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fetchOrSubstituteTree(): Return an accessor

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This prepares lazy access to flake.nix etc.
This commit is contained in:
Eelco Dolstra 2025-02-04 16:14:34 +01:00
parent 3c109095de
commit 1ab97a70f5
4 changed files with 54 additions and 19 deletions
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6
src/libfetchers/fetchers.cc
View file

@ -200,10 +200,6 @@ std::pair<StorePath, Input> Input::fetchToStore(ref<Store> store) const
auto narHash = store->queryPathInfo(storePath)->narHash;
result.attrs.insert_or_assign("narHash", narHash.to_string(HashFormat::SRI, true));
// FIXME: we would like to mark inputs as final in
// getAccessorUnchecked(), but then we can't add
// narHash. Or maybe narHash should be excluded from the
// concept of "final" inputs?
result.attrs.insert_or_assign("__final", Explicit<bool>(true));
assert(result.isFinal());
@ -284,6 +280,8 @@ std::pair<ref<SourceAccessor>, Input> Input::getAccessor(ref<Store> store) const
try {
auto [accessor, result] = getAccessorUnchecked(store);
result.attrs.insert_or_assign("__final", Explicit<bool>(true));
checkLocks(*this, result);
return {accessor, std::move(result)};

58
src/libflake/flake/flake.cc
View file

@ -12,6 +12,7 @@
#include "flake/settings.hh"
#include "value-to-json.hh"
#include "local-fs-store.hh"
#include "fetch-to-store.hh"
#include <nlohmann/json.hpp>
@ -24,7 +25,7 @@ namespace flake {
struct FetchedFlake
{
FlakeRef lockedRef;
StorePath storePath;
ref<SourceAccessor> accessor;
};
typedef std::map<FlakeRef, FetchedFlake> FlakeCache;
@ -40,7 +41,7 @@ static std::optional<FetchedFlake> lookupInFlakeCache(
return i->second;
}
static std::tuple<StorePath, FlakeRef, FlakeRef> fetchOrSubstituteTree(
static std::tuple<ref<SourceAccessor>, FlakeRef, FlakeRef> fetchOrSubstituteTree(
EvalState & state,
const FlakeRef & originalRef,
bool useRegistries,
@ -51,8 +52,8 @@ static std::tuple<StorePath, FlakeRef, FlakeRef> fetchOrSubstituteTree(
if (!fetched) {
if (originalRef.input.isDirect()) {
auto [storePath, lockedRef] = originalRef.fetchTree(state.store);
fetched.emplace(FetchedFlake{.lockedRef = lockedRef, .storePath = storePath});
auto [accessor, lockedRef] = originalRef.lazyFetch(state.store);
fetched.emplace(FetchedFlake{.lockedRef = lockedRef, .accessor = accessor});
} else {
if (useRegistries) {
resolvedRef = originalRef.resolve(
@ -64,8 +65,8 @@ static std::tuple<StorePath, FlakeRef, FlakeRef> fetchOrSubstituteTree(
});
fetched = lookupInFlakeCache(flakeCache, originalRef);
if (!fetched) {
auto [storePath, lockedRef] = resolvedRef.fetchTree(state.store);
fetched.emplace(FetchedFlake{.lockedRef = lockedRef, .storePath = storePath});
auto [accessor, lockedRef] = resolvedRef.lazyFetch(state.store);
fetched.emplace(FetchedFlake{.lockedRef = lockedRef, .accessor = accessor});
}
flakeCache.insert_or_assign(resolvedRef, *fetched);
}
@ -76,14 +77,28 @@ static std::tuple<StorePath, FlakeRef, FlakeRef> fetchOrSubstituteTree(
flakeCache.insert_or_assign(originalRef, *fetched);
}
debug("got tree '%s' from '%s'",
state.store->printStorePath(fetched->storePath), fetched->lockedRef);
debug("got tree '%s' from '%s'", fetched->accessor, fetched->lockedRef);
state.allowPath(fetched->storePath);
return {fetched->accessor, resolvedRef, fetched->lockedRef};
}
static StorePath copyInputToStore(
EvalState & state,
fetchers::Input & input,
ref<SourceAccessor> accessor)
{
auto storePath = fetchToStore(*state.store, accessor, FetchMode::Copy, input.getName());
state.allowPath(storePath);
auto narHash = state.store->queryPathInfo(storePath)->narHash;
