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nix-eval-jobs/src/nix-eval-jobs.cc

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#include <map>
#include <thread>
#include <condition_variable>
#include <nix/config.h>
#include <nix/eval-settings.hh>
#include <nix/common-eval-args.hh>
#include <nix/args/root.hh>
#include <nix/shared.hh>
#include <nix/sync.hh>
#include <nix/terminal.hh>
#include <nix/eval.hh>
#include <nix/path-with-outputs.hh>
#include <nix/local-fs-store.hh>
#include <nix/installable-flake.hh>
#include <nix/get-drvs.hh>
#include <nix/attr-path.hh>
#include <nix/value-to-json.hh>
#include <nix/signals.hh>
#include <nix/derivations.hh>
#include <sys/wait.h>
#include <sys/resource.h>
#include "eval-args.hh"
#include <nlohmann/json.hpp>
using namespace nix;
using namespace nlohmann;
// Safe to ignore - the args will be static.
#ifdef __GNUC__
#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
#elif __clang__
#pragma clang diagnostic ignored "-Wnon-virtual-dtor"
#endif
static MyArgs myArgs;
static Value *releaseExprTopLevelValue(EvalState &state, Bindings &autoArgs) {
Value vTop;
if (myArgs.fromArgs) {
Expr *e = state.parseExprFromString(
myArgs.releaseExpr, state.rootPath(CanonPath::fromCwd()));
state.eval(e, vTop);
} else {
state.evalFile(lookupFileArg(state, myArgs.releaseExpr), vTop);
}
auto vRoot = state.allocValue();
state.autoCallFunction(autoArgs, vTop, *vRoot);
return vRoot;
}
bool queryIsCached(Store &store, std::map<std::string, std::string> &outputs) {
uint64_t downloadSize, narSize;
StorePathSet willBuild, willSubstitute, unknown;
std::vector<StorePathWithOutputs> paths;
for (auto const &[key, val] : outputs) {
paths.push_back(followLinksToStorePathWithOutputs(store, val));
}
store.queryMissing(toDerivedPaths(paths), willBuild, willSubstitute,
unknown, downloadSize, narSize);
return willBuild.empty() && unknown.empty();
}
/* The fields of a derivation that are printed in json form */
struct Drv {
std::string name;
std::string system;
std::string drvPath;
bool isCached;
std::map<std::string, std::string> outputs;
std::map<std::string, std::set<std::string>> inputDrvs;
std::optional<nlohmann::json> meta;
Drv(std::string &attrPath, EvalState &state, DrvInfo &drvInfo) {
auto localStore = state.store.dynamic_pointer_cast<LocalFSStore>();
try {
for (auto out : drvInfo.queryOutputs(true)) {
if (out.second)
outputs[out.first] =
localStore->printStorePath(*out.second);
}
} catch (const std::exception &e) {
throw EvalError("derivation '%s' does not have valid outputs: %s",
attrPath, e.what());
}
if (myArgs.meta) {
nlohmann::json meta_;
for (auto &metaName : drvInfo.queryMetaNames()) {
NixStringContext context;
std::stringstream ss;
auto metaValue = drvInfo.queryMeta(metaName);
// Skip non-serialisable types
// TODO: Fix serialisation of derivations to store paths
if (metaValue == 0) {
continue;
}
printValueAsJSON(state, true, *metaValue, noPos, ss, context);
meta_[metaName] = nlohmann::json::parse(ss.str());
}
meta = meta_;
}
if (myArgs.checkCacheStatus) {
isCached = queryIsCached(*localStore, outputs);
}
drvPath = localStore->printStorePath(drvInfo.requireDrvPath());
auto drv = localStore->readDerivation(drvInfo.requireDrvPath());
for (const auto &[inputDrvPath, inputNode] : drv.inputDrvs.map) {
std::set<std::string> inputDrvOutputs;
for (auto &outputName : inputNode.value) {
inputDrvOutputs.insert(outputName);
}
inputDrvs[localStore->printStorePath(inputDrvPath)] =
inputDrvOutputs;
}
name = drvInfo.queryName();
system = drv.platform;
}
};
static void to_json(nlohmann::json &json, const Drv &drv) {
json = nlohmann::json{{"name", drv.name},
{"system", drv.system},
{"drvPath", drv.drvPath},
{"outputs", drv.outputs},
{"inputDrvs", drv.inputDrvs}};
if (drv.meta.has_value()) {
