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use std::time::Duration;
use serde::ser::{Serialize, Serializer};
/// The amount of CPU time between thread samples.
///
/// This is used in the Firefox Profiler UI to draw an activity graph per thread.
///
/// A thread only runs on one CPU at any time, and can get scheduled off and on
/// the CPU between two samples. The CPU delta is the accumulation of time it
/// was running on the CPU.
#[derive(Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash)]
pub struct CpuDelta {
micros: u64,
}
impl From<Duration> for CpuDelta {
fn from(duration: Duration) -> Self {
Self {
micros: duration.as_micros() as u64,
}
}
}
impl CpuDelta {
/// A CPU delta of zero.
pub const ZERO: Self = Self { micros: 0 };
/// Create a CPU delta from integer nanoseconds.
pub fn from_nanos(nanos: u64) -> Self {
Self {
micros: nanos / 1000,
}
}
/// Create a CPU delta from integer microseconds.
pub fn from_micros(micros: u64) -> Self {
Self { micros }
}
/// Create a CPU delta from float milliseconds.
pub fn from_millis(millis: f64) -> Self {
Self {
micros: (millis * 1_000.0) as u64,
}
}
/// Whether the CPU delta is zero.
pub fn is_zero(&self) -> bool {
self.micros == 0
}
}
impl Serialize for CpuDelta {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
// CPU deltas are serialized as float microseconds, because
// we set profile.meta.sampleUnits.threadCPUDelta to "µs".
self.micros.serialize(serializer)
}
}