forked from lix-project/lix
462421d345
This provides a pluggable mechanism for defining new fetchers. It adds
a builtin function 'fetchTree' that generalizes existing fetchers like
'fetchGit', 'fetchMercurial' and 'fetchTarball'. 'fetchTree' takes a
set of attributes, e.g.
fetchTree {
type = "git";
url = "https://example.org/repo.git";
ref = "some-branch";
rev = "abcdef...";
}
The existing fetchers are just wrappers around this. Note that the
input attributes to fetchTree are the same as flake input
specifications and flake lock file entries.
All fetchers share a common cache stored in
~/.cache/nix/fetcher-cache-v1.sqlite. This replaces the ad hoc caching
mechanisms in fetchGit and download.cc (e.g. ~/.cache/nix/{tarballs,git-revs*}).
This also adds support for Git worktrees (c169ea5904).
122 lines
3.2 KiB
C++
122 lines
3.2 KiB
C++
#include "cache.hh"
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#include "sqlite.hh"
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#include "sync.hh"
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#include "store-api.hh"
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#include <nlohmann/json.hpp>
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namespace nix::fetchers {
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static const char * schema = R"sql(
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create table if not exists Cache (
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input text not null,
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info text not null,
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path text not null,
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immutable integer not null,
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timestamp integer not null,
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primary key (input)
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);
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)sql";
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struct CacheImpl : Cache
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{
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struct State
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{
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SQLite db;
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SQLiteStmt add, lookup;
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};
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Sync<State> _state;
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CacheImpl()
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{
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auto state(_state.lock());
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auto dbPath = getCacheDir() + "/nix/fetcher-cache-v1.sqlite";
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createDirs(dirOf(dbPath));
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state->db = SQLite(dbPath);
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state->db.isCache();
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state->db.exec(schema);
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state->add.create(state->db,
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"insert or replace into Cache(input, info, path, immutable, timestamp) values (?, ?, ?, ?, ?)");
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state->lookup.create(state->db,
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"select info, path, immutable, timestamp from Cache where input = ?");
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}
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void add(
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ref<Store> store,
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const Attrs & inAttrs,
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const Attrs & infoAttrs,
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const StorePath & storePath,
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bool immutable) override
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{
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_state.lock()->add.use()
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(attrsToJson(inAttrs).dump())
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(attrsToJson(infoAttrs).dump())
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(store->printStorePath(storePath))
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(immutable)
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(time(0)).exec();
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}
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std::optional<std::pair<Attrs, StorePath>> lookup(
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ref<Store> store,
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const Attrs & inAttrs) override
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{
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if (auto res = lookupExpired(store, inAttrs)) {
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if (!res->expired)
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return std::make_pair(std::move(res->infoAttrs), std::move(res->storePath));
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debug("ignoring expired cache entry '%s'",
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attrsToJson(inAttrs).dump());
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}
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return {};
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}
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std::optional<Result> lookupExpired(
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ref<Store> store,
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const Attrs & inAttrs) override
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{
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auto state(_state.lock());
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auto inAttrsJson = attrsToJson(inAttrs).dump();
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auto stmt(state->lookup.use()(inAttrsJson));
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if (!stmt.next()) {
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debug("did not find cache entry for '%s'", inAttrsJson);
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return {};
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}
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auto infoJson = stmt.getStr(0);
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auto storePath = store->parseStorePath(stmt.getStr(1));
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auto immutable = stmt.getInt(2) != 0;
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auto timestamp = stmt.getInt(3);
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store->addTempRoot(storePath);
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if (!store->isValidPath(storePath)) {
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// FIXME: we could try to substitute 'storePath'.
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debug("ignoring disappeared cache entry '%s'", inAttrsJson);
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return {};
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}
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debug("using cache entry '%s' -> '%s', '%s'",
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inAttrsJson, infoJson, store->printStorePath(storePath));
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return Result {
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.expired = !immutable && (settings.tarballTtl.get() == 0 || timestamp + settings.tarballTtl < time(0)),
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.infoAttrs = jsonToAttrs(nlohmann::json::parse(infoJson)),
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.storePath = std::move(storePath)
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};
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}
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};
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ref<Cache> getCache()
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{
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static auto cache = std::make_shared<CacheImpl>();
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return ref<Cache>(cache);
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}
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}
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