forked from lix-project/lix
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
parent
cc3a5f4ba2
commit
b631742277
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@ -68,12 +68,8 @@
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- [nix.conf](command-ref/conf-file.md)
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- [nix.conf](command-ref/conf-file.md)
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- [Architecture](architecture/architecture.md)
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- [Architecture](architecture/architecture.md)
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- [Store](architecture/store/store.md)
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- [Store](architecture/store/store.md)
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- [Store Object](architecture/store/store.md#store-object)
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- [Closure](architecture/store/store/closure.md)
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- [Reference](architecture/store/store.md#reference)
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- [Build system terminology](architecture/store/build-system-terminology.md)
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- [Operations](architecture/store/store.md#operations)
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- [Closure](architecture/store/store.md#closure)
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- [Files and Processes](architecture/store/store.md#files-and-processes)
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- [Build system terminology](architecture/store/store.md#build-system-terminology)
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- [Store Path](architecture/store/path.md)
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- [Store Path](architecture/store/path.md)
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- [Digest](architecture/store/path.md#digest)
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- [Digest](architecture/store/path.md#digest)
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- [Input Addressing](architecture/store/path.md#input-addressing)
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- [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
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It is important which store a given store object belongs to:
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It is important which store a given store object belongs to:
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Files in the store object can contain store paths, and processes may read these paths.
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Files in the store object can contain store paths, and processes may read these paths.
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Nix can only guarantee [referential integrity](store.md#closure) if store paths do not cross store boundaries.
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Nix can only guarantee [referential integrity](store/closure.md) if store paths do not cross store boundaries.
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Therefore one can only copy store objects to a different store if
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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
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[ store ] --> collect garbage --> [ store' ]
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[ store ] --> collect garbage --> [ store' ]
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## Closure {#closure}
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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.
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The set of all store objects reachable by following references from a given initial set of store objects is called a *closure*.
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Adding, building, copying and deleting store objects must be done in a way that preserves referential integrity:
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- A newly added store object cannot have references, unless it is a build task.
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- Build results must only refer to store objects in the closure of the build inputs.
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Building a store object will add appropriate references, according to the build task.
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- Store objects being copied must refer to objects already in the destination store.
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Recursive copying must either proceed in dependency order or be atomic.
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- We can only safely delete store objects which are not reachable from any reference still in use.
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<!-- more details in section on garbage collection, link to it once it exists -->
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[referential-integrity]: https://en.m.wikipedia.org/wiki/Referential_integrity
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[garbage-collection]: https://en.m.wikipedia.org/wiki/Garbage_collection_(computer_science)
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[immutable-object]: https://en.m.wikipedia.org/wiki/Immutable_object
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[opaque-data-type]: https://en.m.wikipedia.org/wiki/Opaque_data_type
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[unique-identifier]: https://en.m.wikipedia.org/wiki/Unique_identifier
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## Files and Processes {#files-and-processes}
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## Files and Processes {#files-and-processes}
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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.
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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.
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@ -178,35 +149,3 @@ Examples:
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To make store objects accessible to processes, stores ultimately have to expose store objects through the file system.
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To make store objects accessible to processes, stores ultimately have to expose store objects through the file system.
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## A [Rosetta stone][rosetta-stone] for build system terminology {#build-system-terminology}
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The Nix store's design is comparable to other build systems.
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Usage of terms is, for historic reasons, not entirely consistent within the Nix ecosystem, and still subject to slow change.
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The following translation table points out similarities and equivalent terms, to help clarify their meaning and inform consistent use in the future.
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| generic build system | Nix | [Bazel][bazel] | [Build Systems à la Carte][bsalc] | programming language |
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| -------------------------------- | ---------------- | -------------------------------------------------------------------- | --------------------------------- | ------------------------ |
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| data (build input, build result) | store object | [artifact][bazel-artifact] | value | value |
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| build instructions | builder | ([depends on action type][bazel-actions]) | function | function |
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| build task | derivation | [action][bazel-action] | `Task` | [thunk][thunk] |
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| build plan | derivation graph | [action graph][bazel-action-graph], [build graph][bazel-build-graph] | `Tasks` | [call graph][call-graph] |
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| build | build | build | application of `Build` | evaluation |
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| persistence layer | store | [action cache][bazel-action-cache] | `Store` | heap |
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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).
