nixos/nix
1
1
Fork 0
mirror of https://github.com/NixOS/nix.git synced 2025-12-06 17:11:00 +01:00
Code Activity

Cleanup ContentAddressMethod to match docs

Browse source 
The old `std::variant` is bad because we aren't adding a new case to
`FileIngestionMethod` so much as we are defining a separate concept ---
store object content addressing rather than file system object content
addressing. As such, it is more correct to just create a fresh
enumeration.

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This commit is contained in:
John Ericson 2024-05-16 19:08:28 -04:00
parent 64e599ebe1
commit b51e161af5
25 changed files with 275 additions and 203 deletions
Download patch file Download diff file Expand all files Collapse all files

76
src/libstore/content-address.hh
View file

@ -5,7 +5,6 @@
#include "hash.hh"
#include "path.hh"
#include "file-content-address.hh"
#include "comparator.hh"
#include "variant-wrapper.hh"
namespace nix {
@ -14,24 +13,6 @@ namespace nix {
* Content addressing method
*/
/* We only have one way to hash text with references, so this is a single-value
type, mainly useful with std::variant.
*/
/**
* The single way we can serialize "text" file system objects.
*
* Somewhat obscure, used by \ref Derivation derivations and
* `builtins.toFile` currently.
*
* TextIngestionMethod is identical to FileIngestionMethod::Fixed except that
* the former may not have self-references and is tagged `text:${algo}:${hash}`
* rather than `fixed:${algo}:${hash}`. The contents of the store path are
* ingested and hashed identically, aside from the slightly different tag and
* restriction on self-references.
*/
struct TextIngestionMethod : std::monostate { };
/**
* Compute the prefix to the hash algorithm which indicates how the
* files were ingested.
@ -48,14 +29,51 @@ std::string_view makeFileIngestionPrefix(FileIngestionMethod m);
*/
struct ContentAddressMethod
{
typedef std::variant<
TextIngestionMethod,
FileIngestionMethod
> Raw;
enum struct Raw {
/**
* Calculate a store path using the `FileIngestionMethod::Flat`
* hash of the file system objects, and references.
*
* See `store-object/content-address.md#method-flat` in the
* manual.
*/
Flat,
/**
* Calculate a store path using the
* `FileIngestionMethod::NixArchive` hash of the file system
* objects, and references.
*
* See `store-object/content-address.md#method-flat` in the
* manual.
*/
NixArchive,
/**
* Calculate a store path using the `FileIngestionMethod::Git`
* hash of the file system objects, and references.
*
* Part of `ExperimentalFeature::GitHashing`.
*
* See `store-object/content-address.md#method-git` in the
* manual.
*/
Git,
/**
* Calculate a store path using the `FileIngestionMethod::Flat`
* hash of the file system objects, and references, but in a
* different way than `ContentAddressMethod::Raw::Flat`.
*
* See `store-object/content-address.md#method-text` in the
* manual.
*/
Text,
};
Raw raw;
GENERATE_CMP(ContentAddressMethod, me->raw);
auto operator <=>(const ContentAddressMethod &) const = default;
MAKE_WRAPPER_CONSTRUCTOR(ContentAddressMethod);
@ -141,7 +159,7 @@ struct ContentAddress
*/
Hash hash;
GENERATE_CMP(ContentAddress, me->method, me->hash);
auto operator <=>(const ContentAddress &) const = default;
/**
* Compute the content-addressability assertion
@ -200,7 +218,7 @@ struct StoreReferences
*/
size_t size() const;
GENERATE_CMP(StoreReferences, me->self, me->others);
auto operator <=>(const StoreReferences &) const = default;
};
// This matches the additional info that we need for makeTextPath
@ -217,7 +235,7 @@ struct TextInfo
*/
StorePathSet references;
GENERATE_CMP(TextInfo, me->hash, me->references);
auto operator <=>(const TextInfo &) const = default;
};
struct FixedOutputInfo
@ -237,7 +255,7 @@ struct FixedOutputInfo
*/
StoreReferences references;
GENERATE_CMP(FixedOutputInfo, me->hash, me->references);
auto operator <=>(const FixedOutputInfo &) const = default;
};
/**
@ -254,7 +272,7 @@ struct ContentAddressWithReferences
Raw raw;
GENERATE_CMP(ContentAddressWithReferences, me->raw);
auto operator <=>(const ContentAddressWithReferences &) const = default;
MAKE_WRAPPER_CONSTRUCTOR(ContentAddressWithReferences);