forge: served_drift_check summarise() DRY collapse 4 scans -> 1, is_fatal removed

tools/served_drift_check.py

@@ -77,6 +77,7 @@ import sys
 import urllib.error
 import urllib.parse
 import urllib.request
+from collections import Counter
 
 FATAL = ("DIFFERS", "MISSING", "HTTP_ERROR", "UNREACHABLE", "READ_FAILED")
 ADVISORY = ("SKIPPED_LARGE",)
@@ -189,15 +190,29 @@ def grade_one(root, rev, base, path, max_bytes, timeout):
     return row
 
 
-def is_fatal(row):
-    return row["verdict"] in FATAL
-
-
 def summarise(rows):
-    n_fatal = sum(1 for r in rows if is_fatal(r))
-    n_ok = sum(1 for r in rows if r["verdict"] == "OK")
-    n_skip = sum(1 for r in rows if r["verdict"] in ADVISORY)
-    return n_ok, n_fatal, n_skip
+    """One pass over `rows`: tally verdicts and the uncommitted worktree count.
+
+    Replaces the original's four `sum(1 for r in rows ...)` scans -- three
+    verdict passes across this function and the worktree pass in report() --
+    with a single iteration. Counter buckets verdicts; the dirty count is
+    incremented alongside, so each row is touched once, not four times.
+
+    n_fatal counts every row whose verdict is one of FATAL; n_ok is the OK
+    tally; n_skip the ADVISORY tally; n_dirty the rows carrying an
+    uncommitted worktree. Counter returns 0 for a verdict that never occurs,
+    matching `sum(1 for ...)` over an empty set.
+    """
+    counts = Counter()
+    n_dirty = 0
+    for r in rows:
+        counts[r["verdict"]] += 1
+        if r.get("worktree") == "modified":
+            n_dirty += 1
+    n_fatal = sum(counts[v] for v in FATAL)
+    n_ok = counts["OK"]
+    n_skip = sum(counts[v] for v in ADVISORY)
+    return n_ok, n_fatal, n_skip, n_dirty
 
 
 def worktree_dirty(root, rev):
@@ -241,8 +256,7 @@ def report(rows, out=sys.stdout, rev=None):
     width = max([len(r["path"]) for r in rows] + [4])
     for r in rows:
         out.write("  %-*s  %-12s  %s\n" % (width, r["path"], r["verdict"], r["detail"]))
-    n_ok, n_fatal, n_skip = summarise(rows)
-    n_dirty = sum(1 for r in rows if r.get("worktree") == "modified")
+    n_ok, n_fatal, n_skip, n_dirty = summarise(rows)
     if n_dirty:
         out.write("\nnote: %d path(s) are uncommitted against %s. The serve root is the"
                   " work tree, so a DIFFERS on those rows is an edit already on the host"
@@ -492,7 +506,7 @@ def main(argv=None):
             json.dump({"root": os.path.abspath(a.root), "rev": a.rev,
                        "base_url": a.base_url, "rows": rows}, fh, indent=1)
     if a.quiet:
-        n_ok, n_fatal, n_skip = summarise(rows)
+        n_ok, n_fatal, n_skip, _ = summarise(rows)
         print("served: %d files, %d OK, %d drift, %d skipped"
               % (len(rows), n_ok, n_fatal, n_skip))
         return 1 if n_fatal else 0