Cache nix store paths of generated tarballs

[pinch] / pinch.py

diff --git a/pinch.py b/pinch.py
index a7d5b65dc6af1b58625f2a9ab1801629bb67fc67..732a91f645c036a4692e6ea55083cad4427373d0 100644 (file)
--- a/pinch.py
+++ b/pinch.py
@@ -25,6 +25,9 @@ from typing import (
     Tuple,
 )
 
+import xdg
+
+
 Digest16 = NewType('Digest16', str)
 Digest32 = NewType('Digest32', str)
 
@@ -216,11 +219,20 @@ def fetch_resources(v: Verification, channel: Channel) -> None:
 
 
 def git_cachedir(git_repo: str) -> str:
-    # TODO: Consider using pyxdg to find this path.
-    return os.path.expanduser(
-        '~/.cache/pinch/git/%s' %
-        digest_string(
-            git_repo.encode()))
+    return os.path.join(
+        xdg.XDG_CACHE_HOME,
+        'pinch/git',
+        digest_string(git_repo.encode()))
+
+
+def tarball_cache_file(channel: Channel) -> str:
+    return os.path.join(
+        xdg.XDG_CACHE_HOME,
+        'pinch/git-tarball',
+        '%s-%s-%s' %
+        (digest_string(channel.git_repo.encode()),
+         channel.git_revision,
+         channel.release_name))
 
 
 def verify_git_ancestry(v: Verification, channel: Channel) -> None:
@@ -368,6 +380,12 @@ def git_checkout(v: Verification, channel: Channel, dest: str) -> None:
 
 
 def git_get_tarball(v: Verification, channel: Channel) -> str:
+    cache_file = tarball_cache_file(channel)
+    if os.path.exists(cache_file):
+        cached_tarball = open(cache_file).read(9999)
+        if os.path.exists(cached_tarball):
+            return cached_tarball
+
     with tempfile.TemporaryDirectory() as output_dir:
         output_filename = os.path.join(
             output_dir, channel.release_name + '.tar.xz')
@@ -391,7 +409,11 @@ def git_get_tarball(v: Verification, channel: Channel) -> str:
         process = subprocess.run(
             ['nix-store', '--add', output_filename], capture_output=True)
         v.result(process.returncode == 0)
-        return process.stdout.decode().strip()
+        store_tarball = process.stdout.decode().strip()
+
+        os.makedirs(os.path.dirname(cache_file), exist_ok=True)
+        open(cache_file, 'w').write(store_tarball)
+        return store_tarball
 
 
 def check_channel_metadata(
@@ -494,6 +516,25 @@ def pin(args: argparse.Namespace) -> None:
         config.write(configfile)
 
 
+def fetch_channel(
+        v: Verification,
+        section: str,
+        conf: configparser.SectionProxy) -> str:
+    if 'git_repo' not in conf or 'release_name' not in conf:
+        raise Exception(
+            'Cannot update unpinned channel "%s" (Run "pin" before "update")' %
+            section)
+
+    if 'channel_url' in conf:
+        return fetch_with_nix_prefetch_url(
+            v, conf['tarball_url'], Digest16(
+                conf['tarball_sha256']))
+
+    channel = Channel(**dict(conf.items()))
+    ensure_git_rev_available(v, channel)
+    return git_get_tarball(v, channel)
+
+
 def update(args: argparse.Namespace) -> None:
     v = Verification()
     config = configparser.ConfigParser()
@@ -501,20 +542,10 @@ def update(args: argparse.Namespace) -> None:
     configs = [read_config(filename) for filename in args.channels_file]
     for config in configs:
         for section in config.sections():
-
             if 'alias_of' in config[section]:
                 assert 'git_repo' not in config[section]
                 continue
-
-            if 'channel_url' in config[section]:
-                tarball = fetch_with_nix_prefetch_url(
-                    v, config[section]['tarball_url'], Digest16(
-                        config[section]['tarball_sha256']))
-            else:
-                channel = Channel(**dict(config[section].items()))
-                ensure_git_rev_available(v, channel)
-                tarball = git_get_tarball(v, channel)
-
+            tarball = fetch_channel(v, section, config[section])
             if section in exprs:
                 raise Exception('Duplicate channel "%s"' % section)
             exprs[section] = (