Store Object signals in a HashMap rather than a VMap

[myaaaaaaaaa]

Fixes #69874

[akien-mga]

Can you share benchmark results to assess the gain?

[myaaaaaaaaa]

Sure, with the caveat that these numbers are from a debug build

Code:

extends Benchmark

func build_node(num_signals: int) -> Node3D:
	var mesh := ArrayMesh.new()
	var rt := MeshInstance3D.new()
	for i in num_signals:
		var n := MeshInstance3D.new()
		rt.add_child(n)

		# Implicitly connects a changed signal
		n.mesh = mesh

	return rt

func benchmark_signals():
	for i in [2,20,200,2000]:
		print()
		print("num_signals: ", i)
		var m := Time.get_ticks_usec()
		for j in 10: #More reliable timing
			build_node(i).free()
		print("%.3f ms" % ((Time.get_ticks_usec() - m) / 10 / 1e3))

Before: ( Using #72346 for consistent behavior, see that for details )

num_signals: 2
0.223 ms

num_signals: 20
1.612 ms

num_signals: 200
25.631 ms

num_signals: 2000
1421.480 ms

After: ( Note how scaling is now linear )

num_signals: 2
0.221 ms

num_signals: 20
1.368 ms

num_signals: 200
13.461 ms

num_signals: 2000
124.343 ms

[Calinou]

Tested locally (rebased against latest master), it works. I ran a few projects of mine without issue.

[reduz]

The only problem with this approach is that emission (which is more critical than connection time) could be slower. It would be nice to benchmark this in exchange.

[akien-mga]

The only problem with this approach is that emission (which is more critical than connection time) could be slower. It would be nice to benchmark this in exchange.

@myaaaaaaaaa Would you have time to do a quick test for this?

[myaaaaaaaaa]

The only problem with this approach is that emission (which is more critical than connection time) could be slower. It would be nice to benchmark this in exchange.

@myaaaaaaaaa Would you have time to do a quick test for this?

Preliminary testing (with dev builds) seems to show that the difference is within the margin of error (1.8%)

Code: https://github.com/godotengine/godot-benchmarks/pull/30/files

Results:

{
	"category": "Core > Signal",
	"name": "Emission",
	"results": {
		"time": {
			"a": 1934,
			"b": 1969,
			"a_div_b": 0.9822244794311833
		}
	}
}

[akien-mga]

Thanks!