fix page rendering

apparently it is not possible to link to page anchors with `mdBook`[1]

[1]: https://github.com/rust-lang/mdBook/issues/167
This commit is contained in:
Valentin Gagarin 2022-08-04 14:31:33 +02:00
parent cc3a5f4ba2
commit b631742277
5 changed files with 64 additions and 68 deletions

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@ -68,12 +68,8 @@
- [nix.conf](command-ref/conf-file.md) - [nix.conf](command-ref/conf-file.md)
- [Architecture](architecture/architecture.md) - [Architecture](architecture/architecture.md)
- [Store](architecture/store/store.md) - [Store](architecture/store/store.md)
- [Store Object](architecture/store/store.md#store-object) - [Closure](architecture/store/store/closure.md)
- [Reference](architecture/store/store.md#reference) - [Build system terminology](architecture/store/build-system-terminology.md)
- [Operations](architecture/store/store.md#operations)
- [Closure](architecture/store/store.md#closure)
- [Files and Processes](architecture/store/store.md#files-and-processes)
- [Build system terminology](architecture/store/store.md#build-system-terminology)
- [Store Path](architecture/store/path.md) - [Store Path](architecture/store/path.md)
- [Digest](architecture/store/path.md#digest) - [Digest](architecture/store/path.md#digest)
- [Input Addressing](architecture/store/path.md#input-addressing) - [Input Addressing](architecture/store/path.md#input-addressing)

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@ -39,7 +39,7 @@ This means a store path is not just derived from the referenced store object its
It is important which store a given store object belongs to: It is important which store a given store object belongs to:
Files in the store object can contain store paths, and processes may read these paths. Files in the store object can contain store paths, and processes may read these paths.
Nix can only guarantee [referential integrity](store.md#closure) if store paths do not cross store boundaries. Nix can only guarantee [referential integrity](store/closure.md) if store paths do not cross store boundaries.
Therefore one can only copy store objects to a different store if Therefore one can only copy store objects to a different store if

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@ -89,35 +89,6 @@ As it keeps track of references, it can [garbage-collect][garbage-collection] un
[ store ] --> collect garbage --> [ store' ] [ store ] --> collect garbage --> [ store' ]
## Closure {#closure}
Nix stores ensure [referential integrity][referential-integrity]: for each store object in the store, all the store objects it references must also be in the store.
The set of all store objects reachable by following references from a given initial set of store objects is called a *closure*.
Adding, building, copying and deleting store objects must be done in a way that preserves referential integrity:
- A newly added store object cannot have references, unless it is a build task.
- Build results must only refer to store objects in the closure of the build inputs.
Building a store object will add appropriate references, according to the build task.
- Store objects being copied must refer to objects already in the destination store.
Recursive copying must either proceed in dependency order or be atomic.
- We can only safely delete store objects which are not reachable from any reference still in use.
<!-- more details in section on garbage collection, link to it once it exists -->
[referential-integrity]: https://en.m.wikipedia.org/wiki/Referential_integrity
[garbage-collection]: https://en.m.wikipedia.org/wiki/Garbage_collection_(computer_science)
[immutable-object]: https://en.m.wikipedia.org/wiki/Immutable_object
[opaque-data-type]: https://en.m.wikipedia.org/wiki/Opaque_data_type
[unique-identifier]: https://en.m.wikipedia.org/wiki/Unique_identifier
## Files and Processes {#files-and-processes} ## Files and Processes {#files-and-processes}
Nix maps between its store model and the [Unix paradigm][unix-paradigm] of [files and processes][file-descriptor], by encoding immutable store objects and opaque identifiers as file system primitives: files and directories, and paths. Nix maps between its store model and the [Unix paradigm][unix-paradigm] of [files and processes][file-descriptor], by encoding immutable store objects and opaque identifiers as file system primitives: files and directories, and paths.
@ -178,35 +149,3 @@ Examples:
To make store objects accessible to processes, stores ultimately have to expose store objects through the file system. To make store objects accessible to processes, stores ultimately have to expose store objects through the file system.
## A [Rosetta stone][rosetta-stone] for build system terminology {#build-system-terminology}
The Nix store's design is comparable to other build systems.
Usage of terms is, for historic reasons, not entirely consistent within the Nix ecosystem, and still subject to slow change.
The following translation table points out similarities and equivalent terms, to help clarify their meaning and inform consistent use in the future.
| generic build system | Nix | [Bazel][bazel] | [Build Systems à la Carte][bsalc] | programming language |
| -------------------------------- | ---------------- | -------------------------------------------------------------------- | --------------------------------- | ------------------------ |
| data (build input, build result) | store object | [artifact][bazel-artifact] | value | value |
| build instructions | builder | ([depends on action type][bazel-actions]) | function | function |
| build task | derivation | [action][bazel-action] | `Task` | [thunk][thunk] |
| build plan | derivation graph | [action graph][bazel-action-graph], [build graph][bazel-build-graph] | `Tasks` | [call graph][call-graph] |
| build | build | build | application of `Build` | evaluation |
| persistence layer | store | [action cache][bazel-action-cache] | `Store` | heap |
All of these systems share features of [declarative programming][declarative-programming] languages, a key insight first put forward by Eelco Dolstra et al. in [Imposing a Memory Management Discipline on Software Deployment][immdsd] (2004), elaborated in his PhD thesis [The Purely Functional Software Deployment Model][phd-thesis] (2006), and further refined by Andrey Mokhov et al. in [Build Systems à la Carte][bsalc] (2018).
[rosetta-stone]: https://en.m.wikipedia.org/wiki/Rosetta_Stone
[bazel]: https://bazel.build/start/bazel-intro
[bazel-artifact]: https://bazel.build/reference/glossary#artifact
[bazel-actions]: https://docs.bazel.build/versions/main/skylark/lib/actions.html
[bazel-action]: https://bazel.build/reference/glossary#action
[bazel-action-graph]: https://bazel.build/reference/glossary#action-graph
[bazel-build-graph]: https://bazel.build/reference/glossary#build-graph
[bazel-action-cache]: https://bazel.build/reference/glossary#action-cache
[thunk]: https://en.m.wikipedia.org/wiki/Thunk
[call-graph]: https://en.m.wikipedia.org/wiki/Call_graph
[declarative-programming]: https://en.m.wikipedia.org/wiki/Declarative_programming
[immdsd]: https://edolstra.github.io/pubs/immdsd-icse2004-final.pdf
[phd-thesis]: https://edolstra.github.io/pubs/phd-thesis.pdf
[bsalc]: https://www.microsoft.com/en-us/research/uploads/prod/2018/03/build-systems.pdf

