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In libobjc/: 2011-05-25 Richard Frith-Macdonald <rfm@gnu.org> David Ayers <ayers@fsfe.org>

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In libobjc/:
2011-05-25  Richard Frith-Macdonald <rfm@gnu.org>
	    David Ayers  <ayers@fsfe.org>

	PR libobjc/38037
	* sendmsg.c: Include objc/hash.h.
	(get_implementation): New function, mostly with code from get_imp
	updated to support the new +initialize dispatch table logic.
	(get_imp): Use get_implementation.
	(__objc_responds_to): Updated to support the new +initialize
	dispatch table logic.
	(class_respondsToSelector): Likewise.
	(objc_msg_lookup): Use get_implementation.
	(__objc_init_install_dtable): Removed.
	(__objc_install_methods_in_dtable): Updated arguments.
	(__objc_install_dispatch_table_for_class): Renamed to
	__objc_install_dtable_for_class and updated to support the new
	+initialize dispatch table logic.
	(__objc_update_dispatch_table_for_class): Updated to support the
	new +initialize dispatch table logic.
	(__objc_forward): Call get_implementation instead of get_imp.
	(prepared_dtable_table): New.
	(__objc_prepare_dtable_for_class): New.	
	(__objc_prepared_dtable_for_class): New.
	(__objc_get_prepared_imp): New.
	(__objc_install_prepared_dtable_for_class): New.

Co-Authored-By: David Ayers <ayers@fsfe.org>

From-SVN: r174221
This commit is contained in:
Richard Frith-Macdonald 2011-05-25 18:54:40 +00:00 • committed by Nicola Pero
parent deaf34a90b
commit b5a3450ff7
2 changed files with 412 additions and 205 deletions
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26
libobjc/ChangeLog
View file

@ -1,3 +1,29 @@
2011-05-25 Richard Frith-Macdonald <rfm@gnu.org>
David Ayers <ayers@fsfe.org>
PR libobjc/38037
* sendmsg.c: Include objc/hash.h.
(get_implementation): New function, mostly with code from get_imp
updated to support the new +initialize dispatch table logic.
(get_imp): Use get_implementation.
(__objc_responds_to): Updated to support the new +initialize
dispatch table logic.
(class_respondsToSelector): Likewise.
(objc_msg_lookup): Use get_implementation.
(__objc_init_install_dtable): Removed.
(__objc_install_methods_in_dtable): Updated arguments.
(__objc_install_dispatch_table_for_class): Renamed to
__objc_install_dtable_for_class and updated to support the new
+initialize dispatch table logic.
(__objc_update_dispatch_table_for_class): Updated to support the
new +initialize dispatch table logic.
(__objc_forward): Call get_implementation instead of get_imp.
(prepared_dtable_table): New.
(__objc_prepare_dtable_for_class): New.
(__objc_prepared_dtable_for_class): New.
(__objc_get_prepared_imp): New.
(__objc_install_prepared_dtable_for_class): New.
2011-05-24 Nicola Pero <nicola.pero@meta-innovation.com>
PR libobjc/48177

591
libobjc/sendmsg.c
View file

@ -41,6 +41,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
#include "objc/thr.h"
#include "objc-private/module-abi-8.h"
#include "objc-private/runtime.h"
#include "objc-private/hash.h"
#include "objc-private/sarray.h"
#include "objc-private/selector.h" /* For sel_is_mapped() */
#include "runtime-info.h"
@ -75,10 +76,14 @@ IMP (*__objc_msg_forward2) (id, SEL) = NULL;
/* Send +initialize to class. */
static void __objc_send_initialize (Class);
static void __objc_install_dispatch_table_for_class (Class);
/* Forward declare some functions */
static void __objc_install_dtable_for_class (Class cls);
static void __objc_prepare_dtable_for_class (Class cls);
static void __objc_install_prepared_dtable_for_class (Class cls);
/* Forward declare some functions. */
static void __objc_init_install_dtable (id, SEL);
static struct sarray *__objc_prepared_dtable_for_class (Class cls);
static IMP __objc_get_prepared_imp (Class cls,SEL sel);
/* Various forwarding functions that are used based upon the
return type for the selector.
