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/*
* Run an duk_hobject finalizer. Used for both reference counting
* and mark-and-sweep algorithms. Must never throw an error.
*
* There is no return value. Any return value or error thrown by
* the finalizer is ignored (although errors are debug logged).
*
* Notes:
*
* - The thread used for calling the finalizer is the same as the
* 'thr' argument. This may need to change later.
*
* - The finalizer thread 'top' assertions are there because it is
* critical that strict stack policy is observed (i.e. no cruft
* left on the finalizer stack).
*/
#include "duk_internal.h"
DUK_LOCAL duk_ret_t duk__finalize_helper(duk_context *ctx) {
duk_hthread *thr;
DUK_ASSERT(ctx != NULL);
thr = (duk_hthread *) ctx;
DUK_DDD(DUK_DDDPRINT("protected finalization helper running"));
/* [... obj] */
/* XXX: Finalizer lookup should traverse the prototype chain (to allow
* inherited finalizers) but should not invoke accessors or proxy object
* behavior. At the moment this lookup will invoke proxy behavior, so
* caller must ensure that this function is not called if the target is
* a Proxy.
*/
duk_get_prop_stridx(ctx, -1, DUK_STRIDX_INT_FINALIZER); /* -> [... obj finalizer] */
if (!duk_is_callable(ctx, -1)) {
DUK_DDD(DUK_DDDPRINT("-> no finalizer or finalizer not callable"));
return 0;
}
duk_dup(ctx, -2);
duk_push_boolean(ctx, DUK_HEAP_HAS_FINALIZER_NORESCUE(thr->heap));
DUK_DDD(DUK_DDDPRINT("-> finalizer found, calling finalizer"));
duk_call(ctx, 2); /* [ ... obj finalizer obj heapDestruct ] -> [ ... obj retval ] */
DUK_DDD(DUK_DDDPRINT("finalizer finished successfully"));
return 0;
/* Note: we rely on duk_safe_call() to fix up the stack for the caller,
* so we don't need to pop stuff here. There is no return value;
* caller determines rescued status based on object refcount.
*/
}
DUK_INTERNAL void duk_hobject_run_finalizer(duk_hthread *thr, duk_hobject *obj) {
duk_context *ctx = (duk_context *) thr;
duk_ret_t rc;
#ifdef DUK_USE_ASSERTIONS
duk_idx_t entry_top;
#endif
DUK_DDD(DUK_DDDPRINT("running object finalizer for object: %p", (void *) obj));
DUK_ASSERT(thr != NULL);
DUK_ASSERT(ctx != NULL);
DUK_ASSERT(obj != NULL);
DUK_ASSERT_VALSTACK_SPACE(thr, 1);
#ifdef DUK_USE_ASSERTIONS
entry_top = duk_get_top(ctx);
#endif
/*
* Get and call the finalizer. All of this must be wrapped
* in a protected call, because even getting the finalizer
* may trigger an error (getter may throw one, for instance).
*/
DUK_ASSERT(!DUK_HEAPHDR_HAS_READONLY((duk_heaphdr *) obj));
if (DUK_HEAPHDR_HAS_FINALIZED((duk_heaphdr *) obj)) {
DUK_D(DUK_DPRINT("object already finalized, avoid running finalizer twice: %!O", obj));
return;
}
DUK_HEAPHDR_SET_FINALIZED((duk_heaphdr *) obj); /* ensure never re-entered until rescue cycle complete */
if (DUK_HOBJECT_HAS_EXOTIC_PROXYOBJ(obj)) {
/* This shouldn't happen; call sites should avoid looking up
* _Finalizer "through" a Proxy, but ignore if we come here
* with a Proxy to avoid finalizer re-entry.
*/
DUK_D(DUK_DPRINT("object is a proxy, skip finalizer call"));
return;
}
/* XXX: use a NULL error handler for the finalizer call? */
DUK_DDD(DUK_DDDPRINT("-> finalizer found, calling wrapped finalize helper"));
duk_push_hobject(ctx, obj); /* this also increases refcount by one */
rc = duk_safe_call(ctx, duk__finalize_helper, 0 /*nargs*/, 1 /*nrets*/); /* -> [... obj retval/error] */
DUK_ASSERT_TOP(ctx, entry_top + 2); /* duk_safe_call discipline */
if (rc != DUK_EXEC_SUCCESS) {
/* Note: we ask for one return value from duk_safe_call to get this
* error debugging here.
*/
DUK_D(DUK_DPRINT("wrapped finalizer call failed for object %p (ignored); error: %!T",
(void *) obj, (duk_tval *) duk_get_tval(ctx, -1)));
}
duk_pop_2(ctx); /* -> [...] */
DUK_ASSERT_TOP(ctx, entry_top);
}
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