[PATCH] scripts: avoid redundant re-reading makefiles.

[Alexander Pantyukhin <apantykhin@gmail.com>]

From: alexpantyukhin <apantykhin@gmail.com>

The main goal of the patch is avoid redundant re-reading makefiles 
if these were read before. This is performance improvement.

Additional code improvements are using 'with' when read file and check
if file exists.

Signed-off-by: Alexander Pantyukhin <apantykhin@gmail.com>
---
 scripts/generate_rust_analyzer.py | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index ecc7ea9a4dcf..e949f32b8123 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -98,13 +98,25 @@ def generate_crates(srctree, objtree, sysroot_src):
     # Then, the rest outside of `rust/`.
     #
     # We explicitly mention the top-level folders we want to cover.
+    makefile_path_content = {}
     for folder in ("samples", "drivers"):
         for path in (srctree / folder).rglob("*.rs"):
             logging.info("Checking %s", path)
             name = path.name.replace(".rs", "")
 
             # Skip those that are not crate roots.
-            if f"{name}.o" not in open(path.parent / "Makefile").read():
+            makefile_path = path.parent / "Makefile"
+
+            if makefile_path not in makefile_path_content:
+                if makefile_path.is_file():
+                    with open(makefile_path) as makefile:
+                        makefile_path_content[makefile_path] = makefile.read()
+
+                else:
+                    # If file is missing we consider it as empty-content file.
+                    makefile_path_content[makefile_path] = ""
+
+            if f"{name}.o" not in makefile_path_content[makefile_path]:
                 continue
 
             logging.info("Adding %s", name)
-- 
2.25.1