@ -117,7 +122,7 @@ __objc_get_forward_imp (id rcv, SEL sel)
{
IMP result;
if ((result = __objc_msg_forward (sel)) != NULL)
return result;
return result;
}
/* In all other cases, use the default forwarding functions built
@ -210,7 +215,7 @@ __objc_resolve_instance_method (Class class, SEL sel)
{
objc_mutex_lock (__objc_runtime_mutex);
if (class->class_pointer->dtable == __objc_uninstalled_dtable)
__objc_install_dispatch_table_for_class (class->class_pointer);
__objc_install_dtable_for_class (class->class_pointer);
objc_mutex_unlock (__objc_runtime_mutex);
}
resolveMethodIMP = sarray_get_safe (class->class_pointer->dtable,
@ -231,8 +236,94 @@ __objc_resolve_instance_method (Class class, SEL sel)
return NULL;
}
/* Given a class and selector, return the selector's
implementation. */
/* Given a CLASS and selector, return the implementation corresponding
to the method of the selector.
If CLASS is a class, the instance method is returned.
If CLASS is a meta class, the class method is returned.
Since this requires the dispatch table to be installed, this function
will implicitly invoke +initialize for CLASS if it hasn't been
invoked yet. This also insures that +initialize has been invoked
when the returned implementation is called directly.
The forwarding hooks require the receiver as an argument (if they are to
perform dynamic lookup in proxy objects etc), so this function has a
receiver argument to be used with those hooks. */
static inline
IMP
get_implementation (id receiver, Class class, SEL sel)
{
void *res;
if (class->dtable == __objc_uninstalled_dtable)
{
/* The dispatch table needs to be installed. */
objc_mutex_lock (__objc_runtime_mutex);
/* Double-checked locking pattern: Check
__objc_uninstalled_dtable again in case another thread
installed the dtable while we were waiting for the lock
to be released. */
if (class->dtable == __objc_uninstalled_dtable)
{
__objc_install_dtable_for_class (class);
}
/* If the dispatch table is not yet installed,
we are still in the process of executing +initialize.
But the implementation pointer should be available
in the prepared ispatch table if it exists at all. */
if (class->dtable == __objc_uninstalled_dtable)
{
assert (__objc_prepared_dtable_for_class (class) != 0);
res = __objc_get_prepared_imp (class, sel);
}
else
{
res = 0;
}
objc_mutex_unlock (__objc_runtime_mutex);
/* Call ourselves with the installed dispatch table and get
the real method. */
if (!res)
res = get_implementation (receiver, class, sel);
}
else
{
/* The dispatch table has been installed. */
res = sarray_get_safe (class->dtable, (size_t) sel->sel_id);
if (res == 0)
{
/* The dispatch table has been installed, and the method
is not in the dispatch table. So the method just
doesn't exist for the class. */
/* Try going through the +resolveClassMethod: or
+resolveInstanceMethod: process. */
if (CLS_ISMETA (class))
{
/* We have the meta class, but we need to invoke the
+resolveClassMethod: method on the class. So, we
need to obtain the class from the meta class,
which we do using the fact that both the class
and the meta-class have the same name. */
Class realClass = objc_lookUpClass (class->name);
if (realClass)
res = __objc_resolve_class_method (realClass, sel);
}
else
res = __objc_resolve_instance_method (class, sel);
if (res == 0)
{
res = __objc_get_forward_imp (receiver, sel);
}
}
}
return res;
}
inline
IMP
get_imp (Class class, SEL sel)
@ -248,70 +339,7 @@ get_imp (Class class, SEL sel)
void *res = sarray_get_safe (class->dtable, (size_t) sel->sel_id);
if (res == 0)
{
/* Not a valid method. */
if (class->dtable == __objc_uninstalled_dtable)
{
/* The dispatch table needs to be installed. */
objc_mutex_lock (__objc_runtime_mutex);
/* Double-checked locking pattern: Check
__objc_uninstalled_dtable again in case another thread
installed the dtable while we were waiting for the lock
to be released. */
