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

   1 # nix-pin-deps: gc-pin dependencies of a partially-built derivation
   2 #
   3 # This program is free software: you can redistribute it and/or modify it
   4 # under the terms of the GNU General Public License as published by the
   5 # Free Software Foundation, version 3.
   6
   7
   8 from contextlib import contextmanager
   9 import json
  10 import os
  11 import subprocess
  12 import sys
  13 import xml.sax
  14 import xml.sax.handler
  15
  16 from typing import Any, Dict, Iterator, List, Set
  17
  18
  19 @contextmanager
  20 def log(msg: str) -> Iterator[None]:
  21     print(msg, file=sys.stderr, end='', flush=True)
  22     try:
  23         yield
  24     finally:
  25         print('\r', file=sys.stderr, end='', flush=True)
  26
  27
  28 class ParseNixStoreQueryGraphML(xml.sax.handler.ContentHandler):
  29     def __init__(self) -> None:
  30         super().__init__()
  31         self.roots: Set[str] = set()
  32         self.non_roots: Set[str] = set()
  33         self.deps: Dict[str, List[str]] = {}
  34
  35     def startElement(self, name: str, attrs: Any) -> None:
  36         if name == "edge":
  37             source = attrs.getValue("source")
  38             target = attrs.getValue("target")
  39             self.non_roots.add(target)
  40             self.deps.setdefault(source, []).append(target)
  41             if target in self.roots:
  42                 self.roots.remove(target)
  43             if source not in self.non_roots:
  44                 self.roots.add(source)
  45
  46
  47 def getDeps(drv: str) -> ParseNixStoreQueryGraphML:
  48     with log("Loading dependency tree..."):
  49         with subprocess.Popen(
  50                 ["nix-store", "--query", "--graphml", drv], stdout=subprocess.PIPE) as process:
  51             parser = ParseNixStoreQueryGraphML()
  52             assert process.stdout
  53             xml.sax.parse(process.stdout, parser)
  54             assert process.wait() == 0
  55         return parser
  56
  57
  58 def getDrvInfo(drv: str) -> Any:
  59     with log(f"Loading {drv}..."):
  60         with subprocess.Popen(
  61                 ["nix", "--experimental-features", "nix-command",
  62                     "show-derivation", "/nix/store/" + drv],
  63                 stdout=subprocess.PIPE) as process:
  64             assert process.stdout
  65             info = json.load(process.stdout)
  66             assert process.wait() == 0
  67         return info
  68
  69
  70 def allBuilt(drv: str) -> bool:
  71     # TODO: How to pin outputs one at a time?
  72     # Currently, we only pin when all outputs are available.
  73     # It would be better to pin the outputs we've got.
  74     return all(os.path.exists(o['path']) for d in getDrvInfo(
  75         drv).values() for o in d['outputs'].values())
  76
  77
  78 def isDrv(thing: str) -> bool:
  79     return thing.endswith(".drv")
  80
  81
  82 def removesuffix(s: str, suf: str) -> str:
  83     return s[:-len(suf)] if s.endswith(suf) else s
  84
  85
  86 def pin(drv: str) -> None:
  87     outPath = os.path.join(sys.argv[2], removesuffix(drv, ".drv"))
  88     if not os.path.exists(outPath):
  89         subprocess.run(["nix-store", "--realise", "--add-root",
  90                        outPath, "/nix/store/" + drv], check=True)
  91
  92
  93 def pinBuiltThings(thing: str,
  94                    done: Set[str],
  95                    deps: Dict[str, List[str]]) -> None:
  96     if thing in done:
  97         return
  98     done.add(thing)
  99     if not isDrv(thing) or allBuilt(thing):
 100         pin(thing)
 101         return
 102     for dep in deps.get(thing, []):
 103         pinBuiltThings(dep, done, deps)
 104
 105
 106 def main() -> None:
 107     dep_graph = getDeps(sys.argv[1])
 108     for root in dep_graph.roots:
 109         pinBuiltThings(root, set(), dep_graph.deps)
 110
 111
 112 if __name__ == '__main__':
 113     main()