json["meta"] = drv.meta.value();
}
if (myArgs.checkCacheStatus) {
json["isCached"] = drv.isCached;
}
}
std::string attrPathJoin(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;
});
}
[[nodiscard]] static int tryWriteLine(int fd, std::string s) {
s += "\n";
std::string_view sv{s};
while (!sv.empty()) {
checkInterrupt();
ssize_t res = write(fd, sv.data(), sv.size());
if (res == -1 && errno != EINTR) {
return -errno;
}
if (res > 0) {
sv.remove_prefix(res);
}
}
return 0;
}
class LineReader {
public:
LineReader(int fd) {
stream = fdopen(fd, "r");
if (!stream) {
throw Error("fdopen failed: %s", strerror(errno));
}
}
~LineReader() {
fclose(stream);
free(buffer);
}
LineReader(LineReader &&other) {
stream = other.stream;
other.stream = nullptr;
buffer = other.buffer;
other.buffer = nullptr;
len = other.len;
other.len = 0;
}
[[nodiscard]] std::string_view readLine() {
ssize_t read = getline(&buffer, &len, stream);
if (read == -1) {
return {}; // Return an empty string_view in case of error
}
// Remove trailing newline
return std::string_view(buffer, read - 1);
}
private:
FILE *stream = nullptr;
char *buffer = nullptr;
size_t len = 0;
};
static void worker(ref<EvalState> state, Bindings &autoArgs, AutoCloseFD &to,
AutoCloseFD &from) {
nix::Value *vRoot = [&]() {
if (myArgs.flake) {
auto [flakeRef, fragment, outputSpec] =
parseFlakeRefWithFragmentAndExtendedOutputsSpec(
myArgs.releaseExpr, absPath("."));
InstallableFlake flake{
{}, state, std::move(flakeRef), fragment, outputSpec,
{}, {}, myArgs.lockFlags};
return flake.toValue(*state).first;
} else {
return releaseExprTopLevelValue(*state, autoArgs);
}
}();
LineReader fromReader(from.release());
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 (!hasPrefix(s, "do ")) {
fprintf(stderr, "worker error: received invalid command '%s'\n",
s.data());
abort();
}
auto path = json::parse(s.substr(3));
auto attrPathS = attrPathJoin(path);
debug("worker process %d at '%s'", getpid(), path);
/* Evaluate it and send info back to the collector. */
json reply = json{{"attr", attrPathS}, {"attrPath", path}};
try {
auto vTmp =
findAlongAttrPath(*state, attrPathS, autoArgs, *vRoot).first;
auto v = state->allocValue();
state->autoCallFunction(autoArgs, *vTmp, *v);
if (v->type() == nAttrs) {
if (auto drvInfo = getDerivation(*state, *v, false)) {
auto drv = Drv(attrPathS, *state, *drvInfo);
reply.update(drv);
/* Register the derivation as a GC root. !!! This
registers roots for jobs that we may have already
done. */
if (myArgs.gcRootsDir != "") {
Path root = myArgs.gcRootsDir + "/" +
std::string(baseNameOf(drv.drvPath));
if (!pathExists(root)) {
auto localStore =
state->store
.dynamic_pointer_cast<LocalFSStore>();
auto storePath =
localStore->parseStorePath(drv.drvPath);
localStore->addPermRoot(storePath, root);
}
}
} else {
auto attrs = nlohmann::json::array();
bool recurse =
myArgs.forceRecurse ||
path.size() == 0; // Dont require `recurseForDerivations
// = true;` for top-level attrset
for (auto &i :
v->attrs->lexicographicOrder(state->symbols)) {
const std::string &name = state->symbols[i->name];
attrs.push_back(name);
if (name == "recurseForDerivations" &&
!myArgs.forceRecurse) {
auto attrv =
v->attrs->get(state->sRecurseForDerivations);
recurse = state->forceBool(
*attrv->value, attrv->pos,
"while evaluating recurseForDerivations");
}
}
if (recurse)
reply["attrs"] = std::move(attrs);
else
reply["attrs"] = nlohmann::json::array();
}
} else {
// We ignore everything that cannot be build
reply["attrs"] = nlohmann::json::array();
}
} catch (EvalError &e) {
auto err = e.info();
std::ostringstream oss;
showErrorInfo(oss, err, loggerSettings.showTrace.get());
auto msg = oss.str();
// Transmits the error we got from the previous evaluation
// in the JSON output.
