[Lorenz] Write git metadata to dependency graph .jsons

This makes it possible to know what revision a graph corresponds to,
so that users know how old the graph they are viewing is and makes it
possible to track regressions.

Bug: 1115268
Change-Id: Iedceabe885d90b14bb639e810dcaa75f48be844a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2353292Reviewed-by: Mohamed Heikal <mheikal@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821836}

tools/android/dependency_analysis/generate_json_dependency_graph.py

@@ -10,14 +10,13 @@ import math
 import multiprocessing
 import pathlib
 import os
-import subprocess
-import sys
 
 from typing import List, Tuple
 
 import class_dependency
 import package_dependency
 import serialization
+import subprocess_utils
 
 SRC_PATH = pathlib.Path(__file__).resolve().parents[3]  # src/
 JDEPS_PATH = SRC_PATH.joinpath('third_party/jdk/current/bin/jdeps')
@@ -89,28 +88,11 @@ class JavaClassJdepsParser(object):
             from_node.add_nested_class(nested_to)
 
 
-
-def _run_command(command: List[str]) -> str:
-    """Runs a command and returns the output.
-
-    Raises an exception and prints the command output if the command fails."""
-    try:
-        run_result = subprocess.run(command,
-                                    capture_output=True,
-                                    text=True,
-                                    check=True)
-    except subprocess.CalledProcessError as e:
-        print(f'{command} failed with code {e.returncode}.', file=sys.stderr)
-        print(f'\nSTDERR:\n{e.stderr}', file=sys.stderr)
-        print(f'\nSTDOUT:\n{e.stdout}', file=sys.stderr)
-        raise
-    return run_result.stdout
-
-
 def _run_jdeps(jdeps_path: str, filepath: pathlib.Path) -> str:
     """Runs jdeps on the given filepath and returns the output."""
     print(f'Running jdeps and parsing output for {filepath}')
-    return _run_command([jdeps_path, '-R', '-verbose:class', filepath])
+    return subprocess_utils.run_command(
+        [jdeps_path, '-R', '-verbose:class', filepath])
 
 
 def _run_gn_desc_list_dependencies(build_output_dir: str, target: str,
@@ -118,7 +100,7 @@ def _run_gn_desc_list_dependencies(build_output_dir: str, target: str,
     """Runs gn desc to list all jars that a target depends on.
 
     This includes direct and indirect dependencies."""
-    return _run_command(
+    return subprocess_utils.run_command(
         [gn_path, 'desc', '--all', build_output_dir, target, 'deps'])
 
 
@@ -191,7 +173,7 @@ def main():
                             help='Path to the gn executable.')
     arguments = arg_parser.parse_args()
 
-    # gn must be run from inside the git checkout.
+    # gn and git must be run from inside the git checkout.
     os.chdir(SRC_PATH)
 
     print('Getting list of dependency jars...')

tools/android/dependency_analysis/git_utils.py

+# Lint as: python3
+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Helper module for retrieving git metadata."""
+
+import re
+
+import subprocess_utils
+
+
+def get_last_commit_hash() -> str:
+    """Get the git hash of the last git commit to the git repo.
+
+    The cwd must be a git repository.
+    """
+    return _get_last_commit_with_format('%H')
+
+
+def get_last_commit_time() -> str:
+    """Get the commit date/time of the last git commit to the git repo.
+
+    The cwd must be a git repository.
+    """
+    return _get_last_commit_with_format('%cd')
+
+
+def get_last_commit_cr_position() -> str:
+    """Get the cr position of the last git commit to the git repo.
+
+    This is the number that follows "Cr-Commit-Position:". In the absence of
+    this value, returns an empty string.
+
+    The cwd must be a chromium git repository.
+    """
+    description: str = _get_last_commit_with_format('%b')
+    # Will capture from
+    # '[lines...]Cr-Commit-Position: refs/heads/master@{#123456}' the string
+    # '123456'.
+    CR_POSITION_REGEX = r'Cr-Commit-Position: .*{#([0-9]+)}'
+    match: re.Match = re.search(CR_POSITION_REGEX, description)
+    if match is None:
+        return ''
+    return match.group(1)
+
+
+def _get_last_commit_with_format(format: str) -> str:
+    output_str: str = subprocess_utils.run_command(
+        ['git', 'show', '--no-patch', f'--pretty=format:{format}'])
+    return output_str.strip('\n')

tools/android/dependency_analysis/json_consts.py

@@ -12,7 +12,13 @@ EDGES = 'edges'
 BEGIN = 'begin'
 END = 'end'
 
+# Build metadata attributes.
+COMMIT_HASH = 'commit_hash'
+COMMIT_CR_POSITION = 'commit_cr_position'
+COMMIT_TIME = 'commit_time'
+
 # Miscellaneous attributes.
 PACKAGE_GRAPH = 'package_graph'
 CLASS_GRAPH = 'class_graph'
+BUILD_METADATA = 'build_metadata'
 META = 'meta'

tools/android/dependency_analysis/serialization.py

@@ -8,6 +8,7 @@ from typing import Dict, Tuple
 
 import class_dependency
 import class_json_consts
+import git_utils
 import graph
 import json_consts
 import package_dependency
@@ -92,6 +93,17 @@ def create_class_graph_from_json_obj(
     return class_graph
 
 
+def create_build_metadata() -> Dict:
+    """Creates metadata about the build the graph was extracted from.
+    """
+    return {
+        json_consts.COMMIT_HASH: git_utils.get_last_commit_hash(),
+        json_consts.COMMIT_CR_POSITION:
+        git_utils.get_last_commit_cr_position(),
+        json_consts.COMMIT_TIME: git_utils.get_last_commit_time(),
+    }
+
+
 def dump_class_and_package_graphs_to_file(
         class_graph: class_dependency.JavaClassDependencyGraph,
         package_graph: package_dependency.JavaPackageDependencyGraph,
@@ -113,6 +125,7 @@ def dump_class_and_package_graphs_to_file(
     json_obj = {
         json_consts.CLASS_GRAPH: create_json_obj_from_graph(class_graph),
         json_consts.PACKAGE_GRAPH: create_json_obj_from_graph(package_graph),
+        json_consts.BUILD_METADATA: create_build_metadata(),
     }
     with open(filename, 'w') as json_file:
         json.dump(json_obj, json_file, separators=(',', ':'))

tools/android/dependency_analysis/subprocess_utils.py

+#!/usr/bin/env python3
+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Utils to run subprocesses."""
+
+import subprocess
+import sys
+
+from typing import List
+
+
+def run_command(command: List[str]) -> str:
+    """Runs a command and returns the output.
+
+    Raises an exception and prints the command output if the command fails."""
+    try:
+        run_result = subprocess.run(command,
+                                    capture_output=True,
+                                    text=True,
+                                    check=True)
+    except subprocess.CalledProcessError as e:
+        print(f'{command} failed with code {e.returncode}.', file=sys.stderr)
+        print(f'\nSTDERR:\n{e.stderr}', file=sys.stderr)
+        print(f'\nSTDOUT:\n{e.stdout}', file=sys.stderr)
+        raise
+    return run_result.stdout