90ad02bf62
The binary cache store can now use HTTP/2 to do lookups. This is much more efficient than HTTP/1.1 due to multiplexing: we can issue many requests in parallel over a single TCP connection. Thus it's no longer necessary to use a bunch of concurrent TCP connections (25 by default). For example, downloading 802 .narinfo files from https://cache.nixos.org/, using a single TCP connection, takes 11.8s with HTTP/1.1, but only 0.61s with HTTP/2. This did require a fairly substantial rewrite of the Downloader class to use the curl multi interface, because otherwise curl wouldn't be able to do multiplexing for us. As a bonus, we get connection reuse even with HTTP/1.1. All downloads are now handled by a single worker thread. Clients call Downloader::enqueueDownload() to tell the worker thread to start the download, getting a std::future to the result.
103 lines
2.8 KiB
C++
103 lines
2.8 KiB
C++
#include "binary-cache-store.hh"
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#include "download.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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MakeError(UploadToHTTP, Error);
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class HttpBinaryCacheStore : public BinaryCacheStore
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{
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private:
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Path cacheUri;
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public:
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HttpBinaryCacheStore(
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const Params & params, const Path & _cacheUri)
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: BinaryCacheStore(params)
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, cacheUri(_cacheUri)
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{
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if (cacheUri.back() == '/')
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cacheUri.pop_back();
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diskCache = getNarInfoDiskCache();
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}
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std::string getUri() override
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{
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return cacheUri;
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}
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void init() override
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{
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// FIXME: do this lazily?
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if (!diskCache->cacheExists(cacheUri, wantMassQuery_, priority)) {
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try {
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BinaryCacheStore::init();
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} catch (UploadToHTTP &) {
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throw Error(format("‘%s’ does not appear to be a binary cache") % cacheUri);
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}
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diskCache->createCache(cacheUri, storeDir, wantMassQuery_, priority);
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}
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}
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protected:
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bool fileExists(const std::string & path) override
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{
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try {
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DownloadRequest request(cacheUri + "/" + path);
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request.showProgress = DownloadRequest::no;
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request.head = true;
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request.tries = 5;
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getDownloader()->download(request);
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return true;
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} catch (DownloadError & e) {
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/* S3 buckets return 403 if a file doesn't exist and the
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bucket is unlistable, so treat 403 as 404. */
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if (e.error == Downloader::NotFound || e.error == Downloader::Forbidden)
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return false;
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throw;
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}
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}
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void upsertFile(const std::string & path, const std::string & data) override
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{
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throw UploadToHTTP("uploading to an HTTP binary cache is not supported");
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}
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std::shared_ptr<std::string> getFile(const std::string & path) override
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{
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DownloadRequest request(cacheUri + "/" + path);
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request.showProgress = DownloadRequest::no;
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request.tries = 8;
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try {
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return getDownloader()->download(request).data;
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} catch (DownloadError & e) {
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if (e.error == Downloader::NotFound || e.error == Downloader::Forbidden)
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return 0;
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throw;
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}
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}
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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 (std::string(uri, 0, 7) != "http://" &&
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std::string(uri, 0, 8) != "https://" &&
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(getEnv("_NIX_FORCE_HTTP_BINARY_CACHE_STORE") != "1" || std::string(uri, 0, 7) != "file://")
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) return 0;
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auto store = std::make_shared<HttpBinaryCacheStore>(params, uri);
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store->init();
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return store;
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});
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}
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