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These describe the castore data model, so it should live in the castore crate. Also, some minor edits to //tvix/store/docs/api.md, to honor the move of the castore bits to tvix-castore. Change-Id: I1836556b652ac0592336eac95a8d0647599f4aec Reviewed-on: https://cl.tvl.fyi/c/depot/+/9893 Autosubmit: flokli <flokli@flokli.de> Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
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Data model
This provides some more notes on the fields used in castore.proto.
See //tvix/store/docs/api.md for the full context.
Directory message
Directory messages use the blake3 hash of their canonical protobuf
serialization as its identifier.
A Directory message contains three lists, directories, files and
symlinks, holding DirectoryNode, FileNode and SymlinkNode messages
respectively. They describe all the direct child elements that are contained in
a directory.
All three message types have a name field, specifying the (base)name of the
element (which MUST not contain slashes or null bytes, and MUST not be '.' or '..').
For reproducibility reasons, the lists MUST be sorted by that name and also
MUST be unique across all three lists.
In addition to the name field, the various *Node messages have the following
fields:
DirectoryNode
A DirectoryNode message represents a child directory.
It has a digest field, which points to the identifier of another Directory
message, making a Directory a merkle tree (or strictly speaking, a graph, as
two elements pointing to a child directory with the same contents would point
to the same Directory message.
There's also a size field, containing the (total) number of all child
elements in the referenced Directory, which helps for inode calculation.
FileNode
A FileNode message represents a child (regular) file.
Its digest field contains the blake3 hash of the file contents. It can be
looked up in the BlobService.
The size field contains the size of the blob the digest field refers to.
The executable field specifies whether the file should be marked as
executable or not.
SymlinkNode
A SymlinkNode message represents a child symlink.
In addition to the name field, the only additional field is the target,
which is a string containing the target of the symlink.