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Improve GitHub caching

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In particular, when building a flake lock file, inputs like 'nixpkgs'
are now downloaded only once. Previously, it would fetch
https://api.github.com/repos/<owner>/<repo>/tarball/<ref> and then
later https://api.github.com/repos/<owner>/<repo>/tarball/<rev>, even
though they produce the same result.

Git and GitHub now also share a cache that maps revs to a store path
and other info.
This commit is contained in:
Eelco Dolstra 2019-10-16 00:12:40 +02:00
parent 14a89aa8cd
commit 0ab64729e9
3 changed files with 136 additions and 73 deletions
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37
src/libexpr/flake/flake.cc
View file

@ -170,43 +170,10 @@ static SourceInfo fetchInput(EvalState & state, const FlakeRef & resolvedRef)
// This only downloads only one revision of the repo, not the entire history.
if (auto refData = std::get_if<FlakeRef::IsGitHub>(&resolvedRef.data)) {
// FIXME: use regular /archive URLs instead? api.github.com
// might have stricter rate limits.
auto url = fmt("https://api.github.com/repos/%s/%s/tarball/%s",
refData->owner, refData->repo,
resolvedRef.rev ? resolvedRef.rev->to_string(Base16, false)
: resolvedRef.ref ? *resolvedRef.ref : "master");
std::string accessToken = settings.githubAccessToken.get();
if (accessToken != "")
url += "?access_token=" + accessToken;
CachedDownloadRequest request(url);
request.unpack = true;
request.name = "source";
request.ttl = resolvedRef.rev ? 1000000000 : settings.tarballTtl;
request.getLastModified = true;
auto result = getDownloader()->downloadCached(state.store, request);
if (!result.etag)
throw Error("did not receive an ETag header from '%s'", url);
if (result.etag->size() != 42 || (*result.etag)[0] != '"' || (*result.etag)[41] != '"')
throw Error("ETag header '%s' from '%s' is not a Git revision", *result.etag, url);
FlakeRef ref(resolvedRef.baseRef());
ref.rev = Hash(std::string(*result.etag, 1, result.etag->size() - 2), htSHA1);
SourceInfo info(ref);
info.storePath = result.storePath;
info.narHash = state.store->queryPathInfo(info.storePath)->narHash;
info.lastModified = result.lastModified;
return info;
return doGit(exportGitHub(state.store, refData->owner, refData->repo, resolvedRef.ref, resolvedRef.rev));
}
// This downloads the entire git history
// This downloads the entire git history.
else if (auto refData = std::get_if<FlakeRef::IsGit>(&resolvedRef.data)) {
return doGit(exportGit(state.store, refData->uri, resolvedRef.ref, resolvedRef.rev, "source"));
}