Re: Q: How to handle zend_op_array.scope and zend_op_array.prototype in opcode cache?

Hi Eric, On Tue, Jun 24, 2014 at 11:08 PM, Eric Stenson <ericsten@microsoft.com> wrote: > PHP Internals folks-- > > I'm working on the opcode cache part of Wincache, and I believe that > Wincache isn't properly handling the scope and prototype fields of the > zend_op_array struct when copying it into shared memory. > > I tried looking at the Zend Opcache code to figure out what The Right > Way(TM) to handle these fields, and I'm curious about how these fields are > used by the Zend engine. > > From what I can tell, Zend Opcache has a per-process HashTable where it > keeps track of which items is has copied into shared memory (xlat_table). > > It looks like the xlat_table is cleared out before each compilation. When > persisting, Zend persists things in the following order: > 1. function_table > 2. class_table > 3. zend_op_array (for the main zend_op_array produced by compile) > > My questions: > * Is there some guarantee that the scope and prototype on the main > zend_op_array exist in the function_table and class_table for the > compilation? > OPcache makes a trick to compile each file completely independent from others, so op_arrays may refer only to classes and functions from the same script or to internal ones. > * Does the scope and prototype fields really matter for the main > zend_op_array? Wincache has been setting them to NULL since day 1, and > everything seems to work just fine... > scope and prototype make sense only for methods. top_level code and regular functions always have them as NULL. > * The xlat_table key is a ulong. Zend Opcache uses the pointer of an > object as the key. On Windows, a ulong is 32 bits. How does this even > work on an x64 Windows box? > #if SIZEOF_SIZE_T <= SIZEOF_LONG /* If sizeof(void*) == sizeof(ulong) we can use zend_hash index functions */ # define accel_xlat_set(old, new) zend_hash_index_update(&ZCG(bind_hash), (ulong)(zend_uintptr_t)(old), &(new), sizeof(void*), NULL) # define accel_xlat_get(old, new) zend_hash_index_find(&ZCG(bind_hash), (ulong)(zend_uintptr_t)(old), (void**)&(new)) #else # define accel_xlat_set(old, new) zend_hash_quick_add(&ZCG(bind_hash), (char*)&(old), sizeof(void*), (ulong)(zend_uintptr_t)(old), (void**)&(new), sizeof(void*), NULL) # define accel_xlat_get(old, new) zend_hash_quick_find(&ZCG(bind_hash), (char*)&(old), sizeof(void*), (ulong)(zend_uintptr_t)(old), (void**)&(new)) #endif So on x64 Windows we use "string" keys. It's less efficient but safe. Thanks. Dmitry. > > Thx! > --E. > > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > >