implement basic github action comment reporting target diffs (#9022)

This is missing logic:
- report average
- don't bother reporting if the results are negligeable
- praise the user if it's improving the situation
- shame the user if it's not improving the situation

bin/shame.py

@@ -0,0 +1,101 @@
+import sys
+import os
+import json
+from github import Github
+
+def parseFile(path):
+    with open(path, "r") as f:
+        data = json.loads(f)
+    for file in data["files"]:
+        if file["name"].endswith(".bin"):
+            return file["name"], file["bytes"]
+
+if len(sys.argv) != 4:
+    print(f"expected usage: {sys.argv[0]} <PR number> <path to old-manifests> <path to new-manifests>")
+    sys.exit(1)
+
+pr_number = int(sys.argv[1])
+
+token = os.getenv("GITHUB_TOKEN")
+if not token:
+    raise EnvironmentError("GITHUB_TOKEN not found in environment.")
+
+repo_name = os.getenv("GITHUB_REPOSITORY")  # "owner/repo"
+if not repo_name:
+    raise EnvironmentError("GITHUB_REPOSITORY not found in environment.")
+
+oldFiles = sys.argv[2]
+old = set(os.path.join(oldFiles, f) for f in os.listdir(oldFiles) if os.path.isfile(f))
+newFiles = sys.argv[3]
+new = set(os.path.join(newFiles, f) for f in os.listdir(newFiles) if os.path.isfile(f))
+
+startMarkdown = "# Target Size Changes\n\n"
+markdown = ""
+
+newlyIntroduced = new - old
+if len(newlyIntroduced) > 0:
+    markdown += "## Newly Introduced Targets\n\n"
+    # create a table
+    markdown += "| File | Size |\n"
+    markdown += "| ---- | ---- |\n"
+    for f in newlyIntroduced:
+        name, size = parseFile(f)
+        markdown += f"| `{name}` | {size}b |\n"
+
+removed = old - new
+if len(removed) > 0:
+    markdown += "\n## Removed Targets\n\n"
+    # create a table
+    markdown += "| File | Size |\n"
+    markdown += "| ---- | ---- |\n"
+    for f in removed:
+        name, size = parseFile(f)
+        markdown += f"| `{name}` | {size}b |\n"
+
+both = old & new
+degradations = []
+improvements = []
+for f in both:
+    oldName, oldSize = parseFile(f)
+    _, newSize = parseFile(f)
+    if oldSize != newSize:
+        if newSize < oldSize:
+            improvements.append((oldName, oldSize, newSize))
+        else:
+            degradations.append((oldName, oldSize, newSize))
+
+if len(degradations) > 0:
+    markdown += "\n## Degradation\n\n"
+    # create a table
+    markdown += "| File | Difference | Old Size | New Size |\n"
+    markdown += "| ---- | ---------- | -------- | -------- |\n"
+    for oldName, oldSize, newSize in degradations:
+        markdown += f"| `{oldName}` | **{oldSize - newSize}b** | {oldSize}b | {newSize}b |\n"
+
+if len(improvements) > 0:
+    markdown += "\n## Improvement\n\n"
+    # create a table
+    markdown += "| File | Difference | Old Size | New Size |\n"
+    markdown += "| ---- | ---------- | -------- | -------- |\n"
+    for oldName, oldSize, newSize in improvements:
+        markdown += f"| `{oldName}` | **{oldSize - newSize}b** | {oldSize}b | {newSize}b |\n"
+
+if len(markdown) == 0:
+    markdown = "No changes in target sizes detected."
+
+g = Github(token)
+repo = g.get_repo(repo_name)
+pr = repo.get_pull(pr_number)
+
+existing_comment = None
+for comment in pr.get_issue_comments():
+    if comment.body.startswith(startMarkdown):
+        existing_comment = comment
+        break
+
+final_markdown = startMarkdown + markdown
+
+if existing_comment:
+    existing_comment.edit(body=final_markdown)
+else:
+    pr.create_issue_comment(body=final_markdown)