Merge unseen-revert-materialize: lazy blob fetch, drop broken prefetch

Co-Authored-By: Claude Opus 4.8 <[email protected]>

benchmarks/unseen/draft.py

@@ -154,7 +154,7 @@ class Clones:
             git = Git(path, runner=self.runner, limit_bytes=self.limit_bytes, deadline_seconds=self.deadline_seconds)
             try:
                 # Full commit graph is needed for temporal thirds and OSV brackets.
-                # repository_changes batches blobs before reading their content.
+                # Content reads fetch blobs on demand through Git's promisor mechanism.
                 done = self.runner(
                     ["git", "-c", "credential.helper=", "clone", "--quiet", "--filter=blob:none", "--no-checkout", url, str(path)],
                     stdin=subprocess.DEVNULL,
@@ -222,8 +222,6 @@ def repository_changes(git, candidate, fixes: set[str], *, seed: int):
         except InstrumentFailure as exc:
             if fix == candidate.fix or not str(exc).startswith("git_exit_"):
                 raise
-    # Batch only resolved histories before diff/show/blame can fetch per-file blobs.
-    git.materialize(["HEAD", *resolved])
     proof = prove_source(git, candidate.parent)
     change = extract.introducing(git, candidate)
     known = set()

benchmarks/unseen/extract.py

@@ -53,12 +53,12 @@ class Git:
             raise ExtractionTimeout("extraction_timeout")
         return min(180, remaining)
 
-    def run(self, *args: str, allowed=(0,), input_data: bytes | None = None) -> str:
+    def run(self, *args: str, allowed=(0,)) -> str:
         timeout = self.command_timeout()
         try:
             done = self.runner(
                 ["git", "-c", "core.quotePath=false", "-C", str(self.path), *args],
-                **({"stdin": subprocess.DEVNULL} if input_data is None else {"input": input_data}),
+                stdin=subprocess.DEVNULL,
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
                 timeout=timeout,
@@ -75,38 +75,6 @@ class Git:
         self.last_blob_bytes = len(done.stdout)
         return done.stdout.decode("utf-8", errors="replace")
 
-    def materialize(self, revisions: list[str]) -> None:
-        """Fetch missing historical blobs in one pack, without changing content reads.
-
-        ordinary_history inspects the complete first-parent history, including both
-        sides, attributes and non-source diffs. Blame -M/-C and log -L can walk all
-        ancestors and copy sources. Include the reachable trees, not only tip files,
-        so these commands keep exactly their original semantics. This is a safe
-        superset (merge-side trees included), still subject to the disk/deadline caps.
-        Missing-object enumeration itself does not trigger lazy blob fetches.
-        """
-        data = ("\n".join(revisions) + "\n").encode()
-        objects = self.run("rev-list", "--objects", "--missing=print", "--stdin", input_data=data)
-        missing = sorted({line[1:] for line in objects.splitlines() if line.startswith("?")})
-        if not all(SHA.fullmatch(oid) for oid in missing):
-            raise InstrumentFailure("invalid_missing_object")
-        if missing:
-            # stdin avoids argv limits; explicit object wants avoid one promisor
-            # request per show/blame. --no-filter overrides clone's stored filter.
-            self.run(
-                "fetch",
-                "--quiet",
-                "--no-tags",
-                "--no-write-fetch-head",
-                "--no-filter",
-                "--stdin",
-                "origin",
-                input_data=("\n".join(missing) + "\n").encode(),
-            )
-            remaining = self.run("rev-list", "--objects", "--missing=print", "--stdin", input_data=data)
-            if any(line.startswith("?") for line in remaining.splitlines()):
-                raise InstrumentFailure("missing_blobs_after_fetch")
-
     def disk_bytes(self) -> int:
         # git churns .git/objects/pack (incl. transient *.rev) during on-demand blob
         # fetches, so a path rglob just listed can vanish before stat(): skip it.

tests/test_unseen_draft.py

@@ -553,9 +553,6 @@ def test_repository_changes_excludes_all_advisory_sites(monkeypatch):
                 return "app.py\n"
             return args[-1] if args[0] == "rev-parse" else ""
 
-        def materialize(self, revisions):
-            assert revisions == ["HEAD", "a" * 40, "d" * 40]
-
         def blob(self, revision, path):
             return "def handler():\n    return 1\n"
 
@@ -615,9 +612,6 @@ def test_repository_extra_fixes_are_best_effort(tmp_path, monkeypatch, stage):
             return subprocess.CompletedProcess(argv, 1, b"", b"unavailable ref")
         if operation == "rev-parse":
             output = ref + "\n"
-        elif operation == "rev-list" and "--objects" in args:
-            assert kwargs["input"] == ("\n".join(["HEAD", *resolved]) + "\n").encode()
-            output = ""
         elif operation == "rev-list":
             assert ref in resolved
             output = f"{ref} {candidate.parent}\n"
@@ -658,7 +652,7 @@ def test_repository_extra_fixes_are_best_effort(tmp_path, monkeypatch, stage):
         fetches = [args for args, _ in commands if args[0] == "fetch"]
         assert [args[-1] for args in fetches] == [candidate.fix, missing, available]
         assert all("--no-tags" in args for args in fetches[1:])
-        assert sum("--objects" in args for args, _ in commands) == 1
+        assert not any("--objects" in args for args, _ in commands)
         if stage == "extra_fetch":
             assert not any(args == ["rev-parse", missing] for args, _ in commands)
 

tests/test_unseen_extract.py

@@ -374,7 +374,7 @@ def test_disk_bytes_skips_files_that_vanish_mid_walk(tmp_path):
     assert git.disk_bytes() == 30
 
