Struct CountersFile

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pub struct CountersFile { /* private fields */ }

Expand description

View over a counters file region. Owns no memory; constructed from a pointer into a shared-memory mapping or a stack buffer (test only).

Implementations§

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impl CountersFile

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pub unsafe fn init(ptr: NonNull<u8>) -> Self

Initialise a freshly-zeroed reserved region as a counters file. Must be called exactly once per segment, by whichever process creates the segment.

§Safety

ptr must point to at least COUNTERS_FILE_RESERVED_BYTES of writable memory that outlives the returned view, and that memory must be zero-initialised before this call.

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pub unsafe fn attach(ptr: NonNull<u8>) -> Result<Self, AttachError>

Attach to an existing counters file region. Validates the magic and version.

§Safety

ptr must point to at least COUNTERS_FILE_RESERVED_BYTES of readable memory whose lifetime contains the returned view. The memory must already have been initialised by a writer.

Header reference.

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pub fn register( &self, id: u32, flags: u32, label: &str, ) -> Option<CounterHandle>

Reserve a new slot, populate id, flags, and label, and return a writer handle. Returns None when the slot capacity is exhausted.

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pub fn boxed() -> OwnedCountersFile

Allocate a fresh, zero-initialised counters file on the heap and initialise it. Returns an OwnedCountersFile that owns the backing buffer alongside the CountersFile view.

Safe alternative to CountersFile::init for single-process use cases (tests, in-process metrics) where the counters file does not need to be shared across processes via SHM or mmap.

The returned OwnedCountersFile derefs to &CountersFile, so all register / snapshot / etc. operations work directly:

use disruptor_mp::observability::CountersFile;
let file = CountersFile::boxed();
let handle = file.register(1, 0, "events_published").unwrap();
handle.inc();
assert_eq!(file.snapshot()[0].value, 1);

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