input.attrs.insert_or_assign("narHash", narHash.to_string(HashFormat::SRI, true));
#if 0
assert(!originalRef.input.getNarHash() || fetched->storePath == originalRef.input.computeStorePath(*state.store));
#endif
return {fetched->storePath, resolvedRef, fetched->lockedRef};
return storePath;
}
static void forceTrivialValue(EvalState & state, Value & value, const PosIdx pos)
@ -136,7 +151,9 @@ static FlakeInput parseFlakeInput(
url = attr.value->string_view();
else if (attr.value->type() == nPath) {
auto path = attr.value->path();
if (path.accessor != flakeDir.accessor)
if (path.accessor != flakeDir.accessor
// FIXME: hack necessary since the parser currently stores all paths as inside rootFS.
&& flakeDir.accessor == state.rootFS)
throw Error("input attribute path '%s' at %s must be in the same source tree as %s",
path, state.positions[attr.pos], flakeDir);
url = "path:" + flakeDir.path.makeRelative(path.path);
@ -301,10 +318,12 @@ static Flake readFlake(
state.symbols[setting.name],
std::string(state.forceStringNoCtx(*setting.value, setting.pos, "")));
else if (setting.value->type() == nPath) {
NixStringContext emptyContext = {};
// FIXME: hack necessary since the parser currently stores all paths as inside rootFS.
SourcePath path(rootDir.accessor, setting.value->path().path);
auto storePath = fetchToStore(*state.store, path, FetchMode::Copy);
flake.config.settings.emplace(
state.symbols[setting.name],
state.coerceToString(setting.pos, *setting.value, emptyContext, "", false, true, true).toOwned());
state.store->toRealPath(storePath));
}
else if (setting.value->type() == nInt)
flake.config.settings.emplace(
@ -349,9 +368,14 @@ static Flake getFlake(
FlakeCache & flakeCache,
const InputAttrPath & lockRootAttrPath)
{
auto [storePath, resolvedRef, lockedRef] = fetchOrSubstituteTree(
// Fetch a lazy tree first.
auto [accessor, resolvedRef, lockedRef] = fetchOrSubstituteTree(
state, originalRef, useRegistries, flakeCache);
// Copy the tree to the store.
auto storePath = copyInputToStore(state, lockedRef.input, accessor);
// Re-parse flake.nix from the store.
return readFlake(state, originalRef, resolvedRef, lockedRef, state.rootPath(state.store->toRealPath(storePath)), lockRootAttrPath);
}
@ -707,8 +731,12 @@ LockedFlake lockFlake(
if (auto resolvedPath = resolveRelativePath()) {
return {*resolvedPath, *input.ref};
} else {
auto [storePath, resolvedRef, lockedRef] = fetchOrSubstituteTree(
auto [accessor, resolvedRef, lockedRef] = fetchOrSubstituteTree(
state, *input.ref, useRegistries, flakeCache);
// FIXME: allow input to be lazy.
auto storePath = copyInputToStore(state, lockedRef.input, accessor);
return {state.rootPath(state.store->toRealPath(storePath)), lockedRef};
}
}();

6
src/libflake/flake/flakeref.cc
View file

@ -289,6 +289,12 @@ std::pair<StorePath, FlakeRef> FlakeRef::fetchTree(ref<Store> store) const
return {std::move(storePath), FlakeRef(std::move(lockedInput), subdir)};
}
std::pair<ref<SourceAccessor>, FlakeRef> FlakeRef::lazyFetch(ref<Store> store) const
{
auto [accessor, lockedInput] = input.getAccessor(store);
return {accessor, FlakeRef(std::move(lockedInput), subdir)};
}
std::tuple<FlakeRef, std::string, ExtendedOutputsSpec> parseFlakeRefWithFragmentAndExtendedOutputsSpec(
const fetchers::Settings & fetchSettings,
const std::string & url,

3
src/libflake/flake/flakeref.hh
View file

@ -71,7 +71,10 @@ struct FlakeRef
const fetchers::Settings & fetchSettings,
const fetchers::Attrs & attrs);
// FIXME: remove
std::pair<StorePath, FlakeRef> fetchTree(ref<Store> store) const;
std::pair<ref<SourceAccessor>, FlakeRef> lazyFetch(ref<Store> store) const;
};
std::ostream & operator << (std::ostream & str, const FlakeRef & flakeRef);