if (class->dtable == __objc_uninstalled_dtable)
{
__objc_install_dispatch_table_for_class (class);
}
objc_mutex_unlock (__objc_runtime_mutex);
/* Call ourselves with the installed dispatch table and get
the real method. */
res = get_imp (class, sel);
}
else
{
/* The dispatch table has been installed. */
/* Get the method from the dispatch table (we try to get it
again in case another thread has installed the dtable just
after we invoked sarray_get_safe, but before we checked
class->dtable == __objc_uninstalled_dtable). */
res = sarray_get_safe (class->dtable, (size_t) sel->sel_id);
if (res == 0)
{
/* The dispatch table has been installed, and the method
is not in the dispatch table. So the method just
doesn't exist for the class. */
/* Try going through the +resolveClassMethod: or
+resolveInstanceMethod: process. */
if (CLS_ISMETA (class))
{
/* We have the meta class, but we need to invoke the
+resolveClassMethod: method on the class. So, we
need to obtain the class from the meta class,
which we do using the fact that both the class
and the meta-class have the same name. */
Class realClass = objc_lookUpClass (class->name);
if (realClass)
res = __objc_resolve_class_method (realClass, sel);
}
else
res = __objc_resolve_instance_method (class, sel);
if (res == 0)
{
/* If that fails, then return the forwarding
implementation. We don't know the receiver (only
its class), so we have to pass 'nil' as the first
argument. Passing the class as first argument is
wrong because the class is not the receiver; it
can result in us calling a class method when we
want an instance method of the same name. */
res = __objc_get_forward_imp (nil, sel);
}
}
}
res = get_implementation(nil, class, sel);
}
return res;
}
@ -337,51 +365,78 @@ method_get_imp (struct objc_method * method)
/* Query if an object can respond to a selector, returns YES if the
object implements the selector otherwise NO. Does not check if the
method can be forwarded. */
method can be forwarded.
Since this requires the dispatch table to installed, this function
will implicitly invoke +initialize for the class of OBJECT if it
hasn't been invoked yet. */
inline
BOOL
__objc_responds_to (id object, SEL sel)
{
void *res;
struct sarray *dtable;
/* Install dispatch table if need be. */
if (object->class_pointer->dtable == __objc_uninstalled_dtable)
/* Install dispatch table if need be */
dtable = object->class_pointer->dtable;
if (dtable == __objc_uninstalled_dtable)
{
objc_mutex_lock (__objc_runtime_mutex);
if (object->class_pointer->dtable == __objc_uninstalled_dtable)
{
__objc_install_dispatch_table_for_class (object->class_pointer);
}
__objc_install_dtable_for_class (object->class_pointer);
/* If the dispatch table is not yet installed,
we are still in the process of executing +initialize.
Yet the dispatch table should be available. */
if (object->class_pointer->dtable == __objc_uninstalled_dtable)
{
dtable = __objc_prepared_dtable_for_class (object->class_pointer);
assert (dtable);
}
else
dtable = object->class_pointer->dtable;
objc_mutex_unlock (__objc_runtime_mutex);
}
/* Get the method from the dispatch table. */
res = sarray_get_safe (object->class_pointer->dtable, (size_t) sel->sel_id);
return (res != 0);
res = sarray_get_safe (dtable, (size_t) sel->sel_id);
return (res != 0) ? YES : NO;
}
BOOL
class_respondsToSelector (Class class_, SEL selector)
{
struct sarray *dtable;
void *res;
if (class_ == Nil || selector == NULL)
return NO;
/* Install dispatch table if need be. */
if (class_->dtable == __objc_uninstalled_dtable)
dtable = class_->dtable;
if (dtable == __objc_uninstalled_dtable)
{
objc_mutex_lock (__objc_runtime_mutex);
if (class_->dtable == __objc_uninstalled_dtable)
{
__objc_install_dispatch_table_for_class (class_);
__objc_install_dtable_for_class (class_);
}
/* If the dispatch table is not yet installed,
we are still in the process of executing +initialize.
