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Merge wave1 branch a28a4552ac56e246c (bug fixes)

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Oleks
2026-07-08 16:30:02 +03:00
parent 31fa848ed0 ffc4494486
commit 53bbcb678d
2 changed files with 190 additions and 14 deletions
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nix_estimator/graph.py
+95 -14
View File
@@ -61,29 +61,31 @@ def derivation_closure(
return {_basename(k): v for k, v in raw.items()}
def to_build_set(
attr: str, system: str | None = None, extra_args: list[str] | None = None
) -> set[str] | None:
"""Set of ``.drv`` paths Nix says *will be built*, or ``None`` if unparseable.
def parse_dry_run_text(text: str, returncode: int = 0) -> set[str] | None:
"""Parse the *human* text of ``nix build --dry-run`` into a to-build set.
``None`` signals the caller to fall back to "the whole closure" (a cold-cache
over-estimate) rather than silently reporting zero work.
Tri-state result (see :func:`to_build_set`):
- a ``set`` of drv basenames when the dry-run structure was recognized
(possibly empty — a fully warm cache prints only "will be fetched");
- ``None`` when no recognizable dry-run structure was found at all, so the
caller cannot tell built-nothing from parse-failure.
A dry-run is considered "recognized" when the process exited cleanly *or* a
known section header ("will be built"/"will be fetched"/"will be copied") was
seen. ``returncode`` is the ``nix`` exit status (0 = success).
"""
cmd = ["nix", "build", "--dry-run", attr]
if system:
cmd += ["--system", system]
if extra_args:
cmd += extra_args
proc = _run(cmd, check=False)
text = proc.stderr + "\n" + proc.stdout
built: set[str] = set()
saw_header = False
grabbing = False
for line in text.splitlines():
s = line.strip()
if re.search(r"will be built", s):
saw_header = True
grabbing = True
continue
if re.search(r"will be fetched|will be copied", s):
saw_header = True
grabbing = False
continue
if grabbing:
@@ -92,7 +94,82 @@ def to_build_set(
built.add(_basename(m.group(1)))
elif s and not s.startswith("/nix/store"):
grabbing = False
return built or None
if not saw_header and returncode != 0:
return None
return built
def parse_dry_run_json(text: str) -> set[str] | None:
"""Parse ``nix build --dry-run --json`` output into a to-build set.
The JSON form is a list of build results; each entry names its derivation
under ``drvPath`` (or, on some schemas, ``drv``). Locale- and wording-proof,
unlike the human text. Returns a ``set`` of drv basenames (possibly empty),
or ``None`` when the payload is not the expected structured shape so the
caller can fall back to the text scraper.
"""
try:
data = json.loads(text)
except (ValueError, TypeError):
return None
if not isinstance(data, list):
return None
built: set[str] = set()
for entry in data:
if not isinstance(entry, dict):
return None
drv = entry.get("drvPath") or entry.get("drv")
if drv:
built.add(_basename(drv))
return built
def _supports_dry_run_json() -> bool:
"""Probe whether this ``nix`` accepts ``build --dry-run --json`` at all.
``--json`` on ``nix build`` is unsupported on older Nix; parsing ``--help``
is cheap and detects support without evaluating anything.
"""
try:
help_text = _run(["nix", "build", "--help"], check=False).stdout
except (OSError, subprocess.SubprocessError):
return False
return "--json" in help_text
def to_build_set(
attr: str, system: str | None = None, extra_args: list[str] | None = None
) -> set[str] | None:
"""Set of ``.drv`` basenames Nix says *will be built*, tri-state.
Returns an empty ``set`` when the dry-run clearly succeeded but nothing will
be built (fully warm cache), a populated ``set`` of the drvs to build, and
``None`` *only* when the dry-run produced nothing recognizable — the sole
case in which the caller should fall back to costing the whole closure.
Prefers structured ``--dry-run --json`` output when this ``nix`` supports it
(robust across versions and locales), falling back to scraping human text.
