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.)
77 lines
2 KiB
C++
77 lines
2 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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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 void enqueueDownload(const DownloadRequest & request,
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std::function<void(const DownloadResult &)> success,
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std::function<void(std::exception_ptr exc)> failure) = 0;
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std::future<DownloadResult> enqueueDownload(const DownloadRequest & request);
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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, Interrupted };
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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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