Yet the dispatch table should be available. */
if (class_->dtable == __objc_uninstalled_dtable)
{
dtable = __objc_prepared_dtable_for_class (class_);
assert (dtable);
}
else
dtable = class_->dtable;
objc_mutex_unlock (__objc_runtime_mutex);
}
/* Get the method from the dispatch table. */
res = sarray_get_safe (class_->dtable, (size_t) selector->sel_id);
return (res != 0);
res = sarray_get_safe (dtable, (size_t) selector->sel_id);
return (res != 0) ? YES : NO;
}
/* This is the lookup function. All entries in the table are either a
@ -394,48 +449,15 @@ objc_msg_lookup (id receiver, SEL op)
IMP result;
if (receiver)
{
/* First try a quick lookup assuming the dispatch table exists. */
result = sarray_get_safe (receiver->class_pointer->dtable,
(sidx)op->sel_id);
if (result == 0)
{
/* Not a valid method. */
if (receiver->class_pointer->dtable == __objc_uninstalled_dtable)
{
/* The dispatch table needs to be installed. This
happens on the very first method call to the
class. */
__objc_init_install_dtable (receiver, op);
/* Get real method for this in newly installed
dtable. */
result = get_imp (receiver->class_pointer, op);
}
else
{
/* The dispatch table has been installed. Check again
if the method exists (just in case the dispatch table
has been installed by another thread after we did the
previous check that the method exists). */
result = sarray_get_safe (receiver->class_pointer->dtable,
(sidx)op->sel_id);
if (result == 0)
{
/* Try going through the +resolveClassMethod: or
+resolveInstanceMethod: process. */
if (CLS_ISMETA (receiver->class_pointer))
result = __objc_resolve_class_method ((Class)receiver, op);
else
result = __objc_resolve_instance_method (receiver->class_pointer,
op);
if (result == 0)
{
/* If the method still just doesn't exist for
the class, attempt to forward the method. */
result = __objc_get_forward_imp (receiver, op);
}
}
}
/* Not found ... call get_implementation () to install the dispatch
table and call +initialize as required, providing the method
implementation or a forwarding function */
result = get_implementation (receiver, receiver->class_pointer, op);
}
return result;
}
@ -485,47 +507,6 @@ __objc_init_dispatch_tables ()
selector_resolveInstanceMethod =sel_registerName ("resolveInstanceMethod:");
}
/* This function is called by objc_msg_lookup when the dispatch table
needs to be installed; thus it is called once for each class,
namely when the very first message is sent to it. */
static void
__objc_init_install_dtable (id receiver, SEL op __attribute__ ((__unused__)))
{
objc_mutex_lock (__objc_runtime_mutex);
/* This may happen, if the programmer has taken the address of a
method before the dtable was initialized... too bad for him! */
if (receiver->class_pointer->dtable != __objc_uninstalled_dtable)
{
objc_mutex_unlock (__objc_runtime_mutex);
return;
}
if (CLS_ISCLASS (receiver->class_pointer))
{
/* receiver is an ordinary object. */
assert (CLS_ISCLASS (receiver->class_pointer));
/* Install instance methods table. */
__objc_install_dispatch_table_for_class (receiver->class_pointer);
/* Call +initialize -- this will in turn install the factory
dispatch table if not already done. :-) */
__objc_send_initialize (receiver->class_pointer);
}
else
{
/* receiver is a class object. */
assert (CLS_ISCLASS ((Class)receiver));
assert (CLS_ISMETA (receiver->class_pointer));
/* Install real dtable for factory methods. */
__objc_install_dispatch_table_for_class (receiver->class_pointer);
__objc_send_initialize ((Class)receiver);
}
objc_mutex_unlock (__objc_runtime_mutex);
}
/* Install dummy table for class which causes the first message to
