forked from lix-project/lix
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.
75 lines
1.9 KiB
C++
75 lines
1.9 KiB
C++
#pragma once
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#include "types.hh"
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#include "hash.hh"
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#include <string>
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#include <future>
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namespace nix {
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struct DownloadRequest
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{
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std::string uri;
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std::string expectedETag;
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bool verifyTLS = true;
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enum { yes, no, automatic } showProgress = yes;
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bool head = false;
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size_t tries = 1;
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unsigned int baseRetryTimeMs = 250;
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DownloadRequest(const std::string & uri) : uri(uri) { }
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};
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struct DownloadResult
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{
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enum Status { Success, NotFound, Forbidden, Misc, Transient };
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Status status;
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bool cached;
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std::string etag;
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std::string effectiveUrl;
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std::shared_ptr<std::string> data;
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};
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class Store;
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struct Downloader
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{
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/* Enqueue a download request, returning a future to the result of
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the download. The future may throw a DownloadError
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exception. */
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virtual std::future<DownloadResult> enqueueDownload(const DownloadRequest & request) = 0;
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/* Synchronously download a file. */
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DownloadResult download(const DownloadRequest & request);
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/* Check if the specified file is already in ~/.cache/nix/tarballs
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and is more recent than ‘tarball-ttl’ seconds. Otherwise,
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use the recorded ETag to verify if the server has a more
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recent version, and if so, download it to the Nix store. */
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Path downloadCached(ref<Store> store, const string & uri, bool unpack, string name = "",
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const Hash & expectedHash = Hash(), string * effectiveUri = nullptr);
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enum Error { NotFound, Forbidden, Misc, Transient };
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};
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/* Return a shared Downloader object. Using this object is preferred
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because it enables connection reuse and HTTP/2 multiplexing. */
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ref<Downloader> getDownloader();
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/* Return a new Downloader object. */
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ref<Downloader> makeDownloader();
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class DownloadError : public Error
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{
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public:
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Downloader::Error error;
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DownloadError(Downloader::Error error, const FormatOrString & fs)
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: Error(fs), error(error)
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{ }
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};
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bool isUri(const string & s);
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}
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