The patch assumes that `struct REnv::cxt` only performs checks with the `OP_BREAK` and `OP_RETURN_BLK` instructions, and does not reference the entity.
Therefore, by changing to a weak reference, it is possible to collect fibers that are no longer directly referenced while in the suspended state.
However, we need to detach the living env objects that remain in the call stack of the fiber.
So, in effect, it involves a revert of following commits.
- commit a3365d8b3f
- commit 57ffa1c150
Examples of the effects of change are shown below.
Note that it was built with `rake MRUBY_CONFIG=host-debug`.
```ruby
f = Fiber.new { (x, y, z) = "X", "Y", "Z"; Fiber.yield -> { [x, y, z] } }
g = f.resume
GC.start
p ObjectSpace.memsize_of_all
# => 59532
g.call
# => ["X", "Y", "Z"]
f = nil
GC.start
ObjectSpace.memsize_of_all
# BEFORE => 59532
# AFTER => 58044
g.call
# => ["X", "Y", "Z"]
```
`mrb_env_unshare()` calls `mrb_realloc_simple()` and follows `mrb_full_gc()` to avoid an infinite loop where `mrb_env_unshare()` is called again.
This does not occur at this time, but may occur in subsequent patches.
`mrb_vm_run()` is,
- It does not change the fiber context.
- When control is returned, only one ci prepared by the caller is popped.
If the ci equals cibase when called, the ci position does not change.
related commits:
- commit 4e84bdb507
- commit 34dd258c63
- commit ebd6636a1e
- commit c6736357a7
- commit 23a4e7149d
- commit 31a961acf1
Previously `\x80` was incorrectly mapped to `0`.
```ruby
"\x80\x80\x80\x80".unpack("m*")
# before => "\x00\x00\x00"
# after => ""
```
The reason is that the C string terminator is placed in `base64_dec_tab[128]` and the array length is obtained by `sizeof`.
Therefore, the length of `base64_dec_tab[]` is strictly specified and replaced with element-by-element initialization.
Also, similar changes are made to `base64chars[]`.
- Don't create multiple envs on one ci.
- Don't share a env to different ci.
- Don't attach a closed env to any ci.
Changes in `envadjust()` can be simplified with those guarantees.
the worst case for `Array#reject!` (i.e. a proc always returning `true`)
is at least 5x worse than the worst case for `Array#select!` (proc
always returning `false`)
this commit unifies these implementations and inlines the (effective)
call of `#select!` in `#keep_if` and `#reject!` in `#delete_if`
Immediately frees the call stack and data stack at the end of a non-root fiber.
If the env object needs to be detached, the data stack is reused through `mrb_realloc()`.
Previously, it was not necessary to take into account that `c->cibase` could be `NULL`.
Note that this is no longer the case due to this patch.
In fact, changes to "mruby-fiber" are now required.
Yukihiro "Matz" Matsumoto