that class (or instances hereof) to be initialized properly. */
@ -544,6 +525,9 @@ __objc_send_initialize (Class class)
assert (CLS_ISCLASS (class));
assert (! CLS_ISMETA (class));
/* class_add_method_list/__objc_update_dispatch_table_for_class
may have reset the dispatch table. The canonical way to insure
that we send +initialize just once, is this flag. */
if (! CLS_ISINITIALIZED (class))
{
DEBUG_PRINTF ("+initialize: need to initialize class '%s'\n", class->name);
@ -606,7 +590,7 @@ __objc_send_initialize (Class class)
guaranteed about what method will be used. Assumes that
__objc_runtime_mutex is locked down. */
static void
__objc_install_methods_in_dtable (Class class, struct objc_method_list * method_list)
__objc_install_methods_in_dtable (struct sarray *dtable, struct objc_method_list * method_list)
{
int i;
@ -614,68 +598,46 @@ __objc_install_methods_in_dtable (Class class, struct objc_method_list * method_
return;
if (method_list->method_next)
__objc_install_methods_in_dtable (class, method_list->method_next);
__objc_install_methods_in_dtable (dtable, method_list->method_next);
for (i = 0; i < method_list->method_count; i++)
{
struct objc_method * method = &(method_list->method_list[i]);
sarray_at_put_safe (class->dtable,
sarray_at_put_safe (dtable,
(sidx) method->method_name->sel_id,
method->method_imp);
}
}
/* Assumes that __objc_runtime_mutex is locked down. */
static void
__objc_install_dispatch_table_for_class (Class class)
{
Class super;
/* If the class has not yet had its class links resolved, we must
re-compute all class links. */
if (! CLS_ISRESOLV (class))
__objc_resolve_class_links ();
DEBUG_PRINTF ("__objc_install_dispatch_table_for_class (%s)\n", class->name);
super = class->super_class;
if (super != 0 && (super->dtable == __objc_uninstalled_dtable))
__objc_install_dispatch_table_for_class (super);
/* Allocate dtable if necessary. */
if (super == 0)
{
objc_mutex_lock (__objc_runtime_mutex);
class->dtable = sarray_new (__objc_selector_max_index, 0);
objc_mutex_unlock (__objc_runtime_mutex);
}
else
class->dtable = sarray_lazy_copy (super->dtable);
__objc_install_methods_in_dtable (class, class->methods);
}
void
__objc_update_dispatch_table_for_class (Class class)
{
Class next;
struct sarray *arr;
/* Not yet installed -- skip it. */
if (class->dtable == __objc_uninstalled_dtable)
return;
DEBUG_PRINTF (" _objc_update_dispatch_table_for_class (%s)\n", class->name);
DEBUG_PRINTF (" _objc_update_dtable_for_class (%s)\n", class->name);
objc_mutex_lock (__objc_runtime_mutex);
/* not yet installed -- skip it unless in +initialize */
if (class->dtable == __objc_uninstalled_dtable)
{
if (__objc_prepared_dtable_for_class (class))
{
/* There is a prepared table so we must be initialising this
class ... we must re-do the table preparation. */
__objc_prepare_dtable_for_class (class);
}
objc_mutex_unlock (__objc_runtime_mutex);
return;
}
arr = class->dtable;
__objc_install_premature_dtable (class); /* someone might require it... */
sarray_free (arr); /* release memory */
/* Could have been lazy... */
__objc_install_dispatch_table_for_class (class);
__objc_install_dtable_for_class (class);
if (class->subclass_list) /* Traverse subclasses. */
for (next = class->subclass_list; next; next = next->sibling_class)
@ -995,7 +957,7 @@ __objc_forward (id object, SEL sel, arglist_t args)
if (__objc_responds_to (object, frwd_sel))
{
imp = get_imp (object->class_pointer, frwd_sel);
imp = get_implementation (object, object->class_pointer, frwd_sel);
return (*imp) (object, frwd_sel, sel, args);
}
@ -1004,7 +966,7 @@ __objc_forward (id object, SEL sel, arglist_t args)
