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Diffstat (limited to 'Frameworks/SPMySQLFramework/Source/SPMySQLArrayAdditions.h')
| -rw-r--r-- | Frameworks/SPMySQLFramework/Source/SPMySQLArrayAdditions.h | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/Frameworks/SPMySQLFramework/Source/SPMySQLArrayAdditions.h b/Frameworks/SPMySQLFramework/Source/SPMySQLArrayAdditions.h index 548c5e48..3605cdbc 100644 --- a/Frameworks/SPMySQLFramework/Source/SPMySQLArrayAdditions.h +++ b/Frameworks/SPMySQLFramework/Source/SPMySQLArrayAdditions.h @@ -37,6 +37,26 @@ */ static inline void SPMySQLMutableArrayInsertObject(NSMutableArray *self, id anObject, NSUInteger anIndex) { + /* A note on CFArrayInsertValueAtIndex(): + * + * This function here does look similar to the CF function, however that is not neccesarily the + * case from a performance standpoint. + * + * CFArrayInsertValueAtIndex() is mostly a wrapper around either + * - _CFArrayReplaceValues(obj, …) *or* + * - objc_msgSend(obj, @selector(insertObject:atIndex:), …) + * + * The first case would be fast, but it will only be used if the object is a native CFArrayRef, not + * a toll-free bridged object. In our case however, we always pass in some object of the NSMutableArray cluster, + * so we would always end up in the slowest path (uncached objc method invocation). + * + * Determing the performance of the objc method is more difficult, because there are multiple implementations + * of NSMutableArray and the "real" -[NSMutableArray insertObject:atIndex:] (located in CoreFoundation.framework) + * is only an abstract stub that will raise an exception if called. + * + * NSCFArray's (for CFArrays bridged to objc) implementation will wind up in _CFArrayReplaceValues(). + * __NSArrayM's (for +[NSMutableArray array]) implementation is completely independent from the aforementioned ones. + */ typedef id (*SPMySQLMutableArrayInsertObjectPtr)(NSMutableArray*, SEL, id, NSUInteger); static SPMySQLMutableArrayInsertObjectPtr cachedMethodPointer; static SEL cachedSelector; |