Add script to find slow-to-highlight files

tests/scripts/find-slow-to-highlight-files.py

@@ -0,0 +1,101 @@
+import time
+import os
+import subprocess as sp
+
+
+# Threshold speed in chars per second
+THRESHOLD_SPEED = 20000
+
+# Maximum time we allow `bat` to run
+BAT_TIMEOUT_SEC = 10
+
+# Maximum number of files to measure
+MAX_NUM_FILES = 100
+
+# Root folder for the search
+SEARCH_ROOT = os.getenv("HOME")
+
+
+def find_slow_files(startup_time, language, glob_pattern):
+    out = sp.check_output(
+        [
+            "fd",
+            "--hidden",
+            "--no-ignore",
+            "--type=file",
+            "--max-results",
+            str(MAX_NUM_FILES),
+            "--glob",
+            glob_pattern,
+            SEARCH_ROOT,
+        ]
+    )
+
+    paths = out.split(b"\n")[:-1]
+    print(f"Language: {language}, glob pattern: {glob_pattern} ({len(paths)} matches)")
+
+    for path in paths:
+        num_chars = int(sp.check_output(["wc", "-c", path]).split(b" ")[0].decode())
+
+        if num_chars < 500:
+            # It is hard to measure the exact speed for short files
+            continue
+
+        try:
+            start = time.time()
+            sp.check_output(["bat", "--color=always", path], timeout=BAT_TIMEOUT_SEC)
+            duration = time.time() - start - startup_time
+
+            if duration <= 0:
+                continue
+
+            highlighting_speed = num_chars / duration
+
+            if highlighting_speed < THRESHOLD_SPEED:
+                print(f"  {highlighting_speed:10.0f} chars/s:  {path.decode()}")
+
+        except sp.CalledProcessError:
+            print(f"  Error while highlighting file '{path.decode()}'.")
+
+        except sp.TimeoutExpired:
+            if num_chars < THRESHOLD_SPEED * BAT_TIMEOUT_SEC:
+                print(f"  Error: bat timed out on file '{path.decode()}'.")
+            else:
+                print(
+                    f"  Warning: bat timed out on file '{path.decode()} (but the file is large)."
+                )
+
+
+def measure_bat_startup_speed():
+    min_duration = None
+    for _ in range(20):
+        start = time.time()
+        p = sp.Popen(
+            ["bat", "--color=always", "--language=py"], stdin=sp.PIPE, stdout=sp.PIPE
+        )
+        p.communicate(input=b"test")
+        duration = time.time() - start
+
+        if not min_duration or duration < min_duration:
+            min_duration = duration
+
+    return min_duration
+
+
+def main():
+    print("Measuring 'bat' startup speed ... ", flush=True, end="")
+    startup_time = measure_bat_startup_speed()
+    print(f"{startup_time * 1000:.1f} ms")
+
+    output = sp.check_output(["bat", "--list-languages"]).decode()
+
+    for line in output.strip().split("\n"):
+        language, extensions = line.split(":")
+        for ext in extensions.split(","):
+            find_slow_files(startup_time, language, ext)
+            if not ext.startswith("."):
+                find_slow_files(startup_time, language, f"*.{ext}")
+
+
+if __name__ == "__main__":
+    main()