reply["error"] = filterANSIEscapes(msg, true);
// Don't forget to print it into the STDERR log, this is
// what's shown in the Hydra UI.
printError(e.msg());
}
if (tryWriteLine(to.get(), reply.dump()) < 0) {
return; // main process died
}
/* If our RSS exceeds the maximum, exit. The collector will
start a new process. */
struct rusage r;
getrusage(RUSAGE_SELF, &r);
if ((size_t)r.ru_maxrss > myArgs.maxMemorySize * 1024)
break;
}
if (tryWriteLine(to.get(), "restart") < 0) {
return; // main process died
};
}
typedef std::function<void(ref<EvalState> state, Bindings &autoArgs,
AutoCloseFD &to, AutoCloseFD &from)>
Processor;
/* Auto-cleanup of fork's process and fds. */
struct Proc {
AutoCloseFD to, from;
Pid pid;
Proc(const Processor &proc) {
Pipe toPipe, fromPipe;
toPipe.create();
fromPipe.create();
auto p = startProcess(
[&,
to{std::make_shared<AutoCloseFD>(std::move(fromPipe.writeSide))},
from{
std::make_shared<AutoCloseFD>(std::move(toPipe.readSide))}]() {
debug("created worker process %d", getpid());
try {
auto state = std::make_shared<EvalState>(
myArgs.searchPath, openStore(*myArgs.evalStoreUrl));
Bindings &autoArgs = *myArgs.getAutoArgs(*state);
proc(ref<EvalState>(state), autoArgs, *to, *from);
} catch (Error &e) {
nlohmann::json err;
auto msg = e.msg();
err["error"] = filterANSIEscapes(msg, true);
printError(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
}
}
},
ProcessOptions{.allowVfork = false});
to = std::move(toPipe.writeSide);
from = std::move(fromPipe.readSide);
pid = p;
}
~Proc() {}
};
struct State {
std::set<json> todo = json::array({json::array()});
std::set<json> active;
std::exception_ptr exc;
};
void handleBrokenWorkerPipe(Proc &proc) {
while (1) {
int rc = waitpid(proc.pid, nullptr, WNOHANG);
if (rc == 0) {
proc.pid = -1; // we already took the process status from Proc, no
// need to wait for it again to avoid error messages
throw Error("BUG: worker pipe closed but worker still running?");
} else if (rc == -1) {
proc.pid = -1;
throw Error("BUG: waitpid waiting for worker failed: %s",
strerror(errno));
} else {
if (WIFEXITED(rc)) {
proc.pid = -1;
throw Error("evaluation worker exited with %d",
WEXITSTATUS(rc));
} else if (WIFSIGNALED(rc)) {
proc.pid = -1;
if (WTERMSIG(rc) == SIGKILL) {
throw Error("evaluation worker killed by SIGKILL, maybe "
"memory limit reached?");
}
throw Error("evaluation worker killed by signal %d",
WTERMSIG(rc));
} // else ignore WIFSTOPPED and WIFCONTINUED
}
}
}
std::function<void()> collector(Sync<State> &state_,
std::condition_variable &wakeup) {
return [&]() {
try {
std::optional<std::unique_ptr<Proc>> proc_;
std::optional<std::unique_ptr<LineReader>> fromReader_;
while (true) {
if (!proc_.has_value()) {
proc_ = std::make_unique<Proc>(worker);
fromReader_ = std::make_unique<LineReader>(
proc_.value()->from.release());
}
auto proc = std::move(proc_.value());
auto fromReader = std::move(fromReader_.value());
/* Check whether the existing worker process is still there. */
auto s = fromReader->readLine();
if (s == "") {
handleBrokenWorkerPipe(*proc.get());
} else if (s == "restart") {
proc_ = std::nullopt;
fromReader_ = std::nullopt;
continue;
} else if (s != "next") {
try {
auto json = json::parse(s);
throw Error("worker error: %s",
(std::string)json["error"]);
} catch (const json::exception &e) {
