test_backend_sizes.py calculates space in the binary each backend uses #7998

bin/test_backend_sizes.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python3
+"""
+Test the sizes in the rclone binary of each backend by compiling
+rclone with and without the backend and measuring the difference.
+
+Run with no arguments to test all backends or a supply a list of
+backends to test.
+"""
+
+all_backends = "backend/all/all.go"
+
+# compile command which is more or less like the production builds
+compile_command = ["go", "build", "--ldflags", "-s", "-trimpath"]
+
+import os
+import re
+import sys
+import subprocess
+
+match_backend = re.compile(r'"github.com/rclone/rclone/backend/(.*?)"')
+
+def read_backends():
+    """
+    Reads the backends file, returning a list of backends and the original file
+    """
+    with open(all_backends) as fd:
+        orig_all = fd.read()
+    # find the backends
+    backends = []
+    for line in orig_all.split("\n"):
+        match = match_backend.search(line)
+        if match:
+            backends.append(match.group(1))
+    return backends, orig_all
+
+def write_all(orig_all, backend):
+    """
+    Write the all backends file without the backend given
+    """
+    with open(all_backends, "w") as fd:
+        for line in orig_all.split("\n"):
+            match = re.search(r'"github.com/rclone/rclone/backend/(.*?)"', line)
+            # Comment out line matching backend
+            if match and match.group(1) == backend:
+                line = "// " + line
+            fd.write(line+"\n")
+
+def compile():
+    """
+    Compile the binary, returning the size
+    """
+    subprocess.check_call(compile_command)
+    return os.stat("rclone").st_size
+        
+def main():
+    # change directory to the one with this script in
+    os.chdir(os.path.dirname(os.path.abspath(__file__)))
+    # change directory to the main rclone source
+    os.chdir("..")
+
+    to_test = sys.argv[1:]
+    backends, orig_all = read_backends()
+    if len(to_test) == 0:
+        to_test = backends
+    # Compile with all backends
+    ref = compile()
+    print(f"Total binary size {ref/1024/1024:.3f} MiB")
+    print("Backend,Size MiB")
+    for test_backend in to_test:
+        write_all(orig_all, test_backend)
+        new_size = compile()
+        print(f"{test_backend},{(ref-new_size)/1024/1024:.3f}")
+    # restore all file
+    with open(all_backends, "w") as fd:
+        fd.write(orig_all)
+
+if __name__ == "__main__":
+    main()