lix/src/libstore/download.hh
Eelco Dolstra e87e4a60d6
Make HttpBinaryCacheStore::narFromPath() run in constant memory
This reduces memory consumption of

  nix copy --from https://cache.nixos.org --to ~/my-nix /nix/store/95cwv4q54dc6giaqv6q6p4r02ia2km35-blender-2.79

from 176 MiB to 82 MiB. (The remaining memory is probably due to xz
decompression overhead.)

Issue https://github.com/NixOS/nix/issues/1681.
Issue https://github.com/NixOS/nix/issues/1969.
2018-05-30 13:42:29 +02:00

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#pragma once
#include "types.hh"
#include "hash.hh"
#include "globals.hh"
#include <string>
#include <future>
namespace nix {
struct DownloadRequest
{
std::string uri;
std::string expectedETag;
bool verifyTLS = true;
bool head = false;
size_t tries = 5;
unsigned int baseRetryTimeMs = 250;
ActivityId parentAct;
bool decompress = true;
std::shared_ptr<std::string> data;
std::string mimeType;
std::function<void(char *, size_t)> dataCallback;
DownloadRequest(const std::string & uri)
: uri(uri), parentAct(getCurActivity()) { }
};
struct DownloadResult
{
bool cached = false;
std::string etag;
std::string effectiveUrl;
std::shared_ptr<std::string> data;
};
class Store;
struct Downloader
{
/* Enqueue a download request, returning a future to the result of
the download. The future may throw a DownloadError
exception. */
virtual void enqueueDownload(const DownloadRequest & request,
Callback<DownloadResult> callback) = 0;
std::future<DownloadResult> enqueueDownload(const DownloadRequest & request);
/* Synchronously download a file. */
DownloadResult download(const DownloadRequest & request);
/* Download a file, writing its data to a sink. The sink will be
invoked on the thread of the caller. */
void download(DownloadRequest && request, Sink & sink);
/* Check if the specified file is already in ~/.cache/nix/tarballs
and is more recent than tarball-ttl seconds. Otherwise,
use the recorded ETag to verify if the server has a more
recent version, and if so, download it to the Nix store. */
Path downloadCached(ref<Store> store, const string & uri, bool unpack, string name = "",
const Hash & expectedHash = Hash(), string * effectiveUri = nullptr, int ttl = settings.tarballTtl);
enum Error { NotFound, Forbidden, Misc, Transient, Interrupted };
};
/* Return a shared Downloader object. Using this object is preferred
because it enables connection reuse and HTTP/2 multiplexing. */
ref<Downloader> getDownloader();
/* Return a new Downloader object. */
ref<Downloader> makeDownloader();
class DownloadError : public Error
{
public:
Downloader::Error error;
DownloadError(Downloader::Error error, const FormatOrString & fs)
: Error(fs), error(error)
{ }
};
bool isUri(const string & s);
/* Decode data according to the Content-Encoding header. */
ref<std::string> decodeContent(const std::string & encoding, ref<std::string> data);
}