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[rosetta-stone]: https://en.m.wikipedia.org/wiki/Rosetta_Stone
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[bazel]: https://bazel.build/start/bazel-intro
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[bazel-artifact]: https://bazel.build/reference/glossary#artifact
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[bazel-actions]: https://docs.bazel.build/versions/main/skylark/lib/actions.html
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[bazel-action]: https://bazel.build/reference/glossary#action
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[bazel-action-graph]: https://bazel.build/reference/glossary#action-graph
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[bazel-build-graph]: https://bazel.build/reference/glossary#build-graph
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[bazel-action-cache]: https://bazel.build/reference/glossary#action-cache
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[thunk]: https://en.m.wikipedia.org/wiki/Thunk
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[call-graph]: https://en.m.wikipedia.org/wiki/Call_graph
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[declarative-programming]: https://en.m.wikipedia.org/wiki/Declarative_programming
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[immdsd]: https://edolstra.github.io/pubs/immdsd-icse2004-final.pdf
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[phd-thesis]: https://edolstra.github.io/pubs/phd-thesis.pdf
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[bsalc]: https://www.microsoft.com/en-us/research/uploads/prod/2018/03/build-systems.pdf
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29
doc/manual/src/architecture/store/store/closure.md
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29
doc/manual/src/architecture/store/store/closure.md
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# Closure
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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.
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The set of all store objects reachable by following references from a given initial set of store objects is called a *closure*.
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Adding, building, copying and deleting store objects must be done in a way that preserves referential integrity:
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- A newly added store object cannot have references, unless it is a build task.
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- Build results must only refer to store objects in the closure of the build inputs.
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Building a store object will add appropriate references, according to the build task.
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- Store objects being copied must refer to objects already in the destination store.
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Recursive copying must either proceed in dependency order or be atomic.
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- We can only safely delete store objects which are not reachable from any reference still in use.
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<!-- more details in section on garbage collection, link to it once it exists -->
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[referential-integrity]: https://en.m.wikipedia.org/wiki/Referential_integrity
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[garbage-collection]: https://en.m.wikipedia.org/wiki/Garbage_collection_(computer_science)
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[immutable-object]: https://en.m.wikipedia.org/wiki/Immutable_object
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[opaque-data-type]: https://en.m.wikipedia.org/wiki/Opaque_data_type
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[unique-identifier]: https://en.m.wikipedia.org/wiki/Unique_identifier
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32
doc/manual/src/architecture/store/store/terminology.md
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32
doc/manual/src/architecture/store/store/terminology.md
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@ -0,0 +1,32 @@
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# A [Rosetta stone][rosetta-stone] for build system terminology {#build-system-terminology}
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The Nix store's design is comparable to other build systems.
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Usage of terms is, for historic reasons, not entirely consistent within the Nix ecosystem, and still subject to slow change.
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The following translation table points out similarities and equivalent terms, to help clarify their meaning and inform consistent use in the future.
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| generic build system | Nix | [Bazel][bazel] | [Build Systems à la Carte][bsalc] | programming language |
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| -------------------------------- | ---------------- | -------------------------------------------------------------------- | --------------------------------- | ------------------------ |
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| data (build input, build result) | store object | [artifact][bazel-artifact] | value | value |
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| build instructions | builder | ([depends on action type][bazel-actions]) | function | function |
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| build task | derivation | [action][bazel-action] | `Task` | [thunk][thunk] |
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| build plan | derivation graph | [action graph][bazel-action-graph], [build graph][bazel-build-graph] | `Tasks` | [call graph][call-graph] |
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| build | build | build | application of `Build` | evaluation |
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| persistence layer | store | [action cache][bazel-action-cache] | `Store` | heap |
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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).
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[rosetta-stone]: https://en.m.wikipedia.org/wiki/Rosetta_Stone
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[bazel]: https://bazel.build/start/bazel-intro
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[bazel-artifact]: https://bazel.build/reference/glossary#artifact
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[bazel-actions]: https://docs.bazel.build/versions/main/skylark/lib/actions.html
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[bazel-action]: https://bazel.build/reference/glossary#action
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[bazel-action-graph]: https://bazel.build/reference/glossary#action-graph
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[bazel-build-graph]: https://bazel.build/reference/glossary#build-graph
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[bazel-action-cache]: https://bazel.build/reference/glossary#action-cache
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[thunk]: https://en.m.wikipedia.org/wiki/Thunk
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[call-graph]: https://en.m.wikipedia.org/wiki/Call_graph
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[declarative-programming]: https://en.m.wikipedia.org/wiki/Declarative_programming
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[immdsd]: https://edolstra.github.io/pubs/immdsd-icse2004-final.pdf
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[phd-thesis]: https://edolstra.github.io/pubs/phd-thesis.pdf
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[bsalc]: https://www.microsoft.com/en-us/research/uploads/prod/2018/03/build-systems.pdf
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