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lix/subprojects/nix-eval-jobs/src/worker.cc
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skye c6b4f30be9 libexpr: Migrate EvalState::autoCallFunction to return a Value
Change-Id: I426c3d413b18848090dd05674a08e5fb6a6a6964
2026-03-01 01:01:47 -05:00

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#include <lix/config.h> // IWYU pragma: keep
// doesn't exist on macOS
// IWYU pragma: no_include <bits/types/struct_rusage.h>
#include <lix/libexpr/attr-path.hh>
#include <lix/libstore/local-fs-store.hh>
#include <lix/libcmd/installable-flake.hh>
#include <sys/resource.h>
#include <stdio.h>
#include <stdlib.h>
#include <lix/libexpr/attr-set.hh>
#include <lix/libutil/canon-path.hh>
#include <lix/libcmd/common-eval-args.hh>
#include <lix/libutil/current-process.hh>
#include <lix/libutil/error.hh>
#include <lix/libexpr/eval-cache.hh>
#include <lix/libexpr/eval-inline.hh>
#include <lix/libexpr/eval.hh>
#include <lix/libexpr/flake/flakeref.hh>
#include <lix/libexpr/get-drvs.hh>
#include <lix/libutil/input-accessor.hh>
#include <lix/libutil/json.hh>
#include <lix/libutil/logging.hh>
#include <lix/libexpr/nixexpr.hh>
#include <lix/libutil/ref.hh>
#include <lix/libstore/store-api.hh>
#include <lix/libexpr/symbol-table.hh>
#include <lix/libutil/types.hh>
#include <lix/libexpr/value.hh>
#include <lix/libutil/terminal.hh>
#include <exception>
#include <numeric>
#include <optional>
#include <sstream>
#include <string>
#include <string_view>
#include <utility>
#include "worker.hh"
#include "drv.hh"
#include "buffered-io.hh"
#include "eval-args.hh"
static nix::Value releaseExprTopLevelValue(nix::EvalState &state,
nix::Bindings &autoArgs,
MyArgs &args) {
nix::Value vTop;
if (args.fromArgs) {
nix::Expr &e = state.ctx.parseExprFromString(args.releaseExpr,
nix::CanonPath::fromCwd());
vTop = state.eval(e);
} else {
vTop = state.evalFile(
state.aio.blockOn(nix::lookupFileArg(state.ctx, args.releaseExpr))
.unwrap());
}
return state.autoCallFunction(autoArgs, vTop, {});
}
static std::string attrPathJoin(nix::JSON input) {
return std::accumulate(input.begin(), input.end(), std::string(),
[](std::string ss, std::string s) {
// Escape token if containing dots
if (s.find(".") != std::string::npos) {
s = "\"" + s + "\"";
}
return ss.empty() ? s : ss + "." + s;
});
}
static std::optional<Constituents>
readConstituents(const nix::Value *v, nix::box_ptr<nix::EvalState> &state,
nix::ref<nix::eval_cache::CachingEvaluator> &evaluator) {
auto a = v->attrs()->get(state->ctx.symbols.create("_hydraAggregate"));
if (a && state->forceBool(a->value, a->pos,
"while evaluating the "
"`_hydraAggregate` attribute")) {
std::vector<std::string> constituents;
std::vector<std::string> namedConstituents;
auto a = v->attrs()->get(state->ctx.symbols.create("constituents"));
if (!a)
state->ctx.errors
.make<nix::EvalError>("derivation must have a constituents "
"attribute")
.debugThrow(nix::always_progresses); // we can't have a debugger here
nix::NixStringContext context;
state->coerceToString(a->pos, a->value, context,
"while evaluating the `constituents` attribute",
nix::StringCoercionMode::ToString, false);
for (auto &c : context)
std::visit(nix::overloaded{
[&](const nix::NixStringContextElem::Built &b) {
constituents.push_back(
b.drvPath.to_string(*evaluator->store));
},
[&](const nix::NixStringContextElem::Opaque &) {},
[&](const nix::NixStringContextElem::DrvDeep &) {},
},
c.raw);
state->forceList(a->value, a->pos,
"while evaluating the "
"`constituents` attribute");
for (unsigned int n = 0; n < a->value.listSize(); ++n) {
auto v = a->value.listElems()[n];
state->forceValue(v, nix::noPos);
if (v.type() == nix::nString)
namedConstituents.emplace_back(v.str());
}
return Constituents(constituents, namedConstituents);
}
return std::nullopt;
}
void worker(nix::AutoCloseFD &to, nix::AutoCloseFD &from, MyArgs &args)
try {
// Increase the default stack size for the evaluator and for
// libstdc++'s std::regex.
nix::ensureStackSizeAtLeast(64 * 1024 * 1024);
#if HAVE_BOEHMGC
// We are doing the garbage collection by killing forks.
GC_disable();
// There is some memory usage overhead on top of the GC heap size.
// A simple model using fixed and proportional overhead already gives reasonable results.
