gdb seems to be not always able to fetch the correct context for
thread locals. Thus, the "if (TSRMLS_CACHE)" clause causes gdb to
show crashes which aren't recognized neither with helgrind nor
in release builds. This is reproducable by setting breakpoints on
the exact line where PHP has a tsrm_get_ls_cache() call.
TLS is already used in TSRM, the way exporting the tsrm cache through
a thread local variable is not portable. Additionally, the current
patch suffers from bugs which are hard to find, but prevent it to
be worky with apache. What is done here is mainly uses the idea
from the RFC patch, but
- __thread variable is removed
- offset math and declarations are removed
- extra macros and definitions are removed
What is done merely is
- use an inline function to access the tsrm cache. The function uses
the portable tsrm_tls_get macro which is cheap
- all the TSRM_* macros are set to placebo. Thus this opens the way
remove them later
Except that, the logic is old. TSRMLS_FETCH will have to be done once
per thread, then tsrm_get_ls_cache() can be used. Things seeming to be
worky are cli, cli server and apache. I also tried to enable bz2
shared and it has worked out of the box. The change is yet minimal
diffing to the current master bus is a worky start, IMHO. Though will
have to recheck the other previously done SAPIs - embed and cgi.
The offsets can be added to the tsrm_resource_type struct, then
it'll not be needed to declare them in the userspace. Even the
"done" member type can be changed to int16 or smaller, then adding
the offset as int16 will not change the struct size. As well on the
todo might be removing the hashed storage, thread_id != thread_id and
linked list logic in favour of the explicit TLS operations.
This needs to go into 5.4 as well, but will wait for Pierre to review win32 situation
# Patch by Lucas Nealan, Arnaud Le Blanc, Brian Shire & Ilia Alshanetsky
TSRM_API void *tsrm_new_interpreter_context(void);
TSRM_API void *tsrm_set_interpreter_context(void *new_ctx);
TSRM_API void tsrm_free_interpreter_context(void *context);
These can be used, with a suitable SAPI, to host multiple interpreters on
the same thread.
Xinchen Hui