From 069bc15030225393f7d05521505316066464bdbd Mon Sep 17 00:00:00 2001
From: Divy Srivastava <dj.srivastava23@gmail.com>
Date: Tue, 19 Nov 2024 16:49:25 +0530
Subject: feat(ext/node): perf_hooks.monitorEventLoopDelay() (#26905)

Fixes https://github.com/denoland/deno/issues/20961

Depends on https://github.com/denoland/deno_core/pull/965 and
https://github.com/denoland/deno_core/pull/966
---
 ext/node/ops/perf_hooks.rs | 135 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)
 create mode 100644 ext/node/ops/perf_hooks.rs

(limited to 'ext/node/ops/perf_hooks.rs')

diff --git a/ext/node/ops/perf_hooks.rs b/ext/node/ops/perf_hooks.rs
new file mode 100644
index 000000000..636d0b2ad
--- /dev/null
+++ b/ext/node/ops/perf_hooks.rs
@@ -0,0 +1,135 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+use deno_core::op2;
+use deno_core::GarbageCollected;
+
+use std::cell::Cell;
+
+#[derive(Debug, thiserror::Error)]
+pub enum PerfHooksError {
+  #[error(transparent)]
+  TokioEld(#[from] tokio_eld::Error),
+}
+
+pub struct EldHistogram {
+  eld: tokio_eld::EldHistogram<u64>,
+  started: Cell<bool>,
+}
+
+impl GarbageCollected for EldHistogram {}
+
+#[op2]
+impl EldHistogram {
+  // Creates an interval EldHistogram object that samples and reports the event
+  // loop delay over time.
+  //
+  // The delays will be reported in nanoseconds.
+  #[constructor]
+  #[cppgc]
+  pub fn new(#[smi] resolution: u32) -> Result<EldHistogram, PerfHooksError> {
+    Ok(EldHistogram {
+      eld: tokio_eld::EldHistogram::new(resolution as usize)?,
+      started: Cell::new(false),
+    })
+  }
+
+  // Disables the update interval timer.
+  //
+  // Returns true if the timer was stopped, false if it was already stopped.
+  #[fast]
+  fn enable(&self) -> bool {
+    if self.started.get() {
+      return false;
+    }
+
+    self.eld.start();
+    self.started.set(true);
+
+    true
+  }
+
+  // Enables the update interval timer.
+  //
+  // Returns true if the timer was started, false if it was already started.
+  #[fast]
+  fn disable(&self) -> bool {
+    if !self.started.get() {
+      return false;
+    }
+
+    self.eld.stop();
+    self.started.set(false);
+
+    true
+  }
+
+  // Returns the value at the given percentile.
+  //
+  // `percentile` ∈ (0, 100]
+  #[fast]
+  #[number]
+  fn percentile(&self, percentile: f64) -> u64 {
+    self.eld.value_at_percentile(percentile)
+  }
+
+  // Returns the value at the given percentile as a bigint.
+  #[fast]
+  #[bigint]
+  fn percentile_big_int(&self, percentile: f64) -> u64 {
+    self.eld.value_at_percentile(percentile)
+  }
+
+  // The number of samples recorded by the histogram.
+  #[getter]
+  #[number]
+  fn count(&self) -> u64 {
+    self.eld.len()
+  }
+
+  // The number of samples recorded by the histogram as a bigint.
+  #[getter]
+  #[bigint]
+  fn count_big_int(&self) -> u64 {
+    self.eld.len()
+  }
+
+  // The maximum recorded event loop delay.
+  #[getter]
+  #[number]
+  fn max(&self) -> u64 {
+    self.eld.max()
+  }
+
+  // The maximum recorded event loop delay as a bigint.
+  #[getter]
+  #[bigint]
+  fn max_big_int(&self) -> u64 {
+    self.eld.max()
+  }
+
+  // The mean of the recorded event loop delays.
+  #[getter]
+  fn mean(&self) -> f64 {
+    self.eld.mean()
+  }
+
+  // The minimum recorded event loop delay.
+  #[getter]
+  #[number]
+  fn min(&self) -> u64 {
+    self.eld.min()
+  }
+
+  // The minimum recorded event loop delay as a bigint.
+  #[getter]
+  #[bigint]
+  fn min_big_int(&self) -> u64 {
+    self.eld.min()
+  }
+
+  // The standard deviation of the recorded event loop delays.
+  #[getter]
+  fn stddev(&self) -> f64 {
+    self.eld.stdev()
+  }
+}
-- 
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