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remove locking in method memoization

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* libguile/goops.c (scm_memoize_method): Don't lock around method
  memoization, as the new protocol will be reeentrant and lock-free.
This commit is contained in:
Andy Wingo 2009-11-08 11:29:48 +01:00
parent 51f66c9120
commit 2c38adf863
1 changed files with 4 additions and 38 deletions
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42
libguile/goops.c
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@ -2222,51 +2222,17 @@ scm_sys_compute_applicable_methods (SCM gf, SCM args)
SCM_SYMBOL (sym_compute_applicable_methods, "compute-applicable-methods"); SCM_SYMBOL (sym_compute_applicable_methods, "compute-applicable-methods");
SCM_VARIABLE_INIT (var_compute_applicable_methods, "compute-applicable-methods", scm_c_define_gsubr (s_sys_compute_applicable_methods, 2, 0, 0, scm_sys_compute_applicable_methods)); SCM_VARIABLE_INIT (var_compute_applicable_methods, "compute-applicable-methods", scm_c_define_gsubr (s_sys_compute_applicable_methods, 2, 0, 0, scm_sys_compute_applicable_methods));
static void SCM
lock_cache_mutex (void *m) scm_memoize_method (SCM cache, SCM args)
{ {
SCM mutex = SCM_PACK ((scm_t_bits) m); SCM gf = SCM_CAR (scm_last_pair (cache));
scm_lock_mutex (mutex);
}
static void
unlock_cache_mutex (void *m)
{
SCM mutex = SCM_PACK ((scm_t_bits) m);
scm_unlock_mutex (mutex);
}
static SCM
call_memoize_method (void *a)
{
SCM args = SCM_PACK ((scm_t_bits) a);
SCM gf = SCM_CAR (args);
SCM x = SCM_CADR (args);
/* First check if another thread has inserted a method between
* the cache miss and locking the mutex.
*/
SCM cmethod = scm_mcache_lookup_cmethod (x, SCM_CDDR (args));
if (scm_is_true (cmethod))
return cmethod;
if (SCM_UNLIKELY (scm_is_false (var_memoize_method_x))) if (SCM_UNLIKELY (scm_is_false (var_memoize_method_x)))
var_memoize_method_x = var_memoize_method_x =
scm_permanent_object scm_permanent_object
(scm_module_variable (scm_module_goops, sym_memoize_method_x)); (scm_module_variable (scm_module_goops, sym_memoize_method_x));
return scm_call_3 (SCM_VARIABLE_REF (var_memoize_method_x), gf, SCM_CDDR (args), x); return scm_call_3 (SCM_VARIABLE_REF (var_memoize_method_x), gf, args, cache);
}
SCM
scm_memoize_method (SCM x, SCM args)
{
SCM gf = SCM_CAR (scm_last_pair (x));
return scm_internal_dynamic_wind (
lock_cache_mutex,
call_memoize_method,
unlock_cache_mutex,
(void *) SCM_UNPACK (scm_cons2 (gf, x, args)),
(void *) SCM_UNPACK (SCM_SLOT (gf, scm_si_cache_mutex)));
} }
/****************************************************************************** /******************************************************************************