lix/src/libstore/local-binary-cache-store.cc
Eelco Dolstra dd77f71afe LocalBinaryCacheStore::upsertFile(): Fix race
When multiple threads try to upsert the same file, this could fail.

Fixes #4667.
2021-03-26 17:10:15 +01:00

118 lines
3 KiB
C++

#include "binary-cache-store.hh"
#include "globals.hh"
#include "nar-info-disk-cache.hh"
#include <atomic>
namespace nix {
struct LocalBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
{
using BinaryCacheStoreConfig::BinaryCacheStoreConfig;
const std::string name() override { return "Local Binary Cache Store"; }
};
class LocalBinaryCacheStore : public virtual LocalBinaryCacheStoreConfig, public virtual BinaryCacheStore
{
private:
Path binaryCacheDir;
public:
LocalBinaryCacheStore(
const std::string scheme,
const Path & binaryCacheDir,
const Params & params)
: StoreConfig(params)
, BinaryCacheStoreConfig(params)
, LocalBinaryCacheStoreConfig(params)
, Store(params)
, BinaryCacheStore(params)
, binaryCacheDir(binaryCacheDir)
{
}
void init() override;
std::string getUri() override
{
return "file://" + binaryCacheDir;
}
static std::set<std::string> uriSchemes();
protected:
bool fileExists(const std::string & path) override;
void upsertFile(const std::string & path,
std::shared_ptr<std::basic_iostream<char>> istream,
const std::string & mimeType) override
{
auto path2 = binaryCacheDir + "/" + path;
static std::atomic<int> counter{0};
Path tmp = fmt("%s.tmp.%d.%d", path2, getpid(), ++counter);
AutoDelete del(tmp, false);
StreamToSourceAdapter source(istream);
writeFile(tmp, source);
if (rename(tmp.c_str(), path2.c_str()))
throw SysError("renaming '%1%' to '%2%'", tmp, path2);
del.cancel();
}
void getFile(const std::string & path, Sink & sink) override
{
try {
readFile(binaryCacheDir + "/" + path, sink);
} catch (SysError & e) {
if (e.errNo == ENOENT)
throw NoSuchBinaryCacheFile("file '%s' does not exist in binary cache", path);
}
}
StorePathSet queryAllValidPaths() override
{
StorePathSet paths;
for (auto & entry : readDirectory(binaryCacheDir)) {
if (entry.name.size() != 40 ||
!hasSuffix(entry.name, ".narinfo"))
continue;
paths.insert(parseStorePath(
storeDir + "/" + entry.name.substr(0, entry.name.size() - 8)
+ "-" + MissingName));
}
return paths;
}
};
void LocalBinaryCacheStore::init()
{
createDirs(binaryCacheDir + "/nar");
createDirs(binaryCacheDir + realisationsPrefix);
if (writeDebugInfo)
createDirs(binaryCacheDir + "/debuginfo");
BinaryCacheStore::init();
}
bool LocalBinaryCacheStore::fileExists(const std::string & path)
{
return pathExists(binaryCacheDir + "/" + path);
}
std::set<std::string> LocalBinaryCacheStore::uriSchemes()
{
if (getEnv("_NIX_FORCE_HTTP_BINARY_CACHE_STORE") == "1")
return {};
else
return {"file"};
}
static RegisterStoreImplementation<LocalBinaryCacheStore, LocalBinaryCacheStoreConfig> regLocalBinaryCacheStore;
}