// The parameters have been determined experimentally using evaluation of nixpkgs.
size_t maxGcHeapSize = std::ldexp(std::max(0.0, 0.9 * (static_cast<double>(args.maxMemorySize) - 150.0)), 20);
if (GC_get_heap_size() > maxGcHeapSize) {
throw nix::Error("The heap is too large. Increase %s or reduce %s.",
"--max-memory-size", "GC_INITIAL_HEAP_SIZE");
}
#endif
auto & aio = args.aio();
auto evalStore = aio.blockOn(args.evalStoreUrl
? nix::openStore(*args.evalStoreUrl)
: nix::openStore());
auto evaluator =
nix::make_ref<nix::eval_cache::CachingEvaluator>(
aio, args.searchPath, evalStore);
nix::Bindings &autoArgs = *args.getAutoArgs(*evaluator);
nix::Value vRoot = [&]() {
auto state = evaluator->begin(aio);
if (args.flake) {
auto [flakeRef, fragment, outputSpec] =
nix::parseFlakeRefWithFragmentAndExtendedOutputsSpec(
args.releaseExpr, nix::absPath("."));
nix::InstallableFlake flake{
{}, evaluator, std::move(flakeRef), fragment, outputSpec,
{}, {}, args.lockFlags};
return flake.toValue(*state).first;
} else {
return releaseExprTopLevelValue(*state, autoArgs, args);
}
}();
LineReader fromReader(from.release());
auto state = evaluator->begin(aio);
while (true) {
/* Wait for the collector to send us a job name. */
if (tryWriteLine(to.get(), "next") < 0) {
return; // main process died
}
auto s = fromReader.readLine();
if (s == "exit") {
break;
}
if (!s.starts_with("do ")) {
std::cerr << "worker error: received invalid command '" << s << "'\n";
abort();
}
auto path = nix::json::parse(s.substr(3));
auto attrPathS = attrPathJoin(path);
/* Evaluate it and send info back to the collector. */
nix::JSON reply =
nix::JSON{{"attr", attrPathS}, {"attrPath", path}};
try {
auto vTmp =
nix::findAlongAttrPath(*state, attrPathS, autoArgs, vRoot)
.first;
nix::Value v = state->autoCallFunction(autoArgs, vTmp, {});
if (v.type() == nix::nAttrs) {
if (auto drvInfo = nix::getDerivation(*state, v, false)) {
std::optional<Constituents> maybeConstituents;
if (args.constituents) {
maybeConstituents =
readConstituents(&v, state, evaluator);
}
auto drv = Drv(attrPathS, *state, *drvInfo, args,
maybeConstituents);
reply.update(drv);
/* Register the derivation as a GC root. !!! This
registers roots for jobs that we may have already
done. */
register_gc_root(args.gcRootsDir, drv.drvPath, evaluator->store, aio);
} else {
auto attrs = nix::JSON::array();
bool recurse =
args.forceRecurse ||
path.size() == 0; // Dont require `recurseForDerivations
// = true;` for top-level attrset
for (auto &i :
v.attrs()->lexicographicOrder(evaluator->symbols)) {
const std::string_view name = evaluator->symbols[i->name];
attrs.emplace_back(name);
if (name == "recurseForDerivations" &&
!args.forceRecurse) {
auto attrv = v.attrs()->get(
evaluator->symbols.sym_recurseForDerivations);
recurse = state->forceBool(
attrv->value, attrv->pos,
"while evaluating recurseForDerivations");
}
}
if (recurse)
reply["attrs"] = std::move(attrs);
else
reply["attrs"] = nix::JSON::array();
}
} else {
// We ignore everything that cannot be build
reply["attrs"] = nix::JSON::array();
}
} catch (nix::EvalError &e) {
auto err = e.info();
std::ostringstream oss;
nix::showErrorInfo(oss, err, nix::loggerSettings.showTrace.get());
auto msg = oss.str();
// Transmits the error we got from the previous evaluation
// in the JSON output.
reply["error"] = nix::filterANSIEscapes(msg, true);
// Don't forget to print it into the STDERR log, this is
// what's shown in the Hydra UI.
std::cerr << msg << "\n";
} catch (const nix::Interrupted &) {
throw;
} catch ( // NOLINT(lix-foreign-exceptions)
const std::exception &e) { // FIXME: for some reason the catch block
// above, doesn't trigger on macOS (?)
auto msg = e.what();
reply["error"] = nix::filterANSIEscapes(msg, true);
std::cerr << msg << "\n";
}
if (tryWriteLine(to.get(), reply.dump()) < 0) {
return; // main process died
}
// If the memory limit is exceeded, exit.
// The collector will start a new process.
#if HAVE_BOEHMGC
if (GC_get_heap_size() > maxGcHeapSize) {
break;
}
#else
struct rusage r;
getrusage(RUSAGE_SELF, &r);
if ((size_t)r.ru_maxrss > args.maxMemorySize * 1024) {
break;
}
#endif
}
if (tryWriteLine(to.get(), "restart") < 0) {
return; // main process died
};
} catch (const nix::Interrupted &) {
// The coordinator should get the interrupt too, so it doesn't need to be logged.
} catch (nix::Error &e) {
nix::JSON err;
auto msg = e.msg();
err["error"] = nix::filterANSIEscapes(msg, true);
printError("%1%", nix::Uncolored(msg));
if (tryWriteLine(to.get(), err.dump()) < 0) {
return; // main process died
};
// Don't forget to print it into the STDERR log, this is
// what's shown in the Hydra UI.
if (tryWriteLine(to.get(), "restart") < 0) {
return; // main process died
}
}