fetch-assets: add --delete option to clear targetdir of unwanted files

This removes all files we no longer need from the target, while keeping
files where the mtime and size match and wont re-download them.

This is useful for keeping a directory in sync via a cron job for example.

autobuild.py

@@ -1164,7 +1164,7 @@ def upload_assets(args: Any) -> None:
 
 def fetch_assets(args: Any) -> None:
     repo = get_repo()
-    target_dir = args.targetdir
+    target_dir = os.path.abspath(args.targetdir)
     fetch_all = args.fetch_all
 
     all_patterns: Dict[str, List[str]] = {}
@@ -1185,7 +1185,7 @@ def fetch_assets(args: Any) -> None:
                         (pkg["name"], build_type, pkg.get_status_details(build_type)))
 
     all_assets = {}
-    to_download: Dict[str, List[GitReleaseAsset]] = {}
+    assets_to_download: Dict[str, List[GitReleaseAsset]] = {}
     for repo_type, patterns in all_patterns.items():
         if repo_type not in all_assets:
             release = get_release(repo, 'staging-' + repo_type)
@@ -1200,46 +1200,82 @@ def fetch_assets(args: Any) -> None:
             matches = fnmatch.filter(assets_mapping.keys(), pattern)
             if matches:
                 found = assets_mapping[matches[0]]
-                to_download.setdefault(repo_type, []).extend(found)
+                assets_to_download.setdefault(repo_type, []).extend(found)
 
-    todo = []
-    done = []
-    for repo_type, assets in to_download.items():
+    to_fetch = {}
+    for repo_type, assets in assets_to_download.items():
         for asset in assets:
             asset_dir = Path(target_dir) / get_repo_subdir(repo_type, asset)
-            asset_dir.mkdir(parents=True, exist_ok=True)
             asset_path = asset_dir / get_asset_filename(asset)
-            if asset_path.exists():
+            to_fetch[str(asset_path)] = asset
+
+    def file_is_uptodate(path, asset):
+        asset_path = Path(path)
+        if not asset_path.exists():
+            return False
         if asset_path.stat().st_size != asset.size:
-                    print(f"Warning: {asset_path} already exists "
-                          f"but has a different size")
+            return False
         if get_asset_mtime_ns(asset) != asset_path.stat().st_mtime_ns:
-                    print(f"Warning: {asset_path} already exists "
-                          f"but has a different mtime")
-                done.append(asset)
-                continue
-            todo.append((asset, asset_path))
+            return False
+        return True
+
+    # find files that are either wrong or not what we want
+    to_delete = []
+    not_uptodate = []
+    for root, dirs, files in os.walk(target_dir):
+        for name in files:
+            existing = os.path.join(root, name)
+            if existing in to_fetch:
+                asset = to_fetch[existing]
+                if not file_is_uptodate(existing, asset):
+                    to_delete.append(existing)
+                    not_uptodate.append(existing)
+            else:
+                to_delete.append(existing)
+
+    if args.delete and not args.pretend:
+        # delete unwanted files
+        for path in to_delete:
+            os.remove(path)
+
+        # delete empty directories
+        for root, dirs, files in os.walk(target_dir, topdown=False):
+            for name in dirs:
+                path = os.path.join(root, name)
+                if not os.listdir(path):
+                    os.rmdir(path)
+
+    # Finally figure out what to download
+    todo = {}
+    done = []
+    for path, asset in to_fetch.items():
+        if not os.path.exists(path) or path in not_uptodate:
+            todo[path] = asset
+            Path(path).parent.mkdir(parents=True, exist_ok=True)
+        else:
+            done.append(path)
 
     if args.verbose and all_blocked:
         import pprint
         print("Packages that are blocked and why:")
         pprint.pprint(all_blocked)
 
-    print(f"downloading: {len(todo)}, done: {len(done)}, "
+    print(f"downloading: {len(todo)}, done: {len(done)} "
           f"blocked: {len(all_blocked)} (related builds missing)")
 
     print("Pass --verbose to see the list of blocked packages.")
     print("Pass --fetch-all to also fetch blocked packages.")
+    print("Pass --delete to clear the target directory")
 
     def fetch_item(item):
-        asset, asset_path = item
+        asset_path, asset = item
         if not args.pretend:
             download_asset(asset, asset_path)
         return item
 
     with ThreadPoolExecutor(8) as executor:
-        for i, item in enumerate(executor.map(fetch_item, todo)):
-            print(f"[{i + 1}/{len(todo)}] {get_asset_filename(item[0])}")
+        for i, item in enumerate(executor.map(fetch_item, todo.items())):
+            print(f"[{i + 1}/{len(todo)}] {get_asset_filename(item[1])}")
 
     print("done")
 
@@ -1404,6 +1440,8 @@ def main(argv: List[str]) -> None:
     sub = subparser.add_parser(
         "fetch-assets", help="Download all staging packages", allow_abbrev=False)
     sub.add_argument("targetdir")
+    sub.add_argument(
+        "--delete", action="store_true", help="Clear targetdir of unneeded files")
     sub.add_argument(
         "--verbose", action="store_true", help="Show why things are blocked")
     sub.add_argument(