diff options
Diffstat (limited to 'libobjc/class.c')
| -rw-r--r-- | libobjc/class.c | 78 |
1 files changed, 31 insertions, 47 deletions
diff --git a/libobjc/class.c b/libobjc/class.c index ade5a71..d606a35 100644 --- a/libobjc/class.c +++ b/libobjc/class.c @@ -26,11 +26,9 @@ a copy of the GCC Runtime Library Exception along with this program; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see <http://www.gnu.org/licenses/>. */ -/* - The code in this file critically affects class method invocation +/* The code in this file critically affects class method invocation speed. This long preamble comment explains why, and the issues - involved. - + involved. One of the traditional weaknesses of the GNU Objective-C runtime is that class method invocations are slow. The reason is that when you @@ -44,7 +42,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see objc_get_class returns the class pointer corresponding to the string `NSArray'; and because of the lookup, the operation is more - complicated and slow than a simple instance method invocation. + complicated and slow than a simple instance method invocation. Most high performance Objective-C code (using the GNU Objc runtime) I had the opportunity to read (or write) work around this problem by @@ -61,7 +59,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see In this case, you always perform a class lookup (the first one), but then all the [arrayClass new] methods run exactly as fast as an instance method invocation. It helps if you have many class method - invocations to the same class. + invocations to the same class. The long-term solution to this problem would be to modify the compiler to output tables of class pointers corresponding to all the @@ -70,14 +68,14 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see to perform precisely as fast as instance method invocations, because no class lookup would be involved. I think the Apple Objective-C runtime uses this technique. Doing this involves synchronized - modifications in the runtime and in the compiler. + modifications in the runtime and in the compiler. As a first medicine to the problem, I [NP] have redesigned and rewritten the way the runtime is performing class lookup. This doesn't give as much speed as the other (definitive) approach, but at least a class method invocation now takes approximately 4.5 times an instance method invocation on my machine (it would take approx 12 - times before the rewriting), which is a lot better. + times before the rewriting), which is a lot better. One of the main reason the new class lookup is so faster is because I implemented it in a way that can safely run multithreaded without @@ -97,11 +95,11 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see #include <string.h> /* For memset */ /* We use a table which maps a class name to the corresponding class - * pointer. The first part of this file defines this table, and - * functions to do basic operations on the table. The second part of - * the file implements some higher level Objective-C functionality for - * classes by using the functions provided in the first part to manage - * the table. */ + pointer. The first part of this file defines this table, and + functions to do basic operations on the table. The second part of + the file implements some higher level Objective-C functionality for + classes by using the functions provided in the first part to manage + the table. */ /** ** Class Table Internals @@ -145,7 +143,7 @@ static class_node_ptr class_table_array[CLASS_TABLE_SIZE]; static objc_mutex_t __class_table_lock = NULL; /* CLASS_TABLE_HASH is how we compute the hash of a class name. It is - a macro - *not* a function - arguments *are* modified directly. + a macro - *not* a function - arguments *are* modified directly. INDEX should be a variable holding an int; HASH should be a variable holding an int; @@ -176,7 +174,8 @@ class_table_setup (void) } -/* Insert a class in the table (used when a new class is registered). */ +/* Insert a class in the table (used when a new class is + registered). */ static void class_table_insert (const char *class_name, Class class_pointer) { @@ -221,18 +220,15 @@ class_table_replace (Class old_class_pointer, Class new_class_pointer) { hash++; if (hash < CLASS_TABLE_SIZE) - { - node = class_table_array[hash]; - } + node = class_table_array[hash]; } else { Class class1 = node->pointer; if (class1 == old_class_pointer) - { - node->pointer = new_class_pointer; - } + node->pointer = new_class_pointer; + node = node->next; } } @@ -267,9 +263,7 @@ class_table_get_safe (const char *class_name) for (i = 0; i < length; i++) { if ((node->name)[i] != class_name[i]) - { - break; - } + break; } if (i == length) @@ -309,9 +303,7 @@ class_table_next (struct class_table_enumerator **e) next = class_table_array[enumerator->hash]; } else - { - next = enumerator->node->next; - } + next = enumerator->node->next; if (next != NULL) { @@ -385,18 +377,16 @@ class_table_print_histogram (void) { printf ("%4d:", i + 1); for (j = 0; j < counter; j++) - { - printf ("X"); - } + printf ("X"); + printf ("\n"); counter = 0; } } printf ("%4d:", i + 1); for (j = 0; j < counter; j++) - { - printf ("X"); - } + printf ("X"); + printf ("\n"); } #endif /* DEBUGGING FUNCTIONS */ @@ -409,7 +399,7 @@ class_table_print_histogram (void) should be via the class_table_* functions. */ /* This is a hook which is called by objc_get_class and - objc_lookup_class if the runtime is not able to find the class. + objc_lookup_class if the runtime is not able to find the class. This may e.g. try to load in the class using dynamic loading. This hook was a public, global variable in the Traditional GNU @@ -558,9 +548,7 @@ objc_getClassList (Class *returnValue, int maxNumberOfClassesToReturn) if (count < maxNumberOfClassesToReturn) returnValue[count] = node->pointer; else - { - return count; - } + return count; } count++; node = node->next; @@ -869,20 +857,16 @@ __objc_update_classes_with_methods (struct objc_method *method_a, struct objc_me /* If the method is one of the ones we are looking for, update the implementation. */ if (method == method_a) - { - sarray_at_put_safe (class->dtable, - (sidx) method_a->method_name->sel_id, - method_a->method_imp); - } + sarray_at_put_safe (class->dtable, + (sidx) method_a->method_name->sel_id, + method_a->method_imp); if (method == method_b) { if (method_b != NULL) - { - sarray_at_put_safe (class->dtable, - (sidx) method_b->method_name->sel_id, - method_b->method_imp); - } + sarray_at_put_safe (class->dtable, + (sidx) method_b->method_name->sel_id, + method_b->method_imp); } } |