Migrate OTel/dogstatsd common functions to src/common

This commit is in preparation for more extensive changes to the OTel metrics
payload. I have scooted common configuration and string selection functions up
into the crate common sub-tree.

REF SMPTNG-659

Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>

Author: blt

lading_payload/src/common.rs

@@ -1 +1,2 @@
+pub(crate) mod config;
 pub(crate) mod strings;

lading_payload/src/common/config.rs

@@ -0,0 +1,67 @@
+use rand::distr::uniform::SampleUniform;
+use serde::{Deserialize, Serialize as SerdeSerialize};
+use std::cmp;
+
+/// Range expression for configuration
+#[derive(Debug, Deserialize, SerdeSerialize, Clone, PartialEq, Copy)]
+#[serde(deny_unknown_fields)]
+#[serde(rename_all = "snake_case")]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+
+pub enum ConfRange<T>
+where
+    T: PartialEq + cmp::PartialOrd + Clone + Copy,
+{
+    /// A constant T
+    Constant(T),
+    /// In which a T is chosen between `min` and `max`, inclusive of `max`.
+    Inclusive {
+        /// The minimum of the range.
+        min: T,
+        /// The maximum of the range.
+        max: T,
+    },
+}
+
+impl<T> ConfRange<T>
+where
+    T: PartialEq + cmp::PartialOrd + Clone + Copy,
+{
+    /// Returns true if the range provided by the user is valid, false
+    /// otherwise.
+    pub(crate) fn valid(&self) -> (bool, &'static str) {
+        match self {
+            Self::Constant(_) => (true, ""),
+            Self::Inclusive { min, max } => (min < max, "min must be less than max"),
+        }
+    }
+
+    pub(crate) fn start(&self) -> T {
+        match self {
+            ConfRange::Constant(c) => *c,
+            ConfRange::Inclusive { min, .. } => *min,
+        }
+    }
+
+    pub(crate) fn end(&self) -> T {
+        match self {
+            ConfRange::Constant(c) => *c,
+            ConfRange::Inclusive { max, .. } => *max,
+        }
+    }
+}
+
+impl<T> ConfRange<T>
+where
+    T: PartialEq + cmp::PartialOrd + Clone + Copy + SampleUniform,
+{
+    pub(crate) fn sample<R>(&self, rng: &mut R) -> T
+    where
+        R: rand::Rng + ?Sized,
+    {
+        match self {
+            ConfRange::Constant(c) => *c,
+            ConfRange::Inclusive { min, max } => rng.random_range(*min..=*max),
+        }
+    }
+}

lading_payload/src/common/strings.rs

@@ -1,9 +1,9 @@
 //! Code for the quick creation of randomize strings
 
+use crate::common::config::ConfRange;
+use rand::{Rng, distr::uniform::SampleUniform, seq::IndexedRandom};
 use std::ops::Range;
 
-use rand::distr::uniform::SampleUniform;
-
 const ALPHANUM: &[u8] = b"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
 /// A pool of strings
@@ -131,6 +131,70 @@ impl Pool {
     }
 }
 
