Create a new node subtype to allow execution directly in Meshroom environment

[Alxiice]

Meshroom/meshroom/core/node.py

Lines 705 to 707 in 507e2dc

	if not inCurrentEnv and self.node.getMrNodeType() == MrNodeType.NODE:
	self._processInIsolatedEnvironment()
	return

Because of this when we launch graph execution, any node based on desc.Node will execute in a subprocess.

On several occasions this isn't necessary, for example for nodes that will do a simple file lookup and don't require a specific environment. There is a workaround which is using desc.CommandLineNode with the processChunk method:

import os
from meshroom.core import desc

class GetFileExt(desc.CommandLineNode):
    inputs = [
        desc.File(
            name="path",
            value="",
            exposed=True,
        ),
    ]

    outputs = [
        desc.StringParam(
            name="extension",
            value=None,
        ),
    ]

    def processChunk(self, chunk):
        chunk.node.extension.value = os.path.splitext(chunk.node.path.value)[1]

Comparison:

mode	time
desc.Node	4.8s
desc.CommandLineNode	0.02s