Cache debugger skip frame predicate

[Carreau]

I'm not 100% sure this is correct as technically the value of
debugger_skip could change in the current frame while we are
stepping into it, but that is likely super rare, and the slowdown
that this create is problematic.

There is still a small overhead for me, but this should make the
experience much better.

See spyder-ide/spyder-kernels#458, #13972, spyder-ide/spyder#20571, #14382

[Carreau]

Here is a quick way to test:

$ ipython
Python 3.11.0 | packaged by conda-forge | (main, Oct 25 2022, 06:21:25) [Clang 14.0.4 ]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.24.0.dev -- An enhanced Interactive Python. Type '?' for help.

In [1]: !cat test.py
from time import perf_counter

now = perf_counter()
for x in range(1000000):
    if x % 100_000 == 0:
        print(x)
print("done", perf_counter() - now)

In [2]: %run -d test.py
Breakpoint 1 at /Users/bussonniermatthias/test.py:1
NOTE: Enter 'c' at the ipdb>  prompt to continue execution.
> /Users/bussonniermatthias/test.py(1)<module>()
1---> 1 from time import perf_counter
      2
      3 now = perf_counter()
      4 for x in range(1000000):
      5     if x % 100_000 == 0:

ipdb> skip_predicates debuggerskip true
ipdb> c
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
done 3.4291042499244213

In [3]: %run -d test.py
Breakpoint 1 at /Users/bussonniermatthias/test.py:1
NOTE: Enter 'c' at the ipdb>  prompt to continue execution.
> /Users/bussonniermatthias/test.py(1)<module>()
1---> 1 from time import perf_counter
      2
      3 now = perf_counter()
      4 for x in range(1000000):
      5     if x % 100_000 == 0:

ipdb> skip_predicates debuggerskip false
ipdb> c
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
done 3.189767000032589

On 8.23, the version with skip_predicates debuggerskip true, will be unbearably slow (18sec vs 3.5sec on my machine)

You can try to change the values of debugger skip before entering the debugger.

ip = get_ipython()
if not ip.InteractiveTB.pdb:
    ip.InteractiveTB.pdb = ip.InteractiveTB.debugger_cls()

ip.InteractiveTB.pdb._predicates['debuggerskip'] = False # True by default.