[PATCH net-next] tools: ynl: try to avoid the very slow YAML loader

[Jakub Kicinski <kuba@kernel.org>]

Turns out Python YAML defaults to a pure Python loader for YAML
files which is a lot slower than the C loader (using libyaml).
Try to use the C one whenever possible.

The avg time to run:
  $ tools/net/ynl/pyynl/cli.py --family tc --no-schema
drops from 300+ ms to 115 ms with this change (40 samples).

We could drop the load time further to 85 ms if we "compiled"
the specs to JSON. Slightly tricky parts are that we don't
currently install the specs at all on make install, so it's
unclear where to put the conversion. Also JSON has questionable
support for comments and we need an SPDX line.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: donald.hunter@gmail.com
---
 tools/net/ynl/pyynl/lib/nlspec.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/net/ynl/pyynl/lib/nlspec.py b/tools/net/ynl/pyynl/lib/nlspec.py
index fcffeb5b7ba3..0469a0e270d0 100644
--- a/tools/net/ynl/pyynl/lib/nlspec.py
+++ b/tools/net/ynl/pyynl/lib/nlspec.py
@@ -439,6 +439,11 @@ import yaml as pyyaml
     # To be loaded dynamically as needed
     jsonschema = None
 
+    try:
+        _yaml_loader = pyyaml.CSafeLoader
+    except AttributeError:
+        _yaml_loader = pyyaml.SafeLoader
+
     def __init__(self, spec_path, schema_path=None, exclude_ops=None):
         with open(spec_path, "r", encoding='utf-8') as stream:
             prefix = '# SPDX-License-Identifier: '
@@ -448,7 +453,7 @@ import yaml as pyyaml
             self.license = first[len(prefix):]
 
             stream.seek(0)
-            spec = pyyaml.safe_load(stream)
+            spec = pyyaml.load(stream, Loader=self._yaml_loader)
 
         self.fixed_header = None
         self._resolution_list = []
@@ -464,7 +469,7 @@ import yaml as pyyaml
             schema_path = os.path.dirname(os.path.dirname(spec_path)) + f'/{self.proto}.yaml'
         if schema_path:
             with open(schema_path, "r", encoding='utf-8') as stream:
-                schema = pyyaml.safe_load(stream)
+                schema = pyyaml.load(stream, Loader=self._yaml_loader)
 
             if SpecFamily.jsonschema is None:
                 SpecFamily.jsonschema = importlib.import_module("jsonschema")
-- 
2.54.0