Enum WantPolicy 

pub enum WantPolicy {
    AdvertisedTips,
    ReachableFromRefs,
    Any,
}

Which object ids a client is allowed to ask for.

git spells this as three separate uploadpack.allow*SHA1InWant settings, and the middle one is not optional for a server that advertises filter: a partial clone’s lazy fetch asks for bare blob ids that were never advertised, so WantPolicy::AdvertisedTips turns every git checkout in a blob:none clone into “the remote end hung up unexpectedly”.

Variants

AdvertisedTips

Only ids that appeared in the advertisement.

The strictest setting, and the one that breaks partial clone.

ReachableFromRefs

Anything reachable from a reference. This is git’s uploadpack.allowReachableSHA1InWant, and the default here.

The cost is honest and real: proving reachability means walking the repository’s whole object closure once per request that names a non-tip id. The git package’s __gunnar_reach__ bitmaps are what make this cheap; until they exist, this walk is the price of partial clone.

Any

Anything present in the store, reachable or not.

Makes every object that was ever pushed fetchable by whoever can name it, including on branches that have since been deleted.

Implementations

impl WantPolicy

pub fn advertises(self, promise: WantPolicy) -> bool

Does this policy make good on a capability row that requires promise?

Why the answer is a match and not a >=

The three variants happen to be orderable, and encoding that as an ordering would make adding a fourth silently inherit whichever neighbours it landed between. Written out, a new variant does not compile until someone decides what it promises — which is the property that was missing, not the ordering.

The mapping is git’s, bit for bit: ALLOW_TIP_SHA1 prints allow-tip-sha1-in-want, ALLOW_REACHABLE_SHA1 prints allow-reachable-sha1-in-want, and ALLOW_ANY_SHA1 is both bits set, so it prints both (upload-pack.c, send_ref).

WantPolicy::AdvertisedTips promises nothing, on purpose: gunnar hides no reference, so “only ids in the advertisement” is exactly what a v0 client assumes when neither capability is present.

Trait Implementations

impl Clone for WantPolicy

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for WantPolicy

impl Debug for WantPolicy

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

Formats the value using the given formatter.

impl Default for WantPolicy

fn default() -> Self

Returns the “default value” for a type.

impl Eq for WantPolicy

impl PartialEq for WantPolicy

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for WantPolicy