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@ -0,0 +1,29 @@
# Closure
Nix stores ensure [referential integrity][referential-integrity]: for each store object in the store, all the store objects it references must also be in the store.
The set of all store objects reachable by following references from a given initial set of store objects is called a *closure*.
Adding, building, copying and deleting store objects must be done in a way that preserves referential integrity:
- A newly added store object cannot have references, unless it is a build task.
- Build results must only refer to store objects in the closure of the build inputs.
Building a store object will add appropriate references, according to the build task.
- Store objects being copied must refer to objects already in the destination store.
Recursive copying must either proceed in dependency order or be atomic.
- We can only safely delete store objects which are not reachable from any reference still in use.
<!-- more details in section on garbage collection, link to it once it exists -->
[referential-integrity]: https://en.m.wikipedia.org/wiki/Referential_integrity
[garbage-collection]: https://en.m.wikipedia.org/wiki/Garbage_collection_(computer_science)
[immutable-object]: https://en.m.wikipedia.org/wiki/Immutable_object
[opaque-data-type]: https://en.m.wikipedia.org/wiki/Opaque_data_type
[unique-identifier]: https://en.m.wikipedia.org/wiki/Unique_identifier

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@ -0,0 +1,32 @@
# A [Rosetta stone][rosetta-stone] for build system terminology {#build-system-terminology}
The Nix store's design is comparable to other build systems.
Usage of terms is, for historic reasons, not entirely consistent within the Nix ecosystem, and still subject to slow change.
The following translation table points out similarities and equivalent terms, to help clarify their meaning and inform consistent use in the future.
| generic build system | Nix | [Bazel][bazel] | [Build Systems à la Carte][bsalc] | programming language |
| -------------------------------- | ---------------- | -------------------------------------------------------------------- | --------------------------------- | ------------------------ |
| data (build input, build result) | store object | [artifact][bazel-artifact] | value | value |
| build instructions | builder | ([depends on action type][bazel-actions]) | function | function |
| build task | derivation | [action][bazel-action] | `Task` | [thunk][thunk] |
| build plan | derivation graph | [action graph][bazel-action-graph], [build graph][bazel-build-graph] | `Tasks` | [call graph][call-graph] |
| build | build | build | application of `Build` | evaluation |
| persistence layer | store | [action cache][bazel-action-cache] | `Store` | heap |
All of these systems share features of [declarative programming][declarative-programming] languages, a key insight first put forward by Eelco Dolstra et al. in [Imposing a Memory Management Discipline on Software Deployment][immdsd] (2004), elaborated in his PhD thesis [The Purely Functional Software Deployment Model][phd-thesis] (2006), and further refined by Andrey Mokhov et al. in [Build Systems à la Carte][bsalc] (2018).
[rosetta-stone]: https://en.m.wikipedia.org/wiki/Rosetta_Stone
[bazel]: https://bazel.build/start/bazel-intro
[bazel-artifact]: https://bazel.build/reference/glossary#artifact
[bazel-actions]: https://docs.bazel.build/versions/main/skylark/lib/actions.html
[bazel-action]: https://bazel.build/reference/glossary#action
[bazel-action-graph]: https://bazel.build/reference/glossary#action-graph
[bazel-build-graph]: https://bazel.build/reference/glossary#build-graph
[bazel-action-cache]: https://bazel.build/reference/glossary#action-cache
[thunk]: https://en.m.wikipedia.org/wiki/Thunk
[call-graph]: https://en.m.wikipedia.org/wiki/Call_graph
[declarative-programming]: https://en.m.wikipedia.org/wiki/Declarative_programming
[immdsd]: https://edolstra.github.io/pubs/immdsd-icse2004-final.pdf
[phd-thesis]: https://edolstra.github.io/pubs/phd-thesis.pdf
[bsalc]: https://www.microsoft.com/en-us/research/uploads/prod/2018/03/build-systems.pdf