"""
base = ["nix", "build", "--dry-run", attr]
if system:
base += ["--system", system]
if extra_args:
base += extra_args
if _supports_dry_run_json():
try:
proc = _run(base + ["--json"], check=False)
except (OSError, subprocess.SubprocessError):
proc = None
if proc is not None:
parsed = parse_dry_run_json(proc.stdout)
if parsed is not None:
return parsed
# JSON unavailable/unusable at runtime: fall through to text scraper.
proc = _run(base, check=False)
text = proc.stderr + "\n" + proc.stdout
return parse_dry_run_text(text, proc.returncode)
def build_dag(
@@ -101,6 +178,10 @@ def build_dag(
"""Return ``(preds, nodes)`` where ``preds[d]`` are the in-graph derivations
``d`` depends on. Restricted to ``to_build`` when given (edges to already-cached
inputs are dropped — they contribute no build time).
``to_build`` is tri-state: ``None`` means "cache state unknown" so the whole
closure is costed; an *empty* set means "nothing to build" (warm cache) and
yields no nodes; a populated set restricts to those drvs.
"""
nodes = set(closure) if to_build is None else (set(to_build) & set(closure))
preds: dict[str, list[str]] = {}
tests/test_graph.py
+95
View File
@@ -0,0 +1,95 @@
"""Tests for dry-run parsing and DAG restriction in :mod:`nix_estimator.graph`."""
from nix_estimator import graph
# --- captured `nix build --dry-run` text (issue #5) ------------------------
WARM = """\
this path will be fetched (0.02 MiB download, 0.10 MiB unpacked):
/nix/store/aaa-hello-2.12.1
"""
PARTIAL = """\
these 2 derivations will be built:
/nix/store/bbb-foo-1.0.drv
/nix/store/ccc-bar-2.0.drv
these 3 paths will be fetched (1.0 MiB download):
/nix/store/ddd-baz-3.0
"""
GARBAGE = """\
error: some totally unrelated failure with no dry-run structure
traceback blah blah
"""
def test_warm_cache_only_fetched_is_empty_set():
# dry-run succeeded, nothing to build: distinct from a parse failure
result = graph.parse_dry_run_text(WARM, returncode=0)
assert result == set()
def test_partial_returns_only_built_drvs():
result = graph.parse_dry_run_text(PARTIAL, returncode=0)
assert result == {"bbb-foo-1.0.drv", "ccc-bar-2.0.drv"}
def test_garbage_without_header_and_failure_is_none():
assert graph.parse_dry_run_text(GARBAGE, returncode=1) is None
def test_clean_exit_without_header_is_empty_not_none():
# exit 0 but no recognizable header still counts as "nothing to build"
assert graph.parse_dry_run_text("", returncode=0) == set()
# --- structured `nix build --dry-run --json` output (issue #8) -------------
JSON_PARTIAL = """\
[
{"drvPath": "/nix/store/bbb-foo-1.0.drv", "outputs": {"out": "/nix/store/e-foo"}},
{"drvPath": "/nix/store/ccc-bar-2.0.drv", "outputs": {"out": "/nix/store/f-bar"}}
]
"""
JSON_WARM = "[]"
JSON_ALT_KEY = '[{"drv": "/nix/store/ggg-qux-9.drv"}]'
def test_json_partial_returns_built_drvs():
assert graph.parse_dry_run_json(JSON_PARTIAL) == {
"bbb-foo-1.0.drv",
"ccc-bar-2.0.drv",
}
def test_json_warm_cache_is_empty_set():
assert graph.parse_dry_run_json(JSON_WARM) == set()
def test_json_alternate_drv_key():
assert graph.parse_dry_run_json(JSON_ALT_KEY) == {"ggg-qux-9.drv"}
def test_json_non_structured_is_none():
# human text or an unexpected shape must fall back (None), not crash
assert graph.parse_dry_run_json(WARM) is None
assert graph.parse_dry_run_json('{"not": "a list"}') is None
assert graph.parse_dry_run_json("not json at all") is None
def test_build_dag_empty_set_yields_no_nodes():
closure = {"a.drv": {"inputDrvs": {}}, "b.drv": {"inputDrvs": {"a.drv": {}}}}
preds, nodes = graph.build_dag(closure, set())
assert nodes == set()
assert preds == {}
def test_build_dag_none_costs_whole_closure():
closure = {
"a.drv": {"inputDrvs": {}},
"b.drv": {"inputDrvs": {"/nix/store/x-a.drv": {}}},
}
_, nodes = graph.build_dag(closure, None)
assert nodes == {"a.drv", "b.drv"}