git.scottworley.com Git - nix-pin-deps/blob - nix_pin_deps.py

   1 from contextlib import contextmanager
   2 import json
   3 import os
   4 import subprocess
   5 import sys
   6 import xml.sax
   7 import xml.sax.handler
   8
   9 from typing import Any, Dict, Iterator, List, Set
  10
  11
  12 @contextmanager
  13 def log(msg: str) -> Iterator[None]:
  14     print(msg, file=sys.stderr, end='', flush=True)
  15     try:
  16         yield
  17     finally:
  18         print('\r', file=sys.stderr, end='', flush=True)
  19
  20
  21 class ParseNixStoreQueryGraphML(xml.sax.handler.ContentHandler):
  22     def __init__(self) -> None:
  23         super().__init__()
  24         self.roots: Set[str] = set()
  25         self.non_roots: Set[str] = set()
  26         self.deps: Dict[str, List[str]] = {}
  27
  28     def startElement(self, name: str, attrs: Any) -> None:
  29         if name == "edge":
  30             source = attrs.getValue("source")
  31             target = attrs.getValue("target")
  32             self.non_roots.add(target)
  33             self.deps.setdefault(source, []).append(target)
  34             if target in self.roots:
  35                 self.roots.remove(target)
  36             if source not in self.non_roots:
  37                 self.roots.add(source)
  38
  39
  40 def getDeps(drv: str) -> ParseNixStoreQueryGraphML:
  41     with log("Loading dependency tree..."):
  42         with subprocess.Popen(
  43                 ["nix-store", "--query", "--graphml", drv], stdout=subprocess.PIPE) as process:
  44             parser = ParseNixStoreQueryGraphML()
  45             assert process.stdout
  46             xml.sax.parse(process.stdout, parser)
  47             assert process.wait() == 0
  48         return parser
  49
  50
  51 def getDrvInfo(drv: str) -> Any:
  52     with log(f"Loading {drv}..."):
  53         with subprocess.Popen(
  54                 ["nix", "--experimental-features", "nix-command",
  55                     "show-derivation", "/nix/store/" + drv],
  56                 stdout=subprocess.PIPE) as process:
  57             assert process.stdout
  58             info = json.load(process.stdout)
  59             assert process.wait() == 0
  60         return info
  61
  62
  63 def allBuilt(drv: str) -> bool:
  64     # TODO: How to pin outputs one at a time?
  65     # Currently, we only pin when all outputs are available.
  66     # It would be better to pin the outputs we've got.
  67     return all(os.path.exists(o['path']) for d in getDrvInfo(
  68         drv).values() for o in d['outputs'].values())
  69
  70
  71 def isDrv(thing: str) -> bool:
  72     return thing.endswith(".drv")
  73
  74
  75 def removesuffix(s: str, suf: str) -> str:
  76     return s[:-len(suf)] if s.endswith(suf) else s
  77
  78
  79 def pin(drv: str) -> None:
  80     outPath = os.path.join(sys.argv[2], removesuffix(drv, ".drv"))
  81     if not os.path.exists(outPath):
  82         subprocess.run(["nix-store", "--realise", "--add-root",
  83                        outPath, "/nix/store/" + drv], check=True)
  84
  85
  86 def pinBuiltThings(thing: str,
  87                    done: Set[str],
  88                    deps: Dict[str, List[str]]) -> None:
  89     if thing in done:
  90         return
  91     done.add(thing)
  92     if not isDrv(thing) or allBuilt(thing):
  93         pin(thing)
  94         return
  95     for dep in deps.get(thing, []):
  96         pinBuiltThings(dep, done, deps)
  97
  98
  99 dep_graph = getDeps(sys.argv[1])
 100 for root in dep_graph.roots:
 101     pinBuiltThings(root, set(), dep_graph.deps)