Struct Capabilities 

#[non_exhaustive]
pub struct Capabilities {
    pub hard_link: bool,
    pub sync_dir: bool,
    pub atomic_rename: bool,
    pub file_lock: bool,
    pub threads: bool,
    pub durable_sync: bool,
}

What a given Env can actually do.

regolith reads this at open and adapts: an environment without hard_link copies bytes for a checkpoint, and one without sync_dir is warned about at open and reported through crate::Db::capabilities rather than being allowed to claim a durability it does not provide.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

hard_link: bool

Env::hard_link creates a real link. false makes checkpoints copy bytes instead.

sync_dir: bool

Env::sync_dir is real. false narrows regolith’s crash guarantee to file contents: a create, rename, or unlink may be lost even though the bytes survived.

atomic_rename: bool

Env::rename over an existing entry is atomic across a crash.

file_lock: bool

Env::lock_file excludes other processes. false does not mean no exclusion at all: every environment regolith ships refuses a second crate::Db on one directory inside one process, and on a single-process target such as wasm that is the whole guarantee. What false says is that a second process is not excluded, so concurrent access from one is undefined.

threads: bool

Env::spawn can create a thread.

durable_sync: bool

WriteFile::sync_all makes bytes durable.

Implementations

impl Capabilities

pub const fn none() -> Self

Nothing available. The starting point for a backend that then declares only what it can genuinely do.

pub const fn posix() -> Self

Everything a POSIX filesystem with threads provides.

pub const fn with_hard_link(self, yes: bool) -> Self

Set Capabilities::hard_link.

pub const fn with_sync_dir(self, yes: bool) -> Self

Set Capabilities::sync_dir.

pub const fn with_atomic_rename(self, yes: bool) -> Self

Set Capabilities::atomic_rename.

pub const fn with_file_lock(self, yes: bool) -> Self

Set Capabilities::file_lock.

pub const fn with_threads(self, yes: bool) -> Self

Set Capabilities::threads.

pub const fn with_durable_sync(self, yes: bool) -> Self

Set Capabilities::durable_sync.

Trait Implementations

impl Clone for Capabilities

fn clone(&self) -> Capabilities

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Capabilities

impl Debug for Capabilities

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Capabilities

impl PartialEq for Capabilities

fn eq(&self, other: &Capabilities) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Capabilities