+pub(crate) fn choose_or_not_ref<'a, R, T>(mut rng: &mut R, pool: &'a [T]) -> Option<&'a T>
+where
+    R: rand::Rng + ?Sized,
+{
+    if rng.random() {
+        pool.choose(&mut rng)
+    } else {
+        None
+    }
+}
+
+pub(crate) fn choose_or_not_fn<R, T, F>(rng: &mut R, func: F) -> Option<T>
+where
+    T: Clone,
+    R: rand::Rng + ?Sized,
+    F: FnOnce(&mut R) -> Option<T>,
+{
+    if rng.random() { func(rng) } else { None }
+}
+
+#[inline]
+/// Generate a total number of strings randomly chosen from the range `min_max` with a maximum length
+/// per string of `max_length`.
+pub(crate) fn random_strings_with_length<R>(
+    pool: &Pool,
+    min_max: Range<usize>,
+    max_length: u16,
+    rng: &mut R,
+) -> Vec<String>
+where
+    R: Rng + ?Sized,
+{
+    let total = rng.random_range(min_max);
+    let length_range = ConfRange::Inclusive {
+        min: 1,
+        max: max_length,
+    };
+
+    random_strings_with_length_range(pool, total, length_range, rng)
+}
+
+#[inline]
+/// Generate a `total` number of strings with a maximum length per string of
+/// `max_length`.
+pub(crate) fn random_strings_with_length_range<R>(
+    pool: &Pool,
+    total: usize,
+    length_range: ConfRange<u16>,
+    mut rng: &mut R,
+) -> Vec<String>
+where
+    R: Rng + ?Sized,
+{
+    let mut buf = Vec::with_capacity(total);
+    for _ in 0..total {
+        let sz = length_range.sample(&mut rng) as usize;
+        buf.push(String::from(
+            pool.of_size(&mut rng, sz)
+                .expect("failed to generate string"),
+        ));
+    }
+    buf
+}
+
 #[cfg(test)]
 mod test {
     use proptest::prelude::*;

lading_payload/src/dogstatsd.rs

@@ -1,17 +1,19 @@
 //! `DogStatsD` payload.
 
-use std::{cmp, fmt, io::Write, ops::Range, rc::Rc};
+use std::{fmt, io::Write, rc::Rc};
 
-use rand::{
-    Rng,
-    distr::{uniform::SampleUniform, weighted::WeightedIndex},
-    prelude::Distribution,
-    seq::IndexedRandom,
-};
+use rand::{Rng, distr::weighted::WeightedIndex, prelude::Distribution};
 use serde::{Deserialize, Serialize as SerdeSerialize};
 use tracing::{debug, warn};
 
-use crate::{Serialize, common::strings};
+use crate::{
+    Serialize,
+    common::{
+        config::ConfRange,
+        strings,
+        strings::{random_strings_with_length, random_strings_with_length_range},
+    },
+};
 
 use self::{
     common::tags, event::EventGenerator, metric::MetricGenerator,
@@ -144,69 +146,6 @@ impl Default for ValueConf {
         }
     }
 }
-/// Range expression for configuration
-#[derive(Debug, Deserialize, SerdeSerialize, Clone, PartialEq, Copy)]
-#[serde(deny_unknown_fields)]
-#[serde(rename_all = "snake_case")]
-#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
-
-pub enum ConfRange<T>
-where
-    T: PartialEq + cmp::PartialOrd + Clone + Copy,
-{
-    /// A constant T
-    Constant(T),
-    /// In which a T is chosen between `min` and `max`, inclusive of `max`.
-    Inclusive {
-        /// The minimum of the range.
-        min: T,
-        /// The maximum of the range.
-        max: T,
-    },
-}
-
-impl<T> ConfRange<T>
-where
-    T: PartialEq + cmp::PartialOrd + Clone + Copy,
-{
-    /// Returns true if the range provided by the user is valid, false
-    /// otherwise.
-    fn valid(&self) -> (bool, &'static str) {
-        match self {
-            Self::Constant(_) => (true, ""),
-            Self::Inclusive { min, max } => (min < max, "min must be less than max"),
-        }
-    }
-
-    fn start(&self) -> T {
-        match self {
-            ConfRange::Constant(c) => *c,
-            ConfRange::Inclusive { min, .. } => *min,
-        }
-    }
-
-    fn end(&self) -> T {
-        match self {
-            ConfRange::Constant(c) => *c,
-            ConfRange::Inclusive { max, .. } => *max,
-        }
-    }
-}
-
-impl<T> ConfRange<T>
-where
-    T: PartialEq + cmp::PartialOrd + Clone + Copy + SampleUniform,
-{
-    fn sample<R>(&self, rng: &mut R) -> T
-    where
-        R: rand::Rng + ?Sized,
-    {
-        match self {
-            ConfRange::Constant(c) => *c,
-            ConfRange::Inclusive { min, max } => rng.random_range(*min..=*max),
-        }
-    }
-}
 
