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Diffstat (limited to 'doc/manual')
| -rw-r--r-- | doc/manual/src/architecture/architecture.md | 1 | ||||
| -rw-r--r-- | doc/manual/src/architecture/store/store.md | 51 |
2 files changed, 48 insertions, 4 deletions
diff --git a/doc/manual/src/architecture/architecture.md b/doc/manual/src/architecture/architecture.md index 8000aecd1..3d17074cc 100644 --- a/doc/manual/src/architecture/architecture.md +++ b/doc/manual/src/architecture/architecture.md @@ -37,7 +37,6 @@ The command line and Nix language are what users interact with most. ::: {.note} The Nix language itself does not have a notion of *packages* or *configurations*. As far as we are concerned here, the inputs and results of a derivation are just data. -In practice this amounts to a set of files in a file system. ::: Underlying these is the [Nix store](./store/store.md), a mechanism to keep track of build plans, data, and references between them. diff --git a/doc/manual/src/architecture/store/store.md b/doc/manual/src/architecture/store/store.md index f421a9ec3..d2d64dd53 100644 --- a/doc/manual/src/architecture/store/store.md +++ b/doc/manual/src/architecture/store/store.md @@ -39,7 +39,7 @@ A reference will always point to exactly one store object. An added store object cannot have references, unless it is a build task. Building a store object will add appropriate references, according to provided build instructions. -These references can only come from declared build inputs, and are not known by build instructions a priori. +These references can only come from declared build inputs, and are not known to build instructions a priori. ```haskell data Data = Data | Task BuildTask @@ -55,14 +55,59 @@ Garbage collection will delete all store objects that cannot be reached from any <!-- more details in section on garbage collection, link to it once it exists --> +## Files and Processes + +Nix provides a mapping between its store model and the [Unix paradigm](https://en.m.wikipedia.org/wiki/Everything_is_a_file) on the interplay of [files and processes](https://en.m.wikipedia.org/wiki/File_descriptor). + +Nix encodes immutable store objects and opaque identifiers as file system primitives: files, directories, and paths. +That allows processes to resolve references contained in files and thus access the contents of store objects. + +``` ++-----------------------------------------------------------------+ +| Nix | +| [ commmand line interface ]------, | +| | | | +| evaluates | | +| | manages | +| V | | +| [ configuration language ] | | +| | | | +| +-----------------------------|-------------------V-----------+ | +| | store evaluates to | | +| | | | | +| | referenced by V builds | | +| | [ build input ] ---> [ build plan ] ---> [ build result ] | | +| | ^ | | | +| +---------|----------------------------------------|----------+ | ++-----------|----------------------------------------|------------+ + | | + file system object store path + | | ++-----------|----------------------------------------|------------+ +| operating system +------------+ | | +| '------------ | | <-----------' | +| | file | | +| ,-- | | <-, | +| | +------------+ | | +| execute as | | read, write, execute | +| | +------------+ | | +| '-> | process | --' | +| +------------+ | ++-----------------------------------------------------------------+ +``` + +Store objects are therefore implemented as the pair of + + - a *file system object* for data + - a set of *store paths* for references. + There exist different types of stores, which all follow this model. Examples: - store on the local file system - remote store accessible via SSH - binary cache store accessible via HTTP -Every store with a file system representation has a *store directory*, which contains that store’s objects accessible through [store paths](paths.md). -The store directory defaults to `/nix/store`, but is in principle arbitrary. +Every store ultimately has to make store objects accessible to processes through the file system. ## A [Rosetta stone][rosetta-stone] for build system terminology |