err_sel = sel_get_any_uid ("doesNotRecognize:");
if (__objc_responds_to (object, err_sel))
{
imp = get_imp (object->class_pointer, err_sel);
imp = get_implementation (object, object->class_pointer, err_sel);
return (*imp) (object, err_sel, sel);
}
@ -1024,7 +986,7 @@ __objc_forward (id object, SEL sel, arglist_t args)
err_sel = sel_get_any_uid ("error:");
if (__objc_responds_to (object, err_sel))
{
imp = get_imp (object->class_pointer, err_sel);
imp = get_implementation (object, object->class_pointer, err_sel);
return (*imp) (object, sel_get_any_uid ("error:"), msg);
}
@ -1074,3 +1036,222 @@ objc_get_uninstalled_dtable (void)
{
return __objc_uninstalled_dtable;
}
static cache_ptr prepared_dtable_table = 0;
/* This function is called by:
objc_msg_lookup, get_imp and __objc_responds_to
(and the dispatch table installation functions themselves)
to install a dispatch table for a class.
If CLS is a class, it installs instance methods.
If CLS is a meta class, it installs class methods.
In either case +initialize is invoked for the corresponding class.
The implementation must insure that the dispatch table is not
installed until +initialize completes. Otherwise it opens a
potential race since the installation of the dispatch table is
used as gate in regular method dispatch and we need to guarantee
that +initialize is the first method invoked an that no other
thread my dispatch messages to the class before +initialize
completes.
*/
static void
__objc_install_dtable_for_class (Class cls)
{
/* If the class has not yet had its class links resolved, we must
re-compute all class links */
if (! CLS_ISRESOLV (cls))
__objc_resolve_class_links ();
/* Make sure the super class has its dispatch table installed
or is at least preparing.
We do not need to send initialize for the super class since
__objc_send_initialize will insure that.
*/
if (cls->super_class
&& cls->super_class->dtable == __objc_uninstalled_dtable
&& !__objc_prepared_dtable_for_class (cls->super_class))
{
__objc_install_dtable_for_class (cls->super_class);
/* The superclass initialisation may have also initialised the
current class, in which case there is no more to do. */
if (cls->dtable != __objc_uninstalled_dtable)
{
return;
}
}
/* We have already been prepared but +initialize hasn't completed.
The +initialize implementation is probably sending 'self' messages.
We rely on _objc_get_prepared_imp to retrieve the implementation
pointers. */
if (__objc_prepared_dtable_for_class (cls))
{
return;
}
/* We have this function cache the implementation pointers
for _objc_get_prepared_imp but the dispatch table won't
be initilized until __objc_send_initialize completes. */
__objc_prepare_dtable_for_class (cls);
/* We may have already invoked +initialize but
__objc_update_dispatch_table_for_class invoked by
class_add_method_list may have reset dispatch table. */
/* Call +initialize.
If we are a real class, we are installing instance methods.
If we are a meta class, we are installing class methods.
The __objc_send_initialize itself will insure that the message
is called only once per class. */
if (CLS_ISCLASS (cls))
__objc_send_initialize (cls);
else
{
/* Retreive the class from the meta class. */
Class c = objc_lookup_class (cls->name);
assert (CLS_ISMETA (cls));
assert (c);
__objc_send_initialize (c);
}
/* We install the dispatch table correctly when +initialize completed. */
__objc_install_prepared_dtable_for_class (cls);
}
/* Builds the dispatch table for the class CLS and stores
it in a place where it can be retrieved by
__objc_get_prepared_imp until __objc_install_prepared_dtable_for_class
installs it into the class.