 /// Configure the `DogStatsD` payload.
 #[derive(Debug, Deserialize, SerdeSerialize, Clone, PartialEq, Copy)]
@@ -359,70 +298,6 @@ impl Config {
     }
 }
 
-fn choose_or_not_ref<'a, R, T>(mut rng: &mut R, pool: &'a [T]) -> Option<&'a T>
-where
-    R: rand::Rng + ?Sized,
-{
-    if rng.random() {
-        pool.choose(&mut rng)
-    } else {
-        None
-    }
-}
-
-fn choose_or_not_fn<R, T, F>(rng: &mut R, func: F) -> Option<T>
-where
-    T: Clone,
-    R: rand::Rng + ?Sized,
-    F: FnOnce(&mut R) -> Option<T>,
-{
-    if rng.random() { func(rng) } else { None }
-}
-
-#[inline]
-/// Generate a total number of strings randomly chosen from the range `min_max` with a maximum length
-/// per string of `max_length`.
-fn random_strings_with_length<R>(
-    pool: &strings::Pool,
-    min_max: Range<usize>,
-    max_length: u16,
-    rng: &mut R,
-) -> Vec<String>
-where
-    R: Rng + ?Sized,
-{
-    let total = rng.random_range(min_max);
-    let length_range = ConfRange::Inclusive {
-        min: 1,
-        max: max_length,
-    };
-
-    random_strings_with_length_range(pool, total, length_range, rng)
-}
-
-#[inline]
-/// Generate a `total` number of strings with a maximum length per string of
-/// `max_length`.
-fn random_strings_with_length_range<R>(
-    pool: &strings::Pool,
-    total: usize,
-    length_range: ConfRange<u16>,
-    mut rng: &mut R,
-) -> Vec<String>
-where
-    R: Rng + ?Sized,
-{
-    let mut buf = Vec::with_capacity(total);
-    for _ in 0..total {
-        let sz = length_range.sample(&mut rng) as usize;
-        buf.push(String::from(
-            pool.of_size(&mut rng, sz)
-                .expect("failed to generate string"),
-        ));
-    }
-    buf
-}
-
 #[derive(Debug, Clone)]
 struct MemberGenerator {
     kind_weights: WeightedIndex<u16>,

lading_payload/src/dogstatsd/event.rs

@@ -5,7 +5,9 @@ use rand::{Rng, distr::StandardUniform, prelude::Distribution};
 
 use crate::{Error, Generator, common::strings};
 
-use super::{ConfRange, choose_or_not_fn, common};
+use self::strings::choose_or_not_fn;
+
+use super::{ConfRange, common};
 
 #[derive(Debug, Clone)]
 pub(crate) struct EventGenerator {

lading_payload/src/dogstatsd/metric.rs

@@ -11,8 +11,10 @@ use rand::{
 use crate::{Error, Generator, common::strings, dogstatsd::metric::template::Template};
 use tracing::debug;
 
+use self::strings::choose_or_not_ref;
+
 use super::{
-    ConfRange, ValueConf, choose_or_not_ref,
+    ConfRange, ValueConf,
     common::{self, NumValueGenerator},
 };
 

lading_payload/src/dogstatsd/service_check.rs

@@ -3,12 +3,9 @@ use std::fmt;
 
 use rand::{Rng, distr::StandardUniform, prelude::Distribution, seq::IndexedRandom};
 
-use crate::{Error, Generator};
+use crate::{Error, Generator, common::strings::choose_or_not_ref};
 
-use super::{
-    choose_or_not_ref,
-    common::{self, tags::Tagset},
-};
+use super::common::{self, tags::Tagset};
 
 #[derive(Debug, Clone)]
 pub(crate) struct ServiceCheckGenerator {