forked from lix-project/lix
75989bdca7
The fact that queryPathInfo() is synchronous meant that we needed a thread for every concurrent binary cache lookup, even though they end up being handled by the same download thread. Requiring hundreds of threads is not a good idea. So now there is an asynchronous version of queryPathInfo() that takes a callback function to process the result. Similarly, enqueueDownload() now takes a callback rather than returning a future. Thus, a command like nix path-info --store https://cache.nixos.org/ -r /nix/store/slljrzwmpygy1daay14kjszsr9xix063-nixos-16.09beta231.dccf8c5 that returns 4941 paths now takes 1.87s using only 2 threads (the main thread and the downloader thread). (This is with a prewarmed CloudFront.)
104 lines
2.6 KiB
C++
104 lines
2.6 KiB
C++
#include "binary-cache-store.hh"
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#include "globals.hh"
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#include "nar-info-disk-cache.hh"
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namespace nix {
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class LocalBinaryCacheStore : public BinaryCacheStore
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{
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private:
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Path binaryCacheDir;
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public:
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LocalBinaryCacheStore(
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const Params & params, const Path & binaryCacheDir)
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: BinaryCacheStore(params)
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, binaryCacheDir(binaryCacheDir)
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{
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}
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void init() override;
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std::string getUri() override
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{
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return "file://" + binaryCacheDir;
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}
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protected:
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bool fileExists(const std::string & path) override;
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void upsertFile(const std::string & path, const std::string & data) override;
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void getFile(const std::string & path,
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std::function<void(std::shared_ptr<std::string>)> success,
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std::function<void(std::exception_ptr exc)> failure) override
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{
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sync2async<std::shared_ptr<std::string>>(success, failure, [&]() {
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try {
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return std::make_shared<std::string>(readFile(binaryCacheDir + "/" + path));
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} catch (SysError & e) {
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if (e.errNo == ENOENT) return std::shared_ptr<std::string>();
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throw;
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}
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});
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}
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PathSet queryAllValidPaths() override
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{
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PathSet paths;
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for (auto & entry : readDirectory(binaryCacheDir)) {
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if (entry.name.size() != 40 ||
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!hasSuffix(entry.name, ".narinfo"))
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continue;
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paths.insert(storeDir + "/" + entry.name.substr(0, entry.name.size() - 8));
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}
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return paths;
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}
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};
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void LocalBinaryCacheStore::init()
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{
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createDirs(binaryCacheDir + "/nar");
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BinaryCacheStore::init();
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}
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static void atomicWrite(const Path & path, const std::string & s)
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{
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Path tmp = path + ".tmp." + std::to_string(getpid());
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AutoDelete del(tmp, false);
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writeFile(tmp, s);
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if (rename(tmp.c_str(), path.c_str()))
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throw SysError(format("renaming ‘%1%’ to ‘%2%’") % tmp % path);
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del.cancel();
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}
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bool LocalBinaryCacheStore::fileExists(const std::string & path)
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{
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return pathExists(binaryCacheDir + "/" + path);
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}
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void LocalBinaryCacheStore::upsertFile(const std::string & path, const std::string & data)
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{
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atomicWrite(binaryCacheDir + "/" + path, data);
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}
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static RegisterStoreImplementation regStore([](
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const std::string & uri, const Store::Params & params)
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-> std::shared_ptr<Store>
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{
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if (getEnv("_NIX_FORCE_HTTP_BINARY_CACHE_STORE") == "1" ||
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std::string(uri, 0, 7) != "file://")
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return 0;
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auto store = std::make_shared<LocalBinaryCacheStore>(params, std::string(uri, 7));
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store->init();
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return store;
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});
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}
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