diff options
Diffstat (limited to 'src/emacs-module.c')
| -rw-r--r-- | src/emacs-module.c | 108 |
1 files changed, 79 insertions, 29 deletions
diff --git a/src/emacs-module.c b/src/emacs-module.c index 3d1827c7dad..e4e7da088d7 100644 --- a/src/emacs-module.c +++ b/src/emacs-module.c @@ -78,6 +78,7 @@ To add a new module function, proceed as follows: #include "emacs-module.h" #include <stdarg.h> +#include <stdbool.h> #include <stddef.h> #include <stdint.h> #include <stdlib.h> @@ -154,11 +155,11 @@ struct emacs_value_frame /* A structure that holds an initial frame (so that the first local values require no dynamic allocation) and keeps track of the current frame. */ -static struct emacs_value_storage +struct emacs_value_storage { struct emacs_value_frame initial; struct emacs_value_frame *current; -} global_storage; +}; /* Private runtime and environment members. */ @@ -371,10 +372,57 @@ module_get_environment (struct emacs_runtime *runtime) } /* To make global refs (GC-protected global values) keep a hash that - maps global Lisp objects to reference counts. */ + maps global Lisp objects to 'struct module_global_reference' + objects. We store the 'emacs_value' in the hash table so that it + is automatically garbage-collected (Bug#42482). */ static Lisp_Object Vmodule_refs_hash; +/* Pseudovector type for global references. The pseudovector tag is + PVEC_OTHER since these values are never printed and don't need to + be special-cased for garbage collection. */ + +struct module_global_reference { + /* Pseudovector header, must come first. */ + union vectorlike_header header; + + /* Holds the emacs_value for the object. The Lisp_Object stored + therein must be the same as the hash key. */ + struct emacs_value_tag value; + + /* Reference count, always positive. */ + ptrdiff_t refcount; +}; + +static struct module_global_reference * +XMODULE_GLOBAL_REFERENCE (Lisp_Object o) +{ + eassert (PSEUDOVECTORP (o, PVEC_OTHER)); + return XUNTAG (o, Lisp_Vectorlike, struct module_global_reference); +} + +/* Returns whether V is a global reference. Only used to check module + assertions. If V is not a global reference, increment *N by the + number of global references (for debugging output). */ + +static bool +module_global_reference_p (emacs_value v, ptrdiff_t *n) +{ + struct Lisp_Hash_Table *h = XHASH_TABLE (Vmodule_refs_hash); + /* Note that we can't use `hash_lookup' because V might be a local + reference that's identical to some global reference. */ + for (ptrdiff_t i = 0; i < HASH_TABLE_SIZE (h); ++i) + { + if (!EQ (HASH_KEY (h, i), Qunbound) + && &XMODULE_GLOBAL_REFERENCE (HASH_VALUE (h, i))->value == v) + return true; + } + /* Only used for debugging, so we don't care about overflow, just + make sure the operation is defined. */ + INT_ADD_WRAPV (*n, h->count, n); + return false; +} + static emacs_value module_make_global_ref (emacs_env *env, emacs_value value) { @@ -383,21 +431,30 @@ module_make_global_ref (emacs_env *env, emacs_value value) Lisp_Object new_obj = value_to_lisp (value), hashcode; ptrdiff_t i = hash_lookup (h, new_obj, &hashcode); + /* Note: This approach requires the garbage collector to never move + objects. */ + if (i >= 0) { Lisp_Object value = HASH_VALUE (h, i); - EMACS_INT refcount = XFIXNAT (value) + 1; - if (MOST_POSITIVE_FIXNUM < refcount) + struct module_global_reference *ref = XMODULE_GLOBAL_REFERENCE (value); + bool overflow = INT_ADD_WRAPV (ref->refcount, 1, &ref->refcount); + if (overflow) overflow_error (); - value = make_fixed_natnum (refcount); - set_hash_value_slot (h, i, value); + return &ref->value; } else { - hash_put (h, new_obj, make_fixed_natnum (1), hashcode); + struct module_global_reference *ref + = ALLOCATE_PLAIN_PSEUDOVECTOR (struct module_global_reference, + PVEC_OTHER); + ref->value.v = new_obj; + ref->refcount = 1; + Lisp_Object value; + XSETPSEUDOVECTOR (value, ref, PVEC_OTHER); + hash_put (h, new_obj, value, hashcode); + return &ref->value; } - - return allocate_emacs_value (env, &global_storage, new_obj); } static void @@ -411,25 +468,21 @@ module_free_global_ref (emacs_env *env, emacs_value global_value) Lisp_Object obj = value_to_lisp (global_value); ptrdiff_t i = hash_lookup (h, obj, NULL); - if (i >= 0) + if (module_assertions) { - EMACS_INT refcount = XFIXNAT (HASH_VALUE (h, i)) - 1; - if (refcount > 0) - set_hash_value_slot (h, i, make_fixed_natnum (refcount)); - else - { - eassert (refcount == 0); - hash_remove_from_table (h, obj); - } + ptrdiff_t n = 0; + if (! module_global_reference_p (global_value, &n)) + module_abort ("Global value was not found in list of %"pD"d globals", + n); } - if (module_assertions) + if (i >= 0) { - ptrdiff_t count = 0; - if (value_storage_contains_p (&global_storage, global_value, &count)) - return; - module_abort ("Global value was not found in list of %"pD"d globals", - count); + Lisp_Object value = HASH_VALUE (h, i); + struct module_global_reference *ref = XMODULE_GLOBAL_REFERENCE (value); + eassert (0 < ref->refcount); + if (--ref->refcount == 0) + hash_remove_from_table (h, obj); } } @@ -1250,7 +1303,7 @@ value_to_lisp (emacs_value v) ++num_environments; } /* Also check global values. */ - if (value_storage_contains_p (&global_storage, v, &num_values)) + if (module_global_reference_p (v, &num_values)) goto ok; module_abort (("Emacs value not found in %"pD"d values " "of %"pD"d environments"), @@ -1467,10 +1520,7 @@ module_handle_nonlocal_exit (emacs_env *env, enum nonlocal_exit type, void init_module_assertions (bool enable) { - /* If enabling module assertions, use a hidden environment for - storing the globals. This environment is never freed. */ module_assertions = enable; - initialize_storage (&global_storage); } /* Return whether STORAGE contains VALUE. Used to check module |