From: Scott Worley <scottworley@scottworley.com>
Date: Tue, 2 Jun 2020 18:17:17 +0000 (-0700)
Subject: Cache nix store paths of generated tarballs
X-Git-Tag: 1.3~1
X-Git-Url: http://git.scottworley.com/pinch/commitdiff_plain/eb0c6f1b9ad97954d3ee229428ac84d8f33be546

Cache nix store paths of generated tarballs

This eliminates the slow "Generating tarball for git revision" step for
tarballs that have already been generated and are already in the nix store.
---

diff --git a/pinch.py b/pinch.py
index 10481e4..732a91f 100644
--- a/pinch.py
+++ b/pinch.py
@@ -222,8 +222,17 @@ def git_cachedir(git_repo: str) -> str:
     return os.path.join(
         xdg.XDG_CACHE_HOME,
         'pinch/git',
-        digest_string(
-            git_repo.encode()))
+        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:
@@ -371,6 +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')
@@ -394,7 +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(