
 
+Capability *
+ioManagerStartCap (Capability *cap)
+{
+    return rts_evalIO(cap,&base_GHCziConc_ensureIOManagerIsRunning_closure,NULL);
+}
+
 void
 ioManagerStart (void)
 {
@@ -131,7 +137,7 @@ ioManagerStart (void)
     Capability *cap;
     if (io_manager_pipe < 0) {
        cap = rts_lock();
-       cap = rts_evalIO(cap,&base_GHCziConc_ensureIOManagerIsRunning_closure,NULL);
+       cap = ioManagerStartCap(cap);
        rts_unlock(cap);
     }
 }

diff --git a/rts/posix/Signals.h b/rts/posix/Signals.h
index 4d0a5a5..b80f711 100644 (file)
--- a/rts/posix/Signals.h
+++ b/rts/posix/Signals.h
@@ -24,6 +24,8 @@ extern siginfo_t *next_pending_handler;
 void startSignalHandlers(Capability *cap);
 #endif
 
+Capability *ioManagerStartCap (Capability *cap);
+
 extern StgInt *signal_handlers;
 
 END_RTS_PRIVATE