Struct LocklessRingBuffer 

pub struct LocklessRingBuffer { /* private fields */ }

Implementations

impl LocklessRingBuffer

pub const PAGE_HEADER_SIZE: usize = 16

pub const TYPE_OR_LENGTH_BITS: u32 = 5

The number of low bits of an ftrace record header that hold type_or_length.

pub const TIME_DELTA_BITS: u32 = 27

The number of high bits of an ftrace record header that hold the time delta. A TIME_STAMP record puts the low TIME_DELTA_BITS of its time there.

pub const MAX_TIME_DELTA_NANOS: u64

The largest time delta, in nanoseconds, that a record header holds.

pub const RINGBUF_TYPE_TIME_STAMP: u32 = 31

The type_or_length of a TIME_STAMP record (RINGBUF_TYPE_TIME_STAMP in Linux include/linux/ring_buffer.h).

pub const TIME_STAMP_RECORD_SIZE: usize = 8

The size of a TIME_STAMP record: the header and a u32 with the high bits of the time.

pub fn new( size_bytes: usize, overwrite: bool, write_event_async_id: Id, ) -> Result<Self, Errno>

Creates a new LocklessRingBuffer. size_bytes: Size of the ring buffer. Must be at least PAGE_SIZE * 3 and will be rounded up to a multiple of PAGE_SIZE. overwrite: If true, old pages will be dropped when the ring is full. If false, writes will fail until the data is read. write_event_async_id: The async trace event ID for write events.

impl LocklessRingBuffer

pub fn reserve( &self, size: usize, ) -> Result<(Reservation<'_>, BootInstant, Duration<BootTimeline>), Errno>

Reserves size bytes for a record.

Returns the reservation, the record’s time, and the delta from the previous record (0 for the first record on a page). The delta can exceed what a record header holds; write Reservation::header_time_delta() into the header instead.

pub fn reserve_with_clock( &self, size: usize, current_boot_time: impl Fn() -> BootInstant, ) -> Result<(Reservation<'_>, BootInstant, Duration<BootTimeline>), Errno>

Like reserve(), but reads the current time from current_boot_time, so that tests can control timestamps.

pub fn commit(&self, reservation: Reservation<'_>)

pub fn read(&self, buf: &mut dyn OutputBuffer) -> Result<usize, Errno>

pub fn size_bytes(&self) -> usize

pub fn is_enabled(&self) -> bool

pub fn disable(&self) -> Result<u64, Errno>

pub fn enable(&self) -> Result<BootInstant, Errno>

If the ring is disabled, resets it to empty, enables it, and returns the time of the reset.

If the ring is already enabled, does nothing, so in-flight writers and readers, and the tail_page generation, are unaffected. In that case it returns the time of the last reset, by new() or by an earlier enable().

Trait Implementations

impl Drop for LocklessRingBuffer

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl RcuDroppable for LocklessRingBuffer

where Vmo: RcuDroppable, SharedBuffer: RcuDroppable, Vec<Node>: RcuDroppable, AtomicUsize: RcuDroppable, AtomicTailVal: RcuDroppable, bool: RcuDroppable, AtomicU64: RcuDroppable, Id: RcuDroppable, AtomicBool: RcuDroppable, LockDepMutex<BootInstant, PerfRingBufferStateLock>: RcuDroppable,