eldritch horrors
6f18e1ebde
it's just a uri and some headers now. those can be function arguments with no loss of clarity. *actual* additional arguments, for example a TLS context with additional certificates, could be added on a new and improved FileTransfer class that carries not just a backend reference but some real, visible context for its transfers. curl not being very multi-threading-friendly when using multi handles will make sharing a bit hard anyway once we drop the single global download worker thread Change-Id: Id2112c95cbd118c6d920488f38d272d7da926460
137 lines
4.2 KiB
C++
137 lines
4.2 KiB
C++
#pragma once
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///@file
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#include "box_ptr.hh"
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#include "ref.hh"
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#include "logging.hh"
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#include "serialise.hh"
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#include "types.hh"
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#include "config.hh"
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#include <string>
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#include <future>
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namespace nix {
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struct FileTransferSettings : Config
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{
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Setting<bool> enableHttp2{this, true, "http2",
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"Whether to enable HTTP/2 support."};
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Setting<std::string> userAgentSuffix{this, "", "user-agent-suffix",
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"String appended to the user agent in HTTP requests."};
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Setting<size_t> httpConnections{
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this, 25, "http-connections",
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R"(
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The maximum number of parallel TCP connections used to fetch
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files from binary caches and by other downloads. It defaults
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to 25. 0 means no limit.
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)",
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{"binary-caches-parallel-connections"}};
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Setting<unsigned long> connectTimeout{
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this, 0, "connect-timeout",
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R"(
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The timeout (in seconds) for establishing connections in the
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binary cache substituter. It corresponds to `curl`’s
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`--connect-timeout` option. A value of 0 means no limit.
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)"};
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Setting<unsigned long> stalledDownloadTimeout{
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this, 300, "stalled-download-timeout",
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R"(
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The timeout (in seconds) for receiving data from servers
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during download. Lix cancels idle downloads after this
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timeout's duration.
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)"};
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Setting<unsigned int> tries{this, 5, "download-attempts",
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"How often Lix will attempt to download a file before giving up."};
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};
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extern FileTransferSettings fileTransferSettings;
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struct FileTransferResult
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{
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bool cached = false;
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std::string etag;
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std::string effectiveUri;
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std::string data;
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/* An "immutable" URL for this resource (i.e. one whose contents
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will never change), as returned by the `Link: <url>;
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rel="immutable"` header. */
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std::optional<std::string> immutableUrl;
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};
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class Store;
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struct FileTransfer
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{
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virtual ~FileTransfer() { }
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/**
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* Enqueues a download request, returning a future for the result of
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* the download. The future may throw a FileTransferError exception.
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*/
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virtual std::future<FileTransferResult>
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enqueueDownload(const std::string & uri, const Headers & headers = {}) = 0;
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/**
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* Upload some data. May throw a FileTransferError exception.
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*/
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virtual std::future<FileTransferResult>
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enqueueUpload(const std::string & uri, std::string data, const Headers & headers = {}) = 0;
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/**
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* Checks whether the given URI exists. For historical reasons this function
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* treats HTTP 403 responses like HTTP 404 responses and returns `false` for
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* both. This was originally done to handle unlistable S3 buckets, which may
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* return 403 (not 404) if the reuqested object doesn't exist in the bucket.
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*
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* ## Bugs
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*
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* S3 objects are downloaded completely to answer this request.
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*/
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virtual bool exists(const std::string & uri, const Headers & headers = {}) = 0;
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/**
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* Download a file, returning its contents through a source. Will not return
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* before the transfer has fully started, ensuring that any errors thrown by
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* the setup phase (e.g. HTTP 404 or similar errors) are not postponed to be
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* thrown by the returned source. The source will only throw errors detected
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* during the transfer itself (decompression errors, connection drops, etc).
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*/
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virtual box_ptr<Source> download(const std::string & uri, const Headers & headers = {}) = 0;
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enum Error { NotFound, Forbidden, Misc, Transient, Interrupted };
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};
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/**
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* @return a shared FileTransfer object.
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*
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* Using this object is preferred because it enables connection reuse
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* and HTTP/2 multiplexing.
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*/
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ref<FileTransfer> getFileTransfer();
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/**
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* @return a new FileTransfer object
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*
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* Prefer getFileTransfer() to this; see its docs for why.
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*/
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ref<FileTransfer> makeFileTransfer(std::optional<unsigned int> baseRetryTimeMs = {});
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class FileTransferError : public Error
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{
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public:
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FileTransfer::Error error;
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/// intentionally optional
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std::optional<std::string> response;
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template<typename... Args>
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FileTransferError(FileTransfer::Error error, std::optional<std::string> response, const Args & ... args);
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};
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}
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