Struct SubMsTimer 

pub struct SubMsTimer { /* private fields */ }

Autostart stopwatch with named checkpoints. Not thread-safe; use one per task or synchronise externally.

Implementations

impl SubMsTimer

pub fn nanos_now() -> u64

Single source of truth for monotonic-clock reads across the subms harness. Returns nanoseconds since a process-local epoch (snapshotted on first call); meaningful only as a delta against another nanos_now() reading.

Prefer SubMsTimer::tick + SubMsTick::elapsed_ns in hot loops - it’s one fewer atomic load + one fewer arithmetic op because we don’t normalise against the process epoch on each call.

pub fn tick() -> SubMsTick

Snapshot the monotonic clock for the “start tick / do work / read delta” pattern. Recipes use this inside their bench loops instead of std::time::Instant::now(). Cost is identical to a raw Instant::now() (the return is a #[repr(transparent)] wrapper).

pub fn measure_ns<F, T>(f: F) -> (T, u64)

where F: FnOnce() -> T,

Time a closure. Returns the closure result and elapsed nanoseconds. Convenient when the call is on the hot path and the caller doesn’t care about retaining a tick handle.

pub fn unnamed() -> SubMsTimer

Autostart unnamed timer.

pub fn new(name: &str) -> SubMsTimer

Autostart timer with a display name (printed in the header).

pub fn start(&mut self) -> &mut SubMsTimer

Reset to t=0 and clear all checkpoints.

pub fn reset(&mut self) -> &mut SubMsTimer

Alias of start.

pub fn mark(&mut self, label: &str) -> u64

Record a checkpoint with the given label. Returns the elapsed-since-start ns.

pub fn lap(&mut self, label: &str) -> u64

Alias of mark - emphasises “split / next leg” semantics.

pub fn stop(&mut self, label: &str) -> u64

Final checkpoint; the timer stops accumulating after this.

pub fn is_stopped(&self) -> bool

true after stop is called.

pub fn elapsed_ns(&self) -> u64

Elapsed since start. Frozen at stop-time if stopped.

pub fn name(&self) -> &str

pub fn checkpoints(&self) -> &[SubMsTimerCheckpoint]

pub fn print<W>(&self, out: &mut W) -> Result<(), Error>

where W: Write,

Print a fixed-width timeline. Byte-equivalent to Java’s SubMsTimer.print.

Layout:

timer "parse-request"  total=3.2us
  headers-read         +1.1us       1.1us
  body-decoded         +800ns       1.9us
  served *             +1.3us       3.2us