Use v8::Persistent handle to keep module instances around.
Objects cannot be shared between isolates anyhow, hence moved
modules_loaded map from global V8JSG structure to php_v8js_ctx.
Besides fixes a use-after-free on normalised_module_id.
This is yet a first hack to prove applicability. Currently
unwind environment is held in a global variable, i.e. solution
is neither thread safe nor reentrant yet.
The timer_ctx was being popped & freed in terminate_execution, from the
timer thread (not the main thread), and then popped again in the main
thread when execution was aborted. Do all pop/free work in main thread.
Also, remember to pop the timer_ctx when just a memory limit is set.
Transfer stesie's comment from the c3512587acf2f6aeeb80d7cc753f08a784c4c86b
commit message so that future additions to v8js_globals maintain the
proper ZTS behavior.
Deleting the global object implicitly deletes all the properties,
i.e. PHP objects we previously attached to it (and for which we
increased the reference counter).
Since the following idle notifications trigger the weak callbacks,
the references on the PHP objects are finally decreased.
Before the idle notifications to V8 were sent without a special
Isolate entered, which results in V8 using it's default isolate
(which we don't use at all). Hence those were pretty useless
anyways (if they were called, which was unlikely).
Besides V8 seems to not trigger the weak object callbacks if
the isolate is destroyed, hence the PHP objects we add-ref'ed
before will leak.
Therefore this removes the previous idle notification logic
and forces garbage collection from the V8Js object destructor.
If ZTS is disabled, the v8js_globals instance is declared right
in the BSS and hence automatically initialized by C++ compiler.
Most of the variables are just zeroed.
If ZTS is enabled however, v8js_globals just points to a freshly
allocated, unitialized piece of memory, hence we need to
initialize all fields on our own. Likewise on shutdown we have to
run the destructors manually.