 
-def test_partial_clone_batch_matches_lazy_bytes_without_per_file_fetches(history, tmp_path):
+def test_partial_clone_lazy_fetch_preserves_extraction_content(history, tmp_path):
     """Real promisor packs over file:// only: count lazy fetches via Git's trace."""
     import json
     import os
@@ -388,59 +388,23 @@ def test_partial_clone_batch_matches_lazy_bytes_without_per_file_fetches(history
     git.run("config", "uploadpack.allowFilter", "true")
     git.run("config", "uploadpack.allowAnySHA1InWant", "true")
     baseline = [e.introducing(git, candidate), e.ordinary_history(git, "HEAD")]
-    results, fetches = [], []
-    for batch in (False, True):
-        path = tmp_path / ("batch" if batch else "lazy")
-        trace = tmp_path / (path.name + ".trace")
-        # Local file transport only, no network. No checkout: all blobs start missing.
-        subprocess.run(
-            ["git", "clone", "--quiet", "--filter=blob:none", "--no-checkout", tmp_path.as_uri(), str(path)],
-            check=True,
-            capture_output=True,
-        )
-        commands = []
-
-        def runner(argv, commands=commands, trace=trace, **kwargs):
-            commands.append(argv)
-            return subprocess.run(argv, **kwargs, env={**os.environ, "GIT_TRACE": str(trace), "GIT_ALLOW_PROTOCOL": "file"})
-
-        partial = e.Git(path, runner=runner)
-        missing = partial.run("rev-list", "--objects", "--missing=print", "HEAD")
-        assert sum(line.startswith("?") for line in missing.splitlines()) >= 60
-        if batch:
-            partial.materialize(["HEAD", candidate.fix])
-        results.append([e.introducing(partial, candidate), e.ordinary_history(partial, "HEAD")])
-        assert partial.files_read > 0 and partial.bytes_read > 0
-        fetches.append(sum("built-in: git fetch " in line for line in trace.read_text().splitlines()))
-        if batch:
-            assert sum("fetch" in argv for argv in commands) == 1
-            partial.materialize(["HEAD", candidate.fix])  # Already hydrated: no second fetch.
-            assert sum("fetch" in argv for argv in commands) == 1
-    assert json.dumps(results[0], sort_keys=True).encode() == json.dumps(results[1], sort_keys=True).encode()
-    assert results[1] == baseline
-    assert fetches[0] >= 12 and fetches[1] == 1
-
-
-def test_materialize_timeout_uses_repository_deadline_and_checks_completeness(tmp_path):
-    oid = "a" * 40
-    calls = []
-    now = [0.0]
+    path = tmp_path / "lazy"
+    trace = tmp_path / "lazy.trace"
+    # Local file transport only, no network. No checkout: all blobs start missing.
+    subprocess.run(
+        ["git", "clone", "--quiet", "--filter=blob:none", "--no-checkout", tmp_path.as_uri(), str(path)],
+        check=True,
+        capture_output=True,
+        env={**os.environ, "GIT_ALLOW_PROTOCOL": "file"},
+    )
 
     def runner(argv, **kwargs):
-        calls.append((argv, kwargs))
-        if "fetch" in argv:
-            assert kwargs["timeout"] == 3
-            assert kwargs["input"] == (oid + "\n").encode()
-            raise subprocess.TimeoutExpired(argv, kwargs["timeout"])
-        now[0] += 7
-        return subprocess.CompletedProcess(argv, 0, ("?" + oid + "\n").encode(), b"")
+        return subprocess.run(argv, **kwargs, env={**os.environ, "GIT_TRACE": str(trace), "GIT_ALLOW_PROTOCOL": "file"})
 
-    with pytest.raises(e.ExtractionTimeout, match="extraction_timeout"):
-        e.Git(tmp_path, runner=runner, deadline_seconds=10, _now=lambda: now[0]).materialize(["HEAD"])
-    assert len(calls) == 2
-
-    def incomplete(argv, **kwargs):
-        return subprocess.CompletedProcess(argv, 0, ("?" + oid + "\n").encode(), b"")
-
-    with pytest.raises(e.InstrumentFailure, match="missing_blobs_after_fetch"):
-        e.Git(tmp_path, runner=incomplete).materialize(["HEAD"])
+    partial = e.Git(path, runner=runner)
+    missing = partial.run("rev-list", "--objects", "--missing=print", "HEAD")
+    assert sum(line.startswith("?") for line in missing.splitlines()) >= 60
+    result = [e.introducing(partial, candidate), e.ordinary_history(partial, "HEAD")]
+    assert partial.files_read > 0 and partial.bytes_read > 0
+    assert json.dumps(result, sort_keys=True).encode() == json.dumps(baseline, sort_keys=True).encode()
+    assert sum("built-in: git fetch " in line for line in trace.read_text().splitlines()) >= 12