Reference-count global setup/teardown

This fixes surprises like this one : module loaded in thread 1, then in
thread 2, then thread 1 ends and now the module does not work anymore in
thread 2 (even though it should).

diff --git a/Magic.xs b/Magic.xs
index cf5bc21472701075610c731a660948e45cbc9404..f3ed0d6775754f061744351420ca66de67445011 100644 (file)
--- a/Magic.xs
+++ b/Magic.xs
@@ -1745,24 +1745,35 @@ static I32 vmg_svt_val(pTHX_ IV action, SV *sv) {
 
 #endif /* VMG_UVAR */
 
-/* --- Global setup/teardown ----------------------------------------------- */
+/* --- Module setup/teardown ----------------------------------------------- */
 
-static VOL U32 vmg_initialized = 0;
-
-static void vmg_global_teardown_late(pTHX) {
-#define vmg_global_teardown_late() vmg_global_teardown_late(aTHX)
 #if VMG_THREADSAFE
+
+static I32 vmg_loaded = 0;
+
+/* We must use preexistent global mutexes or we will never be able to destroy
+ * them. */
+# if VMG_HAS_PERL(5, 9, 3)
+#  define VMG_LOADED_LOCK   MUTEX_LOCK(&PL_my_ctx_mutex)
+#  define VMG_LOADED_UNLOCK MUTEX_UNLOCK(&PL_my_ctx_mutex)
+# else
+#  define VMG_LOADED_LOCK   OP_REFCNT_LOCK
+#  define VMG_LOADED_UNLOCK OP_REFCNT_UNLOCK
+# endif
+
+static void vmg_global_teardown_late_locked(pTHX) {
+#define vmg_global_teardown_late_locked() vmg_global_teardown_late_locked(aTHX)
  MUTEX_DESTROY(&vmg_op_name_init_mutex);
  MUTEX_DESTROY(&vmg_vtable_refcount_mutex);
-#endif
 
- vmg_initialized = 0;
+ vmg_loaded = 0;
 
  return;
 }
 
 static int vmg_global_teardown_free(pTHX_ SV *sv, MAGIC *mg) {
- vmg_global_teardown_late();
+ vmg_global_teardown_late_locked();
+ VMG_LOADED_UNLOCK;
 
  return 0;
 }
@@ -1821,52 +1832,36 @@ static signed char vmg_destruct_level(pTHX) {
  return lvl;
 }
 
-static void vmg_global_teardown(pTHX_ void *root) {
- if (!vmg_initialized)
-  return;
+#endif /* VMG_THREADSAFE */
+
+static void vmg_teardown(pTHX_ void *interp) {
+ dMY_CXT;
 
 #if VMG_MULTIPLICITY
- if (aTHX != root)
+ if (aTHX != interp)
   return;
 #endif
 
- if (vmg_destruct_level() == 0) {
-  vmg_global_teardown_late();
- } else {
-  if (!PL_strtab)
-   PL_strtab = newHV();
-  vmg_sv_magicext((SV *) PL_strtab, NULL, &vmg_global_teardown_vtbl, NULL, 0);
- }
-
- return;
-}
-
-static void vmg_global_setup(pTHX) {
-#define vmg_global_setup() vmg_global_setup(aTHX)
- if (vmg_initialized)
-  return;
-
 #if VMG_THREADSAFE
- MUTEX_INIT(&vmg_vtable_refcount_mutex);
- MUTEX_INIT(&vmg_op_name_init_mutex);
-#endif
+ VMG_LOADED_LOCK;
 
-#if VMG_MULTIPLICITY
- call_atexit(vmg_global_teardown, aTHX);
-#else
- call_atexit(vmg_global_teardown, NULL);
+ if (vmg_loaded <= 1) {
+  assert(vmg_loaded == 1);
+  if (vmg_destruct_level() == 0) {
+   vmg_global_teardown_late_locked();
+   VMG_LOADED_UNLOCK;
+  } else {
+   if (!PL_strtab)
+    PL_strtab = newHV();
+   vmg_sv_magicext((SV *) PL_strtab, NULL, &vmg_global_teardown_vtbl, NULL, 0);
+   /* Lock until vmg_global_teardown_free() is called */
+  }
+ } else {
+  --vmg_loaded;
+  VMG_LOADED_UNLOCK;
+ }
 #endif
 
- vmg_initialized = 1;
-
- return;
-}
-
-/* --- Interpreter setup/teardown ------------------------------------------ */
-
-static void vmg_local_teardown(pTHX_ void *param) {
- dMY_CXT;
-
  if (MY_CXT.depth == 0 && MY_CXT.freed_tokens) {
   vmg_magic_chain_free(MY_CXT.freed_tokens, NULL);
   MY_CXT.freed_tokens = NULL;
@@ -1875,12 +1870,25 @@ static void vmg_local_teardown(pTHX_ void *param) {
  return;
 }
 
-static void vmg_local_setup(pTHX) {
-#define vmg_local_setup() vmg_local_setup(aTHX)
+static void vmg_setup(pTHX) {
+#define vmg_setup() vmg_setup(aTHX)
  HV *stash;
  int c;
-
  MY_CXT_INIT;
+
+#if VMG_THREADSAFE
+ VMG_LOADED_LOCK;
+
+ if (vmg_loaded <= 0) {
+  assert(vmg_loaded == 0);
+  MUTEX_INIT(&vmg_vtable_refcount_mutex);
+  MUTEX_INIT(&vmg_op_name_init_mutex);
+ }
+ ++vmg_loaded;
+
+ VMG_LOADED_UNLOCK;
+#endif
+
  for (c = OPc_NULL; c < OPc_MAX; ++c)
   MY_CXT.b__op_stashes[c] = NULL;
 
@@ -1922,7 +1930,11 @@ static void vmg_local_setup(pTHX) {
  newCONSTSUB(stash, "VMG_OP_INFO_NAME",    newSVuv(VMG_OP_INFO_NAME));
  newCONSTSUB(stash, "VMG_OP_INFO_OBJECT",  newSVuv(VMG_OP_INFO_OBJECT));
 
- call_atexit(vmg_local_teardown, NULL);
+#if VMG_MULTIPLICITY
+ call_atexit(vmg_teardown, aTHX);
+#else
+ call_atexit(vmg_teardown, NULL);
+#endif
 
  return;
 }
@@ -1978,8 +1990,7 @@ PROTOTYPES: ENABLE
 
 BOOT:
 {
- vmg_global_setup();
- vmg_local_setup();
+ vmg_setup();
 }
 
 #if VMG_THREADSAFE
@@ -2008,6 +2019,10 @@ PPCODE:
   }
   MY_CXT.depth        = old_depth;
   MY_CXT.freed_tokens = NULL;
+  VMG_LOADED_LOCK;
+  assert(vmg_loaded > 0);
+  ++vmg_loaded;
+  VMG_LOADED_UNLOCK;
  }
  XSRETURN(0);