The dispatch table should not be installed into the class until
+initialize has completed. */
static void
__objc_prepare_dtable_for_class (Class cls)
{
struct sarray *dtable;
struct sarray *super_dtable;
/* This table could be initialized in init.c.
We can not use the class name since
the class maintains the instance methods and
the meta class maintains the the class methods yet
both share the same name.
Classes should be unique in any program. */
if (! prepared_dtable_table)
prepared_dtable_table
= objc_hash_new(32,
(hash_func_type) objc_hash_ptr,
(compare_func_type) objc_compare_ptrs);
/* If the class has not yet had its class links resolved, we must
re-compute all class links */
if (! CLS_ISRESOLV (cls))
__objc_resolve_class_links ();
assert (cls);
assert (cls->dtable == __objc_uninstalled_dtable);
/* If there is already a prepared dtable for this class, we must replace
it with a new version (since there must have been methods added to or
otherwise modified in the class while executing +initialize, and the
table needs to be recomputed. */
dtable = __objc_prepared_dtable_for_class (cls);
if (0 != dtable)
{
objc_hash_remove (prepared_dtable_table, cls);
sarray_free (dtable);
}
/* Now prepare the dtable for population. */
assert (cls != cls->super_class);
if (cls->super_class)
{
/* Inherit the method list from the super class.
Yet the super class may still be initializing
in the case when a class cluster sub class initializes
its super classes. */
if (cls->super_class->dtable == __objc_uninstalled_dtable)
__objc_install_dtable_for_class (cls->super_class);
super_dtable = cls->super_class->dtable;
/* If the dispatch table is not yet installed,
we are still in the process of executing +initialize.
Yet the dispatch table should be available. */
if (super_dtable == __objc_uninstalled_dtable)
super_dtable = __objc_prepared_dtable_for_class (cls->super_class);
assert (super_dtable);
dtable = sarray_lazy_copy (super_dtable);
}
else
dtable = sarray_new (__objc_selector_max_index, 0);
__objc_install_methods_in_dtable (dtable, cls->methods);
objc_hash_add (&prepared_dtable_table,
cls,
dtable);
}
/* This wrapper only exists to allow an easy replacement of
the lookup implementation and it is expected that the compiler
will optimize it away. */
static struct sarray *
__objc_prepared_dtable_for_class (Class cls)
{
struct sarray *dtable = 0;
assert (cls);
if (prepared_dtable_table)
dtable = objc_hash_value_for_key (prepared_dtable_table, cls);
/* dtable my be nil,
since we call this to check whether we are currently preparing
before we start preparing. */
return dtable;
}
/* Helper function for messages sent to CLS or implementation pointers
retrieved from CLS during +initialize before the dtable is installed.
When a class implicitly initializes another class which in turn
implicitly invokes methods in this class, before the implementation of
+initialize of CLS completes, this returns the expected implementation.
Forwarding remains the responsibility of objc_msg_lookup.
This function should only be called under the global lock.
*/
static IMP
__objc_get_prepared_imp (Class cls,SEL sel)
{
struct sarray *dtable;
IMP imp;
assert (cls);
assert (sel);
assert (cls->dtable == __objc_uninstalled_dtable);
dtable = __objc_prepared_dtable_for_class (cls);
assert (dtable);
assert (dtable != __objc_uninstalled_dtable);
imp = sarray_get_safe (dtable, (size_t) sel->sel_id);
/* imp may be Nil if the method does not exist and we
may fallback to the forwarding implementation later. */
return imp;
}
/* When this function is called +initialize should be completed.
So now we are safe to install the dispatch table for the
class so that they become available for other threads
that may be waiting in the lock.
*/
static void
__objc_install_prepared_dtable_for_class (Class cls)
{
assert (cls);
assert (cls->dtable == __objc_uninstalled_dtable);
cls->dtable = __objc_prepared_dtable_for_class (cls);
assert (cls->dtable);
assert (cls->dtable != __objc_uninstalled_dtable);
objc_hash_remove (prepared_dtable_table, cls);
}