[Feature #18339]
After experimenting with the initial version of the API I figured there is a need
for an exit event to cleanup instrumentation data. e.g. if you record data in a
{thread_id -> data} table, you need to free associated data when a thread goes away.
Ref: https://bugs.ruby-lang.org/issues/18339
Design:
- This tries to minimize the overhead when no hook is registered.
It should only incur an extra unsynchronized boolean check.
- The hook list is protected with a read-write lock as to cause
contention when some hooks are registered.
- The hooks MUST be thread safe, and MUST NOT call into Ruby as they
are executed outside the GVL.
- It's simply a noop on Windows.
API:
```
rb_internal_thread_event_hook_t * rb_internal_thread_add_event_hook(rb_internal_thread_event_callback callback, rb_event_flag_t internal_event, void *user_data);
bool rb_internal_thread_remove_event_hook(rb_internal_thread_event_hook_t * hook);
```
You can subscribe to 3 events:
- READY: called right before attempting to acquire the GVL
- RESUMED: called right after successfully acquiring the GVL
- SUSPENDED: called right after releasing the GVL.
The hooks MUST be threadsafe, as they are executed outside of the GVL, they also MUST NOT call any Ruby API.
According to MSVC manual (*1), cl.exe can skip including a header file
when that:
- contains #pragma once, or
- starts with #ifndef, or
- starts with #if ! defined.
GCC has a similar trick (*2), but it acts more stricter (e. g. there
must be _no tokens_ outside of #ifndef...#endif).
Sun C lacked #pragma once for a looong time. Oracle Developer Studio
12.5 finally implemented it, but we cannot assume such recent version.
This changeset modifies header files so that each of them include
strictly one #ifndef...#endif. I believe this is the most portable way
to trigger compiler optimizations. [Bug #16770]
*1: https://docs.microsoft.com/en-us/cpp/preprocessor/once
*2: https://gcc.gnu.org/onlinedocs/cppinternals/Guard-Macros.html
zlib and bignum both contain unblocking functions which are
async-signal-safe and do not require spawning additional
threads.
We can execute those functions directly in signal handlers
without incurring overhead of extra threads, so provide C-API
users the ability to deal with that. Other C-API users may
have similar need.
This flexible API can supercede existing uses of
rb_thread_call_without_gvl and rb_thread_call_without_gvl2 by
introducing a flags argument to control behavior.
Note: this API is NOT finalized. It needs approval from other
committers. I prefer shorter name than previous
rb_thread_call_without_gvl* functions because my eyes requires
big fonts.
[Bug #15499]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66712 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
meaning of function.
This function is called with same parameters of
`rb_thread_call_without_gvl()'.
However, if interrupts are detected, when return immediately.
* thread.c: implement `rb_thread_call_without_gvl2()'.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37938 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
`func' from `int *skip_interrupt' to `VALUE *flags'.
If (flags & RUBY_CALL_WO_GVL_FLAG_SKIP_CHECK_INTS) is not zero,
then skip checking interrupt.
[ruby-core:46547]
* include/ruby/thread.h: ditto.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37681 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
it can skip last CHECK_INTS. See document for more details.
Document about it was updated a bit.
* include/ruby/thread.h (decl. of rb_thread_call_without_gvl2): added.
* thread.c (rb_thread_call_with_gvl): remove "EXPERIMENTAL!"
warning from a document.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36433 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
