Check if Rust lib needs rebuilding. (#13759)

This protects against the common mistake of failing to remember to rebuild Rust code after making changes.

synapse/util/rust.py

@@ -0,0 +1,84 @@
+# Copyright 2022 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import sys
+from hashlib import blake2b
+
+import synapse
+from synapse.synapse_rust import get_rust_file_digest
+
+
+def check_rust_lib_up_to_date() -> None:
+    """For editable installs check if the rust library is outdated and needs to
+    be rebuilt.
+    """
+
+    if not _dist_is_editable():
+        return
+
+    synapse_dir = os.path.dirname(synapse.__file__)
+    synapse_root = os.path.abspath(os.path.join(synapse_dir, ".."))
+
+    # Double check we've not gone into site-packages...
+    if os.path.basename(synapse_root) == "site-packages":
+        return
+
+    # ... and it looks like the root of a python project.
+    if not os.path.exists("pyproject.toml"):
+        return
+
+    # Get the hash of all Rust source files
+    hash = _hash_rust_files_in_directory(os.path.join(synapse_root, "rust", "src"))
+
+    if hash != get_rust_file_digest():
+        raise Exception("Rust module outdated. Please rebuild using `poetry install`")
+
+
+def _hash_rust_files_in_directory(directory: str) -> str:
+    """Get the hash of all files in a directory (recursively)"""
+
+    directory = os.path.abspath(directory)
+
+    paths = []
+
+    dirs = [directory]
+    while dirs:
+        dir = dirs.pop()
+        with os.scandir(dir) as d:
+            for entry in d:
+                if entry.is_dir():
+                    dirs.append(entry.path)
+                else:
+                    paths.append(entry.path)
+
+    # We sort to make sure that we get a consistent and well-defined ordering.
+    paths.sort()
+
+    hasher = blake2b()
+
+    for path in paths:
+        with open(os.path.join(directory, path), "rb") as f:
+            hasher.update(f.read())
+
+    return hasher.hexdigest()
+
+
+def _dist_is_editable() -> bool:
+    """Is distribution an editable install?"""
+    for path_item in sys.path:
+        egg_link = os.path.join(path_item, "matrix-synapse.egg-link")
+        if os.path.isfile(egg_link):
+            return True
+    return False