#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"
/* 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.
{
IMP result;
if ((result = __objc_msg_forward (sel)) != NULL)
- return result;
+ return result;
}
/* In all other cases, use the default forwarding functions built
{
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,
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)
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;
}
/* 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
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;
}
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. */
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);
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;
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)
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);
}
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);
}
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);
}
{
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);
+}
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