Filtered Search

A predicate in the DenseSearchConfig admits only the keys it approves, while non-matching entries still route the traversal, so recall does not collapse at low selectivity. PredicateArguments.of compiles a Mojo function into the handler, judging a batch of keys per call against a state it reads through a pointer; a usearch_predicate_callback_t compiled in C installs unchanged through the same struct.

def admits_tenant(keys: Span[Key, ImmUntrackedOrigin], admissions: Span[Admission, MutUntrackedOrigin], tenant: UInt64):
    for position in range(len(keys)):
        var owned = keys[position].as_integer().value() >> 32 == tenant
        admissions[position] = Admission.ADMIT if owned else Admission.REJECT

var predicate = PredicateArguments.of[admits_tenant](tenant_slot)
var admitted = index.search(queries, 10, arena, DenseSearchConfig(predicate=predicate))

The predicate runs on the executor’s threads together, so it must be safe for concurrent use. A progress knob on the configs of the long verbs hears how far a call has come, and a handler installed by ProgressArguments.of stops it by answering Continuation.CANCEL. An insertion’s handler reports but never cancels, so an insert batch stays all-or-nothing: every fallible step runs before the first entry is claimed, and a rejected batch publishes no entry. Mojo handlers work on linux-64 in Mojo 1.2; AArch64 and macOS are confirmed by CI.