throw Error(
"Received invalid JSON from worker: %s '%s'",
e.what(), s);
}
}
/* Wait for a job name to become available. */
json attrPath;
while (true) {
checkInterrupt();
auto state(state_.lock());
if ((state->todo.empty() && state->active.empty()) ||
state->exc) {
if (tryWriteLine(proc->to.get(), "exit") < 0) {
handleBrokenWorkerPipe(*proc.get());
}
return;
}
if (!state->todo.empty()) {
attrPath = *state->todo.begin();
state->todo.erase(state->todo.begin());
state->active.insert(attrPath);
break;
} else
state.wait(wakeup);
}
/* Tell the worker to evaluate it. */
if (tryWriteLine(proc->to.get(), "do " + attrPath.dump()) < 0) {
handleBrokenWorkerPipe(*proc.get());
}
/* Wait for the response. */
auto respString = fromReader->readLine();
if (respString == "") {
handleBrokenWorkerPipe(*proc.get());
}
json response;
try {
response = json::parse(respString);
if (response.find("error") != response.end()) {
throw Error("worker error: %s",
(std::string)response["error"]);
}
} catch (const json::exception &e) {
throw Error("Received invalid JSON from worker: %s '%s'",
e.what(), respString);
}
/* Handle the response. */
std::vector<json> newAttrs;
if (response.find("attrs") != response.end()) {
for (auto &i : response["attrs"]) {
json newAttr = json(response["attrPath"]);
newAttr.emplace_back(i);
newAttrs.push_back(newAttr);
}
} else {
auto state(state_.lock());
std::cout << respString << "\n" << std::flush;
}
proc_ = std::move(proc);
fromReader_ = std::move(fromReader);
/* Add newly discovered job names to the queue. */
{
auto state(state_.lock());
state->active.erase(attrPath);
for (auto p : newAttrs) {
state->todo.insert(p);
}
wakeup.notify_all();
}
}
} catch (...) {
auto state(state_.lock());
state->exc = std::current_exception();
wakeup.notify_all();
}
};
}
int main(int argc, char **argv) {
/* Prevent undeclared dependencies in the evaluation via
$NIX_PATH. */
unsetenv("NIX_PATH");
/* We are doing the garbage collection by killing forks */
setenv("GC_DONT_GC", "1", 1);
return handleExceptions(argv[0], [&]() {
initNix();
initGC();
myArgs.parseArgs(argv, argc);
/* FIXME: The build hook in conjunction with import-from-derivation is
* causing "unexpected EOF" during eval */
settings.builders = "";
/* Prevent access to paths outside of the Nix search path and
to the environment. */
evalSettings.restrictEval = false;
/* When building a flake, use pure evaluation (no access to
'getEnv', 'currentSystem' etc. */
if (myArgs.impure) {
evalSettings.pureEval = false;
} else if (myArgs.flake) {
evalSettings.pureEval = true;
}
if (myArgs.releaseExpr == "")
throw UsageError("no expression specified");
if (myArgs.gcRootsDir == "") {
printMsg(lvlError, "warning: `--gc-roots-dir' not specified");
} else {
myArgs.gcRootsDir = std::filesystem::absolute(myArgs.gcRootsDir);
}
if (myArgs.showTrace) {
loggerSettings.showTrace.assign(true);
}
Sync<State> state_;
/* Start a collector thread per worker process. */
std::vector<std::thread> threads;
std::condition_variable wakeup;
for (size_t i = 0; i < myArgs.nrWorkers; i++)
threads.emplace_back(std::thread(collector(state_, wakeup)));
for (auto &thread : threads)
thread.join();
auto state(state_.lock());
if (state->exc)
std::rethrow_exception(state->exc);
});
}
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